Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: GODO on August 23, 2004, 12:18:04 PM
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When you jaw left of right, the body of the aircraft (the side surface and the rudder itself) acts as an airbrake and the aircraft slows down losing energy. When you turn left or right the brake effect comes mostly from the upper surface of the aircraft and the elevators.
Assuming this is true, planes with large upper surfaces (wings and body) should lose energy quicker than smaller planes, all that being still above stall speed, that is, still having extra lift to keep flying.
But what we see is that small planes like 190s or 109s lose E much faster than much larger ones like P51s or Spits when turning well above stall speeds.
I understand than large winged planes with smaller wingloading will keep turning tighter and at slower speed than small planes with more wingload, but the small ones should lose speed at a lower rate and the others until they reach stall speeds.
Where am I wrong?
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Assuming this is true, planes with large upper surfaces (wings and body) should lose energy quicker than smaller planes, all that being still above stall speed, that is, still having extra lift to keep flying.
This is an incorect assumption.
Planes with more wing area, also need a smaller AOA to produce the same turn rate. High wingloaded planes also suffer from more induced drag in most conditions do to the higher LCO needed for turns.
Also in your basic premiss about more side area on a plane when in a yaw condition, you are not looking at the force generated to produce a turn. And it does not neascarly follow that more side area would produce more drag in a slip. You also need to consider what the slip angle is.
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Mandoble:
HT beat me to it already :). Size or surface area is only a single factor. You're forgetting the contribution that induced drag plays into the equation which impacts higher wing-loaded aircraft more vs. lower wing-loaded aircraft in a relative turn performance / energy-bleed comparison.
Tango, XO
412th FS Braunco Mustangs
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Originally posted by hitech
Planes with more wing area, also need a smaller AOA to produce the same turn rate.
Certainly they will need smaller AOA for same turn rate but is that more E-consuming than the brake effect of the upper large surface? With the higher AOA a small part of the front and lower surface is generating more drag, but the whole upper side (wing and body) is the one displacing more quantity of air and probably, generating more drag? Or is the opposite?
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I forgot to say. Im assuming both pilots are tightening the turn from a hi/medium speed as fast as possible pulling hard the stick for some seconds, not just substaning the same turn circle. This just what we do when scissoring, for example or when breaking hard left of right, not just turning in circles over and over.
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You need to stop thinking it about area shown foward, to begin to understand the relationship between drag/weight/lift and turn radius you will need to understand the basic lift & drag equations. Then start looking at it from what happens in a given situation. It is not somthing that can be easly visulized.
HiTech
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hitech,
Im refering to instantaneous (or short) turns, not just substained turns, sorry, I didnt clarify this well in my first post. In a substained turn where you keep turn rate, what I described as "brake effect" of the upper surface may be secondary and minimal (you are not tightering the turn very fast). But when you pull hard on the stick for few seconds things are probably different. This is the case where the wing area are really displacing a big ammount of air in a short time, in this last case I see the wings as the real big brakes (you are increasing AOA very fast, not just substaining a determined AOA).
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Definitions of instantainious and sustained have nothing to do with AOA.
The amount of drag produced will be higher for the for higher wingloaded plane given the same speed, and same turn radius. The effect will be more pronouced the hard you pull on the stick.
What you seem to be missing is that the lower wing loaded plane dosn't need to pull as hard, to turn with the higher wingloaded plane.
HiTech
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This is the case where the wing area are really displacing a big ammount of air in a short time, in this last case I see the wings as the real big brakes
Mandoble: You're assuming that wings have significant boundary layer separation that occur to increase profile/pressure drag while in a hard turn and that the larger the wing the more drag you would have. This doesn't happen because the wing would not be flying since massive boundary layer separation occurs at post stall. The URL below gives you a picture of this:
http://www.centennialofflight.gov/essay/Theories_of_Flight/Two_dimensional_coef/TH14G4.htm (http://www.centennialofflight.gov/essay/Theories_of_Flight/Two_dimensional_coef/TH14G4.htm)
Lift-dependent profile drag increase does occur as you increase AOA but it's contribution to the total drag of the aircraft is in addition to the induced drag (a signficant contributor to drag in a turn) of the aircraft as well.
Tango, XO
412th FS Braunco Mustangs
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Very clear link dtango, that was what I was pointing, the larger the wing, the larger the turbulent wake producing larger pressure drag. That is the effect that should be present when you perform violent scissors, you increase the AOA as much as possible without stalling (avobe maximum lift), keep the turn for very few seconds (now reducing the AOA) and then repeat in the opposite direction. This is also what happens in a hard break turn (may be you only turn 45 degrees but probably past the stall angle, losing lift and aproaching the stall).
As the drawings show, the turbulent wake affects all the upper surface of the wing (supposedly, the larger the wing, the larger the effect for the similar AOA). Now the question is how this affects the speed of the plane.
IMO, the example playing with rudders is similar. Full rudder right and your nose starts pointing right, but not your flight path initially, similar as increasing your AOA. The larger the lateral surface of the plane and the larger the lose of speed. Keeping full right rudder further and the flight path and the nose angle difference starts to decrease, as well as the "brake" effect.
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Hi Mandoble:
I'm afraid you're missing the point I was trying to make :).
Firstly- massive boundary layer separation occurs AFTER the stall not before.
2ndly - a higher wing-loaded aircraft will be at an higher aoa to match turn performance of a lower wing loaded aircraft therefore any pressure drag caused by some separation will affect it more than the lower wing loaded aircraft.
3rdly - surface area of the wing doesn't play a part in boundary layer separation. The shape / camber of the wing does.
4thly - not pictured here is the affect of induced drag which the higher wing-loaded aircraft will pay a higher penalty for. On top of that shorter wingspan increases the amount of induced drag as well.
Tango, XO
412th FS Braunco Mustangs
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Guys:
Does not the Chord and even spanloading twist into this?
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dtango,
I'm not talking about plane A trying to match the turn of plane B, but doing a similar movement, just imagine both reaching similar AOA and keeping it for few seconds.
Lets suppose a 190 is bounced by a 262 and breaks hard to the left to negate guns solution. In that case, the defender just turned few degrees while keeping a very high AOA. But in the process a noticeable amount of speed was lost. Now the bounced is a P51, it breaks hard also with very high AOA but the decrease of speed was not so noticeable.
In these examples, both planes increased AOA very fast well above the needed to keep a substained turn and probably reaching similar distance between separation points in the wings. But the turbulent wake generated by the P51 will affect a larger section of the wing area.
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Hi Mandoble:
Critical aoa for a specific aircraft is the same no matter the type of turn. You can't have an aoa above what is needed for a sustained turn because the maximum aoa for a sustained turn is the same as that for an instantaneous turn.
Comparing aoa in a turn of a 190 vs. P-51 is comparing apples and oranges. The example you've given doesn't mean much unless you have specific data spelled out you're working with - flight config, conditions, specific type of plane, alt, speeds etc.
You're "greater wing surface equals more drag" theory is ignoring the aerodynamics. The condition you're thinking about primarily exists after the wing is stalled and no longer flying.
Tango, XO
412th FS Braunc Mustangs
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Mandoble: IF you are asking which has more drag in a stalled condition. Note this is not turning but falling, Then in most cases I would say the bigger wing does.
You also seem to have a missunderstanding of what AOA is, just simply because you use statments like rapidly increasing AOA. And turns little but keeps a High AOA.
For this discusion just think of AOA as how far you are holding the stick back.
HiTech
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Removing all the "techno-babble" a plane with higher wingloading has to "work harder" than a plane with lower wing loading to achieve the same result under the conditions you describe. So the more efficient wing will get a bigger return for each unit measure of energy expended. Basically the "gas milage" of the wings is significantly different. Your confusing size and design. Each wing was designed to maximize results under different variables...(at least thats what I come to boiling all this stuff into english)
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Originally posted by hitech
For this discusion just think of AOA as how far you are holding the stick back.
Correct, and is in that "violent" pull of the stick where I find the noticeable initial lose of speed. Then the speed lose rate seems to stabilize. What I mean is that this initial violent pull of the stick seems to affect more to the small winged planes. I understand that this movement may end in an earlier stall for the smallwinged planes while the lose of speed would be more noticeable in the large-winged ones.
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Just the act of turning in ANY A/C under G's bleeds tremendous amounts of Energy over the Potential Energy the plane had flying straight and level.
Crumpp
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I understand that this movement may end in an earlier stall for the smallwinged planes while the lose of speed would be more noticeable in the large-winged ones.
Mandoble: Think about the statement you just made- "...earlier stall for a small-winged planes...".
What does the "earlier stall" mean? It means high aoa = very high induced drag + some rise in pressure drag due to increased boundary layer separation (as pictured). All this means significant bleed in speed for the "small-winged plane".
This means that aerodynamics is in contradiction with the rest of your statement "...while the lose of speed would be more noticeable in large-winged ones.".
Tango, XO
412th FS Braunco Mustangs
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dtango, lets use a contemporary example, Su27 and Cobra manouvre. It suddenly gains great AOA just pulling the stick violently and chopping throttle, the wings and body of the plane act like a big airbrake and the plane almost stops in the air pointing up. Being the Flanker smaller (smaller wings and body), the "brake" effect would be less noticeable. Now, at a much minor scale, that should be present also with WW2 planes.
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Here's a simplified way to look at it.
Plane A weighs 9000 lbs and has a wing loading of 40 lbs/ sq. ft.
Plane B weighs 9000 lbs and has a wing loading of 30 lbs/ sq. ft.
Assume they have a similar wing design, just a different area.
Both are traveling the same speed and make a sharp turn, pulling the same G force. They weigh the same, and so they have to produce the same amount of lift to turn at the same G. Plane A's wing has to work harder - pull higher AoA - to produce the necessary lift to turn at the same G.
Now parasite drag is basically unaffected - the aircrafts shape hasn't changed (assuming no flaps are in use etc.).
What does increase is induced drag. Think of induced drag as the rearward component of lift - the higher AoA you use the more you will create. In normal flight at 0 Aoa the lift vector of the wing is exactly perpendicular to the direction of travel of the airframe, and so all the lift of the wing goes towards lifting the plane. But as you increase the angle of attack to increase lift, the wing is tilted back from the direction of travel. Now part of the lifting force created by the wing is acting against your forward motion! This is induced drag.
In our example with plane A and B, Plane A is producing more induced drag turning at the same G force as plane B because it is having to pull a higher AoA.
In the real world it gets more complicated because different wing designs produce differing levels of lift at different angles of attack. So wing loading doesn't tell the whole story. And if a plane has a big power advantage it can partially overcome the drag it is creating. But generally the worse turning plane will bleed more E pulling the same G from the same speed as a better turning plane.
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Mandoble:
The cobra maneuver is a specialized case but it is not an example of dumping E not because of the size of the wing but because of improvements in aerodynamics to achieve greater AOA without departing flight - in the neighborhood Cl of 2.5. The canards and thrust vectoring of the Su27 has a lot to do with this - not the size of it's wings acting like airbrakes.
Tango, XO
412th FS Braunco Mustangs
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Sable, Isnt that drag a function of AOA and also of the wing area? can we assume that in your example both planes can suffer from similar inducted drag, one because higher AOA and the other because higher wing area while lower AOA?
dtango, basic Su27 performing Cobra doesnt has neither canards nor thrust vectoring.
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Actually,
The Lower wingloaded plane DOES produce more drag. For induced drag it depends on the Aspect ratio and the wip tip efficiency factor.
Lift-to-Drag = Low Wingloading = MORE REFERENCE AREA = more drag.
The drag coefficient Cd is equal to the drag D divided by the quantity: density r times half the velocity V squared times the reference area A.
http://www.grc.nasa.gov/WWW/K-12/airplane/dragco.html
http://www.av8n.com/how/htm/aoa.html#sec-weight-drag-speed
Induced drag greatly depends on the ASPECT RATIO and WING TIP "e" factor. More so on the AR (bigger number) than the "e" factor (usually 1 or less).
Low Wingloading = More lift = More induced drag
http://www.grc.nasa.gov/WWW/K-12/airplane/induced.html
http://www.av8n.com/how/htm/airfoils.html#sec-induced-drag
Instantaneous turn is NOT sustained turn. A low wingloaded plane usually has a great sustained turn rate but that has nothing to with cornering speed and instantaneous turn. In fact most (not all) low-wingloaded planes have low instantaneous turn speeds and are crappy high speed turners. Just look at the Zeke.
Doubling the Velocity Quadruples the Force = ALL the Force = DRAG and LIFT.
http://www.grc.nasa.gov/WWW/K-12/airplane/momntm.html
Crumpp
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This is another factor that having a low aspect ratio hurts.
Downwash
http://www.grc.nasa.gov/WWW/K-12/airplane/downwash.html
Crumpp
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Low Wingloading = More lift = More induced drag
err... no.
A plane will produce the same needed lift in order to fly level reguardless of wingloading.
Lowering the wingload (say increase size) will result in less induced drag when flying level.
Bozon
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GODO, as far as induced drag, the lower wingloaded plane is going to make less for the same G (assuming all else is identical).
As far as parasite drag (the form drag that all airplanes experience), yes having more surface area hurts you - however this parasite drag is only varying based on speed or configuration changes (lower landing gear etc). Turning in and off itself doesn't change parasite drag.
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There is a lot of confusion here. Just listen to HT, he knows of which he speaks. Got me thinking about one my my favorite hobbies though.
Check out http://www.reeseproductions.com/mpegs.html
Look at the dynamic soaring videos. Now THAT is draining energy in turns.
g00b
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err... no.
errr -yes.
Induced drag is a function of Aspect ratio and wing tip efficiency.
Lower wingloading produces a higher Cl too.
Lowering the wingload (say increase size) will result in less induced drag when flying level.
Lower wingloading will make up for it in increased Drag. Not induced drag which is totally seperate. Drag is a function of AREA. To be a low wingloading plane usually means more surface AREA. Induced drag is reduced with speed. HOWEVER, Drag quadruples with velocity.
Crumpp
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As far as parasite drag (the form drag that all airplanes experience), yes having more surface area hurts you - however this parasite drag is only varying based on speed or configuration changes (lower landing gear etc). Turning in and off itself doesn't change parasite drag.
Yes, IF you make a 1 G turn. Pull any G's and your drag increases in proportion to the Force/Area and that force is quadrupled with velocity. Hence you put the brakes on in a turn.
Crumpp
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Originally posted by Crumpp
Actually,
The Lower wingloaded plane DOES produce more drag. For induced drag it depends on the Aspect ratio and the wip tip efficiency factor.
Lift-to-Drag = Low Wingloading = MORE REFERENCE AREA = more drag.
Reference area is used in calculating parasite drag, and isn't part of any formula for induced drag. It isn't even a real value in most cases until the modern era as it is just too hard to determine the actual surface area of a complex object like an airplane when all you have is a tape measure and a slide rule.
Induced drag greatly depends on the ASPECT RATIO and WING TIP "e" factor. More so on the AR (bigger number) than the "e" factor (usually 1 or less).
Low Wingloading = More lift = More induced drag
[/b]
Well I agree with the first part of this - Aspect Ratio and E factor are important.
But Low Wingloading doesn't mean more lift. Guess how much lift a 9000 lbs plane has to create to pull 2 Gs? 18,000 lbs! Doesn't matter whether it has the wings off a 747, or off a dodo. Either way the same lift has to be produced to pull 2 Gs.
Here's a formula for lift:
CL x 1/2 rho V^2 x S (wing area)
Here's a formula for induced drag:
CL^2 / (Aspect Ratio x E factor) x 1/2 rho V^2 x S
that is
Coefficient of lift squared divided by Aspect Ratio times E factor time 1/2 rho (density of the air) times Velocity squared times wing area
Now look at that. Supposing our two hypothetical aircraft are producing the same amount of lift from the first formula (both pulling 2 Gs for instance). Now since the low wingloaded plane has a larger value for S, and 1/2 rho V ^2 is the same for both, then the higher wing loaded plane has a higher CL to reach the same lift. This is illustrating that the higher wingloaded plane is pulling a higher angle of attack to achieve the same total lift.
Now if we go to calculate the induced drag notice that wing area (S) is still only counted once, but now CL is squared! That means that a higher CL is going to disporportionally increase the result vs. the trade off for a high S value. Again this is assuming Aspect Ratio and E factor are the same.
So all else being equal, the lower wingloading is going to produce less induced drag.
Instantaneous turn is NOT sustained turn. A low wingloaded plane usually has a great sustained turn rate but that has nothing to with cornering speed and instantaneous turn. In fact most (not all) low-wingloaded planes have low instantaneous turn speeds and are crappy high speed turners. Just look at the Zeke.
Doubling the Velocity Quadruples the Force = ALL the Force = DRAG and LIFT.
[/B]
Actually the formulas for lift and induced drag don't care about instantaneous vs. sustained. And the fact that a certain plane with a low wing loading has a poor ability to turn at high airspeed has nothing to do with it's wing loading. The zeke sucks at high speed turns for two reasons.
1. At 300mph for instance, the stick forces are so high that you can no longer pull the same number of G's as something like a P-51. That's because of it's elevator and stick design. If you gave it hydraulic elevator boost (and wore a G-suit) you could probably rip it's wings off with the amount of G's you could pull.
2. It loses speed like crazy in a hard turn at high speed. This is because at 300mph on the deck a Zeke is near it's maximum velocity! All of it's power is being used up overcoming parasite drag, so there is almost none available to overcome the addition of the induced drag from the turn. The P-51 is making a lot more induced drag, but it has a ton of excess power at 300mph to help balance that.
Now all my discussion earlier was ignoring Aspect Ratio and E factor. A high aspect ratio is good for reducing induced drag, and a taper wing giving you a high E factor is also good.
Comparing the P-51 and the Fw190 Godo mentioned earlier, they have nearly identical aspect ratios (6 for the 190, vs. 5.9 for the P-51). Their wings have very similar taper, and fairly similar squared wingtips so their E factor is probably pretty close to even. The two big differences between them are the P-51's lower wingloading, and much higher top speed (meaning it has much more excess power at higher speeds) as compared to a Fw190A-8. As a result, the P-51 bleeds less E performing the same high speed, high G turn.
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Originally posted by Crumpp
errr -yes.
Induced drag is a function of Aspect ratio and wing tip efficiency.
Lower wingloading produces a higher Cl too.
Lower wingloading will make up for it in increased Drag. Not induced drag which is totally seperate. Drag is a function of AREA. To be a low wingloading plane usually means more surface AREA. Induced drag is reduced with speed. HOWEVER, Drag quadruples with velocity.
Crumpp
No a lower wing loading doesn't change the Cl. Cl is independent of wing loading, and varies based on angle of attack. Like I just put in my previous post, a lower wingloaded plane has a lower Cl value at a given amount of lift.
And the mistake you are making is assuming that Parasite drag (form and pressure drag) are impacted by angle of attack. As the author of that AV8N site says the coefficient of parasite drag is essentially constant in relation to angle of attack. He even has a chart of it right here. (http://www.av8n.com/how/htm/4forces.html#fig-coeff-alpha)
The coefficient of parasite drag only just starts to increase before you reach a stall. Induced drag however increases dramatically with AoA. That's why the lower wingloaded aircraft bleeds less E - it's pulling less AoA for a given turn!
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Mandoble:
Regardless, the Su27 cobra maneuver isn't dependent upon some notion that a larger wing becomes an airbrake absent any other sophisticated engine, aerodynamic, and flight control systems.
The high AOA and high Cl are functions of aerodynamic improvements and thrust available combined with nifty flight control systems to keep the Su27 from departing flight.
It is not relevant to lift-dependent profile drag discussions as it relates to WW2 aircraft because the Su-27 super-maneuver would be outside the envelope of capable flight for WW2 fighters.
Your idea that there is some increase in profile drag in a turn is not incorrect. The problem is that it's contribution is not as substantial compared to the impact of induced drag on the aircraft. 2ndly the change in profile drag with aoa is not dependent on the size of the wings.
There's some oversimplification in my statements but it's not worth the trouble to try and explain the details.
Tango, XO
412th FS Braunco Mustangs
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Crumpp:
I'm sorry buddy. You don't seem to know what you're talking about and are really confusing the issue.
Tango, XO
412th FS Braunco Mustangs
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Seems to be alot of confusion on exactly what difference between a coefficient and a force and what is effected by what.
http://www.av8n.com/how/htm/4forces.html#fig-coeff-alpha
http://www.av8n.com/how/htm/4forces.html#fig-coeff-ias
http://www.av8n.com/how/htm/4forces.html#fig-power-ias
http://www.av8n.com/how/htm/4forces.html#fig-force-ias
If you conduct a LEVEL turn then you are cashing in your LEVEL Speed to maintain ALTITUDE. Hence you are cashing in your energy NOT gaining it.
Here is what is going on in a turn:
http://www.av8n.com/how/htm/4forces.html#sec-defer-forces
Which does NOT havemuch in common with High G steep break turns we seen pulled in AH.
Now lets look at a steep turn:
Imagine that you are initially trimmed for straight and level flight at, say, 100 knots. Then you inadvertently enter a steeply banked turn. Figure 6.12 shows the forces acting on the plane in level flight and in the turn. Let’s imagine that the plane weighs exactly one ton. In level flight the downward force of gravity is exactly canceled by the lift produced by the wings, so the wings must be producing one ton of lift. In the turn, though, the wings must produce enough force not only to support the weight of the airplane (vertically), but also to change the airplane’s direction of motion (horizontally). The total force can be quite large: In a 60° turn, two tons of force is required. In a 75° turn, almost four tons of force is required, as shown in figure 6.13.
http://www.av8n.com/how/htm/aoastab.html#sec-spiral-dive
So far it looks pretty close to what your saying. We can bank sharply and suddenly increase our SPEED!!! Coooooollll!!
Wait?? Aren't we creating energy?? NO, Here is why! It ONLY appears we are making a level Turn. In fact we have lost lots of ALTITUDE.
http://www.av8n.com/how/htm/vdamp.html#sec-vertical-damping
We see that the vertical component of lift is insufficient to balance the weight of the airplane. (Compare this figure with figure 6.12 or figure 6.13.) The unbalanced force will cause the airplane to drop straight down. This is the same as the “albatross effect” discussed in section 5.2. Then, as soon as any appreciable downward velocity develops, the airplane will pitch down and speed up --- because the airplane wants to maintain its trimmed angle of attack11 as discussed in section 6.1.
Well now we have traded altitude for Airspeed just to bank. If we maintain altitude then we trade speed for altitude again.
Energy can niether be created nor destroyed. You cannot perform a steep bank turn and not trade energy for altitude in one form or another.
In a turn a plane needs a MUCH higher Cl to maintain the turn. It gets this by angle of attack AND by dropping the nose to gain speed. It wants to speed up. However if you drop the nose then you are exchanging altitude for Airspeed. Hence you are cashing in your Energy NOT gaining it.
If you conduct a LEVEL turn then you are cashing in your LEVEL Speed to maintain ALTITUDE. Hence you are cashing in your energy NOT gaining it.
It is either maintain your altitude and lose your speed.
Or
It is lose altitude and gain speed.
Can't do both, Physics won't allow it.
Crumpp
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And the mistake you are making is assuming that Parasite drag (form and pressure drag) are impacted by angle of attack.
Looks like it goes up to me.
http://www.av8n.com/how/htm/4forces.html#fig-coeff-alpha
The problem is that it's contribution is not as substantial compared to the impact of induced drag on the aircraft.
Since an A/C has to gain speed by cashing in level speed or altitude in a steep bank I would say your wrong.
Force of drag goes up.
In a steep bank lower wingloaded A/C do not bleed less Energy. Lower Wingloaded A/C burn more Energy at speed due to parasitic drag.
http://www.av8n.com/how/htm/4forces.html#fig-force-ias
Crumpp
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Originally posted by Crumpp
Looks like it goes up to me.
http://www.av8n.com/how/htm/4forces.html#fig-coeff-alpha
Since an A/C has to gain speed by cashing in level speed or altitude in a steep bank I would say your wrong.
You do realise that the point where it starts to rise is right around the critical angle of attack for most airfoils? That means that as the wing is stalling the parasite drag starts to increase as a results of angle of attack. But we aren't talking about stalls, we're talking about energy loss in high speed turns.
And why does the aircraft need to accelerate? We are talking about deceleration as a result of turning at high speed.
Force of drag goes up.
In a steep bank lower wingloaded A/C do not bleed less Energy. Lower Wingloaded A/C burn more Energy at speed due to parasitic drag.
Crumpp [/B]
Yes the force of parasite drag goes up with airspeed. So what? We all know this. That's why airplanes have a top speed. And you are wrong about lower wingloaded A/C burning more energy at speed. As I will show below parasitic drag doesn't change meaningfully in any turn that isn't right at a stall (and when it does increase, it inevitably affects the higher winloaded plane first as it will stall first at a given speed and load factor).
The original question was: why do some planes bleed energy faster in a high speed turn then others? Lets go over this scenario again.
Plane A: FW190A8 - higher wingloading, lower max speed
Plane B: P-51D - lower wingloading, higher max speed
Otherwise their wings and weights are pretty similar.
Both are at 50ft, traveling 350mph. They both make a 3g turn.
Which one is going to bleed airspeed faster?
First: how much lift are they producing?
Lift = CL x 1/2 rho V^2 x S
Since the weight is similar, and they are pulling the same load factor, they are both making right around the same lift so we can say: Lift (P-51) = Lift (Fw190)
Now the P-51 has a larger wing area (S) so in order for the values to be equal the Fw-190 needs a higher CL (since they are going the same speed in the same density of air 1/2 rho V^2 is the same for both sides of the equation). The 190 pilot provides this higher CL by pulling a little more angle of attack too achieve his 3G turn.
Next: How much drag is being created by this extra lift?
Induced drag = CL^2 / (Aspect Ratio x E Factor) x 1/2 rho V^2 x S
Note that CL (the FW's value is higher) is getting weighted heavier then S (the P-51s value is higher) since it is squared in the induced drag formula. So that means that the Fw190's induced drag is going to be higher assuming Aspect Ratio and E factor are the same (and as I pointed out in my previous post, they are pretty similar with these two aircraft). So we know that the Fw190 is creating more induced drag in this turn. Now what about parasite drag?
Parasite drag = CL x 1/2 rho V^2 x A
Now from the link here (http://www.av8n.com/how/htm/4forces.html#fig-coeff-alpha) we can see that CL isn't going to change with angle of attack for either aircraft. We aren't stalling so we aren't getting close to the 15-17 degree critical angle of attack where CL just starts to increase (and even if we were the increase would still be very small). Neither aircraft has started decelerating yet so 1/2 rho V^2 is still equal. And now we come to A, or the reference area.
Now the reference area isn't an exact measurement of the surface area of the aircraft ... like I said earlier that would be nearly impossible for anything but a modern supercomputer. It's a guesstimate that is established at the same time as the CD from wind tunnel testing. Here's a quote from "The Illustrated Guide to Aerodynamics" by HC Skip Smith:
"The customary procedure for bluff bodies (such as the fueselage, nacelle, or landing gear), is to use the projected frontal area, or maximum cross section. For thin profile bodies, such as the wing or tail surfaces, the planform (top view) area is normally used."
As you can see the reference area has nothing to do with the orientation of the object, the CD is what would reflect changes to that, and as we can see from the link above it doesn't change meaningfully until after we've stalled the airfoil.
So parasite drag is unchanged at the moment we start the turn.
Finally: Total Drag vs. Excess Power
So now we can see that the Fw190's induced drag increased more then the P-51's and parasite drag was unchanged. Just by that alone, we can see the Fw190 is going to decelerate faster. Now consider Excess Power. At 350mph at 50ft the Fw190 is at Vmax - it can't go any faster under it's own power. Any manuever that requires more power then it has will result in immediate deceleration. The P-51 on the other hand is still about 17mph below it's Vmax - it still has excess power to be used to accelerate, or climb, or overcome additional drag from turning. So not only did the P-51 create less drag turning, it also has more power available to try and counter this additional drag. Also consider that as load factor increases the higher wing loaded plane will eventually reach it's critical AoA (where the parasite drag that Crumpp mentions actualy starts to have some effect) before the low wing loaded aircraft. So that is why an Fw190 bleeds more E then a P-51 in a high speed turn.
And before someone asks: Why does the Spitfire bleed so little E even though it's a fairly slow plane and doesn't have the excess power advantage of the P-51?
Because the Spitfire's wing loading is much lower, it's Aspect ratio is higher then either aircraft mentioned, and the E Factor of the elliptical wing is REALLY good.
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Originally posted by Crumpp
Since an A/C has to gain speed by cashing in level speed or altitude in a steep bank I would say your wrong.
Force of drag goes up.
In a steep bank lower wingloaded A/C do not bleed less Energy. Lower Wingloaded A/C burn more Energy at speed due to parasitic drag.
completly wrong from a to z.
I don't even know where to begin, the in-sentence contradiction, the wrong physics or the wrong aerodynamics.
Bozon
edit:
this much is true, but not necessarily:
Lower Wingloaded A/C burn more Energy at speed due to parasitic drag.
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The original question was: why do some planes bleed energy faster in a high speed turn then others? Lets go over this scenario again.
I understood the original question.
What I want to know is how can some planes in AH make 90 degree banks in a lag turn, and still have energy to spare??
They cannot.
completly wrong from a to z.
And why does the aircraft need to accelerate? We are talking about deceleration as a result of turning at high speed.
really?
It's right here.
Imagine that you are initially trimmed for straight and level flight at, say, 100 knots. Then you inadvertently enter a steeply banked turn. Figure 6.12 shows the forces acting on the plane in level flight and in the turn. Let’s imagine that the plane weighs exactly one ton. In level flight the downward force of gravity is exactly canceled by the lift produced by the wings, so the wings must be producing one ton of lift. In the turn, though, the wings must produce enough force not only to support the weight of the airplane (vertically), but also to change the airplane’s direction of motion (horizontally). The total force can be quite large: In a 60° turn, two tons of force is required. In a 75° turn, almost four tons of force is required, as shown in figure 6.13.
We see that the vertical component of lift is insufficient to balance the weight of the airplane. (Compare this figure with figure 6.12 or figure 6.13.) The unbalanced force will cause the airplane to drop straight down. This is the same as the “albatross effect” discussed in section 5.2. Then, as soon as any appreciable downward velocity develops, the airplane will pitch down and speed up --- because the airplane wants to maintain its trimmed angle of attack11 as discussed in section 6.1.
http://www.av8n.com/how/htm/aoastab.html#sec-spiral-overview
Now check out what speed does to drag:
http://www.av8n.com/how/htm/4forces.html#fig-force-ias
Consquently the amount of energy dissipation goes up:
http://www.av8n.com/how/htm/4forces.html#fig-power-ias
You do realise that the point where it starts to rise is right around the critical angle of attack for most airfoils?
Yes I realize that. You said this:
As the author of that AV8N site says the coefficient of parasite drag is essentially constant in relation to angle of attack.
It goes up before the stall.
http://www.av8n.com/how/htm/4forces.html#fig-coeff-alpha
Good explaination Sable. Now how do you explain the FW-190A had the same turn radius as the P51B? In the tactical trial the P51B had a "slight" advantage in the turn with the FW-190 test pilot admitting he could no get maximum turn performance.
An FW-190A8 outturned a P51D.
The info is down at the bottom.
http://www.anycities.com/user/j22/j22/aero.htm
This is who did it.
http://www.anycities.com/user/j22/j22/lednicer.htm
This is where he works:
http://www.am-inc.com/
Guess he has one of those supercomputers.
Crumpp
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Crumpp,
His Mustang Cdo is to high.
Also his turn rate data seems strange. How can he show sustained turn rate being equal to instantanious? The best they should be is equal IMHO.
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So all else being equal, the lower wingloading is going to produce less induced drag. sable
I think this is an accepted truism in aviation engineering/design. tons of actual flight test data exist for all the planes modeled here. The horse died along time ago guys....
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Also his turn rate data seems strange. How can he show sustained turn rate being equal to instantanious? The best they should be is equal IMHO.
Here is the chart explained:
Instantaneous turn performance is in direct proportion to the wing loading. Lower wing loading equals better instantaneous turn. Sustained turn performance is a combination of Wing loading and power loading. Best sustained turn performance is with a low wing loading and a low power loading. I have not taken stick force gradients and stability into consideration here.
His Mustang Cdo is to high.
I would trust his numbers until someone more qualified comes along. Given the mans background as an aeronautical engineer and his access to much more powerful fluid dynamics computations than anyone is capable of making here. This data was written for an article in Sport Aviation Magazine. Not for some flight sim.
Cd is a very salamanderly problem to calculate.
The drag coefficient contains not only the complex dependencies of object shape and inclination, but also the effects of air viscosity and compressibility.
http://www.grc.nasa.gov/WWW/K-12/airplane/dragco.html
http://www.grc.nasa.gov/WWW/K-12/airplane/airsim.html
And very importantly you have to know the reference area.
This is also why Lower wingloaded A/C generally speaking produce MORE DRAG (not induced drag which is a different animal). More Surface = More Drag
I think this is an accepted truism in aviation engineering/design. tons of actual flight test data exist for all the planes modeled here. The horse died along time ago guys....
Doubling the area doubles the drag.
http://www.grc.nasa.gov/WWW/K-12/airplane/sized.html
You need access to engineering fluid dynamics to even come close.
The Only guys calculations in this whole thing that matter though are HTC's.
The turn sable so nicely calculated is NOT the same dynamics as a steep turn. No, A lower wing loaded plane could pull gentle 1 G turns all day long and not lose much E. Crank it over 90 degrees and pull G's in the turn and EVERY A/C is burning Energy. You will and should wind up with Less Energy than you started the turn with.
Oversimplifying here so don't jump to your calculators. :rolleyes: Low Wing loaded or High wing loaded, they all pay the piper in one form or another. Because of the speed increase in a sharp bank, parasitic drag increases and the Low Wing loaded planes pay the price. Low speed maneuvering High Wing loaded = higher induced drag = crappy sustained turn rate and they pay the price.
Crumpp
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Crump, there is no such thing as a 1g turn.
There is no such thing as a 90 deg turn.
The term Turn generaly is taken to generaly meen holding a constant altitude.
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Crump, there is no such thing as a 1g turn.
There is a gentle low G bank as opposed to a steep high G bank.
Crumpp
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http://www.av8n.com/how/htm/4forces.html#sec-defer-forces
http://www.av8n.com/how/htm/aoastab.html#fig-spiral-start
Crumpp
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I would trust his numbers until someone more qualified comes along. Given the mans background as an aeronautical engineer and his access to much more powerful fluid dynamics computations than anyone is capable of making here. This data was written for an article in Sport Aviation Magazine. Not for some flight sim.
Well funny you should say that. Because I don't trust the word of a guy who writes for sports aviation magazines more than I do the engineers at Vought or North American.
I received this document from the Vought archives and scanned it. It shows the P-51B Cdo at .017.
(http://mywebpages.comcast.net/markw4/alliedchrts1.jpg)
Also in his instantious turn data he shows no weights for the A/C. Without weight you don't know wing loading or power loading so how can you compare?
Also the chart does not show the speed that the G force can be pulled. I assume by the Mustangs approx 2.5 that the speed is around 150MPH but without weight I can't tell what conditions the other A/C are in. Also the P-51D and B have the same intantanious turn rate. This is wrong because the D was heavier empty than the B.
To much assumption in his artical.
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You don't see the whole article, bro. It's just exerpts.
Be VERY careful with Co-efficients.
Here is what a NASA Engineer says about Co-efficients:
-----------------------------------------------------------------------------------
Hey XXXX,
The lift coefficient equation (and the whole idea of lift coefficients)
works for both 2D and 3D. The idea was developed many years ago .. before the Wright brothers. In fact, lift coefficients were defined a little bit differently in the days of the Wright brothers than they are today:
http://wright.nasa.gov/airplane/liftold.html
http://wright.nasa.gov/airplane/lifteq.html
but the idea is the same: we relate the lift force to some other known or measurable force, with the lift coefficient just being a factor .. a ratio ..between the lift and some known or measurable force. In the old days, before computers, people would measure the lift of an object .. and knowing the reference force, would generate tables or graphs of lift coefficients for all kinds of shapes, sizes, designs .. etc. The measurements were made on
models in wind tunnels .. and then applied to full scale airplane designs.
As computers came along, we figured out how to calculate the flow around a shape to get the lift coefficient. It's obviously easier to calculate a 2D shape than a 3D shape .. but the idea works for either one. Now, equally obvious .. the value of the lift coefficient for a 2D shape is different
than the value for a 3D wing. So an engineer has to be very careful when using lift coefficients. You have to find out how the particular value was generated (2D or 3D model) .. and there some other aerodynamics effects (like boundary layers and shock waves) which can effect the value as well. You can only apply the lift coefficient to a real case which is similar to how the original model was tested. Check out:
http://www.grc.nasa.gov/WWW/K-12/airplane/airsim.html
for some more details.
Tom
------------------------------------------------------------------------------------
Cdo is even more squirrelly. The theories change and so do the formulas. Without knowing what formula, theory, reference area, etc...
That Cdo is useless and could very well be the same thing as what the more modern Aeronautical engineer calculated just using a different scale.
Crumpp
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He does not list the P51B's drag. The P51D's Cdo is alot lower on his calculations. I would say he is using a different formula.
Crumpp
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Hiya F4UDOA:
I'm not sure where the perf. numbers on the J22 site come from though. My impression is Mr. Lednicer does know what he's talking about. I have several of David Lednicer's papers (very technical) including the one being mentioned. It (nor the others) doesn't have any reference to turn performance numbers so I can only assume the author of the J22 page calculated those figures. I agree that the numbers look funny especially in the case of the 190D-9 instantaneous vs. sustained turn.
The CD0 values for the Mustang come from revisiting how wetted surface area used for parasite drag is calculated.
Now crumpp on the other hand - bless his soul, I'm afraid that the more he states about aerodynamics the more I scratch my head! I don't even know where to start to try and help him "see the light".
Crumpp:
It's simple really. Try doing some comparative calculations of total drag for different aircraft in a given turn and see what you come up with. It's pretty clear. Maybe you'll see it then.
Tango, XO
412th FS Braunco Mustangs
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Comparative calculations are easy to do assuming that the the wing area is the referance area and standard conditions.
As an example we can easily do a quick and dirty comparison between calculated high speed Cd0 of the P-51B, Fw 190A and Spitfire IX at the altitude where we know the exact speed and the engine output.
First we collect a little bit of data:
P-51B => 679 km/h at 4755 m, the first FTH (USAAF test data)
Fw 190A => 537 km/h at sea level (US NAVY test data)
Spitfire IX => 603 km/h at 2896 m, the first FTH (average A&AEE test data)
Then thrust assuming 85% propeller efficiency and 120 kp exhaust thrust:
P-51B (V-1650-3 at 67") => 1600 hp => 6553 N
Fw 190A (1,42 ata 2700 rpm) => 1740 ps => 8470 N
Spitfire IX (Merlin 66 +18lbs) => 1705 hp => 7624 N
Because the thrust equals drag at steady speed, the total drag for the flat plate area with Cd=1 is easy to calculate:
P-51B => 0,381 m2
Fw 190A => 0,486 m2
Spitfire IX => 0,443 m2
Now we can calculate Cd for the reference area:
P-51B => 21,78 m2 => Cd=0,0175 (mach 0,59)
Fw 190A => 18,3 m2 => Cd=0,0265
Spitfire IX => 22,48m2 => Cd=0,0205
Then we just calculate Cdi, E factors are purely approximated:
P-51B => 4128 kg AR=5,87 E=0,75 => Cdi=0,00139
Fw 190 => 3942 kg AR=6,02 E=0,8 => Cdi=0,00159
Spitfire IX => 3395 kg AR=5,61 E=0,9 => Cdi=0,00083
Because Cd=Cd0+Cdi, the Cd0 values are easy to solve:
P-51B => Cd0=0,0161
Fw 190 => Cd0=0,0249
Spitfire IX => Cd0=0,0197 (mach 0,51)
In the end we can calculate flat plate area for the Cd0 with the reference area:
P-51B => 0,350 m2 = 3,772 sqft
Fw-190A => 0,456 m2 = 4,913 sqft
Spitfire IX => 0,433 m2 = 4,764 sqft
We can also do a little comparison with the test data below.
gripen
(http://personal.inet.fi/koti/soon.moro/drag.jpg)
(http://personal.inet.fi/koti/soon.moro/Spit+drag+2.jpg)
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I would love to get a copy of the full article.
Now crumpp on the other hand - bless his soul, I'm afraid that the more he states about aerodynamics the more I scratch my head! I don't even know where to start to try and help him "see the light".
See the Light on what?
That Airplanes should be able to make steep banks and pull high G's all day?
That High Speed turn radius in NOT a function of Wingloading but rather LIFT LOADING??
Ask a fighter pilot what that does for you.
In fact Shaw talks about "load factor" killing speed in a turn citing it is one of the most important things a fighter has to control if he going to turn.
