Spit 5

[Crumpp]

Can't follow the link Milo.

Your welcome.  I did not think you did confuse PS and Hp in this case but it is easy to do, especially when you are scanning through mounds of data.  I have done it before.  I had to go back and redo the entire comparison.

It is extremely easy to get confused on the FW-190 Rustsatz, Umsatzrustaz, and einsatz's variants.  It is no wonder there is a huge weight variance.

There are two basic fighter versions and two basic jabo versions.
These two basic fighter versions can be outfitted with 9 different kits to perform different tasks.  This does not include other "accessories" like the 115-liter aux tank, GM-1, and Nachtjagd kits. Additionally the plane saw lots of Geschwader level modification, like removing the outboard MG151's.  It is probably the correct weight, but for what version and mission is it equipped?


An FW-190A8 "fighter" can weigh anywhere from just over 4000kg's to almost 4900 kgs all in what mission it is equipped to perform.

It was kind of the "Jeep" of Luftwaffe fighters.  IMO, to properly model it, the hanger menu will need to offer a few more choices.

One thing is certain.  The performance has a wide variation based on the "accessories".   All the way from very good maneuverability to "it barely flys".  The choices you make in the hanger will probably reflect this fact.

Crumpp

[MiloMorai]

Try this then,

w^3.allaboutwarfare.com/files/uploads20/10905814338yb0.jpg

w^3 = www


I know very well what 'kits' were used on the 190. Not all the /U and /R were fitted to 'combat' a/c. There was even two /R1s.

/R1 - FuG16Z- E for A-4, -5
/R1 - WB151/20 for A-6, -7, -8

There is also two meanings for the 'R'. which does not help either.

[gripen]

Originally posted by Charge
I'd like to remind you that to counter the stall characteristics of the elliptical wing there is washout in the wings which places the outer portion of the wing into more liftless angle when the mainpart of the wing (the root) is in position where it does the lifting job, so to me it seems that when determining the lift for Spit's wing only part of the wing can be considered effective depending on the speed and AoI of the main part of the wing. So when determining the AoI of the wing the washout and its effects to overall lift capabilities of the wing should not be forgotten.

Well, even with washout it's still entire wing which does the lift. However washout will effect on distribution of the lift (ie towards center section) so it will reduce efficiency factor if compared to ideal elliptic form, but unlikely very much. Otherwise the washout will ad some amount of form drag as you pointed out in your later post.

Originally posted by VO101_Isegrim
The Spitfire`s Max. Lift Coefficient was 1.12.

This value is from NACA test on Spitfire V. The RAE got different results and critisized NACA tests on this (RAE TN No. 1106):

Originally posted by Crumpp
Efficiency factor of the wingtip is only used when calculating CDi not the downwash.  The "raw" Cl is converted to the true Cl and that is used in all other calculations.  Gripen has taken the "raw" Cl and used it without factoring in the downwash.  The Cl will be much more evenly matched when entered into the Cdi formula.

Well, as usual Crumpp has no clue what he is talking about. The Cl formula:

Cl=L/(r * (V^2/2) * A)

Gives directly the true Cl of the plane, if Crumpp can prove otherwise he is most welcome to do so.

The downwash effect formula:

Cl = Clo / (1 + Clo /[pi * AR])

Is a formula to convert the 2D (infinite, ie no downwash effect) wing profile Clo value on given AoA for the 3D (finite) wing of known aspect ratio.

Originally posted by Crumpp
According to everything I have read, the higher the Aspect ratio the better for manuverability.

It's well known that (true) high aspect ratio has bad effect on roll performance as well as inertia effects might be serious. As an example Ta 152H much worse rate of roll than the Fw 190, another well know example is the P-38.

Originally posted by Crumpp
The FW-190 went with a High Aspect ratio and smaller wing area.

There is very little difference between aspect ratio of the Fw 190 and the Spitfire. And so far no one else has said that the Fw 190 had high aspect ratio, actually around 6 was quite normal. Here is a little list:

Fw 190 6,02
Ta 152H   8,95
P-38 8,24
Bf 109F 6,13
Bf 109H 8,05
Spitfire VII 6,50
P-51 5,88
Ki-61 7,20
P-47 5,53
D.520 6,50
MC.202 6,65
Hurricane 6,21

gripen

[Crumpp]

Gripen

Please feel free to show us the 2D formula.  It is not listed on NASA's website. All it says is that if you want to use a 3D wing then you must factor in the downwash to the Cl from the only formula to calculate Cl provided.  That's the one you used, right?