Pulling G's causes a huge rise in your Drag profile. If you look at the Drag formula it uses AREA not the wieght, the AREA of the surface. More Area = More Drag
http://www.grc.nasa.gov/WWW/K-12/airplane/sized.html
http://www.grc.nasa.gov/WWW/K-12/airplane/dragco.html
Page 408 "Fighter Combat" reads:
"As a Load factor is increased at a given Airspeed, turn performance improves but total drag increases. Eventually a load factor is reached in which the entire thrust of the engine is needed to just to offset this drag"
In AH we have some planes that can "break turn" all day long and actually seem to gain energy in the turn.
I have seen planes conduct a tight high angle bank 180 degree LAG turn at the merge. Then watched them zoom up ABOVE a heavier fighter that pulled a 25 degree zoom at the merge. All on fighter did was pull up!
Now an Aircraft that just conducted a tight bank will need to bleed some of the energy he had to gain when altitude was lost. That will be spent regaining to the same or slightly lower altitude he was at in the begining of the turn.
Nobody is saying that a High wingloaded plane should outturn a low wingloaded in the sustained turn realm or anything silly.
Simply saying there is a price to pay for pulling G's that All A/C have to pay. Low wingloaded A/C have more surface therefore more drag.
So infact parasitic drag is a HUGE factor in Load factor.
http://www.av8n.com/how/htm/4forces.html#fig-power-ias
http://www.av8n.com/how/htm/4forces.html#fig-force-ias
Crumpp
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Hi crumpp:
Try doing the calcs for a relative comparison. You'll see it then. You can use gripen's data as a starter. Now adjust the Cdi relative to a given turn g-loading for comparison between the planes. See what you get.
Gripen:
Thank you sir :). Separate question for you - I've been trying to find references as it relates to estimating exhaust thrust. Do you know of any docs that give some principles for doing so? Thanks!
Tango, XO
412th FS Braunco Mustangs
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Again,
Yes the value of the co-efficient does go down.
http://www.av8n.com/how/htm/4forces.html#fig-coeff-ias
However the FORCE goes up.
http://www.av8n.com/how/htm/4forces.html#fig-force-ias
Crumpp
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Originally posted by Crumpp
Again,
Yes the value of the co-efficient does go down.
http://www.av8n.com/how/htm/4forces.html#fig-coeff-ias
However the FORCE goes up.
http://www.av8n.com/how/htm/4forces.html#fig-force-ias
Crumpp
You seem to be thinking of a situation where one aircraft is going faster then the other and pulling a higher load factor, in which case you are now comparing apples and oranges. Of course an airplane going 400mph pulling 5 Gs will have more total drag then one going 200mph pulling 2 Gs. What we were trying to do above is compare two aircraft, at the same speed and load factor.
And as for you statement about area above, please re-read my earlier post. The area reffered to in the drag equation is "Reference Area". It's a guesstimate of the total surface area of the aircraft, and doesn't change with the aircrafts angle of attack. Because the air streamlines around the airplanes body there is really no additional parasite drag up until a stall (at which point a large wake forms behind the wing). That is why the coefficient of parasite drag is basically unchanged vs. angle of attack right up until a stall.
There is additional drag as angle of attack increases from the lift created by the wings and this is calculated with the induced drag formula.
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Crumpp:
I would love to get a copy of the full article.
I missed this earlier. I'll post it later this PM when I get home from work.
Yes the value of the co-efficient does go down....However the FORCE goes up.
This is all true. The problem is you're taking this statement and making a leap to an incorrect conclusion. The statement means nothing until you understand the drag relationship in its entirety and relative to aircraft in comparison.
The best way to understand it all is to do the calculations. The mathematics represent the relationship in it's entirety. Gripen already has given you a set of data to start and work from. Now just vary the Cdi values per plane per turn g-load per velocity and see what it tells you.
Tango, XO
412th FS Braunco Mustangs
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dtango,
So far the best reference I have found on the exhaust thrust is an article, "The Utilization of Exhaust Thrust" by N. Ya. Litvinov, in the old British magazine called "Aircraft Engineering" July 1944. Actually it's a translation from the Russian article and it's based on Russian tests on the Klimov M-105 and Yak-1. Another pretty good one is a NACA test report on the Spitfire V ejector pipes.
For quick and dirty comparison calculations generic assumptions on the exhaust thrust will do good enough; there should be no big differences between above mentioned planes.
gripen
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Gripen- OK thanks. I'll try looking them up. Yeah, I was more interested in some of the nitty-gritty :) - nothing related to your calcs above.
Tango, XO
412th FS Braunco Mustangs
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Try doing the calcs for a relative comparison. You'll see it then. You can use gripen's data as a starter. Now adjust the Cdi relative to a given turn g-loading for comparison between the planes. See what you get.
As far as Cdo calculations go, I will trust David Lednicer's calculations over Gripen.
1. We have three different Airplanes under 3 different conditions. It's impossible to make a valid comparision using co-efficients.
------------------------------------------------------------------------------------
P-51B => 679 km/h at 4755 m, the first FTH (USAAF test data)
Fw 190A => 537 km/h at sea level (US NAVY test data)
Spitfire IX => 603 km/h at 2896 m, the first FTH (average A&AEE test data)
------------------------------------------------------------------------------------
2. We are using drag co-efficients calculated in the 1940's when MANY Aeronautical Engineers would have argued with a slide rule til their last breath that man would never fly in space or break the sound barrier as our "check" to calculations.
Lastly All that is going to prove what I already know and what NOBODY it disputing. In the sustained turn realm. Lower Wingloaded plane have better sustained turn rates.
That is NOT the issue. The issue is the ability to pull SHARP TURNS at High Speed and High G's and still come out with energy to spare.
This issue greatly contributes to the "Bore and Snore" style of energy fighting people complain about.
In AH the penalty for pulling a "break turn" is pretty small. The planes lose no altitude and little speed. In fact they should lose either speed or altitude drastically. In combat nobody break turns except in immediate defense.
Crumpp
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Crumpp wrote
In AH the penalty for pulling a "break turn" is pretty small. The planes lose no altitude and little speed. In fact they should lose either speed or altitude drastically. In combat nobody break turns except in immediate defense.
Crumpp: You do not have the background to even begin to evaluate that situation.
You might wish to do a lot of research before making that statment. Infact you better be able to post exact numbers on the amount of speed loss for a given condition. If you can't post the calculations and numbers required for that evaluation. Then it is imposible to even make an evaluation on your claims. Please start listening to other people like sable,karnak,tango,gripen and myslef who do have a strong knowledge in this subject area.
HiTech
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Sure I will sit down and calculate you some numbers then.
Crumpp: You do not have the background to even begin to evaluate that situation.
How do you know my background and WHO ARE YOU to make that Judgment?
Crumpp
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Just someone who has been doing those caculations for 15 years.
HiTech
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Originally posted by GODO
When you jaw left of right, the body of the aircraft (the side surface and the rudder itself) acts as an airbrake and the aircraft slows down losing energy. When you turn left or right the brake effect comes mostly from the upper surface of the aircraft and the elevators.
Assuming this is true, planes with large upper surfaces (wings and body) should lose energy quicker than smaller planes, all that being still above stall speed, that is, still having extra lift to keep flying.
But what we see is that small planes like 190s or 109s lose E much faster than much larger ones like P51s or Spits when turning well above stall speeds.
I understand than large winged planes with smaller wingloading will keep turning tighter and at slower speed than small planes with more wingload, but the small ones should lose speed at a lower rate and the others until they reach stall speeds.
Where am I wrong?
I don't know if this is already said, but larger planes have bigger engines with more hp.
So in theory it shouldn't differ too much with small aircraft :)
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I don't know if this is already said, but larger planes have bigger engines with more hp.
Not true. The FW-190 and the Merlin Spitfire kept almost exactly the same Horsepower throughout their lifecycles. Surface dimensionally the Spitfire is much larger than the 190.
Just someone who has been doing those caculations for 15 years.
Right, That was my whole point to Gripen. Your calculations are the only ones that matter since you control the artificial world of AH.
Now I am fully capable of doing the math. The formulas are basic high school algebra. I had to take Calc I & II, statistics, and physics in college so the math is definitely not beyond my abilities. I am smart enough to realize that:
1. A co-efficient exists for only an exact condition of flight and applies ONLY to that condition.
2. There are more than 1 theory and formula for most co-efficient. These have and do change.
3. Co-efficient are not comparable unless you know exactly how it was calculated and under what conditions. The conditions of flight have to match exactly along with the calculations used in order to compare.
4. Unless you account for all conditions, ie radiator drag, downwash, induced drag, viscosity, etc....
The number you come up with is just meaningless. It may or very well may not reflect the reality of flight. It also has nothing to do with the level of understanding of the principals behind the math. If you don't believe that just ask any High School Chemistry Teacher.
But I will be glad to work some formulas and smoke the ol' Texas Instruments if that is what is required to achieve some perceived level of credibility.
This is EASY to see comparing Gripens last calculations.
Crumpp
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Attention K-Mart shoppers...dead horse meat on isle 3......
Geez....
Pardon me if I'm ignorant but aren't we (you) beating to death a "non argument". I think 12 different people have stated the basic premise and mathimatical proofs on this 16 different ways. If a total idiot (me) can grasp the over all concepts why continue to beat the dead animal....
BTW you can actually crank up the film viewer and "see" relative E states in action. I do feel at times that the nikki dowsnt bleed enough e but even there you can see relative closure etc pretty easily. When you look at the speed of BOTH planes invariably you can see pretty clearly that by and large things work as they should...
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Do the math crumpp: That is the only thing that will even put a dent in this argument. We have all done the math. It is your turn.
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Sea level speed and output:
P-51B => 560 km/h 1480 hp
Fw 190A => 537 km/h 1740 ps
Spitfire IX => 539 km/h 1586 hp
These result following Cd0 estimates:
P-51B => Cd0=0,0164
Fw 190A => Cd0=0,0249
Spitfire IX => Cd0=0,0192
There is very little difference if compared to the values calculated for 1st FTH.
gripen
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Crumpp the grump!
"Low wingloaded A/C have more surface therefore more drag"
Huh?
2 identical airframes will have the same parasitic drag no matter what they weigh, the lighter one will have LESS induced drag.
Can I have some of what you're smoking?
Instead of arguing with everyone, why don't you attempt to learn, there are some extremely intelligent folks posting to this thread who are trying to help you understand.
g00b
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How are you figuring radiator drag?
Crumpp
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2 identical airframes will have the same parasitic drag no matter what they weigh, the lighter one will have LESS induced drag.
If one has more surface area they are not identical.
But you are absolutely right. Two Identical Airframes will have the same parasitic drag. If one weighs more it will have more induced drag.
Crumpp
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P-51B => 560 km/h 1480 hp
Fw 190A => 537 km/h 1740 ps
Spitfire IX => 539 km/h 1586 hp
Where are you getting this data?
It doesn't match anything I have seen.
http://www.fourthfightergroup.com/eagles/bs428speed.gif
http://www.fourthfightergroup.com/eagles/jl165speed.gif
http://www.terra.es/personal2/matias.s/fw190_A5_speed.gif
http://www.terra.es/personal2/matias.s/fw190-1.jpg
http://www.terra.es/personal2/matias.s/bmw801d-1024.jpg
http://www.fourthfightergroup.com/eagles/merlin66hpchart.jpg
Let me know what value you are using for radiator drag.
Crumpp
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Here's the link to Dave Lednicer's paper. It was a paper that was printed in Aeronautical Journal June/July 1995 and then reprinted in Sports Aviation in 1999.
Lednicer EAAjanuary1999.pdf (http://www.thetongsweb.net/AH/EAAjanuary1999.pdf)
Tango, XO
412th FS Braunco Mustangs
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crumpp:
I have no idea why you're even challenging gripen's calcs and why it's even germane to the conversation. He was trying to help you understand and give you some things to work with.
I have no idea why you're even bringing up radiator drag. If you understood the drag relationship you would realize that cooling drag is embedded in the calculations because it's contribution is already embedded in the aircraft performance numbers. That's like asking someone to tell you the section cl at the 30% span of a wing for an aircraft when it's already accounted for in the overall wing CL which you can easily calculate.
As for challenging gripen's data points, I'm pretty confident that you are barking up the wrong tree when it comes documents he has reference to. The man has pointed out some very interesting bits of data from some pretty obscure technical docs that exist.
Please take HT's advice and do some total drag comparative calcs on aircraft in turning situations.
Tango, XO
412th FS Braunco Mustangs
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I just showed above how to do quick and dirty drag analyses with simple calculations using some datasets which I certainly know to be real world tested. If someone is not happy with the datasets I used, the playground is free for other datasets. I don't know if any of the charts in the Crumpp's source site are real world tested.
The P-51B speed data comes from "Tactical Employment Trials North American P-51B-1", this data can be found from several sources including "America's Hundred Thousand" by F. H. Dean and "The Mustang Story" by K. Delve. The engine output is calculated using engine output chart and rammed FTH of above mentioned test. Output can be also verified from US navy test data on the P-51B.
The Fw 190A speed data comes from the US Navy Fw 190 test. Output data comes directly from the chart Crumpp listed.
The Spitfire speed data is a rough average from several +18 lbs tests made by the A&AEE. Output is calculated same way as in the case of the P-51B and it can be also roughly verified from the chart Crumpp linked above.
gripen
-
Ok,
Did some calculations:
First I did up the Cl that was used in the Drag formula.
The weight data for the FW-190 came from Pilots Manual. The weight data for the Spitfire came from:
http://www.fourthfightergroup.com/eagles/jl165.html
The P51D was much harder. I ran into the same problem with the Focke-Wulf. Empty Weight and Max Weight were easy to find but the takeoff weight of a regular fighter not burdened with extra's was slightly harder. On site listed 10,000 lbs and another site listed 9800 lbs. I chose the lesser weight as I felt it was the best data available.
All A/C where calculated under the following conditions:
Tempature - 65 *F
Atmospheric Pressure - 14.696 PSI
Speed = 300 mph
Using the following formula:
http://www.grc.nasa.gov/WWW/K-12/airplane/liftco.html
FW190A8 - Weight = 4272kgs
Wing Area = 735 sq. feet
Cl = .174662988
Spitfire Mk IX Merlin 66 (+25)- Weight = 7400kgs
Wing Area = 831.2 sq feet
Cl = .121352522
P51D- Weight = 9800lbs
Wing Area = 882.2
Cl = .151419443
For the drag calculations I used "Cd wet" out of David Lednicer's article as they are all real world tested with his sources listed at the bottom.
http://www.thetongsweb.net/AH/EAAjanuary1999.pdf
For reference Area I used the Wing Area and the used the following formula:
http://www.grc.nasa.gov/WWW/K-12/airplane/drageq.html
FW-190 Drag = 382.85
CDw = .0071
Ref Area = 735 sq ft
Spitfire Drag = 396.27
CDw = .0065
Ref Area = 831.2 sq ft
P51D Drag = 343.56
CDw = .0053
Ref Area = 882.2 sq ft
I received this document from the Vought archives and scanned it. It shows the P-51B Cdo at .017.
David Lednicer mentions some SNAFU's over the P51's drag testing. Seems there a bunch of calculated Cd's and even a tested Cd or two running around that are wrong. Apparently they tested it without adding things like the exhaust stacks to the test A/C in the tunnel. Nevertheless it does have an extremely low Cd.
P51 was an excellent fighter.
Generally speaking, Lower Wingloaded planes have more surface and therefore more parasitic drag.
Since pulling a tight bank will cause and increase in speed or force the pilot use excess speed to pay for the altitude you maintain the plane with the highest parasitic drag will bleed the most energy due to drag.
http://www.av8n.com/how/htm/aoastab.html#fig-spiral-start
In order to produce 4 tons of lift, the airplane must fly at roughly 200 knots --- twice the wings-level trim speed.
Crumpp
-
Ok,
Did some calculations:
First I did up the Cl that was used in the Drag formula.
The weight data for the FW-190 came from Pilots Manual. The weight data for the Spitfire came from:
http://www.fourthfightergroup.com/eagles/jl165.html
The P51D was much harder. I ran into the same problem with the Focke-Wulf. Empty Weight and Max Weight were easy to find but the takeoff weight of a regular fighter not burdened with extra's was slightly harder. On site listed 10,000 lbs and another site listed 9800 lbs. I chose the lesser weight as I felt it was the best data available.
All A/C where calculated under the following conditions:
Temperature - 65 *F
Atmospheric Pressure - 14.696 PSI
Speed = 300 mph
Using the following formula:
http://www.grc.nasa.gov/WWW/K-12/airplane/liftco.html
FW190A8 - Weight = 4272kgs
Wing Area = 735 sq. feet
Cl = .174662988
Spitfire Mk IX Merlin 66 (+25)- Weight = 7400kgs
Wing Area = 831.2 sq feet
Cl = .121352522
P51D- Weight = 9800lbs
Wing Area = 882.2
Cl = .151419443
For the drag calculations I used "Cd wet" out of David Lednicer's article, as they are all real world tested with his sources listed at the bottom.
http://www.thetongsweb.net/AH/EAAjanuary1999.pdf
For reference Area I used the Wing Area and the used the following formula:
http://www.grc.nasa.gov/WWW/K-12/airplane/drageq.html
FW-190 Drag = 382.85
CDw = .0071
Ref Area = 735 sq ft
Spitfire Drag = 396.27
CDw = .0065
Ref Area = 831.2 sq ft
P51D Drag = 343.56
CDw = .0053
Ref Area = 882.2 sq ft
I received this document from the Vought archives and scanned it. It shows the P-51B Cdo at .017.
David Lednicer mentions some Snafu's over the P51's drag testing. Seems there a bunch of calculated Cd's and even a tested Cd or two running around that are wrong. Apparently they tested it without adding things like the exhaust stacks to the test A/C in the tunnel. Nevertheless it does have an extremely low Cd.
P51 was an excellent fighter.
Generally speaking, lower wing loaded planes have more surface and therefore more parasitic drag. Unless of course there is a large size difference in the first place between the planes.
Since pulling a tight bank will cause and increase in speed or force the pilot use excess speed to pay for the altitude you maintain the plane with the highest parasitic drag will bleed the most energy due to drag.
Yes Low-wing loaded planes can turn the same angle as a high wing loaded plane and pay less for it. However when turning at their max turn rate it they pay the price like every other wing.
http://www.av8n.com/how/htm/aoastab.html#fig-spiral-start
In order to produce 4 tons of lift, the airplane must fly at roughly 200 knots --- twice the wings-level trim speed.
Crumpp
-
Crumpp:
You're getting closer :). However the following statement needs to be evaluated relative to total drag calculations between the aircraft.
Since pulling a tight bank will cause and increase in speed or force the pilot use excess speed to pay for the altitude you maintain the plane with the highest parasitic drag will bleed the most energy due to drag.
Vary the Cdi with relation to Cl per plane per turn g-loading per velocity and calculate total aircraft drag on these params.
Tango, XO
412th FS Braunco Mustangs
-
As speed increases Cdi goes down, right?
As speed increases parasitic drag goes UP, right?
When you conduct a sharp bank, your speed HAS to increase.
Imagine that you are initially trimmed for straight and level flight at, say, 100 knots. Then you inadvertently enter a steeply banked turn. Figure 6.12 shows the forces acting on the plane in level flight and in the turn. Let’s imagine that the plane weighs exactly one ton. In level flight the downward force of gravity is exactly canceled by the lift produced by the wings, so the wings must be producing one ton of lift.
The lift is produced both by angle of attack and a speed increase. If you just banked and immediately slowed down I would wholeheartily agree. At the instant you bank though, I understand the plane drops altitude to trade for speed to increase the lift, lots of speed.
BTW,
I missed your comments on the P51. I am researching a book on the FW-190. All the evidence I have points to the P51 as being the worst allied fighter for a FW-190A to encounter until the Tempest and Spitfire Mk XIV.
The Merlin Powered spits at best equaled the 190. The only advantage the 190A had over the Mustang was roll rate, dive accelleration, and a similar turn radius (51B had a slight advantage). Only if the Mustang let his "E" get lower than the 190 was the fight even IMO.
I hate punchin that calculator. To me its dumb at our level. It's time wasted that I will never get back. Just like David Lednicer says, "Aerodynamics is all about the details." At our level this is like an alchemist saying "I can transmute gold! look at these calculations". We don't have enough of the details.
Just look at the P51, even some of the top Aeronautical engineers of the day did not have the "details".
:(
Crumpp
-
Originally posted by Crumpp
All A/C where calculated under the following conditions:
Temperature - 65 *F
Atmospheric Pressure - 14.696 PSI
Why not standard conditions, ie 15 degrees celsius at sea level?
Overall it would help a lot if all values are in same system metric or US.
Originally posted by Crumpp
FW190A8 - Weight = 4272kgs
Wing Area = 735 sq. feet
Cl = .174662988
Spitfire Mk IX Merlin 66 (+25)- Weight = 7400kgs
Wing Area = 831.2 sq feet
Cl = .121352522
P51D- Weight = 9800lbs
Wing Area = 882.2
Cl = .151419443
The wing area's are all wrong, these are wet areas which Lednicer used as reference area for Cd. My calculations as well as the NACA and RAE graphs linked above use wing area as reference area for Cd. Generally calculations are much easier when the wing area is used as the reference area and then there is also a direct connection to the induced drag.
Originally posted by Crumpp
For the drag calculations I used "Cd wet" out of David Lednicer's article, as they are all real world tested with his sources listed at the bottom.
Lednicer writes:
"There are many conflicting claims as to the equivalent flat plate drag area (f) of these fighter aircraft, based upon my research, what I believe are the most accurate values are shown in Table 1."
Basicly he says that he choosed the ones he thought to be most accurate. The problem with the Lednicer's numbers is that if the wet area and flat plate area values he is using are true, then the planes mentioned could not have reached the real world measured performance.
gripen
-
Basicly he says that he choosed the ones he thought to be most accurate. The problem with the Lednicer's numbers is that if the wet area and flat plate area values he is using are true, then the planes mentioned could not have reached the real world measured performance.
I think the man would have spotted that Gripen.
He seems not only a whole lot more qualified than anyone on this BBS, AND much better equipped to do the analysis.
Crumpp
-
Wetted Area, Swet
The air can only create stress on surfaces that it touches, so the relevant area over which the friction or the pressure will act is the wetted area–the actual area exposed to the air. This value
is completely determined by the geometry of the aircraft and, in actuality, is quite difficult to calculate. CAD packages can make the process easier.
Seems a much more accurate approximation of the drag than just the wing area.
Crumpp
-
Crumpp:
>>>>As speed increases Cdi goes down, right?
Wrong. Cdi varies with AOA. If AOA increases Cdi increases. If AOA decreases Cdi decreases. In level flight AOA decreases with increasing speed therefore Cdi appears to go down as speed increases. In a turn this is thrown out the window because Cdi varies with AOA and not speed.
>>>>As speed increases parasitic drag goes UP, right?
Right.
>>>>When you conduct a sharp bank, your speed HAS to increase.
No your speed does not HAVE to increase at all.
>>>>He seems not only a whole lot more qualified than anyone on this BBS, AND much better equipped to do the analysis.
Whatever.
Tango, XO
412th FS Braunco Mustangs
-
Originally posted by Crumpp
I think the man would have spotted that Gripen.
He seems not only a whole lot more qualified than anyone on this BBS, AND much better equipped to do the analysis.
The whole idea of the equivalent flat plate area is to make calculations as well as comparisons easy. Therefore it can be very easily verified that the Lednicer's flat plate areas appear to be at least partially wrong.
Originally posted by Crumpp
Seems a much more accurate approximation of the drag than just the wing area.
Actually I was talking about using wing area as the reference area which you pretty much completely mixed up in your calculations. With the calculations I used, the drag is approximated from the measured speed and available thrust, not from wing area.
gripen
-
Wrong. Cdi varies with AOA. If AOA increases Cdi increases. If AOA decreases Cdi decreases. In level flight AOA decreases with increasing speed therefore Cdi appears to go down as speed increases. In a turn this is thrown out the window because Cdi varies with AOA and not speed.
Got it.
No your speed does not HAVE to increase at all.
Then your burning energy to keep you altitude. Otherwise the flight instructor and PhD. is putting out wrong information.
Gripen:
I picked 65 degrees just because it's a nice tempature and got the pressure at sea level form a weather website. From there I calculated "r".
You were correct on the wing area's for the CL calc's so I redid them real quick.
All the other parameters are the same.
CL at 300 mph:
FW-190 Cl = .651727567
Spitfire Mk IX Cl = .416810811
P51D Cl = .568493091
Crumpp
-
Then your burning energy to keep you altitude. Otherwise the flight instructor and PhD. is putting out wrong information.
Yes, this is true. However your original statement is misleading because the physics doesn't require a plane to increase it's speed in a turn.
By the way, you don't have to increase your speed to maintain zero energy bleed in a hard turn. A "hard turn" is also a little ambiguous but I think I understand what you're trying to say. You would need to increase acceleration by putting nose down to offset deceleration due to energy bleed in a turn but your velocity could remain constant if you flew it that way. This is what you would to do maintain a constant-g sustained turn (vs. a sustained level turn).
Tango, XO
412th FS Braunco Mustangs
-
Originally posted by Crumpp
I picked 65 degrees just because it's a nice tempature and got the pressure at sea level form a weather website. From there I calculated "r".
It's not very good idea to use other conditions than standard atmosphere. Most performance data is corrected to the some sort of standard conditions which all are quite close to the current standard atmosphere. And if more calculations is needed, the standard atmosphere can be easily embedded to spreadsheet model.
Originally posted by Crumpp
You were correct on the wing area's for the CL calc's so I redid them real quick.
All the other parameters are the same.
CL at 300 mph:
FW-190 Cl = .651727567
Spitfire Mk IX Cl = .416810811
P51D Cl = .568493091
Let's calculate Cl for the Fw 190 at 300 mph near sea level and at 1 g load right from the ground up.
The formula is (from NASA site):
Cl = L / (A * .5 * r * V^2)
where:
L = Lift
A = Wing Area
r = Density
V = Speed
Next we can convert all the needed values to the SI units for simple calculations:
L = 4272 kg * 9,81 m/s2 = 41908,32 N
A = 18,3 m2
r = 1,225 kg/m3
V = 300 mph = 483 km/h = 134 m/s
Then we just calculate Cl:
Cl = 41908,32 / (18,3 * 0,5 * 1,225 * 134^2)= 0,208
It should be also noted that to do total drag comparisons, we should know the thrust and for that we need exact amount of engine output. Therefore the easiest altitude for calculation is FTH.
gripen
-
Then your burning energy to keep you altitude. Otherwise the flight instructor and PhD. is putting out wrong information.
you misunderstood him.
read again:
Imagine that you are initially trimmed for straight and level flight at, say, 100 knots. Then you inadvertently enter a steeply banked turn. Figure 6.12 shows the forces acting on the plane in level flight and in the turn. Let’s imagine that the plane weighs exactly one ton. In level flight the downward force of gravity is exactly canceled by the lift produced by the wings, so the wings must be producing one ton of lift.
he keeps his AoA (and probably throttle setting to hold the speed) constant and roll.
he started with 1G and now he's pulling a 1G turn which means he's falling. In a level turn G-meter will always show G>1.
He doesn't HAVE TO loose energy if he pulls more than 1G. That's what he's got the noisy engine installed for. Given the power, he can pull hard , climb, turn and accelerate simultaniously.
Bozon
-
he keeps his AoA (and probably throttle setting to hold the speed) constant and roll.
I don't think so. He is talking about the forces in steep turn not a roll. He does combine an accidental spiral dive with it because the forces are the same.
Given the power, he can pull hard , climb, turn and accelerate simultaniously.
As for the throttle setting, How many times in AH have you seen someone increase throttle to make a turn or climb? In fact, everyone hits max WEP and yanks the stick.
I don't think there are any WWII fighters with enough power to instantly compensate for 4 times their weight.
You would need to increase acceleration by putting nose down to offset deceleration due to energy bleed in a turn but your velocity could remain constant if you flew it that way. This is what you would to do maintain a constant-g sustained turn (vs. a sustained level turn).
Exactly, by yanking the wings into an extreme bank, you now require more energy just to maintain altitude. You have made a weight change to the A/C in effect and it requires much more lift to balance the forces.
Read about what he calls the "albatross" effect about sudden weight changes. I see this all the time when I am skydiving. A group of jumpers will leave the ramp and the plane will suddenly pitches up in the sky and gains altitude to compensate for their weight. If a C130 has to compensate for a few guys leaving the plane then I am sure our tiny fighter must compensate too.
http://www.av8n.com/how/htm/aoastab.html#fig-bank-noload
http://www.av8n.com/how/htm/vdamp.html#sec-vertical-damping
The weight increases if an albatross flies in the window and sits on the seat beside you.
It's not very good idea to use other conditions than standard atmosphere. Most performance data is corrected to the some sort of standard conditions which all are quite close to the current standard atmosphere. And if more calculations is needed, the standard atmosphere can be easily embedded to spreadsheet model.
Not necessarily Gripen. Unless you can relate your calculations to a particular condition of flight under the exact conditions, they are meaningless. Temperature and humidity play a very large roll in aerodynamics and much of the data we see is collected under real world conditions and not necessarily adjusted to standard atm. Making the assumption it is can certainly lead to wrong conclusions.
Calculating at standard atmospheric conditions is just fine, too. Simply change "r" and recalculate the drag if you want using the area, velocity, and CDwet provided. The resulting numbers will change but their basic line up will not since they were all calculated under the same conditions in the first place.
Crumpp
-
Crumpp:
Exactly, by yanking the wings into an extreme bank, you now require more energy just to maintain altitude. You have made a weight change to the A/C in effect and it requires much more lift to balance the forces.
Yes this is all correct. So the question still is which aircraft would have the greatest e-bleed in a turn - the higher wingloaded or the lower wingloaded? The only way you'll know is to calculate and compare relative total drag.
But if you don't want to do the calculations think about this. Greater bank/greater AOA = greater lift = more induced drag as you have stated which is exactly right. So which aircraft will have the greater AOA per given g-loading the higher wingloaded or the lower wingloaded aircraft?
Just using your calcs take a look at 1g:
CL at 300 mph:
FW-190 Cl = .651727567
Spitfire Mk IX Cl = .416810811
P51D Cl = .568493091
The highest wing-loaded a/c (FW-190) has the highest relative Cl = higest relative AOA = highest relative induced drag. What does that mean? The higher wing-loaded plane is producing more lift than the lower wing-loaded plane.
Now what happens to the Cl for all 3 planes if that becomes a 2g turn, 3g turn, 4g turn or 5g turn? Is the lower wingloaded plane going to produce more lift than the higher wing-loaded plane? The answer is no given equal airspeeds and g-loading. The factors that contribute to higher wing-loaded a/c having greater induced drag remain the same at 1g as they do at 5g's, but now the contribution of Cl/Cdi is more pronounced at higher g's.
But to check just double, triple, quadruple, etc. your weight and recalculate Cl and look at what your Cdi contribution to your to total Cd is.
It gets even more complicated than this actually and gripen alluded to that already because just looking at the total drag side of the equation actually isn't the total picture. You also should factor in thrust contribution to get a more accurate net-drag picture. That being said for a simple analysis you can start with examining relative total-drag between aircraft.
Tango, XO
412th FS Braunco Mustangs
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As for the throttle setting, How many times in AH have you seen someone increase throttle to make a turn or climb? In fact, everyone hits max WEP and yanks the stick.
That's why they get shot down so easily...
I don't think there are any WWII fighters with enough power to instantly compensate for 4 times their weight.
not 4 times, but done gently enough it's possible.
Bozon
-
Originally posted by Crumpp
Not necessarily Gripen. Unless you can relate your calculations to a particular condition of flight under the exact conditions, they are meaningless. Temperature and humidity play a very large roll in aerodynamics and much of the data we see is collected under real world conditions and not necessarily adjusted to standard atm. Making the assumption it is can certainly lead to wrong conclusions.
/B]
Well, in the all tests I have quoted above, the results are corrected to the standard conditions as well as my calculations are in standard atmosphere. There is no need for any assumption.
gripen
-
I just did a quick "flight test" in AH offline.
I upped an FW-190A5 with full fuel and a 500kg bomb.
Climbed to 3000 feet, trimmed for level flight at a speed of 250 mph IAS.
When I released the bomb, hand off the controls, the plane rose to a VSI of 250 FPM and I gained an average of 200 feet in altitude for a 1000 lb loss in weight.
When I took 25 percent fuel the effect was the same.
At 25 percent fuel under the same flight conditions I pulled a 70-80 degree bank.
The slowly went nose down to a VSI close to max and I lost some altitude. However the A/C quickly self recovered leaving me level, at the same altitude and at a faster.
Not a very exact test but enough to know the effects of weight change are not very pronounced in the game.
Crumpp
-
not 4 times, but done gently enough it's possible.
I agree. The contention is on extreme angle break turns which are so common in the game.
Crumpp
-
Crumpp: The effects of weight change in the game are exatly what they should be. Once again before you make claims like "not very pronounced" produce numbers what they realy should be, Then compair them to the AH results.
-
Crumpp: The effects of weight change in the game are exatly what they should be. Once again before you make claims like "not very pronounced" produce numbers what they realy should be, Then compair them to the AH results.
Your absolute right. "not very pronounced" is very vague. I will withdraw that.
However the second part of the test. The one most relevant to this thread is very valid. A/C do not self recover from a spiral dive. That is exactly why it is called a "Graveyard Spin". It will continue to spiral with no appreciable out of trim forces to warn the pilot. So instead fo having to expend E to counteract the forces and remain in a Level turn, the Plane automatically does it for you. So you wind up with an E excess at the end of the turn.
http://www.av8n.com/how/htm/aoastab.html#fig-spiral-75
http://www.av8n.com/how/htm/roll.html#fig-footprint-vec
http://www.av8n.com/how/htm/aoastab.html#fig-pitch-damping
It is still trimmed for cruise angle of attack.
In a coordinated turn, the aircraft is happy to continue turning forever; it will definitely not have any tendency to return to wings-level flight. Indeed, it will have the opposite tendency, called the overbanking tendency, which we now discuss.
Lastly, Do not think for an instant that I think AH is "all messed up". It is in fact IMO and experience the best MMOL flight sim available to today. There are some with better eye-candy but when the rubber meets the road their eye candy cannot cover up their flight model.
We also know that you guys have not gotten around to tweaking the flight models yet. So I imagine some of the "things that make you go MMMMMMM" will in all likelyhood disappear.
Crumpp
-
Hi Guys,
Just jumping in here in the hope I can help.
Originally posted by GODO
But what we see is that small planes like 190s or 109s lose E much faster than much larger ones like P51s or Spits when turning well above stall speeds.
How quickly an aircraft gains or loses energy in a turn depends on its specific excess power, and while that is influenced by the size of the aircraft, that's not the only thing to be considered. If you only look at the size of the aircraft, and leave out other important considerations, it is possible you will arrive at erroneous conclusions.
Here is an EM diagram for the P-51D, the Fw190D9 and the Fw190A5 from Aces High (Haven't done them for Aces High 2 yet) and it shows that, for the conditions indicated in the diagram, both 190s will lose energy more rapidly than the P-51D.
(http://www.badz.pwp.blueyonder.co.uk/Files/Images/P51D v Fw190.jpg)
So, if you are seeing that behaviour in Aces High, it is consistent with this analysis of their flight models. Personally, this characteristic of the Fw190 series in AH makes them extremely dangerous, because they bleed energy more rapidly in a hard turn, if you engage one in a P-51D at high speed, you know they are going to be able to reduce their turn radius more quickly than you and get the first shot. In a one circle fight, or a scissors, that will be fatal. Almost every Fw190 driver I have come across in Aces High is able to take advantage of that to good effect. The ability of the P-51D to sustain its energy in the turn is only an advantage if the P-51D can survive long enough to use it. There are ways to do that, but that becomes a discussion about air combat, and not aircraft performance.
I understand than large winged planes with smaller wingloading will keep turning tighter and at slower speed than small planes with more wingload, but the small ones should lose speed at a lower rate and the others until they reach stall speeds.
Where am I wrong?
As others in this thread have said, you can’t simply focus on the size of an aircraft, and ignore everything else, and expect to reach valid conclusions, you really do need to consider everything.
The EM diagram I posted above does include everything, and it shows that the behaviour you are seeing should be expected, for those aircraft, under those conditions. That of course begs the question, how close are those diagrams to the performance of their real world counterparts? I can only answer that by saying that I have tested a number of flight simulations, the other online simulations, and some big name boxed games, and produced overlays for their aircraft versus some real WW2 fighters for an article I’m writing for SimHQ. The good news is that the AH aircraft show a breathtakingly good correspondence, and are generally closer than the other simulations, in some cases Aces High’s superiority in that respect is extreme!
I Hope that is helpful.
Badboy
PS, Kudos to HTC on AH2... Good work guys!
-
Repost Hitech so you can see the math:
------------------------------------------------------------------------------------
Ok,
Did some calculations:
First I did up the Cl that was used in the Drag formula.
The weight data for the FW-190 came from Pilots Manual. The weight data for the Spitfire came from:
http://www.fourthfightergroup.com/eagles/jl165.html
The P51D was much harder. I ran into the same problem with the Focke-Wulf. Empty Weight and Max Weight were easy to find but the takeoff weight of a regular fighter not burdened with extra's was slightly harder. On site listed 10,000 lbs and another site listed 9800 lbs. I chose the lesser weight as I felt it was the best data available.
All A/C where calculated under the following conditions:
Temperature - 65 *F
Atmospheric Pressure - 14.696 PSI
Speed = 300 mph
Using the following formula:
http://www.grc.nasa.gov/WWW/K-12/airplane/liftco.html
FW190A8 - Weight = 4272kgs
Wing Area = 196.98 sq. feet
Cl = .651727567
Spitfire Mk IX Merlin 66 (+25)- Weight = 7400kgs
Wing Area = 242 sq feet
Cl = .416810811
P51D- Weight = 9800lbs
Wing Area = 882.2
Cl = .568493091
For the drag calculations I used "Cd wet" out of David Lednicer's article, as they are all real world tested with his sources listed at the bottom.
http://www.thetongsweb.net/AH/EAAjanuary1999.pdf
For reference Area I used the Wet Area and the used the following formula:
http://www.grc.nasa.gov/WWW/K-12/airplane/drageq.html
FW-190 Drag = 382.85
CDw = .0071
Ref Area = 735 sq ft
Spitfire Drag = 396.27
CDw = .0065
Ref Area = 831.2 sq ft
P51D Drag = 343.56
CDw = .0053
Ref Area = 882.2 sq ft
quote:
--------------------------------------------------------------------------------
I received this document from the Vought archives and scanned it. It shows the P-51B Cdo at .017.
--------------------------------------------------------------------------------
David Lednicer mentions some Snafu's over the P51's drag testing. Seems there a bunch of calculated Cd's and even a tested Cd or two running around that are wrong. Apparently they tested it without adding things like the exhaust stacks to the test A/C in the tunnel. Nevertheless it does have an extremely low Cd.
P51 was an excellent fighter.
Generally speaking, lower wing loaded planes have more surface and therefore more parasitic drag. Unless of course there is a large size difference in the first place between the planes.
Since pulling a tight bank will cause and increase in speed or force the pilot use excess speed to pay for the altitude you maintain the plane with the highest parasitic drag will bleed the most energy due to drag.
Yes Low-wing loaded planes can turn the same angle as a high wing loaded plane and pay less for it. However when turning at their max turn rate it they pay the price like every other wing.
http://www.av8n.com/how/htm/aoastab...ig-spiral-start
quote:
--------------------------------------------------------------------------------
In order to produce 4 tons of lift, the airplane must fly at roughly 200 knots --- twice the wings-level trim speed.
--------------------------------------------------------------------------------
Crumpp
-
Because the Spitfire's wing loading is much lower, it's Aspect ratio is higher then either aircraft mentioned, and the E Factor of the elliptical wing is REALLY good.
It's aspect ratio is NOT higher than either A/C mentioned.
The FW-190's Aspect Ratio is 6.01 in the FW-190A8.
In the FW-190A6 the wing was changed to accomidate the MG151's in the outboard postions AND to help offset the weight increase from the added armament and the extended engine mounts modified in the FW-190A5.
Aspect ratio FW-190A5 and below = 5.8
Aspect ratio FW-190A6 and above = 6.01
CG adjustments also occurred in the FW-190A8.
Crumpp
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Originally posted by Crumpp
All A/C where calculated under the following conditions:
Temperature - 65 *F
Atmospheric Pressure - 14.696 PSI
Speed = 300 mph
Using the following formula:
http://www.grc.nasa.gov/WWW/K-12/airplane/liftco.html
FW190A8 - Weight = 4272kgs
Wing Area = 196.98 sq. feet
Cl = .651727567
Spitfire Mk IX Merlin 66 (+25)- Weight = 7400kgs
Wing Area = 242 sq feet
Cl = .416810811
P51D- Weight = 9800lbs
Wing Area = 882.2
Cl = .568493091
All the Cl values are wrong as well as the wing area of the P-51D. As an example Cl for the Fw 190 is calculated correctly above.
Originally posted by Crumpp
FW-190 Drag = 382.85
CDw = .0071
Ref Area = 735 sq ft
Spitfire Drag = 396.27
CDw = .0065
Ref Area = 831.2 sq ft
P51D Drag = 343.56
CDw = .0053
Ref Area = 882.2 sq ft
All drag values seem to be wrong? At least the unit is not newton nor kilopond nor pound.
Originally posted by Crumpp
It's aspect ratio is NOT higher than either A/C mentioned.
If the Spitfire had e factor say 0,8 and the Fw 190 say 0,7. Then the Spitfire had effective aspect ratio 4,49 and the Fw 190 4,21. Lednicer notes in the case of the Spitfire that "loading distribution is not elliptical, though it is probably the most optimum of the three from the induced drag standpoint".
Regarding Lednicer's flat plate values, it seems that these are for total drag ie include induced drag which mean that his values are actually quite close my quick and dirty values depending if flat plate area is calculated for Cd 1 or 1,28 (square).
Originally posted by Crumpp
Aspect ratio FW-190A5 and below = 5.8
Aspect ratio FW-190A6 and above = 6.01
Well, from the Fw 190A-1 onwards all the A-series Fw 190s had same wing area and span so these all had same aspect ratio 6,02 (18,3 m2 and 10,5 m). Some early A-0s had smaller wing which had aspect ratio 6,07 (14,9 m2 and 9,51 m).
gripen
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Crumpp: this made me think:
"Since pulling a tight bank will cause and increase in speed or force the pilot use excess speed to pay for the altitude you maintain the plane with the highest parasitic drag will bleed the most energy due to drag.
Yes Low-wing loaded planes can turn the same angle as a high wing loaded plane and pay less for it. However when turning at their max turn rate it they pay the price like every other wing. "
No matter what your calculations show, bear in mind that the finest turning planes of WW2 had a low wingloading. Example: A6m.
Now, a fast aircraft with a low wingloading such as the Spitfire, also has a very good turning ability.
Heavy wingloading, no matter how you calculate, will always bleed everything, except sheer accumulated Newtons. A heavy plane will crash deeper into the ground, it may zoom better, apart from that it's all against the wind. No matter what you calculate.
I'll mail you an excel thingie to look at Newtons in a Climb.
I am no Excel expert, however Newtons are a calculable thing, and this particular formula did show something to me in a rather clear manner which was not to be haired out on these boards.
Regards..
Angus
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My calcs aren't wrong Gripen.
The wing area I used for the P51D is: 234.976 sq ft.
That is a misprint. The Cl's are correct, however and feel free to calculate them yourself.
And post them in English units NOT metric, as mine are in, which you think are wrong.
I wrote David Lednicer to see if he has insight into this. We are just flat out missing to many of the details.
For example Gripen:
You list the wingtip E factor as .8 and the mustang as .75. Where did you get this data? You list the Spitfires as .95 while the NASA site clearly says the Spitfire had an E factor of 1.
The information that is out there is conflicting even among "official" sources. Just look at the Mustang. Since David actually build airplanes and analyzes past aircraft as a hobby he is probably in a better position to give us "the best" data available or at least the closest to actual performance.
Yet this Aircraft has E factor of .95. Niether the FW 190's wing tips or the P51's were "square".
http://www.anycities.com/user/j22/j22/index.htm
And quit carrying your feelings in a glass jar. Last thread as soon as you were questioned you became extremely rude. Your starting it again.
This is what I am trying to do:
1. If you examine the loss records (which the Luftwaffe kept meticulous records of their casualties) you will find this pattern.
The pre-1943 trained pilots took losses on a pretty much steady curve from the beginning to the end of the war. It does go up some in the last years of war when pressure from the Allies in the West was at it's greatest (Big Week and Bodenplatte). Their loss rate stays fairly constant and does not rise dramatically.
The post-1943 trained pilots died like flies with an almost 98 percent loss rate. IF they survived to complete their sixth mission their chances of surviving until the end of war went up astronomically.
After WWII there was a tendency to explain the Luftwaffe high victory levels on Aircraft performance.
Later this was found not be true. Because of the mound of data compiled to disprove the "wonder planes" theories the perception has been created that Luftwaffe planes were poor performers.
This can be seen in Authors such as Alfred Price and Peter Cayhill. Much of the commentary by Price is in direct odds with Eric Browns. Peter Cayhill, a noted spitfire historian, in his book "Combat Legends" takes a tactically sound interception and creates the perception the FW-190 was only good for a high-speed bounce. That is in direct odds with the Luftwaffe pilot anecdotal evidence that says they routinely got into dogfights with the FW-190 AND gave as good as they got.
In fact the Luftwaffe took it's losses for the same reason it achieved it's victories. Luftwaffe pilots had a much greater chance than an allied pilot to encounter the enemy.
Combine that with the tactical realities of the "Defense of the Reich" and it is easy to see why. Men in combat don't say good things about their equipment if it sucks. You won't hear statements like:
" Against 20 Russians trying to shoot you down or even 20 Spitfires, it can be exciting, even fun. But Curve in towards 40 Fortresses and all your past sins flash before your eyes."
Oblt. Hans "Fips" Phillip, Kommandure JG1
FW-190A5 pilot
He was killed by P47's 4 days after that statement, seconds after downing his first B17. The P47's were on his six as he attacked the B17.
One young Luftwaffe pilot who arrived in JG 26 in the summer of 1944 got to fly three combat missions in World War II. Each mission had months in between the sorties because he was shot down each time he took off. He was lucky and survived the war. The day he graduated "flight school" he was the sole survivor, besides his instructor, of his student schwarm. The instructor took them flying down a valley. 3 of the students crashed into the mountain at the end of it following the instructor.
2. In my studies I have never found a situation yet where the science did not line up with history in the Air War.
3. Since I am writing a book I am on an agenda. Not the one you think though to "artificially inflate" my favorite planes performance. There is a wealth of new information out there on these planes performances that has been declassified. With the Internet access to such places as the Luft-archive and the National Archives it is even more widely available.
I believe the actual plane performances will line up with the statistics. This is a great forum to both get a good idea of the science behind the Aircraft and to gauge that performance. In short it is a good tool.
Crumpp
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I'll mail you an excel thingie to look at Newtons in a Climb.
Cool Angus!
Thanks bro.
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Crummp:
Repost Hitech so you can see the math:
The math is for 1g level flight. This is irrelevant if you're trying to compare total aircraft drag in a turn. We've been asking you to calculate total drag in a turn.
Here's the deal - the simplified tota drag coeff eqn. is the following:
CD = CD0 + CDi
You've only attempted to calculate the above at 1g. CDi increases in a turn and becomes even more dramatic the greater the Cl.
Even using your calcs FW-190 (highest wingloaded a/c for comparison) has the greatest Cl hence the greatest Di even at 1g- just that at 1g Di contribution to total drag is only a small fraction of total drag.
Now start increasing load factor for a turn and Di's contribution grows in an exponential progression with increasing load factor.
Here's the kicker which you are missing. The FW-190 already has greater induced drag than the lower wing-loaded aircraft at 1g. This doesn't change at 2g's, 3g's, or 4g's etc. Infact Di's contribution to the % of total drag increases dramatically so that the higher induced drag of the 190 becomes more pronounced vs. the lower wing-loaded aircraft.
I'm tempted to post a table of calcs for you but I don't want to because my sense is that the only way you'll believe it is if you do the calcs yourself and visualize what is happening.
My calcs aren't wrong Gripen....And post them in English units NOT metric, as mine are in, which you think are wrong.
Like gripen said your total drag values don't seem to be in line with anything. If they are in lbs as you say then those values are way low.
Another alternative to try and understand why a better turning plane may lose E slower than a higher wingloaded plane is to study Badboy's EM chart he has posted and what he has stated.
Tango, XO
412th FS Braunco Mustangs
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The math is for 1g level flight. This is irrelevant if you're trying to compare total aircraft drag in a turn. We've been asking you to calculate total drag in a turn.
I did and your right a higher wingloaded A/C does loose more energy in a turn. The Cdi increases dramatically. However I don't think it works like you are claiming.
First we know speed must increase or the A/C will have to trade it's speed to maintain altitude.
At speed:
At high airspeeds, parasite drag is dominant and induced drag becomes almost negligible.
http://www.av8n.com/how/htm/4forces.html#sec-induced-vs-parasite
You seem to be saying the Cl increases throughout the turn.
Now we know the force of lift does not change:
http://www.av8n.com/how/htm/4forces.html#fig-force-ias
And the Cl goes down with speed:
http://www.av8n.com/how/htm/4forces.html#fig-coeff-ias
The Load factor is increased when G's are pulled:
http://www.av8n.com/how/htm/aoastab.html#fig-secant
And consequently:
When you enter a spiral dive, the wing area of the airplane doesn’t change, the density of the air (ñ) doesn’t change, and the coefficient of lift doesn’t change much, either.
http://www.av8n.com/how/htm/aoastab.html#eq-lift-again
So for the intial bank and angle of attack change you will get a penalty in a higher wingloaded plane from increased induced drag. The rest of the high speed, high load turn the plane with the highest parasitic drag will be taking the biggest hit.
I came across a great diagram on the site but I can't find it now. I will look for it in the morning. Basically it showed that once the bank was made and speed increased, the relative wind was changed to the vector the aicraft was traveling in a co-ordinated turn. In other words it was just like forward flight.
Crumpp
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Originally posted by Crumpp
My calcs aren't wrong Gripen.
The wing area I used for the P51D is: 234.976 sq ft.
That is a misprint. The Cl's are correct, however and feel free to calculate them yourself.
And post them in English units NOT metric, as mine are in, which you think are wrong.
The lift coefficient is a dimensioless value. If calculation is correct Cl will be same regardless used unit system. And your Cl values are not true for 1 g and your drag values are not true for Lednicer's flat plate areas at 300 mph near sea level (real values are somewhere around 5000 N).
Originally posted by Crumpp
You list the wingtip E factor as .8 and the mustang as .75. Where did you get this data? You list the Spitfires as .95 while the NASA site clearly says the Spitfire had an E factor of 1.
Just study the Figure 2 in the Lednicers paper. The lift distribution of the Spitfire is not fully elliptical while best of the three. My numbers are purely approximated but probably quite close to the real.
Originally posted by Crumpp
Yet this Aircraft has E factor of .95. Niether the FW 190's wing tips or the P51's were "square".
http://www.anycities.com/user/j22/j22/index.htm
Well, I don't put much weight to that site; the author uses same Cd0 for all Spitfire models despite radiator changes and Cd0 seems to be value which actually is total Cd in the Lednicer's paper.
Originally posted by Crumpp
And quit carrying your feelings in a glass jar. Last thread as soon as you were questioned you became extremely rude. Your starting it again.
Well, in last thread someone called me butthead, lawyer etc. And somehow you concluded that my statement that Clo of the wing profile must be tested in the wind tunnel means that 3D to 2D conversion is impossible according to me. And you also came up with numbers which you could not explain despite requested.
gripen
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I did and your right a higher wingloaded A/C does loose more energy in a turn. The Cdi increases dramatically.
Great, now we're getting somewhere! :)
However I don't think it works like you are claiming.
Let's work on this now...
I'm not sure where you thought I was saying Cl increases in a turn. It would only increase if the pilot increased the AOA to pull a tighter turn.
And the Cl goes down with speed:
Remember we covered this before and you said you got it? Cl does not vary with speed. It varies with AOA.
If you decide to dive and gain airspeed yet maintain the same turn performance your Cl is not going to decrease at all because you'd be at the minimun holding the AOA for the turn you want. If you relaxed your turn then sure your Cl would go down but Cl varies with AOA not airspeed. Whatever the case calculating drag in a dive still uses the CD = CD0 + CDi relationship for starters.
2ndly when you're in a dive the vectors change as well. The relationship that T opposes D directly and L opposes W directly no longer hold as they do for level flight.
In a dive the force equation we're interested in is:
F = T + Wsin(dive angle y) - D
Now you have a portion of weight that is counteracting drag as well. Infact it becomes very significant and more pronounced the steeper the dive angle.
For instance for an 8000 lbs aircraft, just at 10 degrees dive your adding an extra 1389 lbs of thurst force offset against total drag.
Tango, XO
412th FS Braunco Mustangs
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Well, I don't put much weight to that site; the author uses same Cd0 for all Spitfire models despite radiator changes and Cd0 seems to be value which actually is total Cd in the Lednicer's paper.
Yes he mentions the radiator changes. It is not just the radiator. It's the windshield is too far sloped on the Spitfire and the boundry layer seperation for the cooling system occurs just inside the ducting from what I read, not in the entrance.
You can see a late Mk Spitfires radiators here:
http://www.flightjournal.com/fj/store/viewissue.asp?issueid=BSFG
Down at the bottom.
And your Cl values are not true for 1 g and your drag values are not true for Lednicer's flat plate areas at 300 mph near sea level (real values are somewhere around 5000 N).
For the Cl calcs, the only thing that changes is "r" and the rest is easy. Make up a velocity and plug it inot the formula. I cross-referenced my "r value with the constant you use and it behaved exactly as it should. Close but a fraction less dense because the constant is figured at a lower tempature. I did not use the flat plate areas. I used the wet area.
The math is the math Gripen. You run it through the formula and it spits out the numbers. Again we are missing some of the Details.
You are assuming the A/C is at full throttle (horsepower and exhaust thrust). In order to fly at that Airspeed all of the planes must throttle back.
Well, I don't put much weight to that site; the author uses same Cd0 for all Spitfire models despite radiator changes and Cd0 seems to be value which actually is total Cd in the Lednicer's paper.
He does the same for the FW-190. His calculations apply to an FW-190A8 and a Spitfire IX LF from what I read. You keep thinking the radiator problem was fixed. That is Davids point. It was not.
How come you keep trying to discredit this guy? Do you think he is on an agenda to make his favourite fighter better? All human beings make mistake, but I would have to say this guy is much more qualified than anyone here. Is anyone here published in one of the leading homebuilt aircraft organizations in the world periodicals? Does anyone here work for a engineering firm specializing in fluid mechanics and flow problems? Is anyone here an aeronautical engineer?
Calculations at our level are fine for very simple, simple problems. Reading to much into them however is dangerous and can lead to wrong conclusions. It's the same thinking as:
If you live in New Jersey you are an American. Therefore all Americans are from New Jersey.
It still does NOT explain why the fundatmental forces in high speed turn do not act, at least according to the Flight instructor and PhD., like it claimed in this forum. The CL does not change from level flight much. Yet the claims here is that it does. I can see where it would be needed to change the vector. Once the vector is changed however the plane will follow the new vector until acted upon by other forces.
Nor does it explain why our planes self recover from a steep bank.
Well, in last thread someone called me butthead, lawyer etc. And somehow you concluded that my statement that Clo of the wing profile must be tested in the wind tunnel means that 3D to 2D conversion is impossible according to me. And you also came up with numbers which you could not explain despite requested.
I am not going to play the he said she said game. Anybody that is interested can simply read the thread. In my book, you have blown your credibility on several points. If you want to rediscuss that the feel free to start a new thread.
http://www.hitechcreations.com/forums/showthread.php?s=&threadid=125882
Getting back to the subject.
If the spitfire is so efficient in the High Speed Turn then why are they not being used in the Unlimited class racers? The later Mk Spitfire certainly should be able to compete. Yet we see the heavier wingloaded and less draggy aircraft like the P51 being used.
Crumpp
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Originally posted by Crumpp
Yes he mentions the radiator changes. It is not just the radiator. It's the windshield is too far sloped on the Spitfire and the boundry layer seperation for the cooling system occurs just inside the ducting from what I read, not in the entrance.
This has nothing to with credibility of the J22 site. The author there does simple and clear errors in his analyses as noted above.
Originally posted by Crumpp
For the Cl calcs, the only thing that changes is "r" and the rest is easy.
If it is so easy why you can't do it?
Originally posted by Crumpp
I did not use the flat plate areas. I used the wet area.
Do a little math: Multiply the wet area with the Cdwet, just like you do in the drag formula. What is the number you get?
Originally posted by Crumpp
I am not going to play the he said she said game. Anybody that is interested can simply read the thread. In my book, you have blown your credibility on several points. If you want to rediscuss that the feel free to start a new thread.
Actually it's you who started to talk about that thread and now you are blaming me for that.
gripen
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I'm not sure where you thought I was saying Cl increases in a turn. It would only increase if the pilot increased the AOA to pull a tighter turn.
That is where their rub lays. He does not constantly change angle of attack. Aircraft move on using the laws of vector motion.
First Newtons Laws of Motion:
http://www.grc.nasa.gov/WWW/K-12/airplane/newton1.html
http://www.grc.nasa.gov/WWW/K-12/airplane/newton1a.html
http://www.av8n.com/how/htm/motion.html#sec-straight-line-motion
Aircraft manuver using the laws of vector motion. Each vector has a manitude and direction.
http://www.grc.nasa.gov/WWW/K-12/airplane/newton2.html
Each vector has a quality:
http://www.grc.nasa.gov/WWW/K-12/airplane/vectors.html
Once you input the controls, the A/C changes to a new vector and flies along it. If you max out the control inputs at the begining of the turn then you have no more input into the vector. In fact in a maximum turn it is not uncommon for the pilot to end up using maximum rudder and opposite alerion to stop the aircrafts natural tendancy to tighten the turn (overbanking tendancy) and dive.
It is interesting to combine this with what we learned about long-tail slip effect (section 8.9) --- in the slow, steeply banked turn in the glider, you would be holding nearly full inside rudder (to prevent the long-tail slip) and nearly full outside aileron (to counteract the overbanking tendency). If you are not expecting this, it will appear very strange. You are holding completely crossed controls, yet the turn is perfectly coordinated. You can confirm this by observing that the slip string is perfectly centered.
Once you change vector with maximum A/C control input the Aircraft will stay on that vector until control input is changed. When you enter the turn the relative wind changes and while you are on that vector the wing act pretty much like it is in level flight except for assymetrical lift. You will suffer a Cdi hit only when the lift goes up to input the vector change. The instant the forces balance your back in level flight where parasitic drag and speed take over traveling on a new vector. You are assuming the Cl goes up throughout the turn.
This is assuming of course full control inputs and full power which is how 99 percent of the break turns we see in AH are conducted.
BTW. I emailed several aeronautical engineers to find out exactly why the Cl does not go up much in the turn just to confirm.
Remember we covered this before and you said you got it? Cl does not vary with speed. It varies with AOA.
Huh? All I did was post this link I believe. You can see that it does go down by calculating it.
http://www.av8n.com/how/htm/aoa.html#fig-ias-cl
If the airspeed goes down, the coefficient of lift must go up. This relationship is illustrated in figure 2.13.
Cl had a direct relationship with AoA but an inverse relationship to velocity.
Crumpp
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I give up. I've spent far too much energy on the topic.
You are throwing information out all over the place trying to act like you know what you're talking about when infact you don't.
Now you're saying that I said things that I didn't even say - e.g. I never said Cl increases in a turn by definition.
Also you're inferring that you have better access to knowledge than any of us here. Have you considered that I speak with aero engineers or that some of the folks posting here have aero backgrounds?
And lastly your memory is slipping. Look back over the thread regarding the Cl discussion and see what we said about it.
I'm done.
Tango, XO
412th FS Braunco Mustangs
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If it is so easy why you can't do it?
I did it and posted the results.
You are throwing information out all over the place trying to act like you know what you're talking about when infact you don't.
No, actually I don't claim to know all that much about it except for the fact I am getting my pilots license.
I am just trying to reconcile what folks are saying on this BBS with what aerodynamic experts say.
Also you're inferring that you have better access to knowledge than any of us here. Have you considered that I speak with aero engineers or that some of the folks posting here have aero backgrounds?
Sure and I have enjoyed our discussions. I am not inferring anything. Just seeking clarification. Sorry that offends you.
Well, from the Fw 190A-1 onwards all the A-series Fw 190s had same wing area and span so these all had same aspect ratio 6,02 (18,3 m2 and 10,5 m). Some early A-0s had smaller wing which had aspect ratio 6,07 (14,9 m2 and 9,51 m).
I would have to Email you a copy of the original documentation.
This whole thing boils down to:
1. It either like is being claimed here and CL goes up dramatically throughout the turn hence Cdi has a large effect on turn forces
or
2. It is like the PhD. claims - The Cl does not go up in a turn and therefore Cdi doesn't factor in as much as the parasitic drag does in our turn forces.
3. There is an unknown element which is missing from the puzzle.
Crumpp
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Well, from the Fw 190A-1 onwards all the A-series Fw 190s had same wing area and span so these all had same aspect ratio 6,02 (18,3 m2 and 10,5 m). Some early A-0s had smaller wing which had aspect ratio 6,07 (14,9 m2 and 9,51 m).
BTW your correct. Area and Span did not change The cord did though.
The maximum distance between the upper and lower surfaces is called the thickness. Often you will see these values divided by the chord length to produce a non-dimensional or "percent" type of number.
The wing was made thicker to provide more room for the outboard MG 151's.
Crumpp
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My absolute last reply for clarity -
To turn your CL has to increase ABOVE what is necessary for level flight.
To maintain a turn your CL has to remain above what is necessary for level flight. This does not mean CL is increasing in a turn. This does mean that CL has to remain above what is needed for level flight.
To determine contribution of CDi to drag in a turn even with nose low just simply evaluate the CD = CD0 + CDi relationship. You said you've done the math which showed you the relative difference between planes in a level turn. The relationship doesn't change much in a nose low situation.
Best of luck understanding the concepts.
Tango, XO
412th FS Braunco Mustangs
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To turn your CL has to increase ABOVE what is necessary for level flight.
Right you have to change the vector. The Cl jumps up after you bank and pull back on the yoke.
The PhD sent me a reply.
Basically he says it depends on the control inputs. If you max out or hold the same control input then the Cl is the same as level flight. If you have more yoke and you pull it then the CL will go up again.
From what I understand then:
Your stick inputs in the turn will control the amount of Cdi in the turn as long as you don't let your speed drop to much. Just like the Cl the Cdi changes based on the angle of attack to the relative wind.
The relationship doesn't change much in a nose low situation.
Except that the heavier plane will begin to add it's mass to thrust, right?
Crumpp
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Originally posted by Crumpp
I did it and posted the results.
Why your results are not right then? Why don't you post your step by step calculation so we can see what goes wrong?
Originally posted by Crumpp
BTW your correct. Area and Span did not change The cord did though.
The aspect ratio is a simple relation between the wing span and the wing area.
Regarding drag in the turn here is a little quick and dirty comparison at different g loads calculated with Lednicer's flat plate values. Speed is 483km/h ie 300mph and e factor is same for all planes (0,8).
Spitfire IX 3400 kg
1g 5524 N
2g 6481 N
3g 8074 N
4g 10305 N
5g 13174 N
6g 16680 N
P-51B 4200 kg
1g 4716 N
2g 6162 N
3g 8573 N
4g 11947 N
5g 16286 N
6g 21589 N
Fw 190A 4000 kg
1g 5340 N
2g 6854 N
3g 9377 N
4g 12910 N
5g 17452 N
6g 23003 N
The values show how drag of the Spitfire increases at much lower rate than in the other two planes.
gripen
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Why your results are not right then? Why don't you post your step by step calculation so we can see what goes wrong?
There is nothing wrong with my calculations.
Gripen first you calculate the density.
Use the equation of state with the measured values since we are sea level and don't have to account for tempature and pressure changes at altitude.
Tempature - 65*F
Pressure - 14.696psi
http://www.grc.nasa.gov/WWW/K-12/airplane/atmos.html
r= .00163029
Then work the Cl formula in English units.
The aspect ratio is a simple relation between the wing span and the wing area.
Yes and I have said of have original documentation that shows an aspect ratio change. And it is not in the V5. It is in the FW-190A6.
Regarding drag in the turn here is a little quick and dirty comparison at different g loads calculated with Lednicer's flat plate values.
Please show me HOW you are applying the force of G's to the Airframe. The G forces the plane experiences are not the same as what the pilot experiences in a turn. The plane is in its flight envelope and is simply flying on a new vector. It only experiences G's for a few seconds at the begining of the vector change. The pilot, who has no thrust or lift, is trying to move on a different vector and experiences different forces.
If that was the case then calculate the Cl and compare it to the max Cl for the Spitfire. If Clmax is 1.1 like Izzy posted then the Spitfire is incapable of flying a vector that loads the Cl with more than a couple of G's.
Crumpp
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Please show me HOW you are applying the force of G's to the Airframe. The G forces the plane experiences are not the same as what the pilot experiences in a turn. The plane is in its flight envelope and is simply flying on a new vector. It only experiences G's for a few seconds at the begining of the vector change. The pilot, who has no thrust or lift, is trying to move on a different vector and experiences different forces.
If that was the case then calculate the Cl and compare it to the max Cl for the Spitfire. If Clmax is 1.1 like Izzy posted then the Spitfire is incapable of flying a vector that loads the Cl with more than a couple of G's.
Crumpp, email this to your Phd friend, let him try explain it to you.
HiTech
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Actually Hitech,
I already went over to some buddies of mine that are fighter pilots. I work practically on top of an Air Force Base.
Talk about a bunch of guys who love to talk theory about airplanes. Well it started a "heated discussion" among too guys with a Master's in Aeronautical engineering...
Not attempting to educate anyone here just spelling it out how they explained it.
I misunderstood the "G" application and the plane does experience G's in a Break turn. It's not flying a vector and is constantly changing its vector due to the nature of the turn.
The forces are totally different from a coordinated turn.
On the rest of the turn:
The short answer they ended up giving me was...It Depends.
All on the stick inputs.
There is no doubt that when the Cl goes up the Cdi goes up much more so than parasitic drag.
If the pilot makes a coordinated turn then the Cl does not change much at all. He makes a break turn and keeps cranking back then yes:
1. The plane loses lots of altitude at once. In fact they usually make a quick climb then do the break turn.
2. And break turns put the brakes on fast and will kill your speed no matter what the wing loading of the plane. Because of your rapid speed loss the angle of attack does constantly change and the plane does experience constant G's.
Break turns are purely defensive moves according to them. Any pilot that started a fight off with one was putting himself in hurt locker energy wise. It was definitely NOT the preferred method to use at the merge!!
So between High induced drag and low parasitic drag, in the break turn the induced drag does become the dominant force. It is better to have higher parasitic drag and lower induced drag for break turns. In level speed and zoom climb it is better to have the lower parasitic drag.
However NOBODY should be want to make a break turn except for immediate survival.
BTW I just noticed:
According to Gripens Calculations the Spitfire and FW-190 keep about the same ratio of mass to force throughout with the FW-190 pulling out ahead the higher the G's. The clear winner in that line up is the P51! It has less force acting on it and more mass. The Spitfires appears much lower but since it is a much lighter plane it does not need as much force to put the brakes on.
Crumpp
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2. And break turns put the brakes on fast and will kill your speed no matter what the wing loading of the plane. Because of your rapid speed loss the angle of attack does constantly change and the plane does experience constant G's.
That is it depends.
AOA Might be constantant and G's decresing with a loss in speed,
AOA And G Might be constantant and altitude is lost.
G Might be constant and AOA Increases as speed is lost
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That is it depends.
AOA Might be constantant and G's decresing with a loss in speed,
AOA And G Might be constantant and altitude is lost.
G Might be constant and AOA Increases as speed is lost
Yep,
Any of those scenarios though the fighter conducting the break turn ends up with a lot less energy than he started the turn with.
It Depends....Engineers Number 1 answer to everything!!
:(
Crumpp
-
Originally posted by Crumpp
There is nothing wrong with my calculations.
Actually there is quite a lot of wrong in your calculations.
Originally posted by Crumpp
Gripen first you calculate the density.
Use the equation of state with the measured values since we are sea level and don't have to account for tempature and pressure changes at altitude.
Tempature - 65*F
Pressure - 14.696psi
http://www.grc.nasa.gov/WWW/K-12/airplane/atmos.html
r= .00163029
Let's calculate it first right.
Density formula from the NASA site, note the units:
r = p / [1718 * (T + 459,7)]
where:
r = density (slugs/cu ft)
p = pressure (lbs/sq ft)
T = temperature (*F)
So we have:
T = 65*F
p = 14,696 psi = 2116,224 lbs/sq ft
And the density calculation:
2116,224 / [1718 * (65 +459,7)] = 0,002347618 slugs/cu ft
Then Cl calculation for the Fw 190, again note the units:
Cl = L / (A * .5 * r * V^2)
where:
L = Lift (lbs)
A = Wing Area (sq ft)
r = Density (slugs/cu ft)
V = Speed (ft/s)
So we have:
L = 4272 kg = 9418 lbs
A = 18,3 m2 = 197 sq ft
r = 0,002347618 slugs/cu ft
V = 300 mph = 440 ft/s
And the Cl calculation:
9418 / (197 * 0,5 * 0,002347618 * 440^2) = 0,210394
So what went wrong in you your calculation? Obivioysly you have used wrong pressure unit for density calculation because using the psi value results:
0,0000163029
Funny thing is that you have accidentally or purposedly multiplied the result with 100 to get sensible result.
And similar error can be found from the Cl calculation; because your result was:
FW-190 Cl = .651727567
we can easily see that you have used mph value instead ft/s. It's very probable that you have done similar errors also in the drag calculation too.
Originally posted by Crumpp
Yes and I have said of have original documentation that shows an aspect ratio change. And it is not in the V5. It is in the FW-190A6.
Aspect ratio is simply:
AR = S^2 / A
where:
AR = aspect ratio
S = wing span
A = wing area
So if the wing span and the area were unchanged (as you claimed above), there should be no difference in the AR.
Originally posted by Crumpp
Please show me HOW you are applying the force of G's to the Airframe.
Hm... Actually we are just interested about needed lift and that is simply:
L = g * w * 9,81
where:
L = lift (N)
g = g load
w = weight of the plane (kg)
9,81 = normal acceleration (m/s2)
Originally posted by Crumpp
If that was the case then calculate the Cl and compare it to the max Cl for the Spitfire. If Clmax is 1.1 like Izzy posted then the Spitfire is incapable of flying a vector that loads the Cl with more than a couple of G's.
Well, the Cl values are naturally part of the calculation and therefore allready calculated:
Spitfire IX 3400 kg (483 km/h):
1g Cl=0,135
2g Cl=0,269
3g Cl=0,404
4g Cl=0,539
5g Cl=0,674
6g Cl=0,808
7g Cl=0,943
8g Cl=1,078
Regarding the Clmax value of the Spitfire, this has been discused earlier and RAE data gives Clmax 1,36 in glide and 1,89 at full power. The NACA values are quite questionable due to the condition of the tested plane and the testing methods.
gripen
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Actually there is quite a lot of wrong in your calculations.
Not really so don't be a drama queen. I missed two units. Psi instead of PSF and MPH instead FPS.
Not bad for the very first time calculating Cl's.
For Drag I used CDwet from David's article and the Wet Area. Because my "r" was not converted to the correct units then it threw the calculation off.
Aspect ratio is simply:
I know the formula and have posted it. I have also said SEVERAL times that this comes from Original Documentation!! The FW-190A4 that was captured by the RAF has an aspect ratio according to them of 5.8. The Luftwaffe says the FW-190A8 had 6.01. Only wing change to the FW-190 was in the FW-190A6 in order to make room for the Mg151 outboard cannon. Additionally the wing was "modified to provide extra lift to off-set weight gain in the design" according to the Luftwaffe. How exactly it was modified, besides the obvious external modifications which have nothing to do with lift, is unknown.
Now those are the facts. This is one of the things I am digging into to find out what is up. I am NOT nor am I, about too, start standing up and crowing about it. Right now I am searching for pre-FW-190A6 Luftwaffe documentation which shows the Aspect Ratio. And of course Pre V5.
Got a reply back on the Cl increase in a steep bank From an aeronautical engineer:
You asked:
>> Why doesn't the lift co-efficient go up in a Steep turn?
Maybe it does, maybe it doesn't.
The yoke (and trim) give the pilot powerful control over
the coefficient of lift.
LOL Again it all depends on the control input!!!
Regarding drag in the turn here is a little quick and dirty comparison at different g loads calculated with Lednicer's flat plate values. Speed is 483km/h ie 300mph and e factor is same for all planes (0,8).
Those look pretty good. I will check them after I recalculate "r" in the correct units. The P51 is way ahead of the FW-190 and the Spit. The FW-190 is ahead of the Spitfire in parasitic drag. It is interesting to note that that:
According to Gripens Calculations the Spitfire and FW-190 keep about the same ratio of mass to force throughout with the FW-190 pulling out ahead the higher the G's. The clear winner in that line up is the P51! It has less force acting on it and more mass. The Spitfires appears much lower but since it is a much lighter plane it does not need as much force to put the brakes on.
Crumpp
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I don't think that an a/c which is good in retaining E can be good in braking its speed. Meaning that a Spit is forced through a tight turn by its wing area whereas aircraft with higher wing loading will "slip through" in a high G turn and thus brake more efficiently.
Of course a larger braking area is better but here the wing profile comes into play. The elliptical design produces lift with less drag as everything that causes most drag in wing design is left off (->maximum wingarea with least drag). This in turn causes that the elliptical design is not very good in high AoA ->thus the washout in the wing to make it conrollable in high AoA. But what does the outer portion of the wing in level flight as its AoI is different from the root? I find it strange if it manages to produce lift the same way the root does.
:confused:
-C+
-
I don't think that an a/c which is good in retaining E can be good in braking its speed. Meaning that a Spit is forced through a tight turn by its wing area whereas aircraft with higher wing loading will "slip through" in a high G turn and thus brake more efficiently.
I don't beleive the spit was known for retaining E. It was a great turner and master of the spiral climb.
Just read the numbers.
The point is the Spitfire due to it's higher parasitic drag but lower wingloading produced about the same ratio of breaking forces to mass as the FW-190 which has lower parasitic drag but higher induced drag. That ratio favours the FW-190 the more G's you pull.
It's numbers appear lower but it is a light plane and doesn't require as much force.
Crumpp
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I don't think that an a/c which is good in retaining E can be good in braking its speed.
This is a reasonable generalization to make If you do not allow to pull more than x G, but you must be careful with the details. You should also remember that pulling on the stick is not the only way to bleed energy.
Bozon
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Originally posted by Crumpp
Not bad for the very first time calculating Cl's.
So now you announce that screwing up completely a very simple calculation is not bad. Well, maybe in the elementary school.
Originally posted by Crumpp
I have also said SEVERAL times that this comes from Original Documentation!! The FW-190A4 that was captured by the RAF has an aspect ratio according to them of 5.8. The Luftwaffe says the FW-190A8 had 6.01.
The RAE paper gives just a quick and dirty wing area. There was no change in the wing area from the Fw 190A-1 to Fw 190A-9 according to original german documentation.
Originally posted by Crumpp
Right now I am searching for pre-FW-190A6 Luftwaffe documentation which shows the Aspect Ratio. And of course Pre V5.
Well, I have such documentation on my table, not difficult to find.
Originally posted by Crumpp
Got a reply back on the Cl increase in a steep bank From an aeronautical engineer:
"You asked:
>> Why doesn't the lift co-efficient go up in a Steep turn?
Maybe it does, maybe it doesn't.
The yoke (and trim) give the pilot powerful control over
the coefficient of lift."
LOL Again it all depends on the control input!!!
So now you loudly announce that an aeronautical engineer told you that there is a connection between controll input and lift coefficient. That might sound earth shaking but I believe pretty much every one here allready knows that.
Originally posted by Crumpp
According to Gripens Calculations the Spitfire and FW-190 keep about the same ratio of mass to force throughout with the FW-190 pulling out ahead the higher the G's. The clear winner in that line up is the P51! It has less force acting on it and more mass. The Spitfires appears much lower but since it is a much lighter plane it does not need as much force to put the brakes on.
You can't draw anykind of conclusions on turning performance based on the total drag only. What we need to know is the relation between thrust and drag (excess power). These can be easily added to the calculation and with the excess power (positive or negative) and the mass of the plane, we can also easily calculate forward acceleration (positive or negative). As an example below are accelerations calculated for couple planes at 483 km/h at sea level. Note that flat plate areas are now calculated same way as in the Lednicer's paper (Cdwet includes Cdi and Cd=1 for flat plate) and thrust is calculated assuming 85% efficiency and 120 kp exhaust thrust:
Spitfire IX (average), 3400 kg, 1586 hp, flat plate area 6,18 sqft, e factor 0,9
0g 0,74 m/s2
1g 0,66
2g 0,41
2,99g 0
3g -0,01
4g -0,59
5g -1,34
6g -2,26
P-51B 4128 kg, 1480 hp, flat plate area 5,23 sqft, e factor 0,8
0g 0,76 m/s2
1g 0,64
2g 0,30
2,58g 0
3g -0,26
4g -1,05
5g -2,06
6g -3,31
Fw 190 (US Navy) 3940 kg, 1740ps, flat plate area 6,69, e factor 0,8
0g 0,70 m/s2
1g 0,57
2g 0,20
2,38g 0
3g -0,42
4g -1,29
5g -2,41
6g -3,77
So here we can see that the only g load where the P-51 does higher acceleration than the Spitfire is 0 g. The max continous g load at 483 km/h is that value where the acceleration is zero and at higher g loads deacceleration shows relative decrease of the speed at given g load, the Spitfire being clearly better than other two.
It should be noted that above flat plate areas give same sea level speed values as in the real world tests:
Spitfire IX 539 km/h (A&AEE average)
P-51B 560 km/h (USAAF test)
Fw 190 537 km/h (US Navy test)
Lednicer's values would have resulted over 350 mph sea level speed for all planes.
Originally posted by Crumpp
I don't beleive the spit was known for retaining E. It was a great turner and master of the spiral climb.
Just read the numbers.
Well, actually the point is to understand numbers not just read them.
gripen
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The RAE paper gives just a quick and dirty wing area. There was no change in the wing area from the Fw 190A-1 to Fw 190A-9 according to original german documentation.
Which ONE Gripen? There are quite a few reports. LMAO!
You don't even know what report I am refering too. One I have offerred to provide you free of charge. A report which cost almost 200 US dollars to get a copy of from the National Archives. I would say I have been more than generous.
So now you announce that screwing up completely a very simple calculation is not bad. Well, maybe in the elementary school.
It is no more than High School Algebra. I am sure YOU have never made an error. So I got 2 units wrong. Simple conversion and a Simple fix to recalculate. :eek:
However you want to make out like it's huge deal. :rolleyes:
Between fixing my math and you solving your insecurities, I have the far easier task!
Well, I have such documentation on my table, not difficult to find.
Good for you. Thanks I was hoping it would not be hard to find.
So now you loudly announce
It's a Bulletin Board, you can't loudly announce anything. I just thought it was funny the vague response. However, if you were the aeronautical guru you pass yourself off as, you could have saved everyone some time and simply explained it. Since you did not, then obviously you were just like the rest of us and probably learned something in this thread too.
Ohh, And you can do High School Level Algebra better than I can.
:aok
Lednicer's values would have resulted over 350 mph sea level speed for all planes.
Looks to me like all three could do 350 on the deck pretty easily:
Spitfire Mk IX LF - LOOKS like 350 mph to me! Aren't the Spitfire fans always complaining that this data is too slow??
http://www.fourthfightergroup.com/eagles/jl165speed.gif
http://www.fourthfightergroup.com/eagles/jl165.html
FW-190A8 - LOOKS like 350 to me!
http://www.terra.es/personal2/matias.s/fw190-1.jpg
Do I need to post the P51B speed? It was 50 - 70 mph faster than both the FW-190 AND the Spitfire....
the Spitfire being clearly better than other two.
Yeah If I was a Spitfire Fan I would probably recalculate those numbers too.
Sorry Gripen. Looks like fandom to me and an attempt to discredit an actual aeronautical engineer whose analysis is both transparent and public. Not mention one with lots more resources and knowledge to figure out the deal than you with a 5 dollar calculator.
You can't draw any kind of conclusions on turning performance based on the total drag only.
Nobody is drawing any turn performance conclusions. The answer was in braking forces which the FW-190 and the Spitfire are proportionally equal. In the sustained turn the Spitfire ruled supreme between the three.
Note that flat plate areas are now calculated same way as in the Lednicer's paper
Except your values are totally different and not his flat plate areas or CDwet? So how much access did you have to a detailed engineering computer analysis when you did them?
Your ***-U-ME-ing what values? Funny I don't remember reading those words in David's Article at all. In fact, he seems pretty adamant that aeronautical engineers should NOT do that. It leads to the wrong conclusions!
Here you can read it again and look for the assuming part:
http://www.thetongsweb.net/AH/EAAjanuary1999.pdf
Crumpp
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Originally posted by Crumpp
Which ONE Gripen? There are quite a few reports. LMAO!
RAE TN No.1231.