Third paragraph from the top:

For three dimensional wings, the downwash generated near the wing tips reduces the overall lift coefficient of the wing.

http://www.grc.nasa.gov/WWW/K-12/airplane/liftco.html

Reduced lift coefficient is a three dimensional effect related to the wing tips.

 
http://www.grc.nasa.gov/WWW/K-12/airplane/downwash.html

This value is from NACA test on Spitfire V. The RAE got different results and criticized NACA tests on this (RAE TN No. 1106):

Ok, so there are two completely conflicting tested results.  The RAE says they don't agree with the NACA test results and their method is more accurate.

I'm not surprised.  If Israel tested the F16 and said it's not as good as you say I am sure the both General Dynamics and the USAF would refute it with sensible engineering arguments.  However two conflicting test results is not definitive proof.

It's well known that (true) high aspect ratio has bad effect on roll performance as well as inertia effects might be serious.

Is there something untrue about the 190A's Aspect Ratio? Are you trying to imply that the 190 did not have a great roll rate?

I am certainly not attempting to prove the Spitfire couldn't climb well, turn well, or had excellent aerobatic performance.  It's a fact though that Merlin Powered Spits could not zoom with a 190 and have any hope of catching it from a co-energy state.  The 190 got its performance edge from aerodynamics not raw horsepower as many published books allude.  Simply check the SL speeds and Horsepower of a Merlin 66 (+18) and the FW-190A5 at 1.32ata @ 2400U/min.  You have the websites and it is listed below although Isegrim did not adjust the BMW801D's Hp for RAM as the Merlin 66 chart is adjust for RAM.

 

Spitfire VII 6,50

And please print the Aspect Ratio of the Spit Mk IX please.  Not a special High Altitude Spit Version.

http://www.btinternet.com/~lee_mail/spitfire2.html

[gripen]

Originally posted by Crumpp
Please feel free to show us the 2D formula.  It is not listed on NASA's website. All it says is that if you want to use a 3D wing then you must factor in the downwash to the Cl from the only formula to calculate Cl provided.

Here Crumpp purposedly understands NASA site wrong. NASA site gives two formulas to calculate lift coefficient (clearly printed as Cl not Clo)  on different conditions.

The first one  can be used when the  wing area , lift , air density and speed are known:

Cl = L / (A * .5 * r * V^2)

Note that the result of the formula is Cl (not Clo) ie this formula gives true lift coefficient. If a plane can fly at certain speed at certain altitude and it's weight and wing area is known, then this formula gives true Cl which includes all factors.

The second one can be used when the Clo (ie the 2D Cl of a profile at certain angle of attack and Reynolds number)  and aspect ratio of the planned wing is known:

Cl = Clo / (1 + Clo /[pi * AR])

There is no formula for the Clo because it has to be determined  experimentally, with the wind tunnel or with the simulation. As an example the Panel code solver, which Crumpp linked earlier in this thread, is an utility to determine 2D slow speed Clo for some profiles.

Originally posted by Crumpp
Is there something untrue about the 190A's Aspect Ratio? Are you trying to imply that the 190 did not have a great roll rate?

Crumpp's argument that:

" The FW-190 went with a High Aspect ratio"

Is pretty much untrue because the Fw 190 did not have high aspect ratio but a very typical AR for a WWII fighter.

Originally posted by Crumpp
The 190 got its performance edge from aerodynamics not raw horsepower as many published books allude.

It has been pointed out several times in this thread that the differences in the dive and zoom were mainly due to weight differences, not due to aerodynamic differences.

Originally posted by Crumpp
And please print the Aspect Ratio of the Spit Mk IX please.  Not a special High Altitude Spit Version.

I have printed the AR of the Spitfire IX with standard wing tips (5,61) twice above.