Originally posted by Crumpp
Looks to me like all three could do 350 on the deck pretty easily:
Spitfire Mk IX LF - LOOKS like 350 mph to me! Aren't the Spitfire fans always complaining that this data is too slow??
http://www.fourthfightergroup.com/eagles/jl165speed.gif
http://www.fourthfightergroup.com/eagles/jl165.html
FW-190A8 - LOOKS like 350 to me!
http://www.terra.es/personal2/matias.s/fw190-1.jpg
Do I need to post the P51B speed? It was 50 - 70 mph faster than both the FW-190 AND the Spitfire....
Now you are playing plain childish, those are all with higher ratings. The ouputs are mentioned above and the ratings are:
Merlin 66: +18 lbs 3000rpm 1586 hp at sealevel with RAM
V-1650-3: 67" 3000rpm 1480 hp at sealevel with RAM
BNW 801D: 1,42 2700rpm 1740 ps at sealevel with RAM
Originally posted by Crumpp
Nobody is drawing any turn performance conclusions. The answer was in braking forces which the FW-190 and the Spitfire are proportionally equal.
The thrust opposites drag and for one reason or another you don't want to count thrust.
Originally posted by Crumpp
Except your values are totally different and not his flat plate areas or CDwet? So how much access did you have to a detailed engineering computer analysis when you did them?
The guidelines to do simple drag and thrust analysis are given above. My values are calculated from the real world tested performance. If you are not happy with them, you can do your own analysis as several posters have said above.
Originally posted by Crumpp
Your ***-U-ME-ing what values? Funny I don't remember reading those words in David's Article at all. In fact, he seems pretty adamantq1qaz that aeronautical engineers should NOT do that. It leads to the wrong conclusions!
Lednicer says clearly (page 6) that his Cdwet values are for cruise lift coefficient ie the values contains induced drag. The flat plate Cd used can be easily calculated with the wet area and Cdwet.
gripen
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The thrust opposites drag and for one reason or another you don't want to count thrust.
And prop efficiency helps determine thrust. Your's is an AssUme - d VALUE. IN addition to several other key values. Don't see those words in David's analysis.
If you don't think prop efficiency counts ALOT then I will send you a spread sheet showing the Newtons.
RAE TN No.1231.
It is NOT the one I am refering too.
Now you are playing plain childish
No I am just having to deal with you.
ouputs are mentioned above and the ratings are:
I would say David knows the outputs and thrust of the A/C.
you can do your own analysis
I did and I have using Davids numbers. It is totally different from what your calculations with ASSUMED values say.
Lednicer says clearly (page 6) that his Cdwet values are for cruise lift coefficient ie the values contains induced drag.
You used his method but not his values.
And now your making assumptions and trying to pass them off as fact.
Crumpp
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Originally posted by Crumpp
And prop efficiency helps determine thrust. Your's is an AssUme - d VALUE.
I have checked the propeller efficiency with blade element theory (http://xoomer.virgilio.it/pconselv/Manuale/section3ingl.htm) and 85% efficiency seems to be reasonable. Besides it's same for all three. If you are not happy with 85%, you can do your own analysis and prove that assumption wrong, if you can.
Originally posted by Crumpp
It is NOT the one I am refering too.
So what? That report contain mentioned value but so far I have not seen any German documentation which claim AR 5,8 for the Fw 190.
Originally posted by Crumpp
I would say David knows the outputs and thrust of the A/C.
Lednicer's analysis is not based on output but on the drag data taken from tests and his wet area calculations.
Originally posted by Crumpp
I did and I have using Davids numbers. It is totally different from what your calculations with ASSUMED values say.
So far only calculation I have seen from you is just a totally srewed up 1 g drag calculation for 300mph. That proves absolutely nothing about my or Lednicer's numbers.
You must calculate the thrust, the induced drag as well as the Cd0 to check my numbers.
Originally posted by Crumpp
You used his method but not his values.
And now your making assumptions and trying to pass them off as fact.
As noted above, please check with the thrust and drag calculation if my numbers are true.
gripen
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I have checked the propeller efficiency with blade element theory and 85% efficiency seems to be reasonable.
I can read it and throw out a number too.
So what? That report contain mentioned value but so far I have not seen any German documentation which claim AR 5,8 for the Fw 190.
Why do you think I offered to send it too you!!
:eek:
Lednicer's analysis is not based on output.
Your isn't either. It's based off several assumptions.
So far only calculation I have seen from you
We are not comparing MY calculations to yours, Gripen.
You keep saying that David Lednicer's values are WRONG. To do so you are using a bunch of mathmatical assumptions and completely different values.
It does not pass the common sense test.
1. David Lednicer is a qualified Aeronautical Engineer working in the field.
2. He has access to AND uses the correct information for his calculations. He makes NO assumptions. IN fact he exposes several "assumptions" made about the P51.
3. He uses engineering tools and programs YOU don't have access too.
Go look up Assumed in the dictionary:
http://www.google.com/search?hl=en&lr=&ie=UTF-8&oi=defmore&q=define:assumed
That means you don't know! If your making assumptions YOU DON"T KNOW. It's the details that count NOT guessing.
Crumpp
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Originally posted by Crumpp
I can read it and throw out a number too.
So what's the efficiency according to your calculations? I found 85% perfectly fine.
Originally posted by Crumpp
Your isn't either. It's based off several assumptions.
Well, assumptions are mostly same for all compared planes so relative results should be comparable. The only difference is the e factor which according to Lednicer is better in the Spitfire than in other two .
Originally posted by Crumpp
We are not comparing MY calculations to yours, Gripen.
If you want to challenge my calculations on turning performance, the only way is to calculate and point out errors.
Originally posted by Crumpp
You keep saying that David Lednicer's values are WRONG. To do so you are using a bunch of mathmatical assumptions and completely different values.
I have noted that Lednicer's data seems to at least partially wrong. So far I have not found real world tested data which supports assumption that the Fw 190 had signifigantly lower drag than the Spitfire. Lednicer's admits directly that he has choosed the data which he believes to be best.
Originally posted by Crumpp
1. David Lednicer is a qualified Aeronautical Engineer working in the field.
Yes, he seem to be quite professional
Originally posted by Crumpp
2. He has access to AND uses the correct information for his calculations.
Large part of the data is available from the net and I also have copies of some other documents he uses.
Originally posted by Crumpp
He makes NO assumptions. IN fact he exposes several "assumptions" made about the P51.
Actually he admits directly that he has made assumptions as noted above.
Originally posted by Crumpp
3. He uses engineering tools and programs YOU don't have access too.
Anyone can do an output based analysis with accurate speed and output data without anykind of engineering tools. As can be seen above, this method appears to be quite accurate and perfectly fine for relative comparisons.
Besides, Lednicer's analysis contains no Cdi nor energy comparisons which are actually subject of this thread and which I have calculated above.
gripen
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the trouble with aerodynamics and many other science and engineering is that we can hardly improve over some initial accuracy.
Using "better" data will not improve much since the errors are not in the data but mostly in the model. Cooling drag, effects of the props on the airflow behind it and turbulance for example are complicated and therefore poorly modeled.
If you want to argue 50 mph error out of 350mph, i'll belive theory. If you want to argue anything under 10 mph for 350mph plane, no matter what super-computer and accurate data you use i'll only belive actual tests.
That's my confidence level. Yours might be different. Science is not entirely unlike faith.
Bozon
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The only difference is the e factor which according to Lednicer is better in the Spitfire than in other two .
Yes, and it was found to not be very different from the P51 or the FW-190. In fact it was not elliptical due to the wing twist of the Spitfire.
Your data is based on assumptions.
Bozon says:
Using "better" data will not improve much since the errors are not in the data but mostly in the model. Cooling drag, effects of the props on the airflow behind it and turbulance for example are complicated and therefore poorly modeled.
Totally Agree. However, David Lednicer's data is much more encompassing than anyone can present in this thread.
If you want to challenge my calculations on turning performance, the only way is to calculate and point out errors.
That issue is solved. Refer to Hitechs reply and the conditions that exist in a turn.
Your attempting to attack the validity of David Lednicer's analysis.
So far I have not found real world tested data which supports assumption that the Fw 190 had signifigantly lower drag than the Spitfire.
It does NOT have less drag than the Spitfire. Area per Area it has MORE drag than the Spitfire. When you factor in the fact that the FW-190 was a physically smaller aircraft with less surface area THEN it does have LESS parasitic drag. Big Difference.
Lednicer's admits directly that he has choosed the data which he believes to be best.
Yes, he picks the data he believed was the most accurate AND the BEST for ALL THREE PLANES.
You are accusing him of playing favorites.
Actually he admits directly that he has made assumptions as noted above.
No, He exposes assumptions OTHERS have made thereby making the point that assuming in aerodynamics leads to wrong conclusions.
Anyone can do an output based analysis with accurate speed and output data without anykind of engineering tools. As can be seen above, this method appears to be quite accurate and perfectly fine for relative comparisons.
No. You are not accurate and in fact are comparing aircraft that are different states of energy and trying to draw a conclusion.
Example - You list the Horsepower rating of the FW-190A (which one we don't know) at "Climb and Combat Power" for some models and "Emergency Power" for other FW-190A variants.
You have the horsepower for the BMW-801D2 at full throttle height yet you have the altitude set at sea level.
http://www.fourthfightergroup.com/eagles/merlin66hpchart.jpg
http://www.terra.es/personal2/matias.s/bmw801d-1024.jpg
By reading the charts above you can see the output of the BMW-801D2 was significantly lower at sea level and even lower at velocity. The RAF test is horsepower while flying and the dotted line on the NACA test of the BMW-801D2 is adjust for Horsepower at velocity.
Besides, Lednicer's analysis contains no Cdi nor energy comparisons which are actually subject of this thread and which I have calculated above.
Aeronautical engineers and Hitech answered that question already. IT DEPENDS on the stick inputs for the turn.
Your statement that Lednicer uses no CDi in his CDwet is correct. However it is completely contrary to your earlier statement of:
Lednicer says clearly (page 6) that his Cdwet values are for cruise lift coefficient ie the values contains induced drag.
Regarding Lednicer's flat plate values, it seems that these are for total drag ie include induced drag which mean that his values are actually quite close my quick and dirty values depending if flat plate area is calculated for Cd 1 or 1,28 (square).
So which is it?
Crumpp
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Originally posted by Crumpp
Yes, and it was found to not be very different from the P51 or the FW-190. In fact it was not elliptical due to the wing twist of the Spitfire.
Your data is based on assumptions.
I assume e factor 0,9 for the Spitfire and 0,8 for the other two. BTW you claimed e factor 1 for the Spitfire above.
Originally posted by Crumpp
However, David Lednicer's data is much more encompassing than anyone can present in this thread.
Well, my calculations are based on true tested data and resulting speed at given altitude is exactly same as measured in the test as well as relative performance between planes.
Originally posted by Crumpp
That issue is solved. Refer to Hitechs reply and the conditions that exist in a turn.
Well, as Hitech said 08-26-2004 09:30 PM:
"Do the math crumpp: That is the only thing that will even put a dent in this argument. We have all done the math. It is your turn."
And 08-26-2004 08:23 PM:
"Crumpp: You do not have the background to even begin to evaluate that situation.
You might wish to do a lot of research before making that statment. Infact you better be able to post exact numbers on the amount of speed loss for a given condition. If you can't post the calculations and numbers required for that evaluation. Then it is imposible to even make an evaluation on your claims. Please start listening to other people like sable,karnak,tango,gripen and myslef who do have a strong knowledge in this subject area."
So far you have not done any level turning calculations.
Originally posted by Crumpp
It does NOT have less drag than the Spitfire. Area per Area it has MORE drag than the Spitfire. When you factor in the fact that the FW-190 was a physically smaller aircraft with less surface area THEN it does have LESS parasitic drag.
Well, when someone says "less drag" it's a absolute scale not relative. And when someone says"lower Cd" it's a relative scale. So above you first admit that "It does NOT have less drag than the Spitfire" in the absolute scale. Great logic.
Originally posted by Crumpp
Yes, he picks the data he believed was the most accurate AND the BEST for ALL THREE PLANES.
Well, real world test data indicate that the Fw 190 had more drag (in absolute scale) than the Spitfire as pointed out above.
Originally posted by Crumpp
No. You are not accurate and in fact are comparing aircraft that are different states of energy and trying to draw a conclusion.
Well, the test data gives speed at given altitude and engine chart gives output. The rest is simple physics and energy state is given by you ie 300mph and same for all three planes.
Originally posted by Crumpp
Example - You list the Horsepower rating of the FW-190A (which one we don't know) at "Climb and Combat Power" for some models and "Emergency Power" for other FW-190A variants.
You have the horsepower for the BMW-801D2 at full throttle height yet you have the altitude set at sea level.
http://www.terra.es/personal2/matias.s/bmw801d-1024.jpg
By reading the charts above you can see the output of the BMW-801D2 was significantly lower at sea level and even lower at velocity.
I'm directly using that chart and it gives 1740 ps at sea level with RAM (2700rpm 1,42ata). And the critical altitude with RAM in the engine chart is 1400 m (same as in the A-8 speed chart) so I know that the curve is for top speed.
Originally posted by Crumpp
Aeronautical engineers and Hitech answered that question already. IT DEPENDS on the stick inputs for the turn.
Well, great logic again. What I have done is a quick and dirty comparison of momentary energy state change in various g loads. The stick input is adjusted for wanted g load and I have calculated resulting change in the energy state.
Originally posted by Crumpp
Your statement that Lednicer uses no CDi in his CDwet is correct.
Such statement I have not done:
"Lednicer says clearly (page 6) that his Cdwet values are for cruise lift coefficient ie the values contains induced drag."
This means that Cdwet value is for total drag.
"Regarding Lednicer's flat plate values, it seems that these are for total drag ie include induced drag"
This means that Cdwet value is for total drag too.
gripen
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Originally posted by gripen
Well, real world test data indicate that the Fw 190 had more drag (in absolute scale) than the Spitfire as pointed out above.
Hmm, to me it appears the FW 190 would reach equal or higher speeds than the Spitfire with less power involved.
At least the A-5 did 530 km/h at SL with 1490 HP, the Spitfire IX LF did 530-540 km/h with 1680 HP (with similair power, the A-5 did 560 km/h).
So the Spitfire had slightly more drag. Which is quite shocking, but logical, considering it`s "aerodynamics".
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I assume e factor 0,9 for the Spitfire and 0,8 for the other two. BTW you claimed e factor 1 for the Spitfire above.
Key words:
I assume
Well, my calculations are based on true tested data and resulting speed at given altitude is exactly same as measured in the test as well as relative performance between planes.
So are David Lednicer's!
How do you explain your thrust calculations with bogus data?
I'm directly using that chart and it gives 1740 ps at sea level with RAM (2700rpm 1,42ata). And the critical altitude with RAM in the engine chart is 1400 m (same as in the A-8 speed chart) so I know that the curve is for top speed.
Then you are using "climb and combat power" not "emergency power" where the BMW 801D2 developed 2050hp at full throttle height.
You need to reread the Merlin 66 (+18) output at sea level. the chart is adjusted for 400mph RAM. I highly doubt the Spitfire could do 400mph at sea level.
1. You are not using the full power settings for the FW-190 or depending on the Spitfire either.
2. If you are using full power for the Spitfire then it is outclassed at all levels speeds except for a narrow band above 22,000 feet. It is much more in the hurt locker than Fabers FW-190A3 vs Spitfire Mk IX Merlin 61 (+12) performance wise. If you compare it to the FW-190A5 (it's contemprary counterpart) it is even farther behind.
Fw 190 537 km/h (US Navy test)
US Navy Test is an FW-190A5 NOT an FW-190A8. You have added quite a bit of weight. This is easy to confirm in the fact that both aircraft are significantly faster at sea level using 1.42ata @ 2700U/min.
http://www.terra.es/personal2/matias.s/fw190_A5_speed.gif
http://www.terra.es/personal2/matias.s/fw190-1.jpg
Well, my calculations are based on true tested data and resulting speed at given altitude is exactly same as measured in the test as well as relative performance between planes.
What makes you think the above test's are not actual in-flight test. You need to pay attention to the details in those reports. The BMW-801D2 did not like US AVGAS. It consistently fouled spark plugs and quit at altitude. Additionally the aircraft was a recovered wreck serviced by mechanics not familiar with the type.
"Do the math crumpp: That is the only thing that will even put a dent in this argument. We have all done the math. It is your turn."
I did the math Gripen, Again THAT issue is resolved.
The issue at hand is your attempting to assassinate David Lednicer's calculations and work.
So far you have not done any level turning calculations.
So far I have Gripen. See ABOVE.
Well, when someone says "less drag" it's a absolute scale not relative. And when someone says"lower Cd" it's a relative scale. So above you first admit that "It does NOT have less drag than the Spitfire" in the absolute scale. Great logic.
In fact Gripen the drag lines up nicely with history. FW-190's did not angle fight with Spitfires and Spitfires did not Energy fight with 190's.
Why? Aerodynamically the FW-190 had less drag in level flight while the Spitfire had less drag in the turn. Combined with the Mass/Drag advantage FW-190's left the Spitfire behind in the zoom climb.
Well, real world test data indicate that the Fw 190 had more drag (in absolute scale) than the Spitfire as pointed out above.
Again, David Lednicer uses real world tested data in his calculations. You forget that the WRONG drag data for the P51 was REAL WORLD TESTED! The test just did not include details like the engine exhaust stacks!
Besides, Lednicer's analysis contains no Cdi nor energy comparisons which are actually subject of this thread and which I have calculated above.
Exactly and we are not comparing energy. If that was the case the FW-190 would win hands down. It has a lot more potential energy just sitting on the field. When you calculate its Cdi it is always going to be higher as it is a heavier aircraft. It also has more mass to overcome that force and requires much more force to brake.
We are comparing High G break turn performance. The Spitfire and the 190 would be close in energy bleed. The P51 way ahead of both. The Spitfire could, depending on it's CL max, turn a tighter circle and both Aircraft would have significantly lower energy at the end of the turn.
Problem with turning at high speed for the spitfire would be it's poor roll performance. It's aileron reversal speed was 540 mph and it's stick forces were high enough that it could not even get near it's calculated speed of roll at 400 mph.
Crumpp
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Originally posted by Crumpp
How do you explain your thrust calculations with bogus data?
Where do you see bogus data?.
Originally posted by Crumpp
Then you are using "climb and combat power" not "emergency power" where the BMW 801D2 developed 2050hp at full throttle height.
Well, all I need to know is the speed and output combination at what ever rating to calculate Cd0.
Originally posted by Crumpp
You need to reread the Merlin 66 (+18) output at sea level. the chart is adjusted for 400mph RAM. I highly doubt the Spitfire could do 400mph at sea level.
No, the output for the Spitfire IX is calculated using measured speed and measured FTH.
Originally posted by Crumpp
US Navy Test is an FW-190A5 NOT an FW-190A8. You have added quite a bit of weight. This is easy to confirm in the fact that both aircraft are significantly faster at sea level using 1.42ata @ 2700U/min.
Nonsense, the weight I used is same as in the US NAVY test ie 3940 kg.
Originally posted by Crumpp
What makes you think the above test's are not actual in-flight test.
Actually it's up to you to prove that those are really flight tested.
Originally posted by Crumpp
You need to pay attention to the details in those reports. The BMW-801D2 did not like US AVGAS. It consistently fouled spark plugs and quit at altitude. Additionally the aircraft was a recovered wreck serviced by mechanics not familiar with the type.
It's up to you to prove above.
Originally posted by Crumpp
I did the math Gripen, Again THAT issue is resolved.
No, you have not done any level turn calculation yet and you should also add thrust to your calculation.
Originally posted by Crumpp
Aerodynamically the FW-190 had less drag in level flight while the Spitfire had less drag in the turn. Combined with the Mass/Drag advantage FW-190's left the Spitfire behind in the zoom climb.
Actually it's level flight test data which indicates that the Fw 190 had more drag than the Spitfire.
Originally posted by Crumpp
Again, David Lednicer uses real world tested data in his calculations. You forget that the WRONG drag data for the P51 was REAL WORLD TESTED! The test just did not include details like the engine exhaust stacks!
Nonsense, Lednicer says that some wind tunnel data was without exhaust stack. All flight tested data contain all variables.
Originally posted by Crumpp
Exactly and we are not comparing energy.
Actually comparing energy drain is the whole point of this thread and that is exactly what I calculated and my calculation includes mass of the planes.
gripen
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This is getting childish, U all know that don't you?
It's great to read of all these theories and calculations but the personal pooooptossing makes it taste a bit sour..or pooop to be exact.
I guess it is just too much to expect people be able to argue things and at the same time respect different views.
Well, its a BBS after all. I guess this is the way how all discussions should be like. :D
I'm learning. :lol
-C+
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No, the output for the Spitfire IX is calculated using measured speed and measured FTH.
Read the bottom of the chart. The sentence in ENGLISH.
http://www.fourthfightergroup.com/eagles/merlin66hpchart.jpg
"Altitude Performance at 3000 rpm and 400mph RAM (80% pressure and 100% tempature)."
Actually it's up to you to prove that those are really flight tested.
Already been done.
Actually it's level flight test data which indicates that the Fw 190 had more drag than the Spitfire.
Not when you use David Lednicers tested values. What part of "the Navy was having engine problems with that FW-190 do you not understand" Perhaps you are missing information and would like the whole report?
Nonsense, Lednicer says that some wind tunnel data was without exhaust stack. All flight tested data contain all variables.
That is real world tested. What is more, those values continued to be passed around the aeronautical engineering community estabilishing themselves as fact.
Actually comparing energy drain is the whole point of this thread and that is exactly what I calculated and my calculation includes mass of the planes.
Again that issue is resolved. It depends.
Hmm, to me it appears the FW 190 would reach equal or higher speeds than the Spitfire with less power involved.
Absolutely. Just read the chart. At 1.32ata @ 2400 U/min the FW-190A5 matches the speeds of the Merlin 66 (+18) Spitfire.
http://www.terra.es/personal2/matias.s/fw190_A5_speed.gif
Crumpp
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Originally posted by Crumpp
BTW your correct. Area and Span did not change The cord did though.
The wing was made thicker to provide more room for the outboard MG 151's.
Crumpp
Crumpp at it again.:rolleyes:
area = length(span) x width(chord)
If the area (a constant) and span/length (a constant) did not change, then the chord/width can not change. Basic math.
The wing was not made thicker to fit the outboard MG151's greater height, blisters were added.
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Crumpp: This is just a sugestion from me, and it is only a suggestion.
There are 2 things I can see from your post.
1. Your extreamly intrested in what makes a plane fly.
2. You have only begun to have a very basic understanding of the physics.
After the 2 threads I have been involved with you on the physics of flight, it has become almost imposible and very very agravating to discuss flight physics with you. Other seem to be haveing the exact same frustration, note dtango's "wish you luck post, but im done post".
The resone for this agrivation, is that you only try to prove yourself correct. What you don't seem to do is try understand what others are saying.
Or ask your self the question, why are we comming up with different answeres. When data is in conflict, or solutions don't match, what normaly works best is to work with the person on the other side to come to a resone for the data conflict. This is done not by nit picking statments, but wrather work to clairfy premisses. Or work to try find the error in caculations. So wrather than saying your calc's are wrong, rephrase it to did your consider this in your caculations.
If you would try this aproch I belive the following would happen.
1. You would have quite a few people willing to talk about the topic's you love. Because guess what, they don't want to prove themselvs correct. They want to do 2 things.
1. Give their knowledge and excitment to others.
2. Pick up on new knowledge and thoughts that they hadn't seen or thought of before.
If you would try this aproch I belive you would increase your knowledge at a faster rate. You would also have a lot more fun.
Just some friendly advise for what it's worth.
HiTech
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Originally posted by Crumpp
Read the bottom of the chart. The sentence in ENGLISH.
http://www.fourthfightergroup.com/eagles/merlin66hpchart.jpg
"Altitude Performance at 3000 rpm and 400mph RAM (80% pressure and 100% tempature)."
As I have told you allready twice (08-27-2004 10:51 AM and 09-02-2004 04:56 AM) that the output for the Spitfire IX is calculated from the measured speed and FTH data using engine output chart. The result can be roughly confirmed from that chart. Besides that chart is not very good source because it mix up engines with different SC gear.
Originally posted by Crumpp
Already been done.
Where's the proof?
Originally posted by Crumpp
Not when you use David Lednicers tested values.
You are most welcome to calculate energy drain with Lednicer's values.
gripen
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Who says the final word?
Any bets?
:rofl
-C+
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All right then.
Show me how to a Swag test Gripen.
Crumpp
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Oh, come on Crumpp, you don't want Pyro to have the last word on this one ;)
Anyway, did you do some Newton calculations yet?
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No not yet Angus.
Been playing with them some. Trying to find some information on the prop efficiency for the planes.
Did you run the FW-190A8 vs Merlin 66 (+25) thru it yet?
Crumpp
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Regarding propeller efficiency, above linked momentum theory might look complicated in the first look but once you understand the system, it's a quite practical. If you are using excel, the theoretical efficiency can be solved with the solver, after that you can quess 10-15% down from that max value. There are easier systems but with this theory you can check the validity of the approximate and it can used to calculate static thrust too.
The value of the propeller efficiency (as well as amount of the exhaust thrust) is not so critical; you can build the spreadsheet model so that it will allways give right result at top speed.
gripen
edit: Corrected an mixup on theory name
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It only matters cause I want the information for my book on the prop efficiency. Looking for the correct "e" factor as well.
Now are you going to show me how to do a SWAG test?
Crumpp
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Emmm.Crumpp:
"Did you run the FW-190A8 vs Merlin 66 (+25) thru it yet? "
Not yet. Does anyone have weight and time to alt for the 109G series. I'll have a go at it all on a rainy day ;)
As for you Crumpp, what 190 data should I use? Feel sure you have a link ;) Time to 10K and time to 20K will do as well as the weight ;)
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I already sent you back the spreadsheet with some values in it. Included the chart I used and all the other data.
Email me which 109G you need. Got a few graphs and other data for several varients.
Crumpp
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English is not my native language. What is the SWAG test?
gripen
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Quick calculations to confirm data. I am running into lots of conflicting data on the FW-190. Need a good way to determine if it is "good" or "bad". I want to dispel myths, not perpetuate them.
Crumpp
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Grab Zigrat's spreadsheet from F4UDOA's page. It's in english units and it seems to work fine. If compared to my spreadsheet, it's far more sophisticated. In my calculation I check propeller efficiency manually as well as exhaust thrust.
gripen
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Can't find a link F4UDOA's page. If you got one I would appreciate it.
Crumpp
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http://mywebpages.comcast.net/markw4/
There's lots of interesting stuff on there.
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OK got it and been playing with it.
Now how do I know I have "good" data in it?
What are the checks.
Crumpp
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Thanks BTW Nashwan for posting your calculator.
Crumpp
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Originally posted by hitech
If you would try this aproch I belive the following would happen.
1. You would have quite a few people willing to talk about the topic's you love. Because guess what, they don't want to prove themselvs correct. They want to do 2 things.
1. Give their knowledge and excitment to others.
2. Pick up on new knowledge and thoughts that they hadn't seen or thought of before.
If you would try this aproch I belive you would increase your knowledge at a faster rate. You would also have a lot more fun.
Just some friendly advise for what it's worth.
HiTech
Well said HT.
I teach this stuff for a living, and as much as I want to help, I have begun to avoid threads like this one. The reason is that one can easily spend a lot of time trying to help guys who don't really want to be helped at all. It seems that some folk want to learn and share ideas, while others just want to be right, even if they aren't ;-)
Badboy
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It seems that some folk want to learn and share ideas
How about helpin out then.
Now how do I know I have "good" data in it?
What are the checks.
Crumpp
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Well, there is a point there.
A slightly provokative thread usually produces more data :D
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FW-190A8 NM at 10 K = 1.2926E+10
FW-190A8 NM at 20K = 25852821750
Spitfire Mk IX Merlin 66 NM at 10K = 1.0157E+10
Spitfire Mk IX Merlin 66 NM at 20K = 20313000000
Spitfire Mk IX Merlin 66
Wing area S (sq. feet)- 242
Airplane weight, lbs (as tested) - 7400
Wing span, ft - 36.1
Step B - performance #s at a known altitude
Altitude (feet) - 13800
Maximum speed (at test alt.- mph) - 389
Engine Horsepower (bhp at test alt) - 1650
Stall speed (mph, at test alt) - 90
Horsepower rating is at +19.5 max boost @ 3000 rpm at 13,800ft AGL.
FW-190A8 BMW-801D2
Wing area S (sq. feet) - 196.98
Airplane weight, lbs (as tested) - 9418
Wing span, ft - 34.45
Step B - performance #s at a known altitude
Altitude (feet) - 17224
Maximum speed (at test alt.- mph) - 408
Engine Horsepower (bhp at test alt) - 1680
Stall speed (mph, at test alt) - 110
Horsepower rating is at 1.58ata/1.65ata @ 2700U/min
Comparison under same conditions @ 300mph IAS.
Spitfire Mk IX CL=0.196312 D(p)=706.7709 D(i)=97.17467 CD(tot)=0.02132 Drag (tot)=803.94557
FW-190A8 CL= 0.343145 D(p)=595.7239 D(i)=197.875
CD(tot)=0.028915 Drag (tot)=793.59888
thrust (lb) T-D
Spitfire Mk IX 1544.397 740.451
FW-190A8 1550.793 757.1939
Conclusions -
Under 1G the FW-190A8 and the Merlin 66 Spitfire are very similar in total drag. The faster the speed the more the FW 190 moves to advantage. The slower the speed the more the Spitfire moves to advantage.
The FW-190A8 always has much more inertia and potential energy to convert to Altitude or Speed. It also has less braking forces per mass applied to it.
David Lednicers data reflects this conclusion. The FW-190 has less parasitic drag than the Spitfire but produces more induced drag.
The data used for each was:
Spitfire:
Perfomance numbers:
http://www.fourthfightergroup.com/eagles/jl165.html
http://www.fourthfightergroup.com/eagles/jl165speed.gif
Dimensional data is out of:
"British Warplanes of WWII" Edited by Daniel J. March.
Horsepower data was extrapolated using:
http://www.fourthfightergroup.com/eagles/merlin66hpchart.jpg
Focke-Wulf 190A8
Performance numbers:
http://www.terra.es/personal2/matias.s/fw190-1.jpg
Dimensional data is out of:
Flugzeug-Handbuch D(Luft) 2190 A-7 bis A-9 March 1944.
Horsepower data for the BMW-801D2 @ 1.65ata comes from a mechanical engineering anaylsis of the BMW-801D2 motor performance based on the following NACA Bench test analysis:
http://www.terra.es/personal2/matias.s/bmw801d-1024.jpg
I will gladly share the analysis results with anyone.
Special thanks to Angus and Nashwan.
Crumpp
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Originally posted by Crumpp
FW-190A8 NM at 10 K = 1.2926E+10
FW-190A8 NM at 20K = 25852821750
Spitfire Mk IX Merlin 66 NM at 10K = 1.0157E+10
Spitfire Mk IX Merlin 66 NM at 20K = 20313000000
Hm... I quess this is an energy calculation, are these values for potential energy or is there some kinetic energy within? If there is kinetic energy, what's the speed?
Originally posted by Crumpp
Comparison under same conditions @ 300mph IAS.
What's the comparison altitude?
I wonder why IAS values.
Originally posted by Crumpp
The data used for each was:
Spitfire:
Perfomance numbers:
http://www.fourthfightergroup.com/eagles/jl165.html
Why the JL165, it performed way below average?
Originally posted by Crumpp
Horsepower data was extrapolated using:
http://www.fourthfightergroup.com/eagles/merlin66hpchart.jpg
The problem with that chart is that it mix together the engines with different FS gear and your comparison seems to be at FS gear. As an example:
Merlin 66 FS gear ratio 7,06
V-1650-7 FS gear ratio 7,35
In addition that chart is far too unaccurate for analysis.
Originally posted by Crumpp
Horsepower data for the BMW-801D2 @ 1.65ata comes from a mechanical engineering anaylsis of the BMW-801D2 motor performance based on the following NACA Bench test analysis:
http://www.terra.es/personal2/matias.s/bmw801d-1024.jpg
AFAIK That chart is not from the NACA.
gripen
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Crumpp: Not sure if you know or not. But when computing drag & lift with normal equations you should be using TAS not IAS. The same goes for computing energy.
HiTech
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Hey Crumpp:
"Conclusions -
Under 1G the FW-190A8 and the Merlin 66 Spitfire are very similar in total drag. The faster the speed the more the FW 190 moves to advantage. The slower the speed the more the Spitfire moves to advantage.
The FW-190A8 always has much more inertia and potential energy to convert to Altitude or Speed. It also has less braking forces per mass applied to it.
David Lednicers data reflects this conclusion. The FW-190 has less parasitic drag than the Spitfire but produces more induced drag. "
I'm no expert, but as the Spitfire wing presumably produces more lift, it should also produce more induced drag.
Now as far as I know, induced drag is inevitable as a function of what is being lifted, - (LIFT induced drag is it's full name), it still has it's double sides of the coin.
A high lifting wing will reduce A of A, hence also drag.
A lower lifting wing will have to have higher A of A at low speeds in order to fly. However, when speed is ample, lift creation is almost a liability.
About this point here:
"The FW-190A8 always has much more inertia and potential energy to convert to Altitude or Speed."
I have to disagree, regarding altitude.
And yet not......
This is not just that simple....
The 190 has a higher stalling speed than the Spitty, especially under high pitched angles. (Chord thingie )
So, it's not an ALWAYS, but MOST OFTEN subject.
It should at all times have the more energy, however, not always the possibility to convert it into altitude, due to stalling dynamics.
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Comparison under same conditions @ 300mph IAS.
Thanks Hitech, It's a typo - all comparisons are at 300mph TAS.
I recalculated the figures for 4500 ft. ASL because I do not think the table is adjusting the speeds for altitude. Here are the results.
The FW-190 is at 1.42ata @ 2700U/min as my horsepower data is much more accurate for 4500 feet. All data is calculated at 356mph the max level speed of the FW-190A8 at that altitude and power setting. This forms the base information at which the performance at lower speeds can be assessed.
FW-190A8
Wing area S (sq. feet) - 196.98
Airplane weight, lbs (as tested) - 9418
Wing span, ft - 34.45
Step B - performance #s at a known altitude
Altitude (feet) - 4500
Maximum speed (at test alt.- mph) - 356
Engine Horsepower (bhp at test alt) - 1730
Stall speed (mph, at test alt) - 110
speed (mph TAS) @ 4500 feet ASL
300
CL
0.229178
D(p)
952.5006
D(i)
132.1558
CL^2
0.052523
CD(tot)
0.026394
Drag (tot)
1084.6564
thrust (lb)
1667.946
excess power (bhp)
583.2895
P.E.
0.78153
Spitfire Mk IX Merlin 66 (+25) - This data represents full throttle height for the Spitfire and an easy point to calculate from. Since my data is much more complete for the FW-190 it is easier to identify the Spitfire's knowns and then establish the FW-190's performance at the same altitude. Initial data was calculated under the following known conditions:
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 242
Airplane weight, lbs (as tested) - 7400
Wing span, ft - 36.1
Step B - performance #s at a known altitude
Altitude (feet) - 4500
Maximum speed (at test alt.- mph) - 350
Engine Horsepower (bhp at test alt) - 2050
Stall speed (mph, at test alt) - 90
speed (mph TAS) @ 4500 feet ASL
300
CL
0.146573
D(p)
1229.828
D(i)
72.55357
CL^2
0.021484
CD(tot)
0.025796
Drag (tot)
1302.3818
thrust (lb)
1976.468
excess power (bhp)
674.0858
P.E.
0.78153
Data all came from the same sources.
The problem with that chart is that it mix together the engines with different FS gear and your comparison seems to be at FS gear. As an example:
It's the best data I have. If you have better data I would love to get a copy of it and will recalculate the numbers.
Why the JL165, it performed way below average?
It's the best and most complete data I have on the Spitfire Merlin 66 (+25). The S.U. pump data is with a Merlin 66 (+18) and only "estimates" the speed increase. Additionally the speed increase is an average and would not hold true for all altitudes. This can be seen in the increase at full throttle height of a Merlin 66 (+18) is not nearly as large as the "average" with the fuel pump.
Please share your data and I will recalculate. I will share my information on the FW-190 as well.
Not all of it though, gotta save some for the book! :p
AFAIK That chart is not from the NACA.
Your right it is from a 1942 bench test conducted by BMW. The report number is on the graph.
Crumpp
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Hell Crumpp, I have to give it to you, you do an honest work of calculations. :):):):):)
I am collecting a database (anecdotal, image and text) of WW2 aircraft performance and events. Mail me if there is something I can help you with ;)
(Anecdotal is my best field, I have some goodies coming)
But there are so many gaps to fill in, and if you want to have a go at it, I'll be as good a help as I can, collecting various performance data and putting into excel for instance.
That sheet I sent you actually answered many questions about the true performance of the aircraft that were put into it in the beginning, although it's just a simple document.
Calculations and data will at least slow down the flames I hope....
(As much as I like them
:D )
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Why the JL165, it performed way below average?
It's the best and most complete data I have on the Spitfire Merlin 66 (+25).
JL 165 was far far slower than other tested Spit IXs, and had a far lower climb rate.
Here's a graph of what they estimated for Jl 165 at 18 lbs, along with other Spit VIIIs/IXs with Merlin 66:
(http://www.onpoi.net/ah/pics/users/282_1082729993_spitixspeeds4.gif)
JL 165 is in red.
If you use JL 165, you aren't going to get representitive figures for the Spit.
I've just skimmed this thread, so there might be an obvious reason, but why do you need figures for a Spit at 25 lbs?
Won't figures for a Spit at 18 lbs do?
he S.U. pump data is with a Merlin 66 (+18) and only "estimates" the speed increase. Additionally the speed increase is an average and would not hold true for all altitudes. This can be seen in the increase at full throttle height of a Merlin 66 (+18) is not nearly as large as the "average" with the fuel pump.
I don't understand why you keep referring to the SU fuel pump. This was simply a different carb, and had little effect on speed. You can see from the chart above, the yellow line is for MA 648 with an injection pump at 18 lbs, the other aircraft are all at 18 lbs, without the injection pump.
The injection pump increased full throttle height, which of course increased speed at that height as well.
At lower altitudes, there's almost no difference between the injection pump and the normal carb.
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Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 242
Airplane weight, lbs (as tested) - 7400
Wing span, ft - 36.1
Step B - performance #s at a known altitude
Altitude (feet) - 4500
Maximum speed (at test alt.- mph) - 350
Engine Horsepower (bhp at test alt) - 2050
Stall speed (mph, at test alt) - 90
I should probably re read this thread from the begining, but what does this data apply to?
JL 165, slow as it was, still did 362 mph at 4500 ft at 25 lbs.
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Hey Nash, email me at burns@isholf.is and I'll reply with the attached XLS sheet for calculation of lift. Same goes with Gripen of course, or just anybody :)
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I will recheck the data Nashwan. Thanks for posting the comparision.
Angus thank you for the vote of confidence. If their is anything you can use for you project or I can help you with let me know. You have my email.
I should probably re read this thread from the begining, but what does this data apply to?
It is the know data for the A/C.
This refers to the Spitfire listed on this site:
http://www.fourthfightergroup.com/eagles/jl165.html
http://www.fourthfightergroup.com/eagles/jl165speed.gif
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 242
Airplane weight, lbs (as tested) - 7400
Wing span, ft - 36.1
Step B - performance #s at a known altitude
Altitude (feet) - 4500
Maximum speed (at test alt.- mph) - 350
Engine Horsepower (bhp at test alt) - 2050
Stall speed (mph, at test alt) - 90
Your correct Nashwan. I misread the chart and will recalculate.
Crumpp
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I recalculated the figures for Nashwan and here are the results.
The FW-190 is at 1.42ata @ 2700U/min as my horsepower data is much more accurate for 4500 feet. All data is calculated at 356mph the max level speed of the FW-190A8 at that altitude and power setting. This forms the base information at which the performance at lower speeds can be assessed.
FW-190A8 (data is the same)
Wing area S (sq. feet) - 196.98
Airplane weight, lbs (as tested) - 9418
Wing span, ft - 34.45
Step B - performance #s at a known altitude
Altitude (feet) - 4500
Maximum speed (at test alt.- mph) - 356
Engine Horsepower (bhp at test alt) - 1730
Stall speed (mph, at test alt) - 110
speed (mph TAS) @ 4500 feet ASL
300
CL
0.229178
D(p)
952.5006
D(i)
132.1558
CL^2
0.052523
CD(tot)
0.026394
Drag (tot)
1084.6564
thrust (lb)
1667.946
excess power (bhp)
583.2895
P.E.
0.78153
Spitfire Mk IX Merlin 66 (+25) - This data represents full throttle height for the Spitfire and an easy point to calculate from. Since my data is much more complete for the FW-190 it is easier to identify the Spitfire's knowns and then establish the FW-190's performance at the same altitude. Initial data was calculated under the following known conditions:
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 242
Airplane weight, lbs (as tested) - 7400
Wing span, ft - 36.1
Step B - performance #s at a known altitude
Altitude (feet) - 4500
Maximum speed (at test alt.- mph) - 365
Engine Horsepower (bhp at test alt) - 2050
Stall speed (mph, at test alt) - 90
speed (mph TAS) @ 4500 feet ASL
300
CL
0.146573
D(p)
1089.133
D(i)
72.55357
CL^2
0.021484
CD(tot)
0.02301
Drag (tot)
1161.6864
thrust (lb)
1976.468
excess power (bhp)
814.7812
P.E.
0.78153
Data all came from the same sources.
Crumpp
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Originally posted by Nashwan
JL 165 was far far slower than other tested Spit IXs, and had a far lower climb rate.
Here's a graph of what they estimated for Jl 165 at 18 lbs, along with other Spit VIIIs/IXs with Merlin 66:
(http://www.onpoi.net/ah/pics/users/282_1082729993_spitixspeeds4.gif)
JL 165 is in red.
And there Nashwan goes as usual. JL 165, "a standard Spitfire IX with Merlin 66 engine", as the report states, which Nashwan/Hop claims to be extraordinary slow, the worst performer, the sorriest Spit, anything but not that to choose, which according to him, had at least six engine changes, ten airframe overhauls and has to care for six hungry children to feed etc. etc. etc. - despite it`s report DOES NOT mention ANY problem with either the airframe or the engine... "a standard Spitfire IX with Merlin 66 engine", with a tropical filter, which was hardly uncommon, you see Spits with them in the Med, in Russia, in Normandy...
In fact, the tropicalized JL 165 does 389mph, the official RAF datasheet for the tropicalized MkIX say 386mph max speed, the tropicalized MkVIII in Australian reports show 393 mph max speed (with retractable tailwheel and the same new type Vokes filter)... but pray, do not use this data!
Instead, we should rely, he says, on the prototype BS 543, which had an experimental aircrew,that never seen production, that overperformed compared to normal in the tests :
"From BS 543 report:
..."It is a matter of interest that at sea level, Spitfire BS.354 with the RM-9SM engine, although nominally develping 50 B.H.P. more power than the Merlin 66 engines BS.543, is 7 m.p.h. slower, indicating either that the nominal powers were not realized and/or that there was a considerable difference between the drags of the two aircraft.
The powers of the RM-9SM and the Merlin 66 engines in F.S. gear should be identical, since the high speed supercharger gear ratio is the same. It will be seen that on the climb, the performance and boost pressures were similar, within the limits of experimental error, but in level flight above the full throttle height the Merlin 66 engine was developing about 1 lb/sq.inch higher boost pressure than the 9 SM engine, with a consequent higher full throttle height and improved performance. "
No, ignore that all, and use THIS prototype instead of the results for the standard Spitfire IX...
Or let`s use MA 648, another prototype that never were in service, with an experimental fuel pump, LOL. :D
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Either way the story is the same.
The FW-190 had less parasitic drag than the Spitfire Mk IX no matter what varient.
Does anybody have good information on the Merlin 61 bhp?
My information is sketchy on the Merlin 61 and I am using Janes Merlin chart. According to Jane's the Merlin 61 developed 1565Hp @ 3000rpm at 12,250. This is close to the 13,000 feet ASL entry on table IV according to:
http://www.fourthfightergroup.com/eagles/bf274.html
If that Hp is correct then the FW-190A5 was 13mph faster on 165 less Horsepower at that altitude when using 1.42ata @ 2700U/min.
Crumpp
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Hi Gripen:
“Why the JL165, it performed way below average?”
Yes, any cursory review of a half dozen or more trials results will show that to be true. I’ve looked into that issue further and came up with the following report from Rolls-Royce showing results rather closer to average.
JL165 trials (http://www.fourthfightergroup.com/eagles/jl165rr.html)
367 @ 3,200’ M.S., 397 @14,400’ F.S.
Of the performance obtained the report states:
“A further point of note is the full throttle height at + 18 lbs. of boost which is somewhat lower than has previously been obtained with Merlin 66 engines. A check of the air intake efficiency was taken during the tests, a minimum figure of 94% in level flight being shown at + 25 lbs. sq.inch boost pressure. It would seem therefore that the full throttle height of this engine is low.”
A low FTH will give poorer performance.
In addition the condition with tropical filter is not representative of ADGB or ETO configuration.
“The engine was a standard production Merlin 66, the aircraft being a normal Spitfire IX, with 10'9" diameter Hydulignum propeller and standard tropical type of air intake, operating as temperate.”
Gripin, I agree the chart, while interesting and informative, lacks the precision to make accurate analysis.
It should be noted that switching from 100 to 150 octane fuel did not by itself cause a drop off in max top speed. It is apparent, when familiar with the facts, that a +18 Spit IX with max speed of 404 mph will still have a max speed of very close to if not exactly 404 mph when switched to 150 octane fuel.
Nashwan:
“If you use JL 165, you aren't going to get representitive figures for the Spit.”
Yes quite right, the trials data, while not representative, was useful to the RAF in determining that it was worthwhile to place in service these aircraft set up to run 150 octane fuel. It can be useful to us if not distorted and misrepresented ;)
“Won't figures for a Spit at 18 lbs do?” I would think so. BS.543 or BS.310 might do. Perhaps BS.543 would be better given its operational history: BS.543 was built as a Mk V, converted to Mk IX (Merlin 61) at Rolls Royce, Hucknall. First flight 22-10-42. Transferred to AFDU, Duxford 8-11-42; AAEE, Boscombe Down 13-12-42 with Merlin 66 installed; Vickers Armstrong 22-2-43; 403 Sqdn. 9-6-43; 611 Sqdn. 10-6-43; 485 Sqdn. 6-7-43. Failed to return from operations 22-8-43. BS.310 had the all-round better numbers on average though.
Just as an aside, JL.165 ended up in North Africa which suggests they may have used 150 octane in the MTO. That's new on me.
p.s. nice graph and good work :) Gripen, very impressive work you've done here.
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Issy:
"JL 165 was far far slower than other tested Spit IXs, and had a far lower climb rate."
You should not make fun of this, this is quite evident from your chart!
There were roque Spits around, as well as rogue 109's as well ;)
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Originally posted by mw
JL165 trials (http://www.fourthfightergroup.com/eagles/jl165rr.html)
367 @ 3,200’ M.S., 397 @14,400’ F.S.
Of the performance obtained the report states:
“A further point of note is the full throttle height at + 18 lbs. of boost which is somewhat lower than has previously been obtained with Merlin 66 engines. A check of the air intake efficiency was taken during the tests, a minimum figure of 94% in level flight being shown at + 25 lbs. sq.inch boost pressure. It would seem therefore that the full throttle height of this engine is low.”
A low FTH will give poorer performace.
[/b]
Yep, too bad that even the new report on JL 165 did not show lower FTH than the others (save the experimental planes of course).
I guess there`s some wild consipracy going on, because we can see the JL 165 achieved FTH at 397 mph w. +18boost at 20 000 ft....
(http://www.fourthfightergroup.com/eagles/jl165rrspeed.jpg)
....and, for some odd reason, we also have the Merlin 66 power chart which actually shows that the FTH should be exactly at 20 000 feet at 400mph rammed speed.
In other words JL 165 reached exactly the FTH it should at +18lbs, ~20k ft. The "too low FTH" theory fails.
(http://www.fourthfightergroup.com/eagles/merlin66hpchart.jpg)
Furthermore, we see that JL 165 achieved ~14500 FTH at +25 lbs boost. Lookie again on the Merlin chart, the said FTH for +25lbs is again ~ 14 500 feet.
The "too low FTH" theory fails again. JL 165 reached exactly the same Full Throttle Heights in both MS and FS gear it should.
Apart from that, the whole case is pretty simple: Mike and Nashwan are so entitled to that the Spits should be superior to everything (but especially the 109), that they want to use performances measured on experimental machines.
Therefore they try, at every opportunity, discredit the JL 165 tests, despite the test notes it was a normal Spitfire in every aspect, with standard equipment, standard Merlin 66 engine, standard propellor, standard carburator and so on.
And so does, in view of this report, the "JL 165 was underperforming at +18lbs". Uh-oh, it did not.
The results from the other mid-1944 JL 165 report are ESTIMATES for +18lbs, worked out from +25lbs results. Previously MW and Nashwan claimed the JL 165 was "underperforming", pointing to these estimated figures in comparison with results obtained with experimental spitfires such as BS 543.
They believed the raise was far greater than actually, but this reports clearly points out the propellor could not take all the advanatage the increased power offered*, therefore their estimates for +18lbs understate the real speed of the aircraft.
* " It should be noted that there is no increase in the absolute speed obtained by the increase of boost, and it would appear that the efficiency of the propeller is somewhat reduced at the higher rating.
Originally posted by mw
In addition the condition with tropical filter is not representative of ADBG or ETO configuration.
[/B]
I guess Guppy can correct you on this, certainly it`s not hard to find filter equipped Spitfires in ETO, you know, the low mounted intake of the Spitty didn`t really like all the dust of Normandy`s provisional airfields.
“Won't figures for a Spit at 18 lbs do?” I would think so.
BS.543 or BS.310 might do.
Yep, both experimental planes with never-serialized equipment, ROFLOL. Perrrrfeeecct, - and typical Mike Williams. :D
Perhaps BS.543 would be better given its operational history: BS.543 was built as a Mk V, converted to Mk IX (Merlin 61) at Rolls Royce, Hucknall. First flight 22-10-42. Transferred to AFDU, Duxford 8-11-42; AAEE, Boscombe Down 13-12-42 with Merlin 66 installed; Vickers Armstrong 22-2-43; 403 Sqdn. 9-6-43; 611 Sqdn. 10-6-43; 485 Sqdn. 6-7-43. Failed to return from operations 22-8-43. BS.310 had the all-round better numbers on average though.
BS 543, Mr Williams means, the one with the never serialized Rotal XH54D-RM-S5 experimental airscrew. :D
Just as an aside, JL.165 ended up in North Africa which suggests they may have used 150 octane in the MTO. That's new on me.[/B]
Just like the rest of us, Mike, and we all wait in awe for your next flip flop making up the "150 grade Spitfires in ETO".
Like you did make up the +25lbs MkXIVs, which you know very well never existed in service, as their Griffon was derated to +21 lbs due to main bearing troubles. ;)
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Originally posted by Angus
Issy:
"JL 165 was far far slower than other tested Spit IXs, and had a far lower climb rate."
You should not make fun of this, this is quite evident from your chart!
There were roque Spits around, as well as rogue 109's as well ;)
Hmm.. I plotted the newer - better performing - JL 165 tests against the results the Russians got on one of their (1000+) Mk IXLF, and the figures are in very close agreement.
I think Mike can screw his excuses, the JL 165 figures are in perfect agreement with the Merlin 66 charts FTH`s, AND they are in good agreement with performance results obtained in the USSR on a similiar L.F. Mk. IX.
(http://www.onpoi.net/ah/pics/users/715_1094487390_ussrg-2andmkixvsjl165.jpg)
And yes, I know compared to the Gustav the high alt performance is a bit disappointing, but it`s no shame, really.
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Originally posted by gripen
English is not my native language. What is the SWAG test?
gripen
Scientific (or Silly) Wild bellybutton Guess. A term used by
technical teams when establishing high level sizings for large
projects.
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Hey Nash, email me at burns@isholf.is and I'll reply with the attached XLS sheet for calculation of lift.
Thanks. The email should be on it's way in an hour or 2.
I will recheck the data Nashwan. Thanks for posting the comparision.
Cool. I find it difficult enough using these spreadsheets, how anyone can actually do the calculations themselves is beyond me.
And there Nashwan goes as usual. JL 165, "a standard Spitfire IX with Merlin 66 engine",
Which had also been used for lots of tests before A&AEE got their hands on it.
It's still much slower at most heights than any similar Spit I know of, and the climb rate is much worse.
In fact, the tropicalized JL 165 does 389mph, the official RAF datasheet for the tropicalized MkIX say 386mph max speed, the tropicalized MkVIII in Australian reports show 393 mph max speed (with retractable tailwheel and the same new type Vokes filter).
It's note a Vokes filter.
Seeing the new stuff MW has got of the RR tests of JL 165, it seems to me JL 165 had the standard VIII/IX tropical filter without blanking plates.
That's what JF 934 had, and the speeds RR got for JL 165 are pretty close to JF 934.
By the time A&AEE tested it, JL 165 was 12 mph slower at sea level, and had lost hundreds of ft/min in climb rate.
is a matter of interest that at sea level, Spitfire BS.354 with the RM-9SM engine, although nominally develping 50 B.H.P. more power than the Merlin 66 engines BS.543, is 7 m.p.h. slower, indicating either that the nominal powers were not realized and/or that there was a considerable difference between the drags of the two aircraft.
Yes, so? An experimental engine didn't perform as well as expected, and wasn't put into production. And this is an issue because....?
No, ignore that all, and use THIS prototype instead of the results for the standard Spitfire IX...
I'm still waiting for you to put JF 934 on your climb graph with the 109. You did after all claim you were just waiting for "serial production data", and JF 934 was a production aircraft shipped out to Australia for service.
Does anybody have good information on the Merlin 61 bhp?
My information is sketchy on the Merlin 61 and I am using Janes Merlin chart. According to Jane's the Merlin 61 developed 1565Hp @ 3000rpm at 12,250.
That's unrammed, rammed would be somewhat lower HP.
p.s. nice graph and good work
I spent some time on it, collecting various Spit test data from your site. The final one I went to add was MA 648, and what did I see when I clicked on it's performance graph?
The results from the other mid-1944 JL 165 report are ESTIMATES for +18lbs, worked out from +25lbs results. Previously MW and Nashwan claimed the JL 165 was "underperforming", pointing to these estimated figures in comparison with results obtained with experimental spitfires such as BS 543.
They believed the raise was far greater than actually, but this reports clearly points out the propellor could not take all the advanatage the increased power offered*, therefore their estimates for +18lbs understate the real speed of the aircraft.
This is coming from Isegrim, who has spent several years arguing that the estimated figures for JL 165 are the most accurate Spitfire Merlin 66 figures available. BS 543 and BS 551 should be ignored, because JL 165 was the only accurate data available. Now he's saying JL 165 data at 18 lbs isn't accurate at all.
Does this mean you are going to remove it from your climb graph, Isegrim?
I guess Guppy can correct you on this, certainly it`s not hard to find filter equipped Spitfires in ETO, you know, the low mounted intake of the Spitty didn`t really like all the dust of Normandy`s provisional airfields.
Which is probably why they started fitting blanking plates to the Spit air intake.
Spitfire the History gives figures for 3 Spit VIIIs tested with the tropical filter, first the normal Spit VIII type, then with blanking plates fitted.
JF 275 went from 397 mph to 402 mph, JL 163 from 367 to 372 (MS gear), JF 707 363 to 370 (MS gear), EN 654 (PR XI) 381 to 391.5 (MS gear) 410 to 421 (FS gear)
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Izzy:
"Therefore they try, at every opportunity, discredit the JL 165 tests, despite the test notes it was a normal Spitfire in every aspect, with standard equipment, standard Merlin 66 engine, standard propellor, standard carburator and so on. "
Well, no matter what you say, it's a poor performer.
You are correct on one thing though. Increasing the boost to 25 doesn't really increase top speed. It will however drastically increase climb and acceleration. For increased top speed you'd have had to add a propeller blade for instance.
And here's one from you:
"Apart from that, the whole case is pretty simple: Mike and Nashwan are so entitled to that the Spits should be superior to everything (but especially the 109), that they want to use performances measured on experimental machines. "
You've hit your own nuts there Izzy. As it is, you yourself love to compare rather high performing 109's to the lower performing Spitties. Last thing I saw is your chart a tad above in this thread.
Why don't you swap that 109G2 out for a G6, and Swap the Spits to +25 Lf, Hf for alt, and +25 VIII and see the lines change:D
Of course the Alt performance is somewhat disappointing for a Spitty which is customized for LOWER ALT BANDS.
And the grand final:
"and we all wait in awe for your next flip flop making up the "150 grade Spitfires in ETO"
You're saying that there were none? Oh, I almost forgot, the Allies were low on fuel right, especially the good stuff
:D
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I recalculated the figures for Nashwan and reposting it so he does not have to hunt for it. Here are the results.
The FW-190 is at 1.42ata @ 2700U/min as my horsepower data is much more accurate for 4500 feet. All data is calculated at 356mph the max level speed of the FW-190A8 at that altitude and power setting. This forms the base information at which the performance at lower speeds can be assessed.
FW-190A8 (data is the same)
Wing area S (sq. feet) - 196.98
Airplane weight, lbs (as tested) - 9418
Wing span, ft - 34.45
Step B - performance #s at a known altitude
Altitude (feet) - 4500
Maximum speed (at test alt.- mph) - 356
Engine Horsepower (bhp at test alt) - 1730
Stall speed (mph, at test alt) - 110
speed (mph TAS) @ 4500 feet ASL
300
CL
0.229178
D(p)
952.5006
D(i)
132.1558
CL^2
0.052523
CD(tot)
0.026394
Drag (tot)
1084.6564
thrust (lb)
1667.946
excess power (bhp)
583.2895
P.E.
0.78153
Spitfire Mk IX Merlin 66 (+25) - This data represents full throttle height for the Spitfire and an easy point to calculate from. Since my data is much more complete for the FW-190 it is easier to identify the Spitfire's knowns and then establish the FW-190's performance at the same altitude. Initial data was calculated under the following known conditions:
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 242
Airplane weight, lbs (as tested) - 7400
Wing span, ft - 36.1
Step B - performance #s at a known altitude
Altitude (feet) - 4500
Maximum speed (at test alt.- mph) - 365
Engine Horsepower (bhp at test alt) - 2050
Stall speed (mph, at test alt) - 90
speed (mph TAS) @ 4500 feet ASL
300
CL
0.146573
D(p)
1089.133
D(i)
72.55357
CL^2
0.021484
CD(tot)
0.02301
Drag (tot)
1161.6864
thrust (lb)
1976.468
excess power (bhp)
814.7812
P.E.
0.78153
Data all came from the same sources.
That's unrammed, rammed would be somewhat lower HP.
Yeah I did not feel comfortable using it and did not bother to post the results. In my experience the FW-190 and the Merlin Spitfire IX's maintained extremely similar horsepower outputs. Do you think 1400 hp is a fair figure for the Merlin 61 at that altitude? That is the same as the BMW-801D2 at 1.42ata @ 2700U/min at the comparision altitude.
Crumpp
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it seems to me JL 165 had the standard VIII/IX tropical filter without blanking plates.
That's what JF 934 had, and the speeds RR got for JL 165 are pretty close to JF 934.
Which is probably why they started fitting blanking plates to the Spit air intake.
Spitfire the History gives figures for 3 Spit VIIIs tested with the tropical filter, first the normal Spit VIII type, then with blanking plates fitted.
JF 275 went from 397 mph to 402 mph, JL 163 from 367 to 372 (MS gear), JF 707 363 to 370 (MS gear), EN 654 (PR XI) 381 to 391.5 (MS gear) 410 to 421 (FS gear)
Hmm, I think you may be on to something. JL.165 did have the blanking plate installed at AAEE though. Of course those results are rather porked anyway.
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That would be an improvement compared to your current state indeed. Why not go further, and stopping your old habit of jumping on your bandwagon and write hysterical posts every time the word '109' is cast? All threads with the slightest mentioning of axis stuff is loud of your manure and it`s really gets boring.
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You've hit your own nuts there Izzy. As it is, you yourself love to compare rather high performing 109's to the lower performing Spitties. Last thing I saw is your chart a tad above in this thread.
IMO the only meaningful comparison is a fighter's contemporary opponent. Comparing "the best" with "worst" is completely counterproductive to developing an honest appraisal. It leads to wrong conclusions.
Hmm, I think you may be on to something. JL.165 did have the blanking plate installed at AAEE though. Of course those results are rather porked anyway.
Anybody have any test data?
Crumpp
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Originally posted by Nashwan
It's note a Vokes filter.
Seeing the new stuff MW has got of the RR tests of JL 165, it seems to me JL 165 had the standard VIII/IX tropical filter without blanking plates.
Nashwan, how come that you suddenly forget your own mother language in such times? Have you forgotten how to read?
JL 165`s report notes :
"New tropical pattern air intake without gauze, but blanking plate installed.
No ice guard fitted in air intake. "
That's what JF 934 had, and the speeds RR got for JL 165 are pretty close to JF 934.
[/B]
Has as much to do with reality as the previous statement. You never out of manipulation and excuses, are you?
By the time A&AEE tested it, JL 165 was 12 mph slower at sea level, and had lost hundreds of ft/min in climb rate.
Typical Naswhan crap vs. facts type engagement.
Facts :
In october, with R-R`s tests, on +25lbs 362mph was measured on JL 165 at 2000ft.
A few months later, with A&AEEreached 360 mph at 2000ft with JL 165 on +25lbs.
Just read the two reports.
I'm still waiting for you to put JF 934 on your climb graph with the 109. You did after all claim you were just waiting for "serial production data", and JF 934 was a production aircraft shipped out to Australia for service.
So we are supposed to believe JF 934 with low altitude Merlin 66 could outlcimb the 300 lbs lighter Mk IX with high altitude Merlin 70?
Possible in times of desperate need, Nashwan/MW fanboyworld, though...
This is coming from Isegrim, who has spent several years arguing that the estimated figures for JL 165 are the most accurate Spitfire Merlin 66 figures available. BS 543 and BS 551 should be ignored, because JL 165 was the only accurate data available. Now he's saying JL 165 data at 18 lbs isn't accurate at all.
Bark as desperately you want Nash1. Bull**** 543 and Bull**** 551 were experimental planes, rigged in a fashion no serial Spits were. Everyone ackknowladges this, expect you and that other partisan fanboy. Only the mentally challanged would choose to use experimental plane data, when serial plane results are available.
Luckily now new and accurate data, actually tested is available for the JL 165 at +18. It matches well other testing at +18lbs, and can be viewed as representative for serially produced Spits. Naturally, I will revise my older data and use the new, and better/higher data for the Spitfire. Unlike you, I am interested in the historical facts, not sorry fantasies.
Does this mean you are going to remove it from your climb graph, Isegrim?
Hmm, I would, provided the new and better JL 165 data was for Open radiators, which unfurtanately isn`t, and closed rads are hardly conform testing with the RAF, or any other airforce. Provide data for open rads, and you got my word it will be replaced with that one.
BTW, is that climb graph so irritating? Well if THAT`s irritating, ie. the ultimate version of the 109 giving a slap in the face of your Spits, how does you feel to see even the 109G doing 4800 fpm on a limited 1.3ata boost, a full year before those Spit LFs appeared in meaningless numbers?
Which is probably why they started fitting blanking plates to the Spit air intake.
I`ll let you argue then with Mike wheter this was a problem on Spits or not in ETO. You should really decide now, over those many versions you made up till now... ;)
[/b]
Spitfire the History gives figures for 3 Spit VIIIs tested with the tropical filter, first the normal Spit VIII type, then with blanking plates fitted.
JF 275 went from 397 mph to 402 mph, JL 163 from 367 to 372 (MS gear), JF 707 363 to 370 (MS gear), EN 654 (PR XI) 381 to 391.5 (MS gear) 410 to 421 (FS gear) [/B]
That`s a staggering 5 mph increase. Better question is, how much of that was implemented in operational service.
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"So we are supposed to believe JF 934 with low altitude Merlin 66 could outlcimb the 300 lbs lighter Mk IX with high altitude Merlin 70? "
At low alt I would actually expect that it could, with the climbing rate crossing in the 70's favour at higher altitude.
Not sure how much of a difference 300 lbs are, could of course calibrate it into Newtons and look for the true percentage in energy value.
Umm, does anyone have power curves or data for the 66 and 70?
Secondary stage alt?
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FW-190A5 Power setting is at 1.42ata @ 2700U/min.
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 196.98
Airplane weight, lbs (as tested) - 9052.18
Wing span, ft - 34.45
Step B - performance #s at a known altitude
Altitude (feet) - 13000
Maximum speed (at test alt.- mph) - 383
Engine Horsepower (bhp at test alt) - 1400
Stall speed (mph, at test alt) - 110
speed (mph TAS)
300
CL
0.287507
D(p)
598.8078
D(i)
159.3517
CL^2
0.08266
CD(tot)
0.02408
Drag (tot)
758.15952
thrust (lb)
1314.365
excess power (bhp)
556.2053
P.E.
0.761023
Spitfire Mk IX Merlin 61 (+12)
Level speed data is from:
http://www.fourthfightergroup.com/eagles/bf274.html
Table IV Level Speeds. You can see the Spirfire is at (+15.2) boost and I tend to think if 1565hp is full throttle height output @ 15400 for a Merlin 61 @ (+15) emergency power then it's output is probably higher than 1400hp.
The FW-190 only gains about 30 hp between 13,000 feet and full throttle height at 22,000 feet ASL.
Unrammed the FW-190 only achieves around 1490hp at 22,000 feet ASL.
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 242
Airplane weight, lbs (as tested) - 7480
Wing span, ft - 36.1
Step B - performance #s at a known altitude
Altitude (feet) - 13,000
Maximum speed (at test alt.- mph) - 370
Engine Horsepower (bhp at test alt) - 1400
Stall speed (mph, at test alt) - 90
speed (mph TAS)
300
CL
0.193377
D(p)
685.8562
D(i)
96.7565
CL^2
0.037395
CD(tot)
0.020232
Drag (tot)
782.61269
thrust (lb)
1314.365
excess power (bhp)
531.7521
P.E.
0.761023
Crumpp
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I wondered a bit why could not reach same numbers with Zigrat's spreadsheet as with my own. After some crosschecking I found out that there appear to be a conversion error in the Zigrat's sheet; AFAIK one mile is 5280 ft and Zigrat's uses 5350 for mph to ft/s conversion. In addition I changed density formula (for standard atmosphere) to a bit more accurate:
rho=rho_0*(1.- 6.8755856*10^-6 * h)^4.2558797 h<36,089.24ft
where rho_0 = 0.002376892 slugs/ft^3
With these modifications Zigrat's spreadsheet gives same values with good enough accuracy (several decimals).
The e factor in the Zigrat's sheet seems to be modeled with somekind of formula which is based on aspect ratio. I don't know the idea behind this; lift distribution is not the function of aspect ratio.
The exhaust thrust is not accounted at all in the Zigrat's sheet but this is not a big problem because all compared planes had about same amount of exhaust thrust.
Originally posted by Crumpp
I recalculated the figures for 4500 ft. ASL because I do not think the table is adjusting the speeds for altitude. Here are the results.
The FW-190 is at 1.42ata @ 2700U/min as my horsepower data is much more accurate for 4500 feet. All data is calculated at 356mph the max level speed of the FW-190A8 at that altitude and power setting. This forms the base information at which the performance at lower speeds can be assessed.
Well, the question remains: Is that data true flight tested data and if it is, is filled and polished surfaces normal?
Originally posted by Crumpp
FW-190A8
Wing area S (sq. feet) - 196.98
Airplane weight, lbs (as tested) - 9418
Wing span, ft - 34.45
Step B - performance #s at a known altitude
Altitude (feet) - 4500
Maximum speed (at test alt.- mph) - 356
Engine Horsepower (bhp at test alt) - 1730
Stall speed (mph, at test alt) - 110
The power chart gives 1770 ps with RAM at 4500 ft which is 1745,79 hp. The stall speed is not really needed and unaccurate due to altitude (far too low).
Originally posted by Crumpp
Spitfire Mk IX Merlin 66 (+25) - This data represents full throttle height for the Spitfire and an easy point to calculate from. Since my data is much more complete for the FW-190 it is easier to identify the Spitfire's knowns and then establish the FW-190's performance at the same altitude. Initial data was calculated under the following known conditions:
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 242
Airplane weight, lbs (as tested) - 7400
Wing span, ft - 36.1
Step B - performance #s at a known altitude
Altitude (feet) - 4500
Maximum speed (at test alt.- mph) - 350
Engine Horsepower (bhp at test alt) - 2050
Stall speed (mph, at test alt) - 90
The JL 165 chart gives actually 364 mph at 4500 ft. The JL165 had MS gear high speed FTH 2800 ft with +25 lbs and the output at that altitude is about 2020 hp (according to the chart you refer). Above that altitude ouput drops about about 0,057944 hp/ft so at 4500 ft the engine output is roughly 1921 hp. It should be noted that the JF275 was about 10mph faster with the same output.
So the flat plate areas at 4500 ft are:
Fw 190A-8: 5,19 sqft (prop ef 80%, e factor 0,8)
JL165: 5,34 sqft (prop ef 80%, e factor 0,9)
JF275: 4,93 sqft
There is no need to calculate the excess power because the Spitfire has clear advantage.
Originally posted by Crumpp
If you have better data I would love to get a copy of it and will recalculate the numbers.
I have a accurate chart (among others) for the V-1650-7 which has same MS gear ratio as the Merlin 66. It lists 1940 hp without RAM at sea level with +25 lbs.
gripen
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Originally posted by gripen
The e factor in the Zigrat's sheet seems to be modeled with somekind of formula which is based on aspect ratio. I don't know the idea behind this; lift distribution is not the function of aspect ratio.
gripen
The number normally represented by the character e in induced drag calculations was originally known as Oswald’s efficiency factor, and his original paper is available for download from the NACA report server. More commonly it has a component of parasite drag lumped in with it and is just called the airplane efficiency factor and can be estimated depending on the aspect ratio, taper ratio, sweep angle and twist. Theoretically an elliptical wing would have an efficiency factor of 1, meaning that it will have a coefficient of induced drag close to the theoretical maximum. Even though it is a function of aspect ratio, sweepback angle, taper ratio and twist, the largest influence on the wing of a WWII fighter with very little sweep or twist comes from aspect ratio and taper ratio and so there are approximate formulae for estimating e that only include aspect and taper ratio, and even more approximate methods that only include aspect ratio. The important thing you must appreciate is that they are only approximate. But better than just assuming a constant value for every aircraft.
Hope that helps...
Badboy
Edit:
Just checked my own teaching notes, and should add that the Oswald efficiency factor is also a function of wing camber and Mach number. In any case, calculating the Oswald efficiency factor from wing geometry is problematic. The values obtained are generally only valid for low AoA work because the calculations require that the flow remains fully attached, whereas in practice that is rarely the case. Generally such methods produce optimistic results.
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Nashwan, how come that you suddenly forget your own mother language in such times? Have you forgotten how to read?
JL 165`s report notes :
"New tropical pattern air intake without gauze, but blanking plate installed.
No ice guard fitted in air intake. "
My mistake, I haven't read the full test for some time.
By the time A&AEE tested it, JL 165 was 12 mph slower at sea level, and had lost hundreds of ft/min in climb rate
-------------------------------
Typical Naswhan crap vs. facts type engagement.
Facts :
In october, with R-R`s tests, on +25lbs 362mph was measured on JL 165 at 2000ft.
A few months later, with A&AEEreached 360 mph at 2000ft with JL 165 on +25lbs.
I was talking about 18 lbs performance at sea level, but nice switch there.
So we are supposed to believe JF 934 with low altitude Merlin 66 could outlcimb the 300 lbs lighter Mk IX with high altitude Merlin 70?
At low altitude, yes, at high altitude no.
JF 934 climbed at 2200ft/min at 30,000ft. BS 551 did 2600 ft/min at 30,000ft, Bs 310 2240 ft/min, EN 524 2275 ft/min.
At 25,000ft, JF 934 did 2880 ft/min, BS 551 did 3440 ft/min, EN 524 did 3050 ft/min, BS 310 did just over 3000 ft/min.
In other words, all 3 HF IXs outclimbed JF 934 at high alt.
What you are trying to do, Isegrim, is discredit the test of the serial production JF 934 by comparing it with the worst tests you can find. Therefore, if JF 934 did better than the worst Spit HF IX at high level, the test of JF 934 must be wrong.
It doesn't follow, of course, because an average Spit LF could certainly outcllimb a poor HF, even at high altitude.
Bark as desperately you want Nash1. Bull**** 543 and Bull**** 551 were experimental planes, rigged in a fashion no serial Spits were.
Here we go with the circular logic. Rather than look at the fact that the test of JF 934 fits nicely with BS 543 and 551, BS 543 and 551 are rejected. JF 934 is then compared with a different Spitfire, which it outperforms, so JF 934 is also rejected.
In fact, whilst most people would look at a series of tests and assume the one in the middle is closest to average, Isegrim rejects every test better than the worst, on the logic that it must be wrong because it's better than the worst.
Unless it's for the 109, or any other German aircraft, in which case any tests worst than the best is rejected, purely because it's worse than the best.
Isegrim, you have for some years claimed JL 165 was the most representitive Merlin 66 Spit you could find. You have now claimed that it's not representitive at all, and the estimates are based on faulty calculation.
What are you going to put on your little graph now?
Luckily now new and accurate data, actually tested is available for the JL 165 at +18. It matches well other testing at +18lbs, and can be viewed as representative for serially produced Spits.
This is going to be good.
JL 165, as tested by RR, using estimated climb figures, with a guesstimate knocked off to provide a reduction due to the radiators being partly closed, rather than actual tested data.
Hmm, I would, provided the new and better JL 165 data was for Open radiators, which unfurtanately isn`t, and closed rads are hardly conform testing with the RAF, or any other airforce.
What was the German testing procedure? I thought, and you have claimed, standard German climb tests were carried out with half open radiators.
Spit IX radiators had an exit area of 1.47 sq/ft port, 1.67 sq ft starboard, when fully open, 0.83 port and 0.83 starboard when "closed".
That makes "closed" radiators on the Spit slightly more than half open, and very comparable to 109 tests.
So under the new figures you want to use from RR, Spit IX climb rate, in a comparable condition to the 109, was 4960 ft/min at sea level, 4970 at 5,000ft, dropping to 4280 ft/min by 10,000ft, 4280 ft/min at 15,000ft.
I look forward to seeing it on the 109 climb chart :)
Hmm, I would, provided the new and better JL 165 data was for Open radiators, which unfurtanately isn`t, and closed rads are hardly conform testing with the RAF, or any other airforce.
Half open do though, don't they? They conform to the Luftwaffe standard, don't they? At least that's what you've always claimed in the past.
BTW, is that climb graph so irritating?
Not at all. I just don't like seeing someone going around claiming to be an authority and posting what he knows are at best flawed comparisons, and closer to outright deceptions.
Your graph is about as irritating as Luft 46, sadly it's neither as informative or as believable.
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I second your opinion on izzi's graph. Bloody Frustrating comparing a fast 109G serieas aircraft to LF +18's especially at altitude.
Just as bloody typical as the famous over the nose view of the squarehead hype :D
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Angus, take a look in my 'Need a laugh?' thread.;) Would make a good sig if it was not so large..
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After some crosschecking I found out that there appear to be a conversion error in the Zigrat's sheet; AFAIK one mile is 5280 ft and Zigrat's uses 5350 for mph to ft/s conversion.
Your correct and I changed it. Raises the speed to 310mph were the FW-190 gains advantage over the Spitfire in drag.
The e factor in the Zigrat's sheet seems to be modeled with somekind of formula which is based on aspect ratio. I don't know the idea behind this; lift distribution is not the function of aspect ratio.
See Badboys explaination.
http://www.aerospaceweb.org/question/aerodynamics/q0184.shtml
Seems much more accurate than an arbitrary "e" factor.
With these modifications Zigrat's spreadsheet gives same values with good enough accuracy (several decimals).
Yep and with those changes at 300mph the total drag is within 20 pounds. At 315mph the difference increases and continues to rise the faster you go in the FW-190's favour. No way around it, even with your values the FW-190 produced less parasitic drag than the spitfire.
Seems to me that the FW-190 has the same amount of braking forces applied to a lot more inertia.
I also emailed Zigrat to see what is up with his density. I changed one of my spreadsheets to reflect the formula you posted.
I will check my calculations and post them in the morning.
The power chart gives 1770 ps with RAM at 4500 ft which is 1745,79 hp. The stall speed is not really needed and unaccurate due to altitude (far too low).
Agree on the stall speed. Wasn't sure what it was at altitude for either plane so I just used the IAS values.
On the Horsepower 3 things:
1. Horsepower varies from engine to engine within the same type of engine. It is not an exact value.
2. You are only talking a 15 Hp difference.
3. 1770PS is at full throttle height and the FW-190 is not at full throttle height but rather just below it.
I will check the chart again but 13000 feet is 3.96 Km and not 5 Km which is roughly the full throttle height of the BMW-801D2 RAM at 1.42ata @ 2700U/min.
Well, the question remains: Is that data true flight tested data and if it is, is filled and polished surfaces normal?
Yes, actually that was a quite common practice for both Axis and Allied. There is one story of a 109 pilot who crashed twice in one week. His crew chief refused to polish anymore planes for him to he could prove he would not crash them.
Many a crew chief on both sides stayed up late at night with some turtle wax and a buffer (in the form of a lesser ranking ground crew member).
I have at least 3 flight graphs for the FW-190A8. All of them are within a few miles per hour, one is faster, the other two are the same. This graph is about average.
All of them including this one were performed as part of the FW-190D / Ta-152 development and testing. Get a copy of:
http://www.schifferbooks.com/newschiffer/book_template.php?isbn=0764318764
It listed this flight as part of the program.
The JL 165 chart gives actually 364 mph at 4500 ft. The JL165 had MS gear high speed FTH 2800 ft with +25 lbs and the output at that altitude is about 2020 hp (according to the chart you refer). Above that altitude ouput drops about about 0,057944 hp/ft so at 4500 ft the engine output is roughly 1921 hp. It should be noted that the JF275 was about 10mph faster with the same output.
And that was corrected and recalculated. The results were the same. The FW-190 moves to advantage over the spitfire in level speed due to having less parasitic drag. It also goes almost as fast with a lot less power.
The numbers are listed above. I will recalculate them using your changes. However, since I have already done the Merlin 61 vs FW-190A5, I am pretty sure the results will be pretty close.
Crumpp
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Looking at the 190 and then the Spitty, I'd have thought they (as well as the 109) have very little difference in parasite drag.
Well, the 190 has a radial engine, which makes a lot of drag, but the rest is extrordinarily sleek ;)
Anyway, the 190 would then have more induced drag at low speeds, crossing over at high speeds, total drag being lower at high speeds right?
Anyway, nice links you're popping up with Crumpp.
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Looking at the 190 and then the Spitty, I'd have thought they (as well as the 109) have very little difference in parasite drag.
Kurt Tank did a great cowling job on the 190A. If you check out the surface area of the Spitfire Mk IX's radiators it is roughly the same surface area as the intake on the FW-190's cowling. Since the Spitfire Mk IX apparently had some boundary layer separation on the inside ducting that was never corrected that definitely accounts for the parasitic drag. Add it the fact that the FW-190 just had much less surface area dimensionally and it just makes sense.
In fact the FW-190 has less parasitic drag throughout the flight envelope.
In a zoom climb induced drag is not a big factor as Thrust takes over for lift. With the 190's lower parasitic drag and greater inertia it's easy to see why there is so much anecdotal evidence that Merlin Power Spits never took on 190A's in the vertical.
It seems the 190A was very efficient at converting Altitude to Speed and back.
Even with Gripen changes the numbers add up to the FW-190 having the advantage in level speed drag. Took me a while to make the changes on the spreadsheet and copy it. I quickly calculated an FW-190A5 and the Merlin 61 but need to research my values since so much has changed over the original ones. You guys keep coming up with new data each post! Lots of wiggling going on! :p
He is correct on the Feet per second error but I am not so sure on the density. I am waiting to hear from the guy who made the spreadsheet to see if what he using. All in All it seems a very detailed and well put together tool.
Here is a nice one too for calculating density:
http://www.aerospaceweb.org/design/scripts/atmos.shtml
That spreadsheet seems to use the Line lift producing theory to generate it's values. Some of the formulas are the same, however some are different. There are more that one theory on the creation of lift and more than one formula to determine Co-efficients.
http://www.aerospaceweb.org/question/aerodynamics/q0005.shtml
http://www.grc.nasa.gov/WWW/K-12/airplane/lifteq.html
http://www.aerospaceweb.org/question/aerodynamics/q0015b.shtml
http://www.aerospaceweb.org/question/aerodynamics/q0136.shtml
So the values might not match exactly.
Crumpp
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Originally posted by Badboy
Even though it is a function of aspect ratio, sweepback angle, taper ratio and twist, the largest influence on the wing of a WWII fighter with very little sweep or twist comes from aspect ratio and taper ratio and so there are approximate formulae for estimating e that only include aspect and taper ratio, and even more approximate methods that only include aspect ratio. The important thing you must appreciate is that they are only approximate. But better than just assuming a constant value for every aircraft.
Hope that helps...