Shortly there is nothing special in the  AR of the Fw 190 and it can't be used to explain differences in the dive and zoom. Infact the P-51B had a lower AR but it dived and zoomed better than the Fw 190A.

gripen

[MiloMorai]

Crumpp did you get the chart?

If not,
 http://www.allaboutwarfare.com/  

> forums > ww2 > 'thread' "Lift and drag coefficients" by Sokol.

post by gabbys near the end.


Willl need your translater though.

[Crumpp]

No I didn't Milo.

The link still is not working.

Crumpp

[Crumpp]

Is pretty much untrue because the Fw 190 did not have high aspect ratio but a very typical AR for a WWII fighter.

It was HIGHER than the Spits.  That was the point Gripen

 

There is no formula for the Clo because it has to be determined experimentally, with the wind tunnel or with the simulation.

You would think that the site would explain it better.  What you are saying is NOT how it reads.  First the site says the Cl is best determined by using a Wind tunnel, which you contend is not necessary. Then it gives the formula. If you follow the link from this page:

http://www.grc.nasa.gov/WWW/K-12/airplane/liftco.html

It clearly says for a 3D wing factor in the downstream effect and links to this page:

http://www.grc.nasa.gov/WWW/K-12/airplane/downwash.html

Which talks about the basic free stream lift coefficient Clo.   Your right it does not say HOW to calculate the Clo anywhere on the page.  

Now YOUR SAYING WE NEED A WIND TUNNEL TO CALCULATE Clo!

I have one question.  If we need to factor in downstream effect to figure out a 3D wing…

How do we fit our 2D wing into the Wind Tunnel?  Won't our paper blow away?  

I think your full of crap.  I think that formula determines the 2D Cl and to convert it to 3D you have to factor in the downstream. Just like the first page says.  Just to make sure I will email the guys that run that site and confirm it.

It has been pointed out several times in this thread that the differences in the dive and zoom were mainly due to weight differences, not due to aerodynamic differences.

Yes, never by you though.  Don't steal another mans laurels, bozon offered the first informed explanation. In fact when the subject started it was on the FW-190A8 vs Merlin (+25) Spit Mk IX.  I stated in my first post that the weight gain of the FW-190A8 improved it's zoom climb and dive acceleration.   Your original contention was that the Spitfire Mk IX Merlin 66 (+25) performed just like the Spit XIV and would handily outperform the FW-190A8.  I said they were equals each with it's own strengths and weaknesses.

 

I have printed the AR of the Spitfire IX with standard wing tips (5,61) twice above.

Yep I gave it to you.
Spitfire Mk IX - 5.61
FW-190A8 - 6.01 (which is .01 higher than what I posted)

Looks like a pretty good spread.

Shortly there is nothing special in the AR of the Fw 190 and it can't be used to explain differences in the dive and zoom. In fact the P-51B had a lower AR but it dived and zoomed better than the FW-190A.

Absolutely, the P51B was a MUCH more dangerous opponent for the FW190 than the Spitfire.

If you read the tactical trials it out zoomed it for two reasons:

1.  It less DRAG and it had weight 9245lbs.
2.  It had a 50 mph speed advantage advancing to 70 mph at altitude.

The FW-190 has less drag than the spitfire.

It doesn't list which FW-190 variant the RAF tested.  Based on the time period it was either Faber's FW-190A3 or one of several FW-190A4 Jabo-einsatz's the RAF repaired and flew.

Or it could be the FW-190A5/U4 Aufklarer tested by the USAAF in Jan '44.  This one needed quite a bit of work and the engine cut out at altitude. You can read about the tactical trials against a Corsair and a Hellcat here:

http://prodocs.netfirms.com/


Crumpp

[gripen]

Originally posted by Crumpp
It was HIGHER than the Spits.  That was the point Gripen

Untrue,  the high altituide Spitfires had higher aspect ratio than the Fw 190A. And no one else is calling the Fw 190A as high aspect ratio plane.

Originally posted by Crumpp
You would think that the site would explain it better.  What you are saying is NOT how it reads.  First the site says the Cl is best determined by using a Wind tunnel, which you contend is not necessary.