Badboy
Edit:
Just checked my own teaching notes, and should add that the Oswald efficiency factor is also a function of wing camber and Mach number. In any case, calculating the Oswald efficiency factor from wing geometry is problematic. The values obtained are generally only valid for low AoA work because the calculations require that the flow remains fully attached, whereas in practice that is rarely the case. Generally such methods produce optimistic results.
Zigrat's spread sheet gives e factors:
Spitfire: 0,878
Fw 190: 0,865
If compared to the Lednicer's chart, the difference seems to be quite low, the Spitfire being much closer elliptical lift distribution than the Fw 190. Maybe adding taper ratio to the calculation would give better estimate. Anyway, e factor itself is not directly related to the aspect ratio, maybe adding taper ratio to the calculation would help.
Originally posted by Crumpp
Your correct and I changed it. Raises the speed to 310mph were the FW-190 gains advantage over the Spitfire in drag.
Hm... Well the JF275 at 4500 ft has advantage in drag over the Fw 190A-8 at all speeds. And in the turning performance even the JL165 has advantage at all speeds.
Originally posted by Crumpp
No way around it, even with your values the FW-190 produced less parasitic drag than the spitfire.
Well, the flat plate areas for Cd0 are:
Fw 190A-8: 4,82
JL165: 5,18
JF275: 4,77
So according to my numbers the JF 275 has lower parasitic drag than the Fw 190 (filled and polished).
Originally posted by Crumpp
Seems to me that the FW-190 has the same amount of braking forces applied to a lot more inertia.
Well, I have allready calculated forward acceleration above with the mass of the planes.
Originally posted by Crumpp
3. 1770PS is at full throttle height and the FW-190 is not at full throttle height but rather just below it.
I will check the chart again but 13000 feet is 3.96 Km and not 5 Km which is roughly the full throttle height of the BMW-801D2 RAM at 1.42ata @ 2700U/min.
I can't read the chart more accurate, 1770 ps seem to be quite exact value for the 4500 ft.
Originally posted by Crumpp
Yes, actually that was a quite common practice for both Axis and Allied. There is one story of a 109 pilot who crashed twice in one week. His crew chief refused to polish anymore planes for him to he could prove he would not crash them.
Well, if we want comparable results, the Spitfires should have been filled and polished too.
Originally posted by Crumpp
I have at least 3 flight graphs for the FW-190A8. All of them are within a few miles per hour, one is faster, the other two are the same. This graph is about average.
Well, the Navy Fw 190 performed quite close to your numbers near sea level given the polishing and filling. Still I don't see evidence that your numbers are flight tested.
Originally posted by Crumpp
However, since I have already done the Merlin 61 vs FW-190A5, I am pretty sure the results will be pretty close.
Well, you are producing enermous amount of numbers and I have no time to check them all (it could be a good idea to limit values to the only relevant part), but couple things should be noted:
Why should the Fw 190A-5 be so much faster than the Navy 190 and the Fw 190A-8 with same power settings?
Are the Fw 190A-5 values really flight tested?
The wartime documentation gives 1520 hp at 1st FTH and 1300 hp at 2nd FTH for the Merlin 61.
gripen
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"Fw 190 (filled and polished)"
What?
-C+
-
"Fw 190 (filled and polished)"
They waxed it.
Crumpp
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Why should the Fw 190A-5 be so much faster than the Navy 190 and the Fw 190A-8 with same power settings?
I don't think it is, Gripen. The best climb speeds line up perfrectly. Not so sure on the level speed I will have to check it out again. Probably not since the Navy was having so much trouble out of the BMW using US AVGAS.
Crumpp
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Here are the results with Gripens changes.
Gripen Can I please get a copy of the Merlin 66 Horsepower chart you are looking at.
Both Horsepower figures are RAM in order to line up the numbers for comparision.
FW-190A8
1.42ata @ 2700U/min
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 196.96
Airplane weight, lbs (as tested) - 9418
Wing span, ft - 34.45
Step B - performance #s at a known altitude
Altitude (feet) - 4500
Maximum speed (at test alt.- mph) - 356
Engine Horsepower (bhp at test alt) - 1730
Stall speed (mph, at test alt) - 110
speed (mph TAS)
300
speed (fps)
440
CL
0.237567
D(p)
926.7646
D(i)
136.9862
CL^2
0.056438
CD(tot)
0.026833
Drag (tot)
1063.7508
thrust (lb)
1617.469
excess power (bhp)
621.1324
P.E.
0.779137
Spitfire Mk IX Merlin 66 (+25)
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 242
Airplane weight, lbs (as tested) - 7400
Wing span, ft - 36.1
Step B - performance #s at a known altitude
Altitude (feet) - 4500
Maximum speed (at test alt.- mph) - 366
Engine Horsepower (bhp at test alt) - 2050
Stall speed (mph, at test alt) - 90
speed (mph TAS)
300
speed (fps)
440
CL
0.151922
D(p)
1051.797
D(i)
75.20623
CL^2
0.02308
CD(tot)
0.023137
Drag (tot)
1127.0037
thrust (lb)
1996.538
excess power (bhp)
869.5343
P.E.
0.779137
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Waxing is not filling. Waxing = polishing.
Polishing was even done in operational units but AFAIK filling was only done on some experimental and speed record a/c.
-C+
-
Polishing was even done in operational units but AFAIK filling was only done on some experimental and speed record a/c.
I am afraid there is plenty of anecdotal evidence showing otherwise.
Both filling and polishing are simple task's that any crew chief on both sides not only could but did do often.
One of the USAAF P47 Aces was famous for flying a filled and polished Jug. His crew chief skill at it was the envy of the other pilots in the squadron.
You can see the above thread for the 109 pilot anecdote.
I fail to understand the double standard being applied here. We want to use only the best available data for the Spitfire but when the results don't turn out how we expect then that data is not good enough.
1. Folks want me to apply data from experimental a/c for the Spitfire because the data listed as the actual Merlin 66 (+25) performance is not good enough.
2. Folks want to complain at the same time over a wax job on the LW A/C.
3. I am using the best available data I have and applying the same standard to both A/C. Playing favourites is totally contrary to what I want to accomplish.
Both Horsepower figures are RAM in order to line up the numbers for comparision.
Darn it. Gripen I posted the wrong one. I did the calculations with your Horsepower figures for both Aircraft.
It brought the total drag of the Aircraft within 1 pound of each other, in the FW's favour, at 300mph. By 315mph the drag had moved almost 100lbs in the FW-190's favour.
I will post the new results when I get back from work.
Crumpp
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From Crumpp
"With the 190's lower parasitic drag and greater inertia it's easy to see why there is so much anecdotal evidence that Merlin Power Spits never took on 190A's in the vertical. "
You are referring to E-to-zoom at high speeds I presume.
I'll post a nice anecdotal evidence of what happened if the 190 had a knife fight with a Spitty and let it's speed go to far down.
(1 Spit IX vs a gaggle of 190's)
I'll try to find out from other sources which IX, and given the date and location your sources might be able to find out about the 190's
It will be an hour or two. Hope I got y0u all drooling
:D
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Originally posted by Crumpp
Not so sure on the level speed I will have to check it out again.
The data set in your source page gives about 20-30 km/h faster speeds at low altitudes than the A-8 data set and the Navy data set.
Originally posted by Crumpp
Probably not since the Navy was having so much trouble out of the BMW using US AVGAS.
Well, if you have evidence on that, please post. Otherwise that is purely speculation. Besides performance numbers are quite close to Fw 190A-8 so the engine probably run fine.
Originally posted by Crumpp
I fail to understand the double standard being applied here. We want to use only the best available data for the Spitfire but when the results don't turn out how we expect then that data is not good enough.
Well, you truly fail to understand that the JF275 had lower drag at all conditions than the Fw 190A-8 despite the Fw was specially prepared (if the Fw was really tested).
Originally posted by Crumpp
1. Folks want me to apply data from experimental a/c for the Spitfire because the data listed as the actual Merlin 66 (+25) performance is not good enough.
The JF275 was a standard Spitfire VIII while the Fw 190A-8 you use was not (if the Fw data is actually tested).
Originally posted by Crumpp
2. Folks want to complain at the same time over a wax job on the LW A/C.
No one complains about wax job but if you want fair comparison between two aircraft, the surface finish should be similar. However, the JF275 did better even without special finish.
Originally posted by Crumpp
3. I am using the best available data I have and applying the same standard to both A/C. Playing favourites is totally contrary to what I want to accomplish.
Well, the evidence above speaks for something else.
Originally posted by Crumpp
It brought the total drag of the Aircraft within 1 pound of each other, in the FW's favour, at 300mph. By 315mph the drag had moved almost 100lbs in the FW-190's favour.
Well, the JF275 had lower flat plate area for Cd0 than your Fw 190A-8. In practice it means that the JF275 had lower drag at all speeds as well as at all reachable g loads.
gripen
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The data set in your source page gives about 20-30 km/h faster speeds at low altitudes than the A-8 data set and the Navy data set.
No that performance graph EXACTLY matches the Focke-Wulf comparison flight test's conducted for the Ta-152 development program. In fact, it is an English translation of the same test and a poor one at that.
The German text describing the condition of the planes reads, "Surface fixed and painted" on the FW-190A8. It was flown to establish performance improvements against 4 different prototypes over several months. It says absolutely NOTHING about "filled and polished".
It means just what it says. Needed repairs were made and the plane was repainted. Totally different from "filled and polished".
I would be glad to provide the graph page from the report so you can evaluate it yourself. In fact I will email it to Hitech.
Well, if you have evidence on that, please post. Otherwise that is purely speculation. Besides performance numbers are quite close to FW 190A-8 so the engine probably run fine.
Unless you have different report, the US Navy test was an FW-190A5 NOT an FW-190A8.
It was the tactical trials of a crash-landed and repaired FW-190A5/U4. The FW-190A5/U4 was later blanket redesignated the FW-190G1. The aircraft needed extensive repairs to both the airframe and the engine before being flown against an F4U and Hellcat.
The engine quit on three attempts to reach service ceiling, which was never reached in the Navy test and at low rpms fouled the plugs consistently. In other words it was not running right. My guess is it did not like the US AVGAS that had a lower aromatic content than the German aviation fuels. If you want to try an experiment with different fuels, just put some MOGAS in your car and see how it runs. The information is listed on Page 4 of the report. I can provide you with a copy of it if you like.
Besides performance numbers are quite close to FW 190A-8 so the engine probably run fine.
If your refering to the level speeds then NO they are not close at all. If you are refering to the horsepower development chart on page 5 then you are correct. Those numbers are a reprint taken from the FW-190A5 pilots manual as are the dive restrictions.
Crumpp
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Well, the JF275
Please provide a link on the performance data for JF275 or an actual report. I cannot any data on it nor is it listed on this site:
http://www.fourthfightergroup.com/eagles/spittest.html
Crumpp
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JF 275 data is at http://www.fourthfightergroup.com/eagles/spit8.html
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You sure you want this version?
Manoeuvrability
5......... There was nothing to choose between either aircraft as regards turning circles at any height; whether on offensive or defensive manoeuvres neither could make any impression on the other. In rate of roll, however, the Spitfire IX was considerably better especially at low altitude. A number of full rolls through 360 degrees were timed by the same pilot flying each aircraft in turn and although quanitative tests are difficult to produce, it appeared that there was often more than 1.5 seconds superiority for the Mark IX over the Mark VIII. The Mark VIII feels fairly light on the ailerons but at high speeds it becomes very heavy, and so this new combination of extended wing and small aileron cannot be considered satisfactory.
Looks like it is outstanding at high altitudes but much worse at lower altitudes than even the Merlin 61.
http://www.fourthfightergroup.com/eagles/jf934level.jpg
I will run the numbers but a quick glance leaves me skeptical on the performance improvement.
There is no chart either for JF275, only a table with no documents to back it up. I will run both the tested data and the table data.
I need the wing area as it has an extended wing and a source.
Thanks!
Crumpp
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FW-190A8 at 1.42ata@2700U/min
Gripen's Horsepower rating for the BMW-801D2 is only 10 hp away from the full throttle height horsepower rating at over a 600 ft. below full throttle height. Using a straight edge on the chart IMO 1730 is more accurate.
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 196.96
Airplane weight, lbs (as tested) - 9418
Wing span, ft - 34.45
Step B - performance #s at a known altitude
Altitude (feet) - 4500
Maximum speed (at test alt.- mph) - 356
Engine Horsepower (bhp at test alt) - 1745
Stall speed (mph, at test alt) - 110
speed (mph TAS)
300
speed (fps)
440
CL
0.237567
D(p)
935.3667
D(i)
136.9862
CL^2
0.056438
CD(tot)
0.02705
Drag (tot)
1072.3529 @310mph - 1127.045 @315mph - 1155.4773
thrust (lb)
1699.492
excess power (bhp)
627.1391
P.E.
0.779137
Spitfire Mk IX Merlin 66 (+25)
Using the horsepower rating Gripen provided. It would be nice to have full disclosure and receive a copy of this chart.
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 242
Airplane weight, lbs (as tested) - 7400
Wing span, ft - 36.1
Step B - performance #s at a known altitude
Altitude (feet) - 4500
Maximum speed (at test alt.- mph) - 366
Engine Horsepower (bhp at test alt) - 1945
Stall speed (mph, at test alt) - 90
speed (mph TAS)
300
speed (fps)
440
CL
0.151922
D(p)
996.2789
D(i)
75.20623
CL^2
0.02308
CD(tot)
0.021998
Drag (tot)
1071.4852 @ 310mph - 1134.2264 @ 315mph - 1166.5965
thrust (lb)
1894.276
excess power (bhp)
822.7911
P.E.
0.779137
The faster you go the more the total drag swings in the FW-190A's favor. The parasitic drag always favors the FW-190.
Also seems to me that the FW-190 also has less braking forces per mass acting on it.
So I would say David Lednicer's conclusions were correct.
Crumpp
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My guess is JF275 was one of the Spitfire Mk VIII's with a standard wing.
http://www.fourthfightergroup.com/eagles/spit8.html
AND
Two interesting modifications were tried on individual Mk VIII's: the first was a six-bladed, contra-rotating propeller; the second was a teardrop canopy to improve the pilot's rearward view. Both these features were adopted as standard on later production variants.
http://www.btinternet.com/~lee_mail/spitfire2.html
Too bad:
In many ways the Mk VIII was the best of the Spitfires, but as it never saw service in Northern Europe, its capabilities largely went unrecognized.
I will run the numbers and see what is up with the MK VIII. This is the version I think Guppy's friend flew. I hope HTC decides to model it. It would have it's place in ToD IMO.
Anybody have the wing area with the extensions on it?
Crumpp
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Originally posted by Crumpp
No that performance graph EXACTLY matches the Focke-Wulf comparison flight test's conducted for the Ta-152 development program.
So they might have used the same calculated curve for comparison.
Originally posted by Crumpp
The German text describing the condition of the planes reads, "Surface fixed and painted" on the FW-190A8.
This might mean same as filled and polished in other words, do you speak german?
Originally posted by Crumpp
Unless you have different report, the US Navy test was an FW-190A5 NOT an FW-190A8.
Well, same airframe, same ratings and almost same results given the difference in the surface finish.
Originally posted by Crumpp
My guess is it did not like the US AVGAS that had a lower aromatic content than the German aviation fuels.
So apparently you have no evidence that the problems at high altitude was caused by US avgas.
Originally posted by Crumpp
Gripen's Horsepower rating for the BMW-801D2 is only 10 hp away from the full throttle height horsepower rating at over a 600 ft. below full throttle height. Using a straight edge on the chart IMO 1730 is more accurate.
Just read the graph at 4500 ft => 1770 ps
Originally posted by Crumpp
The faster you go the more the total drag swings in the FW-190A's favor. The parasitic drag always favors the FW-190.
Also seems to me that the FW-190 also has less braking forces per mass acting on it.
So I would say David Lednicer's conclusions were correct.
You are continously using the below average JL165 data set, please use the JF275 data set.
Originally posted by Crumpp
You sure you want this version?
That's with tropical equipment.
gripen
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Originally posted by Crumpp
Using the horsepower rating Gripen provided. It would be nice to have full disclosure and receive a copy of this chart.
...
Engine Horsepower (bhp at test alt) - 1945
Actually that is the output I calculated assuming 2050 hp output at the first FTH with RAM. But as noted above the real output at the 1st FTH is about 2020hp using the exactly same chart (http://www.fourthfightergroup.com/eagles/merlin66hpchart.jpg) as Crumpp, so we can see that at 2800ft the JL165 and the JF275 had engine output roughly 2020 hp with RAM. And by measuring rate of the power decrease above the first FTH we can calculate that at 4500ft the output was roughly 1922 hp with RAM.
Regarding the E drain in the turn, the real subject of this thread, here is the forward acceleration comparison in the level turn under various g loads at 300 mph and at 4500 ft calculated with the mass of the planes.
JF275
0g 1,551 m/s2
1g 1,452
2g 1,156
3g 0,662
4g -0,029
5g -0,917
6g -2,004
JL165
0g 1,516 m/s2
1g 1,422
2g 1,140
3g 0,670
4g 0,011
5g -0,835
6g -1,870
Fw 190A-8
0g 1,078 m/s2
1g 0,923
2g 0,458
3g -0,317
4g -1,403
5g -2,798
6g -4,503
gripen
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Actually that is the output I calculated assuming 2050 hp output at the first FTH with RAM. But as noted above the real output at the 1st FTH is about 2020hp using the exactly same chart as Crumpp, so we can see that at 2800ft the JL165 and the JF275 had engine output roughly 2020 hp with RAM. And by measuring rate of the power decrease above the first FTH we can calculate that at 4500ft the output was roughly 1922 hp with RAM.
Your right, Just rechecked the chart and I missed the line. So I have the Spitfire going at FTH level speed for less Horsepower than it actually took at a higher altitude than it actually occurred! Let me fix that:
I just went with the listed full throttle height on Table IV and plugged in the full throttle height horsepower. From there I used the same charts for the FW-190A8 to find the speed an horsepower output at the same altitude.
http://www.fourthfightergroup.com/eagles/jl165.html
FW-190A8 1.42ata@2700U/min
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) 196.96
Airplane weight, lbs (as tested) 9418
Wing span, ft 34.45
Step B - performance #s at a known altitude
Altitude (feet) 2800
Maximum speed (at test alt.- mph) 348
Engine Horsepower (bhp at test alt) 1720
Stall speed (mph, at test alt) 110
Speed (fps)
440
CL
0.225749
D(p)
988.1947
D(i)
130.1717
CL^2
0.050963
CD(tot)
0.026807
Drag (tot)
1118.3664
thrust (lb)
1682.389
excess power (bhp)
564.0221
P.E.
0.782506
Spitfire Mk IX Merlin 66 (+25)
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) 242
Airplane weight, lbs (as tested) 7400
Wing span, ft 36.1
Step B - performance #s at a known altitude
Altitude (feet) 2800
Maximum speed (at test alt.- mph) 364
Engine Horsepower (bhp at test alt) 2050
Stall speed (mph, at test alt) 90
Speed (fps)
440
CL
0.144365
D(p)
1071.918
D(i)
71.46502
CL^2
0.020841
CD(tot)
0.022306
Drag (tot)
1143.3834
thrust (lb)
2005.172
excess power (bhp)
861.789
P.E.
0.782506
And of course the faster you go the more it moves to the FW-190's favour. So Lednicer was right about the drag.
Regarding the E drain in the turn, the real subject of this thread, here is the forward acceleration comparison in the level turn under various g loads at 300 mph and at 4500 ft calculated with the mass of the planes.
Probably not exact Gripen but close enough to see that unless the FW-190 is pulling 4 g's or more it's energy bleed is not as bad as the Spitfires.
Crumpp
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Bringing some nice anecdotal stuff into the fire ;)
Pilots account from a mission where Spitfires having a party were jumped by 190's and 109's.
"While scanning the sea, I suddenly saw the shadows of a large number of aircraft on the water, though I could not see the actual aircraft. They were very low down and making for Tunis - Rommel's final reinforcements.
I called up Ian Gleed on the R/T and reported them.
"Can't see them from down here," he replied. "You'll lead on and we'll follow you."
My section followed me down and we soon sighted about eighteen Savoia 82's, three-engined transport aircraft. I selected one for attacking, but my machine was moving too quickly and I overshot.
Throttling back, I attacked another, closed right up and skimmed over the top of him as he went into the sea, broke up and disappeared in masses of spray with the engine cowlings bouncing over the waves.
I had time to shoot down another, which practically landed on the sea; and then a mixed formation of escorting Focke Wulfs and Messerschmitts appeared on the scene and jumped us.
Just as I was about to attack another Savoia I glanced back and a Focke Wulf on my tail. And then, suddenly, the air seemed to be filled with Focke Wulfs. I saw one or two Spitfires leaving the area, and Ian Gleed's no.2 bale out while his aircraft went down in flames. I had the Focke Wulfs to myself. This seemed to be it.
With the engine flat out I flew over the sea, twisting, turning, dodging, gaining a bit of confidence when I found my Spit 9 could turn inside the Focke Wulfs, nearly blacking out sometimes with high G. Finally, in desperation and to get more height to fight, I put the aircraft into a steep climb and after what seemed a life-time found myself alone again."
This pilot flew an unknown mark of Spit IX, sqn is 92 RAF, date 16 apr 1943.
Anyway, I've seen more accounts of this climbing evasive, pilots all so far quite reliable.
Enjoy all ;);););)
-
So those 190s had no energy left to zoom after foolishly trying to beat an IX in a turnfight.
Nice story.
-C+
-
Originally posted by Crumpp
FW-190A8 1.42ata@2700U/min
..
Altitude (feet) 2800
Maximum speed (at test alt.- mph) 348
Engine Horsepower (bhp at test alt) 1720
Actually the speed chart gives roughly 564 km/h (350 mph) at 2800 ft and the output chart gives 1760 ps (1736 hp) at 2800 ft with RAM.
Originally posted by Crumpp
Spitfire Mk IX Merlin 66 (+25)
..
Altitude (feet) 2800
Maximum speed (at test alt.- mph) 364
Engine Horsepower (bhp at test alt) 2050
The output is still wrong, the correct is about 2020 hp. And why not the JF275 data set? It did 374 mph at 2800 ft.
At 2800 ft the flat plate areas are following:
JF275: 4,92 for Cd and 4,77 for Cd0
JL165: 5,34 for Cd and 5,19 for Cd0
FW 190A-8: 5,14 for Cd and 4,78 for Cd0
The JF275 (without filling and polishing) does still better than the Fw 190A-8.
gripen
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It was Neville Duke flying the Spitty.
-
The output is still wrong, the correct is about 2020 hp. And why not the JF275 data set? It did 374 mph at 2800 ft.
Actually the speed chart gives roughly 564 km/h (350 mph) at 2800 ft and the output chart gives 1760 ps (1736 hp) at 2800 ft with RAM.
According to the chart it is 2050hp but I will change it your numbers once again.
For the FW-190A8 you need to recheck that. The FTH for the BMW801D is only 1755 hp RAM and we are 2200 feet below that height.
Why not the J275? Sure I would be glad to run it.
As soon as my questions about it are answered. See above post's because I need some information on it otherwise I am just making a guess.
That is a totally different Spitfire however that never saw service in the European Theater.
With your new numbers the total drag runs out to be:
Spitfire Mk IX Merlin 66 Total Drag at 440fps - 1127.240025
FW-190A8 Total Drag at 440fps - 1102.340435
I will post the complete set of numbers later.
The JF275 (without filling and polishing) does still better than the Fw 190A-8.
The FW-190A8 is not filled and polished either. If you would like a copy of the original German I would be glad to provide it. It says "surface fixed and repainted" which is very different from filled and polished. This has been covered before.
1. Since you have not requested a copy of the original report that I offered you must either be:
a - Not reading my post's.
b - Deliberately attempting to inflame.
Which is it?
Crumpp
-
I put the aircraft into a steep climb and after what seemed a life-time found myself alone again."
Great Story Angus!
Some points that struck me.
1. The confidence in which the 190 pilots closed and "mixed it up" with the Spitfires. They did not make clumsy passes and then extend beyond visual range to reverse. They got in tight and fought.
Anyway, I've seen more accounts of this climbing evasive, pilots all so far quite reliable.
2. In a sustained climb the later Mk IX's ruled.
3. Absolutely, Pilots are telling the truth about actual events. However it is told from one person's perspective and may not neccessarily represent the total reality.
With the engine flat out I flew over the sea, twisting, turning, dodging, gaining a bit of confidence when I found my Spit 9 could turn inside the Focke Wulfs, nearly blacking out sometimes with high G. Finally, in desperation and to get more height to fight, I put the aircraft into a steep climb and after what seemed a life-time found myself alone again."
Empty sky syndrome, we talked about this phenomen before and is quite common amoung fighter pilots. Without accounts from the otherside it is inconclusive. Sounds like it erupted into a massive dogfight and he was lucky to survive.
I have some great stuff coming on JG2 who was flying FW-190's in North Africa around that time period. When it gets here I will see if there is anything interesting noted on these dates.
Crumpp
-
Originally posted by Crumpp
According to the chart it is 2050hp but I will change it your numbers once again.
I wonder how you can read 2050 hp for +25 lbs from this (http://www.fourthfightergroup.com/eagles/merlin66hpchart.jpg) chart?
Originally posted by Crumpp
For the FW-190A8 you need to recheck that. The FTH for the BMW801D is only 1755 hp RAM and we are 2200 feet below that height.
I wonder how you can read something else than 1760 ps (2700rpm and 1,42ata) at 2800 ft (853,44 m) from this (http://www.terra.es/personal2/matias.s/bmw801d-1024.jpg) chart?
Originally posted by Crumpp
Why not the J275? Sure I would be glad to run it.
As soon as my questions about it are answered. See above post's because I need some information on it otherwise I am just making a guess.
That is a totally different Spitfire however that never saw service in the European Theater.
Well, the JF275 had the Merlin 66 so it had standard wing tips ie the wing area was 242 sqft.
The main aerodynamic difference between the Spitfire IX and VIII was the tailwheel and the Spitfire VIII saw service in Italy, I think even USAAF used it there
Originally posted by Crumpp
With your new numbers the total drag runs out to be:
Spitfire Mk IX Merlin 66 Total Drag at 440fps - 1127.240025
FW-190A8 Total Drag at 440fps - 1102.340435
Well, you don't need to calculate anything more with the JL165 data, remember your own words above:
"I am using the best available data I have and applying the same standard to both A/C."
The JL 165 had the largest flat plate area of all tested Spitfire IXs and for one reason or another you continously use it.
Originally posted by Crumpp
I will post the complete set of numbers later.
Just post relevant numbers (preferably flat plate area), posting the whole set is plain waste of bandwidth.
Originally posted by Crumpp
The FW-190A8 is not filled and polished either.
According to the chart (http://www.terra.es/personal2/matias.s/fw190-1.jpg) in your source page it had "External surfaces: Filled + polished".
Originally posted by Crumpp
If you would like a copy of the original German I would be glad to provide it. It says "surface fixed and repainted" which is very different from filled and polished. This has been covered before.
1. Since you have not requested a copy of the original report that I offered you must either be:
a - Not reading my post's.
b - Deliberately attempting to inflame.
Which is it?
It is c
c - get some web space and put the scanned picture there and link it directly to this thread so every one can check the thing.
gripen
-
According to the chart in your source page it had "External surfaces: Filled + polished".
Give me your email addy and I will send it too you. If you can read German you will immediately see it.
As to your C - I don't have any web space and I am not putting all my document out for public consumption yet.
I am however being nice enough to offer it to you and others on this BBS.
Why do you constantly take a crappy attitude? Are you in fear for some score in the game?
I have been trying to just have a discussion with you about this but you ALWAYS turn nasty the moment you shown to be mistaken about anything.
Lets review:
You call into question the Oswald factor calculations and were wrong.
It is not just JL275, I have posted calculations for EVERY Spitfire Mk IX listed on that site. They all confirm David Lednicers data. Even with the density and speed corrections the data does not change much at all. The actual numbers vary but the results are the SAME.
I have made EVERY change you have requested. The above calculations with ALL the changes you wanted!! The conclusions remain the SAME.
All in all you are still running about 50 percent like the rest of us.
I wonder how you can read 2050 hp for +25 lbs from this chart?
I wonder how you don't! AND I made the changes!
I wonder how you can read something else than 1760 ps (2700rpm and 1,42ata) at 2800 ft (853,44 m) from this chart?
I wonder how you don't! And I made the changes!
The main aerodynamic difference between the Spitfire IX and VIII was the tailwheel and the Spitfire VIII saw service in Italy, I think even USAAF used it there
Not according to every reference I have found on the Spitfire Mk VIII. It was a non-pressurized version of the Mk VII with extended wings. Later versions were fitted with the standard wings. It was also the first version fitted with a teardrop canopy and a 6 bladed counter rotating propeller according to some sites.
It was never deployed to the Northern European Theater. Many sites agree it was the best performing Spitfire version produced however by the time it came into service the Mk IX was well in place and it simply was not produced in any numbers.
The discussion was on David Lenicers data with your contention being the Spitfire always had less drag than the 190. That is simply not true. He was correct not you.
http://www.btinternet.com/~lee_mail/spitfire2.html
FW-190A8
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 196.96
Airplane weight, lbs (as tested) - 9418
Wing span, ft - 34.45
Step B - performance #s at a known altitude
Altitude (feet) - 2800
Maximum speed (at test alt.- mph) - 350
Engine Horsepower (bhp at test alt) - 1736
Stall speed (mph, at test alt)- 110
Drag total = 1112.002143@ 440 fps
parasitic drag = 981.8304509
Spitfire Mk IX Merlin 66 (+25)
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 242
Airplane weight, lbs (as tested) - 7400
Wing span, ft - 36.1
Step B - performance #s at a known altitude
Altitude (feet) - 2800
Maximum speed (at test alt.- mph) - 364
Engine Horsepower (bhp at test alt) - 2020
Stall speed (mph, at test alt) - 90
Total Drag = 1127.240025@ 440fps
parasitic drag = 1055.775
Crumpp
-
Here is JB 275's drag numbers at 2800 feet FTH (2020hp).
Total drag = 1051.19806 @ 440 fps
parasitic drag = 972.4078707
FW-190A8
Drag total = 1112.002143@ 440 fps
parasitic drag = 981.8304509
Again it has practically the same amount of force acting on a lot less mass. It will only have an energy retention advantage when both planes are pulling several G's.
For the Spitfire Mk IX Merlin 61 we have in AH:
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 242
Airplane weight, lbs (as tested) - 7480
Wing span, ft - 36.1
Step B - performance #s at a known altitude
Altitude (feet) - 15400
Maximum speed (at test alt.- mph) - 380.5
Engine Horsepower (bhp at test alt) - 1565
Stall speed (mph, at test alt) - 90
Total Drag - 795.641828 @ 440 fps
Parasitic drag - 687.4074265
FW-190A5
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 196.96
Airplane weight, lbs (as tested) - 9052
Wing span, ft - 34.45
Step B - performance #s at a known altitude
Altitude (feet) - 15400
Maximum speed (at test alt.- mph) - 394
Engine Horsepower (bhp at test alt) - 1420
Stall speed (mph, at test alt) - 110
Total Drag -718.2845242@ 440 fps
Parasitic drag - 540.0383219
Crumpp
-
Without getting involved into the calculations:
"Not according to every reference I have found on the Spitfire Mk VIII. It was a non-pressurized version of the Mk VII with extended wings. Later versions were fitted with the standard wings. It was also the first version fitted with a teardrop canopy and a 6 bladed counter rotating propeller according to some sites. "
There were "Specialized" high alt versions of the Mk VIII, already in the med. I can check out dates, but I have no more detail about i.e. pressurized or not etc.
There were pressurised Spits, but what model, I do not know. There were also two-pilot VIII and IX's actually.
None were supplied in the N European theater to my klnowledge, but some in the med, and the rest in SE asia. They may have been used to test some G-Suits down there actually, for they could pull very high G's for a long time, - more than any hardware available.
They were shipped to the med and se Asia because they were all "tropicalized" as far as I know. The filter design was far superior to the slowing-down Vokes filter.
And they did have a retractable tailwheel, and were cleared for 25 boost.
I never heard about the canopy or the counter-prop, but I'll check out from books as well as the ultimate roll rate of the final Spit series.
(digging for my book all over the house)
Anyway, best of luck and good night
Angus
-
Thanks Angus!
Good night bro.
Crumpp
-
Spitfire The History has a few details on JF 275's tests at 25 lbs.
It had a standard Rotol prop of 10 ft 9 in diameter (this rules out the contraprop) , standard wing with B armament (ie 2 20mm, 4 303s), takeoff weight 7700 lbs.
There's a photo of JF 275 as well, it doesn't have the bubble canopy. Of course, it might have been modified later, but I doubt it, there's nothing that I can see to indicate it was.
As to your C - I don't have any web space and I am not putting all my document out for public consumption yet.
If you've got any pics you do want to post, try picture hanger:
http://www.onpoi.net/ah/
Accounts are free, and for each picture you can chose "public" or "private". Private pics people cannot browse to, but you can still link to them from a forum.
-
Originally posted by Crumpp
As to your C - I don't have any web space and I am not putting all my document out for public consumption yet.
Just do like Angus and Nashwan said or do like Isegrim and join to the X-plane.org (http://www.x-plane.org/) and you have 50MB free web space.
Originally posted by Crumpp
I am however being nice enough to offer it to you and others on this BBS.
Using the free web space you can be nice for every one here, and for visitors too.
Originally posted by Crumpp
Why do you constantly take a crappy attitude? Are you in fear for some score in the game?
Well, you own doings in the past might have something to with this. I quess no one likes if some one call him/her with harsh words.
Originally posted by Crumpp
You call into question the Oswald factor calculations and were wrong.
Well, I wonder what you mean? Please show me the mathematical relation between the e factor and the aspect ratio.
Originally posted by Crumpp
It is not just JL275, I have posted calculations for EVERY Spitfire Mk IX listed on that site. They all confirm David Lednicers data.
Let's see, here are flat plate areas at the 1st FTH for Cd:
BF274: 5,21
BS428: 4,93
BS543: 4,46
BS551: 5,12
EN524: 5,06
BS310: 5,22
JL165: 5,34 (A&AEE)
JL165: 5,27 (RR)
MA648: 4,53
JF275: 4,93 (Spitfire VIII)
As can be seen the JL165 had the highest drag of all tested Spitfire IXs. Only the high altitude Spitfires came close, naturally because the compressibility effect. None of the results support directly Lednicer's value with default assumptions, only the Jl165 come close.
Originally posted by Crumpp
I wonder how you don't!
Well, the value is certainly much less than one quarter of the distance between 2000 and 2200 hp.
Originally posted by Crumpp
I wonder how you don't!
That is easy to read => 1760 ps at 2800 ft
Originally posted by Crumpp
Not according to every reference I have found on the Spitfire Mk VIII.
Just read Nashwan's post. The high altitude Spitfires had hig altitude engines (like the merlin 63 or 70) and the JF275 had the medium/low altitude Merlin 66.
Originally posted by Crumpp
It was never deployed to the Northern European Theater.
Well, it fought well against the LW in the MTO.
Originally posted by Crumpp
Many sites agree it was the best performing Spitfire version produced...
Well, as can be seen from the flat plate comparison, the drag difference was not big between the Spitfire IX and the VIII.
Originally posted by Crumpp
...however by the time it came into service the Mk IX was well in place and it simply was not produced in any numbers.
According to your link above 1658 built and 1231 of these with the Merlin 66.
Originally posted by Crumpp
The discussion was on David Lenicers data...
Actually the discussion is about "Draining E in turns", and that is what I have been calculating.
Originally posted by Crumpp
...with your contention being the Spitfire always had less drag than the 190. That is simply not true. He was correct not you.
I have not made such contention but I have stated that the there appear to be no large differences in drag between the Spitfire and Fw 190.
Originally posted by Crumpp
Here is JB 275's drag numbers at 2800 feet FTH (2020hp).
Total drag = 1051.19806 @ 440 fps
parasitic drag = 972.4078707
FW-190A8
Drag total = 1112.002143@ 440 fps
parasitic drag = 981.8304509
Ah... finaly.
gripen
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For the Spitfire Mk IX Merlin 61 we have in AH:
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 242
Airplane weight, lbs (as tested) - 7480
Wing span, ft - 36.1
Step B - performance #s at a known altitude
Altitude (feet) - 15400
Maximum speed (at test alt.- mph) - 380.5
Engine Horsepower (bhp at test alt) - 1565
Stall speed (mph, at test alt) - 90
Total Drag - 795.641828 @ 440 fps
Parasitic drag - 687.4074265
FW-190A5
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 196.96
Airplane weight, lbs (as tested) - 9052
Wing span, ft - 34.45
Step B - performance #s at a known altitude
Altitude (feet) - 15400
Maximum speed (at test alt.- mph) - 394
Engine Horsepower (bhp at test alt) - 1420
Stall speed (mph, at test alt) - 110
Total Drag -718.2845242@ 440 fps
Parasitic drag - 540.0383219
FW-190A8
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 196.96
Airplane weight, lbs (as tested) - 9418
Wing span, ft - 34.45
Step B - performance #s at a known altitude
Altitude (feet) - 2800
Maximum speed (at test alt.- mph) - 350
Engine Horsepower (bhp at test alt) - 1736
Stall speed (mph, at test alt)- 110
Drag total = 1112.002143@ 440 fps
parasitic drag = 981.8304509
Spitfire Mk IX Merlin 66 (+25)
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 242
Airplane weight, lbs (as tested) - 7400
Wing span, ft - 36.1
Step B - performance #s at a known altitude
Altitude (feet) - 2800
Maximum speed (at test alt.- mph) - 364
Engine Horsepower (bhp at test alt) - 2020
Stall speed (mph, at test alt) - 90
Total Drag = 1127.240025@ 440fps
parasitic drag = 1055.775
BF274: 5,21
BS428: 4,93
BS543: 4,46
BS551: 5,12
EN524: 5,06
BS310: 5,22
JL165: 5,34 (A&AEE)
JL165: 5,27 (RR)
MA648: 4,53
JF275: 4,93 (Spitfire VIII
IS NOT THE SAME AS THIS:
Gripen says:
As an example below are accelerations calculated for couple planes at 483 km/h at sea level. Note that flat plate areas are now calculated same way as in the Lednicer's paper (Cdwet includes Cdi and Cd=1 for flat plate) and thrust is calculated assuming 85% efficiency and 120 kp exhaust thrust:
Spitfire IX (average), 3400 kg, 1586 hp, flat plate area 6,18 sqft, e factor 0,9
Fw 190 (US Navy) 3940 kg, 1740ps, flat plate area 6,69 sqft, e factor 0,8
Which you calculated earlier in this thread at 300mph (440 fps) and have stuck too for the majority of it. Which is contrary to David Lednicer's data. Don't play coy, Gripen. It is not what men do.
As for the turning issue you need check about 3 pages back. That issue was resolved. Again you don't bother to read responses.
According to your link above 1658 built and 1231 of these with the Merlin 66.
vs How many Spitfire Mk IX's?
Yeah and according to that link it did not see much service and NONE of them served in the Northern European theater.
Again you do not read peoples responses and you wonder why they lose patience with you. About 4 post's back when the subject first came up on the Spitfire Mk VIII, I commented that I hoped HTC brings it to AH. Simply because I know there are Spitfire fans who have personal ties to the plane. Maybe they can add the FW-190A9 as well.
Well, I wonder what you mean? Please show me the mathematical relation between the e factor and the aspect ratio.
It has to do with the whole LIFT thing Gripen.....Again you don't bother to read peoples response's. It was explained by a man who teaches aeronautics!
You know the thing induced drag is a function of?
I have not made such contention but I have stated that the there appear to be no large differences in drag between the Spitfire and Fw 190.
Flat out BS. You debunked Lednicers data from the beginining.
Ah... finaly.
Yeah and it is NOT a Spit IX. NONE of the Spit IX's have less parasistic drag. I would be glad to go through them all and post the data. You can look at a photo of JG275 and see why. Guppy posted one in another thread.
If you've got any pics you do want to post, try picture hanger:
Thanks Nashwan!
Great info on the Spitfire too.
Crumpp
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Originally posted by Crumpp
IS NOT THE SAME AS THIS:
Which you calculated earlier in this thread at 300mph (440 fps) and have stuck too for the majority of it. Which is contrary to David Lednicer's data. Don't play coy, Gripen. It is not what men do.
Well, my original calculations had exhaust thrust modeled as well as propeller thrust was adjusted according to the momentary theory. Shortly, default assumptioms are different than in the Zigrat's spreadsheet.
Originally posted by Crumpp
It has to do with the whole LIFT thing Gripen.....Again you don't bother to read peoples response's. It was explained by a man who teaches aeronautics!
I don't see any mathematical connection between the e factor and the aspect ratio in Badboy's response which I actually quoted above.
Originally posted by Crumpp
You know the thing induced drag is a function of?
Actually I have been teaching that to you in two threads and finaly you are beginning to understand.
Originally posted by Crumpp
Flat out BS. You debunked Lednicers data from the beginining.
Well, the difference in the Lednicer's values (5,22 and 5,4) is about 4%, much less than variation between various tested Spitfire IXs.
Originally posted by Crumpp
Yeah and it is NOT a Spit IX. NONE of the Spit IX's have less parasistic drag.
Let's see, here are flat plate areas for Cd0 for couple tested Spitfire IX and the JF275:
JF275: 4,77
BS543: 4,34
MA648: 4,34
Some of the high altitude Spit IX might also have lower value at low altitudes.
gripen
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Found some more of the Mk VIII.
It served in Europe, but no squadron of it operated from the UK.
There were high alt variants of them, but not with pressurized cockpits, - those were Mk VII's. Some high alt variants served in the med.
Drop tank equipped Mk VIII's roamed far north in the Italian campaign and had frequent encounters with LW's 109's and 190's.
Will post more when I find more.
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don't see any mathematical connection between the e factor and the aspect ratio in Badboy's response which I actually quoted above.
"e" factor is an arbitrary value assigned IAW the tip of the wing.
Oswalds is calculated based on:
Even though it is a function of aspect ratio, sweepback angle, taper ratio and twist, the largest influence on the wing of a WWII fighter with very little sweep or twist comes from aspect ratio and taper ratio
It is calculated with a simple manipulation of this formula:
http://www.grc.nasa.gov/WWW/K-12/airplane/induced.html
To solve for "e"
Shortly, default assumptioms are different than in the Zigrat's spreadsheet.
Difference is assumptions vs. calculations. I prefer calculations when they are available. I just don't like to those calcs myself! :o
Actually I have been teaching that to you in two threads and finaly you are beginning to understand.
No, I wouldn't label it that. You're the only one in the short time I have known you that feels that way.
I would have to say you have been a cataylst in increasing my understanding. Because of your obvious prejudice towards the Spitfire.
Well, the difference in the Lednicer's values (5,22 and 5,4) is about 4%, much less than variation between various tested Spitfire IXs.
How does that change this:
Flat out BS. You debunked Lednicers data from the beginning.
It does not and is called "excuses". Rather than making the point that "drag varies" among different A/C of the same type, TEACHER, you chose to argue that Lednicer was wrong, you were right, and the FW-190 is ALWAY's has more drag throughout the flight envelope.
Only when other calculations started appearing with correct values did you begin to back off that assumption. Never did you come out and say, "this only occurs in SOME spitfires" before then.
I will run the numbers on the other Spitfires and cross-reference with their set up's.
Which one do you guys think is most representative of the service model found in the squadrons?
Crumpp
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I had wrong output value for the Merlin 66 so here is the corrected listing of flat plate areas for Cd0:
BF274: 4,93
BS428: 4,68
BS534: 4,70
BS551: 4,80
EN524: 4,82
BS310: 4,98
MA648: 4,69
JF275: 4,77
JL165: 5,19
Results are still the same; the BS428, BS534 and MA648 had lower flat plate area than the JF275. In addition here is corrected listing of flat plate values for Cd:
BF274: 5,21
BS428: 4,93
BS534: 4,91
BS551: 5,04
EN524: 5,06
BS310: 5,22
MA648: 4,88
JF275: 4,92
JL165: 5,34
Originally posted by Crumpp
"e" factor is an arbitrary value assigned IAW the tip of the wing.
Oswalds is calculated based on:
"Even though it is a function of aspect ratio, sweepback angle, taper ratio and twist, the largest influence on the wing of a WWII fighter with very little sweep or twist comes from aspect ratio and taper ratio"
The aspect ratio itself does not give anykind of information about the lift distribution nor exact information about the shape of the wing. I don't see how it can be used alone to estimate the e factor. Maybe with the taper ratio but not alone.
Originally posted by Crumpp
Difference is assumptions vs. calculations. I prefer calculations when they are available. I just don't like to those calcs myself! :o
Well, IMHO my original calculation is more accurate than Zigrat's because it contains exhaust thrust as well as propeller efficiency calculation based on output and size of the propeller.
gripen
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The aspect ratio itself does not give any kind of information about the lift distribution nor exact information about the shape of the wing. I don't see how it can be used alone to estimate the e factor. Maybe with the taper ratio but not alone.
I highly doubt your estimated figures are nearly as accurate. Just look at your initial conclusions about Lednicer's data.
Well, IMHO my original calculation is more accurate than Zigrat's because it contains exhaust thrust as well as propeller efficiency calculation based on output and size of the propeller.
You factor in your "guestimation".
The man that teaches aeronautics even said these calculations were much more accurate than assigning either the same or arbitrary values to the formulas.
Lets see and compare total drag @ 440fps at the Spitfires FTH altitude:
BF 274 - 795.641828 @ 440 fps
Total Drag FW-190A5 -718.2845242@ 440 fps
All three aircraft were flying with C.G. 5.0 in. aft of the datum, BS. 354 and BS. 543 weighing 7485 lb., and BS. 551 weighing 7470 lb.
BS354 - No data listed except the A/C was 7 mph slower w/50 bhp more output than the Merlin 66 @ (+18)
BS543 - 810.863789
FW-190A5 - 705.7484202
BS551 - 758.4823884
FW-190A5 - 704.890256
EN524 with 4 bladed prop - 765.4635575
FW-190A5 - 702.4712376
BS310 with 4-bladed prop - 793.0539968
FW-190A5 - 751.8834689
BS310 with 5 bladed prop - 794.0663191
FW-190A5 - 749.7161496
JL165 - done to death
MA 648 Merlin 66 (+18) SU Pump - 838.0549776
FW-190A5 - 804.8037275
BS310 - 792.6552588 Parasitic drag - 691.672177
FW-190A8 - 794.3964059 Parasitic drag - 606.4158622
At 315mph the total drag situation changes completely in the FW-190A8 favor.
JL165 vs FW-190A8 has been done to death, again in the FW-190A8's favor.
MA 648 is the ONLY Spitfire Mk IX to beat the FW-190A8 for drag and here is why:
External equipment of the above four aircraft was similar with the exception that MA.648 had the new pattern of air intake.
The RAF must have eliminated the boundary layer separation David Lednicer referred too in his article with new pattern intake.
MA648 - 837.1701001 parasitic drag - 751.6212076
FW-190A8 - 869.2121249 parasitic drag - 709.9624067
The parasitic drag is always in the FW-190's favor but the total drag drops to within a few pounds of each other at 315 Mph but never swings in the FW-190's favor.
So ONE example of the Spitfire Mk IX beats the FW-190A8 in total drag. The others are behind their FW-190A contemporary the whole way.
That about covers the Spitfire Mk IX's vs. their contemporary FW-190 adversary.
Crumpp
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Gripen says:
Well, IMHO my original calculation is more accurate than Zigrat's because it contains exhaust thrust as well as propeller efficiency calculation based on output and size of the propeller.
This is completely at odds with this:
Gripen says:
I wondered a bit why could not reach same numbers with Zigrat's spreadsheet as with my own.
I asked you for a copy of your spreadsheet so we could use the same one BTW.
Only difference is on yours you guestimate the "e" factor, prop efficiency, and exhaust thrust.
Your using an excel spreadsheet like everyone else. It's very easy to do and the formulas are the same. It just saves button pushing time.
Crumpp
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Originally posted by gripen
The aspect ratio itself does not give anykind of information about the lift distribution nor exact information about the shape of the wing. I don't see how it can be used alone to estimate the e factor. Maybe with the taper ratio but not alone.
Glauert was first to derive a theoretical expression for rectangular wings, in the form of a correction to the value for an elliptical wing. With accuracy as good as the assumptions involved in the derivation, empirical equations for Glauert’s correction yield results in good agreement with experimental values. One such equation offered by a Professor Wood, and manipulated slightly (by me) to make it more readable and easy to use, gives good agreement to flight test data for aspect ratios between 2 and 10:
e = 1/(0.9676+0.033AR)
(The original relationship published by Wood was: dCd/dCl^2 = 0.308/AR + 0.0105 which you read as the slope of the graph of drag against the coefficient of lift squared equals 0.308 divided by the aspect ratio plus 0.0105 I just carried out the simplification to the expression above)
You will notice that equation gives close agreement to the value used by Zigrat in his spreadsheet, which indicates that Zigrat either found another empirical formula for e based on other, slightly different data, or that he derived his empirical expression from other data available to him.
There are a large number of sources that clearly state the relationship between the efficiency factor and Aspect Ratio (AR) and several of them also provide graphs of e against AR, examples include:
Principles of Aerodynamics, by Dwinnell, page 144.
Airplane Performance Stability and Control, by Perkins & Hage, page 73.
Elements of Practical Aerodynamics, by Jones, page 73.
Some others publications have multiple curves in order to include taper ratio. A readily available source, for which you can also obtain software, is:
Aerodynamics Aeronautics and Flight Mechanics, by McCormick, page 172.
Many of those sources are out of print, but should be available from university libraries, modern publications focus on other methods for calculating/estimating it, including the lift line method and computational fluid dynamics, that can then include all the other variables I mentioned in my previous post.
Hope that helps.
Badboy
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How absolutely nice
I'll save this thread.
And Crumpp&Gripen.
Your debate has been somewhat in a frustrated tone at times. Still, all keeps going. Shake hands, and if you ever go touring, come to my place and we'll have a heck of a time
(LAN+AHII+BEER, need I say more?. Hotel facilities of course)
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Originally posted by Crumpp
Only difference is on yours you guestimate the "e" factor, prop efficiency, and exhaust thrust.
Crumpp
You need to be careful if this is true because while e is constant, the prop' efficiency and exhaust thrust are not, and can vary by as much as 100% between best climb speed and the top speed used, which may lead to poor results.
Badboy
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Originally posted by Crumpp
I highly doubt your estimated figures are nearly as accurate. Just look at your initial conclusions about Lednicer's data.
Well, I have claimed my assumptions throughout this thread. And my initial assumption was that Lednicer's data is for the Cd0 as claimed in the J22 site. After looking Lednicer's writing I noticed that the data was for total drag.
Originally posted by Crumpp
You factor in your "guestimation".
My "questimation" uses more measurable variables than Zigrat's.
Originally posted by Crumpp
The man that teaches aeronautics even said these calculations were much more accurate than assigning either the same or arbitrary values to the formulas.
Actually "the man" edited his post and added:
"In any case, calculating the Oswald efficiency factor from wing geometry is problematic."
Which I believe is true. In the Zigrat's spreadsheet the e factor simply decreases when the aspect ratio increases. So far I have not yet seen any physical explanation why it should be that way and as far as my limited knowledge goes, there should be no way to estimate e factor from the aspect ratio only.
Originally posted by Crumpp
Lets see and compare total drag @ 440fps at the Spitfires FTH altitude:
BF 274 - 795.641828 @ 440 fps
Total Drag FW-190A5 -718.2845242@ 440 fps
So now you bring in the Fw 190A-5 data which is for unknown reason about 20-30 km/h faster at low altitude than US navy data and the Fw 190A-8 data. Just like in the case of the Fw 190A-8 we have no evidence that the A-5 data set is flight tested but the difference is that the A-8 set seems to be realistic given the used ratings and special finish but the A-5 set low altitude performance seems to be far in the unrealistic side.
Originally posted by Crumpp
MA 648 is the ONLY Spitfire Mk IX to beat the FW-190A8 for drag and here is why:
"External equipment of the above four aircraft was similar with the exception that MA.648 had the new pattern of air intake."
The RAF must have eliminated the boundary layer separation David Lednicer referred too in his article with new pattern intake.
Well, as usual it would help a lot if you actually understand what Lednicer says; he talks about the radiator intakes not about the engine air intake.
Originally posted by Crumpp
This is completely at odds with this:
Actually it was very easy to do a crosscheck; I simply put exhaust thrust to zero and adjusted propeller efficiency and e factor to the same as in the Zigrat's sheet. In couple seconds I found out that results do not match and after that it took just couple minutes to find out with crosschecking what caused the difference.
gripen
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Badboy,
I quess very high aspect ratio wing, say AR over 10, can't reach elliptical lift distribution. But in the case of the WWII fighters aspect ratios are all in the same ball park, say AR around 5-8 and I don't see reason why a generalized formula should give realistic estimate for the e factor.
Regarding Oswald, I dug out his report (http://naca.larc.nasa.gov/reports/1933/naca-report-408/index.cgi?thumbnail11#start) and his analyses seem to based on empirical data.
gripen
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Thanks Badboy! Great explainations.
Gripen says:
Well, I have claimed my assumptions throughout this thread. And my initial assumption was that Lednicer's data is for the Cd0 as claimed in the J22 site. After looking Lednicer's writing I noticed that the data was for total drag.
Yeah it seems to change to whatever supports your position the best.
Gripen says:
My "questimation" uses more measurable variables than Zigrat's.
Please explain. And while you're at it lets have full disclosure on your data. I would be glad to post ALL the data from the Spit Mk IX vs. FW-190 comparison. Only reason I did not is because you complained that it was too detailed and unnecessary.
Badboy says:
There are a large number of sources that clearly state the relationship between the efficiency factor and Aspect Ratio (AR) and several of them also provide graphs of e against AR, examples include:
Sounds cut and dry. Good explanation.
Gripen says:
So far I have not yet seen any physical explanation why it should be that way and as far as my limited knowledge goes, there should be no way to estimate e factor from the aspect ratio only.
See above quote.
So now you bring in the Fw 190A-5 data which is for unknown reason about 20-30 km/h faster at low altitude than US navy data and the Fw 190A-8 data. Just like in the case of the Fw 190A-8 we have no evidence that the A-5 data set is flight tested but the difference is that the A-8 set seems to be realistic given the used ratings and special finish but the A-5 set low altitude performance seems to be far in the unrealistic side.
1. Have you thought about the fact the US Navy data is in Nautical miles?
2. No Gripen I compared the fighters with the adversary they encounter over the skies of Europe. The FW-190A8 was not flying in 1942-3 when most of the test's occurred. I compared it with the 1944 versions it might have encounter. In each case the Focke Wulf had less parasitic drag, which makes sense given the manner, the two aircraft fought one another. The Spitfire in the horizontal and the FW-190 in the vertical. With neither able to gain a decisive advantage on the other aircraft. Pilot skill decided the outcome. Just like Eric Brown says "They remained about as equal as two fighters can get throughout their development."
The data is flight test, no doubt. As far as the "filled and polished" FW-190A8 I was wrong in my translation. It does not say "Surface fixed and painted" in German. It says "Surface primed and painted". The root word for "fixed," "prepared", "spackled" as are all the same in German so it is easy to see the translation error. However the modifying articles definitely referring to "primed" in the case of painting. Got to love how the Germans link old words to form new ones!
Gripen says:
My "questimation" uses more measurable variables than Zigrat's.
Badboy says:
You need to be careful if this is true because while e is constant, the prop' efficiency and exhaust thrust are not, and can vary by as much as 100% between best climb speed and the top speed used, which may lead to poor results.
Gripen says:
thrust is calculated assuming 85% efficiency and 120 kp exhaust thrust:
Gripen says:
Well, assumptions are mostly same for all compared planes so relative results should be comparable. The only difference is the e factor which according to Lednicer is better in the Spitfire than in other two .
I have noted that Lednicer's data seems to at least partially wrong. So far I have not found real world tested data which supports assumption that the Fw 190 had signifigantly lower drag than the Spitfire.
That is because when you are presented with the test's you deny they existed. Even when backed up by mathematical analysis and the historical logs.
In fact the numbers calculated on Zigrat's spreadsheet very closely match Lednicers findings to a tee.
Crumpp
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This report presents general formulas for the determination of all major airplane performance characteristics. A rigorous analysis is used, making no assumption regarding the attitude of the airplane at which maximum rate of climb occurs, but finding the attitude at which the excess thrust horsepower is maximum. Equations and charts are developed which show the variation of performance due to a change in any of the customary design parameters. Performance determination by use of the formulas and charts is rapid and explicit. The results obtained by this performance method have been found to give agreement with flight tests that is, in general, equal or superior to results obtained by present commonly used methods.
Nice report Gripen. Thanks for finding it!
Crumpp
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Originally posted by Badboy
Airplane Performance Stability and Control, by Perkins & Hage, page 73.
This is the only one I have in the hand of those you mentioned and the graphs in the page 73 actually give correction factors of the rectangular wing against aspect ratio.
In the previous page the writers actually say that:
"For an untwisted wing with elliptical planform shape these correction factors are zero"
If I understand this correctly those formulas you gave above work only for the rectangular wings and we can't determine the shape of the wing from the aspect ratio only.
Originally posted by Crumpp
Please explain.
I have allready told you several times that my calculation contain exhaust thrust and propeller efficiency check with momentary theory (with link).
Originally posted by Crumpp
1. Have you thought about the fact the US Navy data is in Nautical miles?
The report gives values in the metric unit too.
gripen
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I have allready told you several times that my calculation contain exhaust thrust and propeller efficiency check with momentary theory (with link).
Let us see your calculations.
The report gives values in the metric unit too.
Please disclose the values.
Look Gripen, My goal in this is not to make you or anybody look silly or to engage in counterproductive flame war. Your a smart guy who obviously knows quite bit about this stuff.
What you claim happens to be the opposite from what another smart guy claims. Additionally the math backs it up the other claim's. So that is 2 out of 3 right now.
I would like to continue this and I will. I just hope we can set a new tone and discuss this without the silly "oneupmanship".
Crumpp
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Originally posted by gripen
This is the only one I have in the hand of those you mentioned and the graphs in the page 73 actually give correction factors of the rectangular wing against aspect ratio.
Correct, Figure 2-44 (b) shows the relationship of those factors to Aspect Ratio for a rectangular wing, and that illustrates the dependency of e to Aspect Ratio. In the previous graph you see the influence that taper ratio has for an aspect ratio of 6. There are other formulae that also include the taper ratio so that values for non rectangular wings can be estimated also.
In the previous page the writers actually say that:
"For an untwisted wing with elliptical planform shape these correction factors are zero"
Correct, and that’s why the elliptical planform theoretically has the least induced drag, in that case the efficiency factor e would equal one.
If I understand this correctly those formulas you gave above work only for the rectangular wings and we can't determine the shape of the wing from the aspect ratio only.
Partly correct… It is true that formulae that only include aspect ratio only apply to a single taper ratio, it just happens that the graph in Perkins & Hage is for zero taper. The previous graph on the same page illustrates the relationship for both taper ratio and aspect ratio but even so the dependency upon aspect ratio is clear.
However, the formulae presented by Professor Wood is for a taper ratio of 0.57 which yields an almost elliptical lift distribution, which is why it fits the experimental data so closely over a wide range of examples. Most WWII aircraft had a taper ratio close to that value (Me109 was approx 0.52) because the designers knew about the benefits of elliptical lift distribution and that it could be achieved quite closely with a wing of that taper, that’s why a formulae that only includes aspect ratio could still be of such good practical use. However, other graphs and formulae that include both taper ratio and aspect ratio were common, today it is just as easy to include everything, including twist, camber, and sweep etc.
Hope that helps
Badboy
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Guess this issue is resolved then.
Thanks for participating!
Crumpp
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Originally posted by Crumpp
Let us see your calculations.
As noted couple times earlier: Just follow the link (http://xoomer.virgilio.it/pconselv/Manuale/section3ingl.htm) and find formula no. 10, collect needed data (speed, altitude, output and propeller diameter), form calculation to the excel and solve the max theoretical efficiency with the solver. As an example the US Navy 190; 537 km/h, sea level, 1740 ps and 3,3 m propeller will result max theoretical efficiency 98,3 %. Effective efficiency is about 10-15 % less than this so 85% seems to be a good aproximate. The exhaust thrust is purely aproximate based on assumption that the exhaust thrust will ad about 15-20% thrust at high speed.
Originally posted by Crumpp
Please disclose the values.
How can I "disclose" values which you can read directly from the US Navy Fw 190 report?
Originally posted by Crumpp
What you claim happens to be the opposite from what another smart guy claims. Additionally the math backs it up the other claim's. So that is 2 out of 3 right now.
May I ask what is opposite from what another smart guy claims?
Originally posted by Badboy
However, the formulae presented by Professor Wood is for a taper ratio of 0.57 which yields an almost elliptical lift distribution, which is why it fits the experimental data so closely over a wide range of examples. Most WWII aircraft had a taper ratio close to that value (Me109 was approx 0.52) because the designers knew about the benefits of elliptical lift distribution and that it could be achieved quite closely with a wing of that taper, that’s why a formulae that only includes aspect ratio could still be of such good practical use.
This is a quite sensible assumption. I have calculated some e factor data for comparison which I will post shortly to the another thread (http://www.hitechcreations.com/forums/showthread.php?s=&threadid=129772).
gripen
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As noted couple times earlier: Just follow the link and find formula no. 10, collect needed data (speed, altitude, output and propeller diameter), form calculation to the excel and solve the max theoretical efficiency with the solver. As an example the US Navy 190; 537 km/h, sea level, 1740 ps and 3,3 m propeller will result max theoretical efficiency 98,3 %. Effective efficiency is about 10-15 % less than this so 85% seems to be a good aproximate. The exhaust thrust is purely aproximate based on assumption that the exhaust thrust will ad about 15-20% thrust at high speed.
Your link is busted.
537km/h doesn't agree with any of the Luftwaffe data. Given the detailed engine trouble the US Navy experienced and the fact the graph agrees with all the performance listing's in the Pilots manual for the FW-190A5 I fail to comprehend why you do not accept the data.
I am sure that if you use such skewed performance figures as 537kph at full emergency power output you will get skewed results. You are using the full horsepower ratings the US Navy copied from the FW-190 pilots manual with an engine that is not developing near that amount of power.
Crumpp
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May I ask what is opposite from what another smart guy claims?
Your flat plate values are totally different from Lednicers. You claim the Spitfire had less parasitic drag and because of it's induced drag maintained less drag throughout the flight envelope. That is not what Lednicers says and the calculations confirm.
The only ammo you have left is too try and call into question Oswalds efficiency factor and it's use in the induced drag formula.
Crumpp
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Now the link should work.
Regarding US Navy data, it's the best one I know for the Fw 190 which I certainly know to be flight tested.
Regarding flat plate areas; these are calculated with certain assumptions and purpose is not to reach same numbers but that the relative difference between planes is comparable.
And if you look above, I wrote:
" I don't see how it can be used alone to estimate the e factor. Maybe with the taper ratio but not alone."
What Badboy pointed out is a quite sensible; the taper ratio should be in the certain ball park in the case of the WWII fighters.
gripen
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Regarding US Navy data, it's the best one I know for the Fw 190 which I certainly know to be flight tested.
Yes I understand that but consider this.
1. The graph I provided is listed as an actual test flight in the FW factory logs.
2. The data lines up perfectly with the other models of the FW-190A.
Example:
The FW-190A3 could do 365kph at sea level using 1.42ata @ 2400U/min. It weighed 3978kg in that flight with the outboard MGFF's.
The FW-190A5 can do 365kph at sea level using 1.42ata @ 2700U/min. It weighed 4106kg's and had some aerodynamic refinements to the cooling gills. The FW-190A3 had gills cut in the side of the fuselage with internal gills that caused some flow problems getting air out of the cowling. The FW-190A5 moved the gills to the outside behind the cowling. It did not gain much weight and it gained some power by being able to increase prop rpm and had a reduction in drag.
The FW-190A8 could do 365kph on the deck. It weighed 4398kg's on take off in that test. It also had a lot more power at 1.58ata@2700U/min than it's predecessors. At the same power outputs as the FW-190A5 the FW-190A8 could only manage 545kph on the deck.
So it make perfect sense. Especially when you consider the fact that the airframe the US Navy test was:
1. A recovered crash that required extensive repairs to both the airframe and the engine.
2. The Allied personnel doing the work were not technical experts on the design. Just read the aileron comments on the FW page I reference. If the FW factory trained personnel had difficulty adjusting certain portions of the plane how can untrained technicians be expected to perform at the same level?
http://www.terra.es/personal2/matias.s/fw190.htm
3. The engine had problems that are noted in the test. IMO this was due to the differences in German aviation fuel and US AVGAS.
Crumpp
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Shake hands, and if you ever go touring, come to my place and we'll have a heck of a time
Same goes bro! If you ever make it to the States you got a place to stay. The NASM is fairly close.
Crumpp
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Regarding flat plate areas; these are calculated with certain assumptions and purpose is not to reach same numbers but that the relative difference between planes is comparable.
That is correct. Your CONCLUSIONS are totally different. However, the more detailed we make the calculations the more Lednicers conclusions are shown to be correct.
Crumpp
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Originally posted by Crumpp
Your CONCLUSIONS are totally different. However, the more detailed we make the calculations the more Lednicers conclusions are shown to be correct.
Hm... I wonder what do you mean? Lednicer's flat plate area values for the Spitfire and the Fw 190 are within 3,4 % from each other. I have pointed out that variation among tested Spitfires was far larger than this.
Besides this has nothing to do with the subject of this thread.
gripen
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Yes and that variation is high enough to lend a drag advantage to ONE Spitfire MK IX with a new air intake design. ALL OF THE OTHERS lose the drag advantage race and none ever win the parasitic drag race. One model is close enough that it's induced drag advantage counts and brings the planes to equality drag wise at high speeds.
Given that same variation you will find many FW-190's that widen that gap even more and a few who completely close it. On average, given the number of Spitfire Mk IX's the FW-190 has less drag than, you can concluded FW-190's had less parasitic drag than the Spitfire.
Especially when the FW-190A8 in question is not "filled and polished" but rather "primed and painted". A frontline fighter finish.
Totally different from the picture you are creating on your calculator.
Crumpp
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Besides this has nothing to do with the subject of this thread.
It has everything to with this thread and is the focus of the matter at hand.
Crumpp
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"Reality Strikes" September - October, 1944
September 13, 1944
Oberflächenschutzliste 8 Os 155:
Released by Blohm & Voss and approved by the RLM, designating the 'green' 81/82 camouflage scheme to be applied to the BV 155. The colours were designated as "Olivbraun 81" and "Hellguen 82" (Hitchcock, 1990, inside front cover & p.19). The following is an exact translation of this document, courtesy of Kenneth Merrick:
Sch/01 Advance announcement B&V 13 Sept. 1944
Camouflage BV155
The E-stelle Travermuende authority provides the following:
The BV155 shall have on the uppersurface the colours 81 Olivebrown and 82 Light Green. The mottling spacing and placement should be similar to the Bf 109 camouflage scheme. The fuselage sides, side of the vertical tail and leading edge of the wing and horizontal stabilizer should be painted in colour 76 (no name given). Hereafter, except for the wing and horizontal stabilizer’s leading edge, the aircraft should be then in a cloudy overspray with colour tones 81 and 82. Also, we look ahead to simplify the paint schemes which we should know shortly and will publish. Afterwards, the above mentioned aircraft which will be used for day service, camouflage on the undersurfaces should be deleted.
With the mottle scheme, it should be applied on the aircraft sheet metal between the camouflage and its painted line. The pattern is to be soft flowing lines. The colour scheme is to be sprayed on at the present time. In case of needed puttying, (aircraft putty 7270.99) it should be applied on bare metal beyond the border lines of the paint scheme and the bare metal should be polished in the usual way but no camouflage on top of the putty. The painting of the undersurface is being deleted to economize.
A/c materials test division for surface protection.
COMMENT: Here is what the author believes is a perfect example of a camouflage document typical of the period. It is important in that it is the first to describe the use of colours 81 and 82, and provides evidence that the descriptive names of these shades were assigned by the manufacturer. Significantly, such was the supply crisis that even at this early date it was ordered that the undersides of the aircraft were to remain unpainted. Another point to ponder: Could "Olivbraun" in fact be RLM 80 Olivgrün, which could have been inserted as a substitute from excess and redundant stocks for the as yet still officially un-described colour RLM 81
September 1944
Factory Camouflage Directive, Fw 190 A:
It is most probable that this document or a related order (possibly a document only and not an Oberflächenschutzliste), existed in some form and specified the 75/83 scheme for the Fw 190 D-9 as well (see above comments).
COMMENT: First operational use of the Dora took place in early October 1944 with III./JG 54 whose aircraft were camouflaged in the 75/83 scheme that is well documented with photographic evidence.(Smith and Creek, 1986, p.10). However, a change occurred in the camouflage colours used in early 1945, from the standard 75/83 scheme to the 81/82 combination, and it is most probable that a variety of transition schemes existed (e.g., 81/83, 82/83, 75/81, etc.) Furthermore, the seperate production and finishing of the Jumo 213 engines in RLM 83 (or possibly 71) would have also complicated the prescribed and transitional camouflaged schemes
http://www.clubhyper.com/reference/luftcamdb_3.htm
In fact it is the opposite. Filled and Polished is more the standard while "primed and painted" is a substandard Luftwaffe A/C finish.
Makes sense. If you were an A/C company competing for design contracts wouldn't you want the greatest performance gains possible in your new design over the old one?
Crumpp
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A nice story:
Savagely I hauled my reluctant Spitfire around to meet this new attack and the next moment I was engulfed in enemy fighters-above, below and on both sides, they crowded in on my section. Ahead and above, I caught a glimpse of a FW 190 as it poured cannon shells into the belly of an unsuspecting Spitfire. For a brief second the Spitfire seemed to stop in mid-air, and the next instant it folded inwards and broke in two, the two pieces plummeting earthwards; a terrifying demonstration of the punch of the FW 190s, four cannons and two machine-guns.
I twisted and turned my aircraft in an endeavour to avoid being jumped and at the same time to get myself into a favourable position for attack. Never had I seen the Huns stay and fight it out as these Focke-Wulf pilots were doing. In Messerschmitt 109s the Hun tactics had always followed the same pattern-a quick pass and away, sound tactics against Spitfires with their superior turning circle. Not so these FW 190 pilots, they were full of confidence.
There was no lack of targets, but precious few Spitfires to take them on. I could see my number two, Sergeant Murphy, still hanging grimly to my tail but it was impossible to tell how many Spitfires were in the area, or how many had survived the unexpected onslaught which had developed from both sides as the squadron turned to meet the threat from the rear. Break followed attack, attack followed break, and all the time the determined Murphy hung to my tail until finally, when I was just about short of ammunition and pumping what was left at a FW 190, I heard him call:
"Break right, Red One; I'll get him."
As I broke, I saw Murphy pull up after a FW 190 as it veered away from me, thwarted in its attack by his prompt action. My ammunition expended, I sought a means of retreat from a sky still generously sprinkled with hostile enemy fighters, but no Spitfires that I could see. In a series of turns and dives I made my way out until I was clear of the coast, and diving full throttle I headed for home.
Sometime after Alan Deere took over as a Biggen Hill squadron leader in late 1942 or early 1943.
Crumpp
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Well, Crumpp wanted to continue this discussion in the another so I post it here:
Originally posted by Crumpp
You have to look at the evolution of Gripen's flat plate calculations in the thread I linked too. If you don't do the math you won't see it. I don't make those accusations lightly.
Compare his values to the values calculated for ALL the Spitfire Mk IX's for flat plate area. NONE of the Mk IX's have less flat plate area than the FW-190. That was when I realized what was going on.
However the Spitfire Mk VIII does. If you look at Gripens calculations then it becomes clear.
Let's look at the flat plate areas again:
BF274: 5,21
BS428: 4,93
BS534: 4,91
BS551: 5,04
EN524: 5,06
BS310: 5,22
MA648: 4,88
JF275: 4,92
JL165: 5,34
The numbers do not support Crumpp 's story, two Spitfire IX had lower flat plate area than the Spitfire VIII JF275.
gripen
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Originally posted by gripen
Now the link should work.
Regarding US Navy data, it's the best one I know for the Fw 190 which I certainly know to be flight tested.
gripen
Hmm, if you are talking about the same USN test what I have seen, that report clearly states the level speed runs were done for only 2 minutes time, during which the maximal speed may have been not fully developed...
So using those 537 km/h numbers as "max. level speed at SL" values is more than just flawed. Obviously the IAS is the highest at SL, and it takes the longest to achieve the maximum speeds. Ignoring the official German dataset (on what basis, the Germans didnt know the specs of their very own fighters?!!) and replacing it with a lower flight tested result which admittedly by its testers probably do not show the maximum values is curious, to say at least.
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From Izzie:
"Hmm, if you are talking about the same USN test what I have seen, that report clearly states the level speed runs were done for only 2 minutes time, during which the maximal speed may have been not fully developed... "
Not sure which test you are referring to, is it the comparison with the US aircraft?
Anyway, why is there so much difference between the Spit IX flat plate areas? Are some of them clipped?
Regards
Angus.
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The numbers do not support Crumpp 's story, two Spitfire IX had lower flat plate area than the Spitfire VIII JF275.
According to your calculations. You insist on using flawed data from the USN test. How about I post a 4000 feet a minute climb test performed by a captured FW-190A4? We could use EB-104. It was a rated motor but did develop around 100 hp less than the German BMW-801D2 of that time frame. Probably the USAvgas and Spark Plugs.
According to zigrat's spread sheet with YOUR changes you requested. All of the Spitfire Mk IX's have more form drag.
Anyway, why is there so much difference between the Spit IX flat plate areas? Are some of them clipped?
There is going to be some varience in each aircraft just due to manufacturing tolerences, finish, etc.
In fact they are close enough I would say a sloppy FW-190 probably as much or a little more form drag than a well assembled Spitfire.
If you ever get a copy of the evaluation of Faber FW-190A3 (not the tactical trials) read the paragraph about the overall finish and the test pilots comments. Interesting stuff. I may post it.
Crumpp
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Originally posted by VO101_Isegrim
Hmm, if you are talking about the same USN test what I have seen, that report clearly states the level speed runs were done for only 2 minutes time, during which the maximal speed may have been not fully developed...
The US Navy data seems to be supported by FW data on Fw 190A-8, given the special finish of the later.
Anyway you are most wellcome to bring better tested data in.
Originally posted by Crumpp
According to your calculations.
You are most wellcome to proof my calculations wrong if you can.
Originally posted by Crumpp
You insist on using flawed data from the USN test. How about I post a 4000 feet a minute climb test performed by a captured FW-190A4?
So why don't you just bring the data in if you can? Besides as noted several times US NAVY data and FW data on Fw 190 A-8 seems to support each other very well.
Originally posted by Crumpp
According to zigrat's spread sheet with YOUR changes you requested. All of the Spitfire Mk IX's have more form drag.
Oh well, again a statement without anykind of proof. Couple tested Spitfire IX had lower drag than a filled and polished Fw 190A-8 as pointed out above (even your own calculations prove this).
Originally posted by Crumpp
If you ever get a copy of the evaluation of Faber FW-190A3
Actually the speeds of Faber's Fw 190 at 1,42 ata are lower than the in the US navy evaluation (about 520 km/h at sea level and 627 km/h at FTH). Maybe I should run Fw data again with these values.
gripen
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You are most wellcome to proof my calculations wrong if you can.
Already done.
Look above. You need me to repost them??
Remember the ones you claimed were too detailed?
Oh well, again a statement without anykind of proof. Couple tested Spitfire IX had lower drag than a filled and polished Fw 190A-8 as pointed out above (even your own calculations prove this).
The finish has been covered ad-nauseaum. It's not filled and polished Gripen.
Crumpp
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Originally posted by Crumpp
Already done.
Look above. You need me to repost them??
Remember the ones you claimed were too detailed?
Please repost.
Originally posted by Crumpp
The finish has been covered ad-nauseaum. It's not filled and polished Gripen.
The report (http://www.terra.es/personal2/matias.s/fw190-1.jpg) says " External surfaces: Filled + polished " and so far you have not provided anything which proves otherwise.
gripen
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Why YES it does Gripen!!!
You ARE Correct. Gosh to think I just missed that leapin out at me in english and all.
Crumpp
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Lets see and compare total drag @ 440fps at the Spitfires FTH altitude:
BF 274 - 795.641828 @ 440 fps
Total Drag FW-190A5 -718.2845242@ 440 fps
BS354 - No data listed except the A/C was 7 mph slower w/50 bhp more output than the Merlin 66 @ (+18)
BS543 - 810.863789
FW-190A5 - 705.7484202
BS551 - 758.4823884
FW-190A5 - 704.890256
EN524 with 4 bladed prop - 765.4635575
FW-190A5 - 702.4712376
BS310 with 4-bladed prop - 793.0539968
FW-190A5 - 751.8834689
BS310 with 5 bladed prop - 794.0663191
FW-190A5 - 749.7161496
JL165 - done to death
MA 648 Merlin 66 (+18) SU Pump - 838.0549776
FW-190A5 - 804.8037275
BS310 - 792.6552588 Parasitic drag - 691.672177
FW-190A8 - 794.3964059 Parasitic drag - 606.4158622
At 315mph the total drag situation changes completely in the FW-190A8 favor.
JL165 vs FW-190A8 has been done to death, again in the FW-190A8's favor.
MA 648 is the ONLY Spitfire Mk IX to beat the FW-190A8 for drag and here is why:
quote:
--------------------------------------------------------------------------------
External equipment of the above four aircraft was similar with the exception that MA.648 had the new pattern of air intake.
--------------------------------------------------------------------------------
MA648 - 837.1701001 parasitic drag - 751.6212076
FW-190A8 - 869.2121249 parasitic drag - 709.9624067
The parasitic drag is always in the FW-190's favor but the total drag drops to within a few pounds of each other at 315 Mph but never swings in the FW-190's favor.
So ONE example of the Spitfire Mk IX with an experimental air intake beats the FW-190A8 in total drag. The others are behind their FW-190A contemporary the whole way.
That about covers the Spitfire Mk IX's vs. their contemporary FW-190 adversary.
Crumpp
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So how would your 190 rack up against a filled and polished Spit VIII?
My point is that the total drag is short apart.
The Spitfire wins at lower speed because of lower wingloading resulting in lower A.o.A. in level flight, lowering drag.
The curves cross at high speed where the flight goes more level and the parasite drag is a dominat factor.
Am I right?
Anyway, this gets screwed up as soon as the aircraft banks a bit.....
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Originally posted by Crumpp
Total Drag FW-190A5 -718.2845242@ 440 fps
Well, here you use the unrealistic Fw 190 data again (20-30 km/h faster than values than real life tested). But let's look at the flat plate areas (for Cd) calculated from the realistic values again:
BF274: 5,21
BS428: 4,93
BS534: 4,91
BS551: 5,04
EN524: 5,06
BS310: 5,22
MA648: 4,88
JF275: 4,92
JL165: 5,34
And then comparable values for the Fw 190A-8 and the US Navy tested Fw
US NAVY Fw 190A-5: 5,2 (a bit rough estimate)
Fw 190A-8: 5,14
We can see that actually most of the Spitfires had lower drag than a filled and polished Fw 190A-8.
gripen
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The Data is correct Gripen.
I can trace the speed and climb development of the FW-190 from the FW-190V5g to the FW-190A9 all with Focke Wulf data. It works out.
If you talk to a BMW mechanic you will find the 801 series was a very fickle motor.
I could post the horsepower development charts from 1942 thru 1945 so you could see for yourself the development.
I could even post the barometric pressure plate for some of the tests.
Lets see and compare total drag @ 440fps at the Spitfires FTH altitude with the correct data:
BF 274 - 795.641828 @ 440 fps
Total Drag FW-190A5 -718.2845242@ 440 fps
BS354 - No data listed except the A/C was 7 mph slower w/50 bhp more output than the Merlin 66 @ (+18)
BS543 - 810.863789
FW-190A5 - 705.7484202
BS551 - 758.4823884
FW-190A5 - 704.890256
EN524 with 4 bladed prop - 765.4635575
FW-190A5 - 702.4712376
BS310 with 4-bladed prop - 793.0539968
FW-190A5 - 751.8834689
BS310 with 5 bladed prop - 794.0663191
FW-190A5 - 749.7161496
JL165 - done to death
MA 648 Merlin 66 (+18) SU Pump - 838.0549776
FW-190A5 - 804.8037275
BS310 - 792.6552588 Parasitic drag - 691.672177
FW-190A8 - 794.3964059 Parasitic drag - 606.4158622
At 315mph the total drag situation changes completely in the FW-190A8 favor.
JL165 vs FW-190A8 has been done to death, again in the FW-190A8's favor.
MA 648 is the ONLY Spitfire Mk IX to beat the FW-190A8 for drag and here is why:
quote:
--------------------------------------------------------------------------------
External equipment of the above four aircraft was similar with the exception that MA.648 had the new pattern of air intake.
--------------------------------------------------------------------------------
MA648 - 837.1701001 parasitic drag - 751.6212076
FW-190A8 - 869.2121249 parasitic drag - 709.9624067
The parasitic drag is always in the FW-190's favor but the total drag drops to within a few pounds of each other at 315 Mph but never swings in the FW-190's favor.
So ONE example of the Spitfire Mk IX with an experimental air intake beats the FW-190A8 in total drag. The others are behind their FW-190A contemporary the whole way.
That about covers the Spitfire Mk IX's vs. their contemporary FW-190 adversary.
Crumpp
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Originally posted by Crumpp
The Data is correct Gripen.
Well, there is no physical reason why a standard Fw 190A-5 should be a 20-30 km/h faster at same power setting than US Navy tested Fw 190 or a filled and polished Fw 190A-8.
Basicly you found out that you could not support your agenda with the realistic data, so you changed to the unrealistic.
If you have data to support your claims, please post.
gripen
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Well, there is no physical reason why a standard Fw 190A-5 should be a 20-30 km/h faster at same power setting than US Navy tested Fw 190 or a filled and polished Fw 190A-8.
Yeah Gripen,
It called "NOT the same power setting". In the USN test the BMW801 develops over 100 hp less than the 801 in the Luftwaffe test's. Got the Horsepower graphs to prove it.
Reason:
1. Wrong Spark plugs-Listed in the maintenance logs.
2. Wrong Gasoline- Listed in the maintenance logs.
That is why the engine fouled plugs at low rpm and simply quit at altitude as is noted several times in the test.
Crumpp
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Faber's 190 had some trouble as well.
It raced with a Spitfire and a Typhoon, but soon had to pull out due to engine trouble.
Something boggles me there, - after all it was not used much, and I am surprized they could not keep it running so well.
Anyway, it ran for the time it gave on very good power, however I belive it was outrun by both contemporaries.
Will look it up and post in 10 mins.
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Originally posted by Angus
It raced with a Spitfire and a Typhoon, but soon had to pull out due to engine trouble....
it was outrun by both contemporaries.
If this was the same race Quill tells in his book, he was flying Griffon Spitfire prototype.
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Exactly.
At 1000 feet, 6 cannon development design (I see 4 cannons on the pictures though) DP845, single stage early Griffon, flying in July 1942 already. Other contemporaries a Typhoon and a 190.
Opening up from cruising speed, the 190 giving the signal to start (opening up first?).
It seems that the 190 accelerated the fastest, since Quill mentions overhauling it,- either that or the 190 being ahead in the start. Anyway, the Spitty left both behind, the 190 having to abort due to engine troubles, but the Typhoon simply being outrun.
As Quill nicely put it regarding the Spitfire, "The cat was well and truly among the pigeons"
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Originally posted by Crumpp
It called "NOT the same power setting". In the USN test the BMW801 develops over 100 hp less than the 801 in the Luftwaffe test's. Got the Horsepower graphs to prove it.
That explains the difference between the Fw 190 in the US navy test and the Fw 190A-8 but not the 20-30 km/h difference between these and Fw 190A-5 graph.
gripen
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That explains the difference between the Fw 190 in the US navy test and the Fw 190A-8 but not the 20-30 km/h difference between these and Fw 190A-5 graph.
The USN was an FW-190A5 Gripen NOT an FW-190A8.
The graph I posted is a Focke-Wulf factory test flight and matches up perfectly with:
1. The Rechlin flight test report on a Tropicalized FW-190A5.
2. The Rechlin flight test report on investigating raised manifold boost pressures in the BMW-801 series engines
3. The Focke-Wulf flight test investigating the effect of a 12 bladed cooling fan on the FW-190 series.
4. The Focke-Wulf flight test report investigating the BMW801TH/TS and BMW 801F series motors.
5. The Rechlin flight test report investigating the effect of propeller width on aircraft performance.
All of these test use an FW-190A5 with a BMW801D2 motor as a comparison. All the level speed and climb performance is within a 2-3% margin. In fact that graph I used in the calculations hardly represents the top performance for the FW-190A5.
Crumpp
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Anyway, it ran for the time it gave on very good power, however I belive it was outrun by both contemporaries.
Yes it was. Faber FW-190A3 was a derated motor. I can send you the complete performance trials and power tests for Faber FW-190A3. It performed very poorly for an FW-190. I am surprised it did so well in the tactical trials.
I also have the same report for the RAE FW-190A4 and the USAF trails on it conducted at Wright Patterson. It is interesting to compare the engine power/performance with the German test's. Having trained mechanics makes a big difference.
Crumpp
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Originally posted by Crumpp
The USN was an FW-190A5 Gripen NOT an FW-190A8.
No one has claimed so but from the drag view point there is no difference between the Fw 190A-5 and the Fw 190A-8. Basicly same airframe, the main difference being weight.
Originally posted by Crumpp
The graph I posted is a Focke-Wulf factory test flight and matches up perfectly with:
I don't see any kind evidence here.
gripen
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No one has claimed so but from the drag view point there is no difference between the Fw 190A-5 and the Fw 190A-8. Basicly same airframe, the main difference being weight.
Actually there is some difference.
The FW-190A8 gained slightly more drag from the MG131 cowl machineguns and added considerable amounts of horsepower.
The FW-190A5 gained considerable weight over the FW-190A4 and no Horsepower. According to the pilots it was the worst performing FW-190 AFA manuerability.
I don't see any kind evidence here.
And your not going too.
Crumpp
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"Having trained mechanics makes a big difference."
AFAIK FW190 was very dependent of professional groundcrew, especially the early models which suffered from overheating problems so I'd imagine even the A3 not to be "service free".
-C+
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Originally posted by Crumpp
The FW-190A8 gained slightly more drag from the MG131 cowl machineguns
That won't explain the speed difference at same power rating (1,42 ata 2700rpm).
Originally posted by Crumpp
And your not going too.
Oh well, so just statements after statements without proof.
gripen
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This here got me the hickups:
"Faber FW-190A3 was a derated motor."
So, Faber's 190 had a derated engine?
I've heard that for more sources, however on captured 109's.
Seems that the LW aircraft had troubles with the London fog or something :D , - i.e. as soon as they were tested by the Brits, their performance output dropped drastically.
Anyway, seriously, was that the case? Was Faber's 190 late "on the clock"?? I mean, it was an operational 190 whose pilot got disorientated and landed his operational and operating aircraft on a British airfield, without damage.
I remind you, that the before mentioned "race" between the 190, Tiff, and Spit was partially politically influenced. The 190 had been around for almost a year or so, outperforming the Spit V's (and the Spit II's(?)) with speed, roll, firepower and climb.
So, Hawker's had a candidate, and the whole spirit of the show seems to have been to demonstrate that the 190 was indeed very fast, and that new designs would be the answer to the threat, a comparison was definately needed.
Quill mentioned this about the role of the Spitfire in the race:
"Mr average contemporary fighter. It's job would be to come in the last..."
So I rather have the feeling that Faber's 190 ran nicely until it failed, that's my point.
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Originally posted by Angus
This here got me the hickups:
"Faber FW-190A3 was a derated motor."
So, Faber's 190 had a derated engine?
All the early BMW 801s were so called "derated". Basicly it means that the higher ratings were not cleared for service. The Brits just flew the tests without knowing that they used higher ratings than LW in service.
gripen
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As Gripen said. Faber's 190 was derated, like all 190s at the time.
The limit was supposed to be 1.42 ata, 2700 rpm, but in service they were all limited to 1.35ata, 2450 rpm.
The British didn't understand the correct ratings to begin with, and the AFDU test (the test where they compared Spit V, Spit IX, 190, P-51, P-38, Typhoon) was run with the Fw 190 using 1.42 ata, 2700 rpm.
When the RAE got Faber's 190, they worked out the correct (derated) ratings. So depending on the test, it could be derated or not.
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Anyway, seriously, was that the case? Was Faber's 190 late "on the clock"?? I mean, it was an operational 190 whose pilot got disorientated and landed his operational and operating aircraft on a British airfield, without damage.
I remember reading that Faber's normal A/C was in maintenance and he took an excess fighter that morning.
All the early BMW 801s were so called "derated".
Wrong. A motor was de-rated for several reasons:
1. To conserve high grade aviation fuel for combat operations motors would be de-rated and set up to run lower quality fuel. This involved changing spark plugs, regapping the plugs, and adjusting the fuel feed.
Source - Larry Wilson, Simithsonian Garber Facility, Curator Axis Aircraft Archives
2. Depot level maintenance could derate a power egg for minor deficiencies that did not effect operational safety.
Source - Luftwaffe pilots I have interviewed.
Crumpp
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So, when Quill's Spitfire overhauled Faber's 190, the 190 was already running on more boost than it could take?
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So, when Quill's Spitfire overhauled Faber's 190, the 190 was already running on more boost than it could take?
Same boost pressure as a rated motor will develop a lot less horsepower. Fuel feed and spark development play a large role in horsepower development. Just look at the SU pump on the Spitfire Mk IX test.
Fabers derated motor developed around 100 hp less than a rated motor. Wanna see the power graph??
Crumpp
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Originally posted by Crumpp
I remember reading that Faber's normal A/C was in maintenance and he took an excess fighter that morning.
Faber was the Adjutant of III./JG2 and his a/c was marked as it should have been:
(http://www.xs4all.nl/~rhorta/fusgradj.gif)
Must have been a quicky application of the Adj. markings.
Does using words like "power egg" make you more intelligent Crumpp?
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Achtung, Kraftei!!!
What do you mean?
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Julius Meimberg stated in his book that at the time 190 was introduced (in JG2), there was a rumour about that the engine was derated, because they did not want the Brits to discover the true potential of 190 just yet (of course there could have been other reasons as stated becore). IIRC a few higher ranking officers used the maximum power despite that.
Maybe Fabers FW was not derated after all as Meimberg wrote that the Brits became fully aware of FWs potential after Faber incident?
-C+
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Does using words like "power egg" make you more intelligent Crumpp?
That's the correct term milo. The engine, cowling, propeller, etc.. all came as one bolt on piece. It took very little time to completely swap engines. Sort of like a NASCAR. You should be familiar with that.
As Gripen said. Faber's 190 was derated, like all 190s at the time.
Not all FW-190's were derated at the time. The derating had nothing to do with the Spitfire or the RAF. It was a logistical management tool to extend the service life of motors and conserve high grade avaition fuel.
You will find derated motors throughout the war.
Faber was the Adjutant of III./JG2 and his a/c was marked as it should have been:
Your correct Milo. I do remember reading that his aircraft had problems and was in maintenance shortly before his flight. Whether that is the reason for the "derated" motor I don't know. It could simply be that there were not any rated motors available. The BMW-801 series motor were still experiencing teething troubles and reliability was pretty low. The Gruppe Adjutant is not the most likely to encounter the enemy in the Gruppe. So if I had to dole out airframes based on priority, he would be towards the bottom of the list.
Crumpp
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How does one derate a propeller or even a cowling, Crumpp?
Did you not tell me that the LW was not short of avgas? And, they did not even have to transport it by boat like they had to do for Sicily and NA.
Talking at cross purposes Crumpp. If the 801 was experienceing problems at that time, then it is logical to derate all of them.
Examples of derated motors used thoughout the war are..........
Werner Schroer as Adj of I./JG27 seems to have flown and scored. (4 ea in 2 weeks)
8. 30.5.1942 14:05 P-40 Stab I./JG 27 E Bir Hacheim
9. 10.6.1942 7:49 P-40 Stab I./JG 27 5km W Bir Hacheim
10. 15.6.1942 18:06 P-40 Stab I./JG 27 NW El Adem
11. 15.6.1942 18:11 P-40 Stab I./JG 27 NW El Adem
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This is something:
"That's the correct term milo. The engine, cowling, propeller, etc.. all came as one bolt on piece. It took very little time to completely swap engines. Sort of like a NASCAR. You should be familiar with that. "
Now that's what I'd call a clever design! Didn't know that one.
The 109 was pretty clever too, i.e. the possibility to remove the wings without the UC, etc, - it's engine was also quite accessible.
I misunderstood the word "Derated", just plainly took it for "poor performing".
I've heard something about poor performing engins due to wear, most notably the DB (!) actually, but not yet the BMW.
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If the 801 was experienceing problems at that time, then it is logical to derate all of them.
It did not happen that way Milo. Militaries, including the Luftwaffe have a rather large support train. It was their job to rate and derate motors. It's not a hard thing.
How does one derate a propeller or even a cowling, Crumpp?
Surely your not this dense.
Examples of derated motors used thoughout the war are..........
Look at how well Fabers FW-190 did in the tactical trials. A derated motor does not mean a useless aircraft. It just means it does not perform as well as a rated motor would. It was still good enough.
The 801 series had quite a few teething troubles in the begining. It was late 1943 before the Germans started getting more than 30-40 hours of life. The early the timeframe the less engine life an 801 had in it. The test group in 1941 could barely leave the airfield until JG26's TO came up with rerouting the exhaust on the bottom cylinders AFAIK. Engine reliability slowly climbed from that point. It was not the RLM who pushed the FW-190 program. It was the pilots who flew it. In fact the RLM almost cancelled the FW-190 on several occasions due to reliability issues. I believe if Galland had not had such close ties with JG26 and the pilots in the 190 test program it would have been cancelled. By late 1943 the 801 had developed into a reliable powerplant.
Crumpp
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Originally posted by Crumpp
It did not happen that way Milo. Militaries, including the Luftwaffe have a rather large support train. It was their job to rate and derate motors. It's not a hard thing.
:rolleyes: As you state below, the 801 was not reliable until'late 1943' while Faber's a/c was captured in 1942. Now we know you have extra ordinary powers, so tell us how you would know which engine to derate
Surely your not this dense.
Your the one that said the 'power egg' was derated.:eek: Any of the components that made up the 'power egg' could be derated giving the 'power egg' a derating. Should have used just plain old 'engine', eh Crumpp.:)
Look at how well Fabers FW-190 did in the tactical trials. A derated motor does not mean a useless aircraft. It just means it does not perform as well as a rated motor would. It was still good enough.
The 801 series had quite a few teething troubles in the begining. It was late 1943 before the Germans started getting more than 30-40 hours of life. The early the timeframe the less engine life an 801 had in it. The test group in 1941 could barely leave the airfield until JG26's TO came up with rerouting the exhaust on the bottom cylinders AFAIK. Engine reliability slowly climbed from that point. It was not the RLM who pushed the FW-190 program. It was the pilots who flew it. In fact the RLM almost cancelled the FW-190 on several occasions due to reliability issues. I believe if Galland had not had such close ties with JG26 and the pilots in the 190 test program it would have been cancelled. By late 1943 the 801 had developed into a reliable powerplant.
What does this have to do with answering the question of what other engines, as you claim, were derated during the war?
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Originally posted by Crumpp
I remember reading that Faber's normal A/C was in maintenance and he took an excess fighter that morning.
That 190 must have had one heck of a lot of fuel on board to take off in the morning, chase some Bostons and have combat with a Spitfire and land at Pembrey with the sun low on the horizon.
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As you state below, the 801 was not reliable until'late 1943' while Faber's a/c was captured in 1942. Now we know you have extra ordinary powers, so tell us how you would know which engine to derate
It states in the report Moron, Fabers A3 was derated.
That 190 must have had one heck of a lot of fuel on board to take off in the morning, chase some Bostons and have combat with a Spitfire and land at Pembrey with the sun low on the horizon.
Try reading a reply. Additionally, If it was the case and Faber signed for a new plane that morning due to his being in maintenance, I am unaware of any policy that a pilot is required to immediately take off and fly around until his is ready.
Your the one that said the 'power egg' was derated. Any of the components that made up the 'power egg' could be derated giving the 'power egg' a derating. Should have used just plain old 'engine', eh Crumpp.
What hair are you splitting?
What does this have to do with answering the question of what other engines, as you claim, were derated during the war?
Milo,
I have copies of numerous allied reports on at least 5 different FW-190's. Some are derated and some are rated motors.
the Flugzueg-handbuch issues special instructions for rated motors as well.
Crumpp
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You having trouble with English Crumpp?. You were the one that said motors, other than the BMW801, were derated.
Thick between the ears Crumpp? The question was NOT wether Faber's a/c had a derated engine but how, with your crystal ball, would you know if a BMW801 needed derating. Dispite you huffing and puffing, at that time, ALL BMW 801 engines were derated.
So can I hire you, for all your hot air will heat my residence this winter.
Actually, Faber would be ASSIGNED a different a/c if his was in maintainance. Yet he landed in his regular assigned a/c in Wales. He flew with, not the Stab, but 7./JG2 that afternoon. You claim the Adj did not fly often so Faber would not be assigned an a/c until it was close to his flight time. :)
You using a ghost writer for that book Crumpp? Hope so.
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OMG, this is almost like a Spit/109 thread now!
Anyway, looking into this again, Crumpp is saying that from the day Faber landed his whatever 190 at Pembrey, it never developed proper power, right?
And Milo is pointing out that it was not any different than other 190's of the same squadron, right?
Both are pointing out that the BMW at that time had a very short lifespan, right?
You can as far as I see both be correct.
So, this one bothers me.
Faber's 190 got tested untill it broke.
Would it not be normal to conclude that it's inital performance (untill it started giving trouble) would give a good account of a typical operable 190 performance at the time?
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Faber's 190 got tested untill it broke.
Would it not be normal to conclude that it's inital performance (untill it started giving trouble) would give a good account of a typical operable 190 performance at the time?
Or even above. The British removed the restrictions, in effect overboosting the engine.
The problem with the early tests of Faber's aircraft is that the British seem to have mixed up the engine settings they were using.
This, for example, is what the RAE reported for climb rate at 1.35 ata, 2450 rpm:
(http://www.onpoi.net/ah/pics/users/282_1097978826_190climbrates.gif)
The RAE test is in purple. The A3 data comes from a chart Crumpp posted, the A5 I can't remember where I got the graph, but possibly Crumpp as well.
The RAE's data doesn't fit. Whilst they claim 2450 rpm, 1.35 ata, it seems to me the low gear figures (up to 8,000ft) are 1.35 ata, 2450 rpm, but the high gear figure (above 8000 ft) must be for 1.42 ata, 2700 rpm, yet the RAE specifically say 1.35 ata, 2450 rpm for both.
Personally, I take the initial tests of Faber's 190 with a pinch of salt, because I don't think it was tested at the settings the AFDU/RAE thought they were using. The later figures should be better, after they had a chance to get to know the aircraft.
I have copies of numerous allied reports on at least 5 different FW-190's. Some are derated and some are rated motors.
the Flugzueg-handbuch issues special instructions for rated motors as well.
Which A subtypes? AFAIK, derating was no longer standard from some time during A4 production. I believe the British also deliberately ignored some ratings to run the captured aircraft at settings they thought would be common in the future.
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No Angus, I see Crumpp saying, OK this engine for the A-3 will be derated , this next one as well but not the next one........ and so on and so on and so on
Btw, the cockpit of Faber's a/c is suppose to be in an English or Welsh museum.
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Jeffrey Quill actually tested a 190.
He regarded it inferior to the Spit IX in all performance respect except:
a) climb at certain alt bands
b) roll rate
Wish I knew which 190, and which IX.
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Hi Nashwan: There has to be a typo there somewhere. I have a RAE curve for the 190 that shows about 2500 ft/min from 8,000 ft to 18,000 ft. They did test it at 1.42 though, or at least estimate it, as there is a separate line for 1.42 with initial ROC 3,650 ft. , 3,000 ft/min from 10,000 ft to 19,000 ft. The RAE curves I have follow closely the other two you charted. I know you've studied that subject in depth so I'll defer to your expertise. Perhaps I'm missing some nuance of your argument, but that RAE curve you show is nuts! ;)
I believe the British also deliberately ignored some ratings to run the captured aircraft at settings they thought would be common in the future.
I know they based some of their comparisons on how they thought the enemy aircraft could perform in future, for example "Both the Me 109 G and the FW 190 A were originally, and in some cases still are operated at a reduced engine rating. Performances given correspond to the full engine ratings" from here (http://www.fourthfightergroup.com/eagles/spit9.html).
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I have a RAE curve for the 190 that shows about 2500 ft/min from 8,000 ft to 18,000 ft.
Does it give the engine ratings?
The figures I'm using are from a page out of an RAE report that Butch posted on the IL2 boards. It can't be a simple misprint, because they give figures of 3500 ft/min between 10 and 17,500 ft at 1.35ata, 2450 rpm, and also 2800 ft/min at 1.28 ata, 2350 rpm.
I suspect they've read the columns on a chart wrong, and it should be 3500 ft/min at 1.42 ata, 2700 rpm and 2800 ft/min at 1.35 ata, 2450 rpm.
That would seem to fit the other figures pretty well.
Perhaps I'm missing some nuance of your argument, but that RAE curve you show is nuts!
It is nuts, as far as I can see. The only way I can see to get a shape like that is to increase the rpm/ata when you switch to high gear.
What I don't know is whether whatever led to that mistake in the RAE report, also affects the AFDU test, where they seem to have got some odd sustained climb rate figures against the Spitfires.
Probably not, and the figures the RAE reported were just a case of shifting all the results when compiling the tests, so the 1.42 ata figures were used for 1.35 ata, the 1.35 ata figures for 1.28 ata, etc. But it does raise at least the possiblity that when the AFDU say they were using 1.35 ata, 2450 rpm for the sustained climb tests for the 190, they might have actually used 1.42 ata, 2700 rpm. (which would explain a lot about the "sustained climb" figures they found vs the Spit Vb)
I know they based some of their comparisons on how they thought the enemy aircraft could perform in future, for example "Both the Me 109 G and the FW 190 A were originally, and in some cases still are operated at a reduced engine rating. Performances given correspond to the full engine ratings" from
Thanks, I knew I'd read something along those lines, but I searched for hours to find it without success a few weeks ago, and I had another quick look to see if I could find it before my last post. I've got a bad habit of skimming things and missing the bit I'm looking for.
BTW, I really like the "what's new" feature :)
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Nashwan,
Give me your email and I will send you and Angus the entire report on Faber FW-190A3. The performance trails complete with Horsepower, climb, speed, etc...
You will find it very interesting.
Crumpp
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Thanks Crumpp, I've been trying to find more info on Faber's 190 for some time.
Email is nashwantwo@yahoo.co.uk
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It looks to be your lucky day Nashwan, check your email :)
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In another thread rose a question about the drag again:
Originally posted by Angus
Hello guys.
The drag of those two seems to fall short of each other, the 190 being smaller and cleaner if anything, and note, that in the real world it had a better finish.
The flat plate areas calculated for Cd0 are following:
BF274: 4,93
BS428: 4,68
BS534: 4,70
BS551: 4,80
EN524: 4,82
BS310: 4,98
MA648: 4,69
JF275: 4,77
JL165: 5,19
Fw 190A-8: 4,78
Basicly this means that four tested Spitfires had lower Cd0 than a filled and polished Fw190A-8. Generally both planes are in same ballpark.
gripen
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Basicly this means that four tested Spitfires had lower Cd0 than a filled and polished Fw190A-8. Generally both planes are in same ballpark.
Lets compare the Spitfires with their contemprary FW-190 opponents:
Lets see and compare total drag @ 440fps at the Spitfires FTH altitude with the correct data:
BF 274 - 795.641828 @ 440 fps
Total Drag FW-190A5 -718.2845242@ 440 fps
BS354 - No data listed except the A/C was 7 mph slower w/50 bhp more output than the Merlin 66 @ (+18)
BS543 - 810.863789
FW-190A5 - 705.7484202
BS551 - 758.4823884
FW-190A5 - 704.890256
EN524 with 4 bladed prop - 765.4635575
FW-190A5 - 702.4712376
BS310 with 4-bladed prop - 793.0539968
FW-190A5 - 751.8834689
BS310 with 5 bladed prop - 794.0663191
FW-190A5 - 749.7161496
JL165 - done to death
MA 648 Merlin 66 (+18) SU Pump - 838.0549776
FW-190A5 - 804.8037275
BS310 - 792.6552588 Parasitic drag - 691.672177
FW-190A8 - 794.3964059 Parasitic drag - 606.4158622
At 315mph the total drag situation changes completely in the FW-190A8 favor.
JL165 vs FW-190A8 has been done to death, again in the FW-190A8's favor.
MA 648 is the ONLY Spitfire Mk IX to beat the FW-190A8 for drag and here is why:
quote:
--------------------------------------------------------------------------------
External equipment of the above four aircraft was similar with the exception that MA.648 had the new pattern of air intake.
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MA648 - 837.1701001 parasitic drag - 751.6212076
FW-190A8 - 869.2121249 parasitic drag - 709.9624067
The parasitic drag is always in the FW-190's favor but the total drag drops to within a few pounds of each other at 315 Mph but never swings in the FW-190's favor.
So ONE example of the Spitfire Mk IX with an experimental air intake beats the FW-190A8 in total drag. The others are behind their FW-190A contemporary the whole way.
That about covers the Spitfire Mk IX's vs. their contemporary FW-190 adversary.
Crumpp
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Now if somebody just can bring evidence that the Fw 190A-5 was really that much faster than the A-8 at same power setting.
gripen
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Originally posted by gripen
Now if somebody just can bring evidence that the Fw 190A-5 was really that much faster than the A-8 at same power setting.
gripen
Hmm, that makes me wonder... why is any evidence is needed that the A-5 was faster than the A-8?
German docs themselves state that to start with. Add to that that it`s perfectly logical that the more draggy A-8 would be slower with the MG 131 bulges, increased weight, and the lack of l/g fairing due to mounting the bombrack...
Now all I have seen up to now shows the FW 190 made a better homework to convert engine power into speed. That means it was either less draggy and/or that it had a better airscrew. Something which I wouldn`t rule out either, practically everyone who seem to have some idea on the subject tells me how good German prop design was before/during WW2. The new report on JL 165 that Mike put on the site also suggest that the MkIX`s wooden airscrews had some problems with greater powers.
Besides I don`t understand why you guys even adding all those experimental/prototype Spits into the discussion...
Pray tell me why to compare the MK IX L.F. proty BS 543 with the experimental airscrew, the MA 648 with the experimental fuel pump? These hardly tell much of the drag state of the serialized Spitfire aircraft, considering both changes will effect the available thrust itself, which on the other hand you seem to believe to take as the same on all planes...
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Well, the docs (http://www.terra.es/personal2/matias.s/fw190.htm) show over 20 km/h difference at same power setting despite the A-8 external surfaces are claimed to be "filled and polished", without ETC 501, wheel doors fitted...
gripen
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Well, the docs show over 20 km/h difference at same power setting despite the A-8 external surfaces are claimed to be "filled and polished", without ETC 501, wheel doors fitted...
Been whooped to death. Bad translation. Original doc does not say that. It says primed and painted.
Crumpp
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So where is the evidence?
gripen
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What Crummp said. How does the original German sounds like, Crummp?
Besides, Gripen, do you reeeally think 20 km/h is a lot? With all the extra drag of the A-8 added into the picture?
Hell, the non-retractable tailwheel on the 109G-6 alone meant -12 km/h...
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And the Spitfire Mk VIII also had a retractable tailwheel.....:D
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Originally posted by Kurfürst
With all the extra drag of the A-8 added into the picture?
The only drag difference between the A-5 and A-8 appear to mg cowlings which is a minor thing. The difference in weight can't explain the speed difference. Besides I don't even know if the A-8 performance is really flight tested.
Originally posted by Crumpp
It clearly states the finish of the aircraft is "Surface primed and Smooth Painted" Smooth painted refers to standard RLM semi-gloss aircraft paints.
Hm... finally you could actually post some sort of evidence but for one reason or another you posted it to wrong thread. Read the forum rules (http://www.hitechcreations.com/forums/announcement.php?s=&forumid=17)
"Gespachtelt + Blattanstrich" my German abilities are certainly limited but that appear to mean filled and several coats of paint or laquer. However that's not same as polishing.
At least here in Finland the surface quality of the german planes was not considered to be particularly good and there was large variation depending from which factory the planes came.
I can certainly say that in the case of the Bf 109 some parts around canopy and engine cowling were filled, in addition some joints (wing tips and tail parts) were covered with canvas. Otherwise most joints were visible ie not filled and by looking pictures that appear to be the case with the standard Fw 190 too.
AFAIK the only plane which had large surfaces filled as standard was the P-51 and in that case only the wing surfaces.
gripen
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The difference in weight can't explain the speed difference.
One thing that might explain it is the Lufterrad. I have a report showing a average of a 15km speed increase from using a 12 bladed Lufterrad. In the FW-190A8 they began using a 14 bladed Lufterrad.
Unfortunately this particular report is off being translated. I looked it over and dropped in with the others and mailed it. Since then it has become sort of mystery as to why the 14 blade Lufterrad was adopted when it reduced performance.
Crumpp
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"Gespachtelt + Blattanstrich" my German abilities are certainly limited but that appear to mean filled and several coats of paint or laquer. However that's not same as polishing.
The finish refers to RLM aircraft paint. Literally translated it means "smooth painted". Ask any aircraft mechanic. All airplanes are "smooth painted".
At least here in Finland the surface quality of the german planes was not considered to be particularly good and there was large variation depending from which factory the planes came.
That's interesting. The USAAF studied the technology behind RLM finishes and incorporated them into modern USAF fighter finishes. The coatings on an F16 today are direct descendants. All the RLM finishes I have physically touched are very smooth. Even the 60 year old finishes. The paint has a very tiny granular base compared to allied paints of the same time period. There is a very good reason the USAAF went to bare metal finishes. US aircraft paints were horrible.
Crumpp
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Originally posted by Crumpp
One thing that might explain it is the Lufterrad. I have a report showing a average of a 15km speed increase from using a 12 bladed Lufterrad. In the FW-190A8 they began using a 14 bladed Lufterrad.
You mean cooling fan?
Another issue is what's the effect of the ETC 501 and the wheel doors as a standard plane probably had the ETC 501 and no wheel doors?
gripen
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Another issue is what's the effect of the ETC 501 and the wheel doors as a standard plane probably had the ETC 501 and no wheel doors?
It takes less than 2 minutes to remove the ETC and mount the doors. The plane would have been set up the night before based on TO input for the missions the next day.
Crumpp
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Originally posted by Crumpp
Unfortunately this particular report is off being translated. I looked it over and dropped in with the others and mailed it. Since then it has become sort of mystery as to why the 14 blade Lufterrad was adopted when it reduced performance.
Crumpp
Possibly because of the need to increase the cooling with the more powerful engines installed. The increase in a/c weight would put more 'work load' on the engine as well.
Crumpp, did the ratio for the fan change when the fan was change?
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Crumpp, did the ratio for the fan change when the fan was change?
Don't know Milo. I will let you know when the report gets back.
Crumpp
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Emm, Crumpp:
"That's interesting. The USAAF studied the technology behind RLM finishes and incorporated them into modern USAF fighter finishes. The coatings on an F16 today are direct descendants"
This boggles me a bit. A was petting an F15 a couple of years ago, and I was baffled with the finish. I had always thought they were so glossy, but it was quite matt.
Not that it tells much about the granular size, but yet it felt rather matt.
I just thought, well, probably something extremely strong, and now you have so much power that the smoothness or glossyness is maybe not needed.
To bring that into the focus a bit, the aircraft (the Colonels plane) had quite some time on the clock (F15E it was), but the paint was still in perfect condition, - no visible breaks or flakes.
Just a little input.
Regards
Angus
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but the paint was still in perfect condition, - no visible breaks or flakes.
I have touched 300 Liter drop tanks that the finish is over 60 years old and they are still smooth. The finish is powdery and leaves a residue much like chaulk on your fingers after so much time.
Gary says he had a hard time getting the mixture right on the RLM paints. Until he finally got ahold of some ex-Luftwaffe personnel who gave him the "tricks". Once he got the proper ratio of reducer the RLM paints went on much thinner and in one coat than the USAAF paints he used. With the proper mixture he said fisheyeing and orange peeling did not happen.
The RLM paint is much more flexible. The USAAF paints go on and are about 5mm thick with primer and lacquer. When the skins flexs they have a problem of peeling around the rivets. This will quickly cut down on your performance. The RLM paints are around 2-2.5mm thick with primer and sealer. He never experienced any problems with peeling or flaking from skin flexing.
but it was quite matt.
The RLM paints are matt as well. The sealer is a semigloss. The USAF improved the technology so the whole finish is matt. All the modern fighters I have touched are very smooth with a matt finish.
Angus you should have asked him if he had an anti-radar coating. There are finishes the US Military has which absorb some of the radar signals. The early finishes were all black. They now can make them in other colors and they are rough. That roughness is part of their absorbtion capability.
Crumpp
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Originally posted by Crumpp
It takes less than 2 minutes to remove the ETC and mount the doors. The plane would have been set up the night before based on TO input for the missions the next day.
Crumpp
U R positive on that 2 mins required for the ETC rack mount/unmount? I am asking for confirmation, to be sure not to write BS in an article.
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Oleg Maddox, of Il-2 fame, says it was much longer than 2 minutes to remove the ETC501.
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Oleg Maddox, of Il-2 fame, says it was much longer than 2 minutes to remove the ETC501.
Does Oleg Maddox of Il2 fame have direct access to a 190 or ever taken an ETC 501 rack off an FW-190?
I suggest you join:
http://www.white1foundation.org
We need members and you can find out exactly how long it takes to remove the ETC 501 rack.
U R positive on that 2 mins required for the ETC rack mount/unmount?
Honestly, I don't think anyone ever put a stopwatch to it to find out. It does not take very long at all. I would be surprised if it was much over 1 minute to take the rack off.
The entire cockpit can be completely stripped in just a few minutes. The side panels are held in place with latchs like a tool box. The wiring harness is one plug. In under 5 minutes you can remove the seat, side panels, and insturment panel.
Kurt Tank did his homework in the maintenance department on the FW-190.
Bob (chief structure technician) says the P38 he worked on was a nightmare to change out the racks. You actually had to run wiring through the wing to change store types and undo quite a few bolts.
The FW-190 has a universal wiring harness. All the plugs are set up to except all the stores it can carry and the plugs are arranged so that it is impossible to fit the plug in the wrong connection.
Crumpp
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Originally posted by Crumpp
Does Oleg Maddox of Il2 fame have direct access to a 190 or ever taken an ETC 501 rack off an FW-190?
I suggest you join:
http://www.white1foundation.org
We need members and you can find out for yourself exactly how long it takes to remove the ETC 501 rack.
Crumpp
Just stating what he said.;) I called him on the time (iirc 30 min) he said but he never answered.To add, he claims the pilot view in the cockpit of the 190 in his game is the most authentic. He has been shown that it is not so.
The 2 minutes, with how many mechanics. (just a question) I do agree it could be removed in very little time, the 20 bolts holding the fairing in place taking the most time, I bet.
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The 2 minutes, with how many mechanics. (just a question) I do agree it could be removed in very little time, the 20 bolts holding the fairing in place taking the most time, I bet.
They are quarter turn flush screws IIRC on the fairing. I am serious about joining the foundation. We need members and will starting up a newsletter again soon.
In it I plan to include a section "The Plane Facts" which will detail technical information on the design. Be lots of original documents, diagrams, and good information for members.
The Museum, library, and shop is open to members by appointment as well.
The 2 minutes, with how many mechanics.
I was thinking one guy. Same with the cockpit. I can find out exactly how long it takes.
Crumpp
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Bolts (an overkill method ;)) was the wrong word, should have said screws. :)
D-zus fasteners sounds logical.
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Just got off the phone with Dr Timken to find out exactly what the deal on the time for the rack.
The rack and the doors are a little more involved than our previous conversations had led me to believe. A "couple of minutes" is more than 2 minutes.
Conservatively, working at normal not rushed pace:
For one man to remove the rack and mount the doors is an hour.
For a Luftwaffe ground crew it is about 15 minutes work.
The cockpit disassembly times I quoted are correct.
Crumpp
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Very very nice.
I was thinking, when you said a couple of minutes, well, those could be a few ;)
Nice to seeso much research being done.
Regards
Angus
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The Fw-190A-5 (http://www.terra.es/personal2/matias.s/fw190_A5_speed.gif) is claimed to be "Gespachtelt u. poliert" so it certainly had a special finish (if that really is test data).
The ETC501 caused 12-15km/h speed loss (from the same pages).
gripen
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The Fw-190A-5 is claimed to be "Gespachtelt u. poliert" so it certainly had a special finish (if that really is test data).
Yes it is. It is marginally faster and marginally slower depending on the altitude then some of the other normal finished FW-190A5 graphs.
You can definately see now there is not a special finish on the FW-190A8.
The ETC 501 rack speed loss is also listed on the FW-190A8 graph I posted, Gripen.
Crumpp
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Originally posted by Crumpp
You can definately see now there is not a special finish on the FW-190A8.
I can see that the speed difference between the US Navy Fw 190 (no wheel doors) and the Fw 190A-8 is neglible. The speed difference between Fw 190A-8 and the Fw 190A-5 can be mostly explained with the polishing because it gives about 15 km/h speed increase (according to Hoerner and Raunio).
gripen
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The speed difference between Fw 190A-8 and the Fw 190A-5 can be mostly explained with the polishing because it gives about 15 km/h speed increase (according to Hoerner and Raunio).
That would hold if it was not for the fact the other graphs show about the same difference between the FW-190A5 and the FW-190A8.
The FW-190A5 had the 12 bladed Lufterrad which made the FW-190 about 12 Kph faster. Polishing generally does not give such a dramatic increase as 15kph. 3-5 Kph is about right for the finish. Pyro has the other graphs.
Crumpp
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Originally posted by Crumpp
That would hold if it was not for the fact the other graphs show about the same difference between the FW-190A5 and the FW-190A8.
The problem is that I don't see here any evidence of such graphs. If there really is such graphs, these might be with special finish as well. And are those supposed graphs flight tested? Only in the cases of the US Navy and RAE data I have seen evidence that these are flight tested.
The another problem here is that you have used a plane with special finish in a comparison. That is IMHO not fair.
gripen
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The problem is that I don't see here any evidence of such graphs. If there really is such graphs, these might be with special finish as well. And are those supposed graphs flight tested?
Your not going to either Gripen. Pyro has them though.
That is IMHO not fair.
And comparing a Wooden Model to an actual aircraft of a different design is not??
Or data gathered from experimental Spitfire with various fuel pumps, props, intakes, etc...
Don't see you calling the unfair flag on that one.
Crumpp
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Originally posted by gripen
The another problem here is that you have used a plane with special finish in a comparison. That is IMHO not fair.
gripen
Hmm, I think Crummp already showed nicely that the plane has the standard finish, ie. primer etc. So why revert again to the "unfair special finish" thing? Besides, you were using Spit tests that were done with experimental planes with higher performance than the normal ones.. do you consider this 'fair'? Besides I don`t see what`s your problem with the A-5 data. The A-5 Handbuch states the same values, so obviously the data Crumpp uses isn`t anything extraodinary.
Why don`t you first agree which data is representative first, and then moving one step ahead?
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As I stated before there is only a minor difference of 2-3kph comparing that graph to other FW-190A5 graphs.
It just did not have a great effect on the FW-190.
(http://www.onpoi.net/ah/pics/users/503_1100954709_smoothing.jpg)
Crumpp
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gripen, the only way you can compare is 'like with like'.
A scale models data will get you in the 'ballpark' but can't be compared to full size data.
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Originally posted by Crumpp
Your not going to either Gripen.
No proof, no argument.
Originally posted by Crumpp
And comparing a Wooden... blaah blaah
Not subject of this thread and no proof, no argument in that other thread too.
Originally posted by Kurfürst
Hmm, I think Crummp already showed nicely that the plane has the standard finish, ie. primer etc.
I have been only referring sources which are available. Besides if you look back in this thread you will find me saying that the performance of the A-8 seems to be realistic and you will also find Crumpp stating (09-07-2004 11:03 AM): "They waxed it.". Generally it's very difficult to believe a person who continously changes his arguments and can't proof them.
Originally posted by Milo Morai
gripen, the only way you can compare is 'like with like'.
A scale models data will get you in the 'ballpark' but can't be compared to full size data.
Not subject of this thread but three short points:
1. We are not talking there about the total drag but change of the drag due to change of the Cl.
2. I'm not making drag comparisons nor other comparisons between planes there except comparisons to generalized formulas and lift distribution.
3. The Fw data is very probably determined with the models as well.
If you want to discuss more about this, please post to that thread.
gripen
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Besides if you look back in this thread you will find me saying that the performance of the A-8 seems to be realistic and you will also find Crumpp stating (09-07-2004 11:03 AM): "They waxed it.". Generally it's very difficult to believe a person who continously changes his arguments and can't proof them.
LOL,
Squirms of the dying argument....
Gripen that is new one on me. Only thing I recall is your claim that the USN data was correct and the graphs I put up were unrealistic because of the "filled and polished".
Now your claiming your felt the FW-190A8 data was correct the whole time!!
No proof, no argument.
There is proof. You just don't have it and are not going to get it from me.
gripen, the only way you can compare is 'like with like'.
A scale models data will get you in the 'ballpark' but can't be compared to full size data.
Absolutely Correct. You should listen Gripen.
The Fw data is very probably determined with the models as well.
Not hardly. It's off of real aircraft. In December of 1944 the Germans were possesion of several windtunnels large enough to conduct these experiments. Any aeronautical engineer will tell you that trying to get exact drag data off a wooden model will not compare exactly with the full scale flying version of the aircraft. You can only draw general conclusions NOT specific numbers.
Crumpp