Here Crumpp behave really childish, the NASA site says first:

" Cl contains all the complex dependenciesand is usually determined experimentally"

And that is exactly what I have been doing when I use data from the real plane. Just Like Bozon wrote above:

" Crumpp, he's calculating the Cl of a level flying plane at a given speed - this is the same as putting it in the wind tunnel. The engineers want to know this BEFORE they build the actual plane and risk some dumb bellybutton pilot to fly it. But for an actual flying plane the calculation must apply. "

Originally posted by Crumpp
Now YOUR SAYING WE NEED A WIND TUNNEL TO CALCULATE Clo!

The Cl can be determined easily from the flight data. The Clo must be determined in wind tunnel or simulation. Crumpp is plain childish here.

Originally posted by Crumpp
How do we fit our 2D wing into the Wind Tunnel?  Won't our paper blow away?

It's pretty simple, all what  is needed is a wing plate going through wind tunnel so there is no downwash effect.

Originally posted by Crumpp

FW-190A8 - 6.01 (which is .01 higher than what I posted)

Actually:

10, 5^2/18,3=6,0245901639344

gripen

[gripen]

Here  is a good explanation of the wind tunnel testing on 2D lift coefficient.

"The data obtained by wind-tunnel testing of NACA families of airfoil sections is two-dimensional data. This means that since the airfoil was suspended in the wind tunnel from wall to wall, it essentially had no wingtips and simulated a section of a wing of infinite span. The data obtained is associated with just the airfoil and has no association with the span of the wing. "

gripen

[detch01]

Originally posted by GScholz
To make myself clearer: As speed increase the induced drag does not go down. The parasitic drag goes up.

(Note: At very high AoA aproaching the stall limit the induced drag increases due to the deterioration of laminar airflow over the wing, and you must remember that the fuselage changes AoA too, so you get an increase in both form drag and interference drag as well.)

Edit: Oh and the drag created by the wingtip vortex' also increase at high angles of attack.

Sorry GScholz, wrong on several points. Induced drag is caused by angle of attack, as is the creation of lift. As the Cl goes up, so does the angle of attack and the resulting induced drag. Induced drag varies directly with angle of attack. In level flight, as speed increases, the AoA decreases, therefore induced drag decreases. Wingtip vortices are caused by the same forces that cause induced drag and actually are the largest component of induced drag in the equation. Induced drag does vary with the inverse of variation in speed.
  It's easy to see the relationship between AoA and airspeed: take any airplane in Aces High (the FM is very good) and fly it at 150mph in level flight and note where the horizon is in relation to some easily referenced fixed point in the cockpit. The increase your airspeed to 300mph in level flight and check that same fixed reference point and see where the horizon is in relation to it. You'll see a difference: at higher speeds the horizon is higher relative to that fixed point, which means the nose of the airplane is lower. This isn't exactly AoA but it's a very good reference for beginning to understand how AoA works.  

  You are correct on parasitic drag. Parasitic drag increases with the square of the increase in speed - double your speed, quadruple your parasitic drag and also increases with the AoA of the fuselage. BTW interference drag is a component of parasitic drag.

Re: "Note: At very high AoA..."  At very high AoA the total drag increases beyond the capacity of the wing to lift along with the weight of the airplane. This total drag is mostly made up of induced drag, but form drag is a component of it. Once total drag + weight is more than the wings can lift the airplane starts to drop vertically, which rapidly increases AoA (and induced drag) and causes airflow to seperate on the top surface of the wing. This is a wing is in a stalled condition - i.e producing next to no lift.

Earlier in this thread someone (can't remember who) said something confused about Cl, AoA, airspeed and the generation of lift. Here's a great reference for understanding lift generation, lift coefficients and angles of attacks: how it flies

Cheers,

[Crumpp]

Untrue, the high altituide Spitfires had higher aspect ratio than the Fw 190A. And no one else is calling the Fw 190A as high aspect ratio plane.

Yeah they were great.  That's why they made so many.

http://www.btinternet.com/~lee_mail/spitfire2.html

The Cl can be determined easily from the flight data. The Clo must be determined in wind tunnel or simulation. Crumpp is plain childish here.

Really, Gripen?

Well running your numbers for the FW-190 at 300Km through the downwash formula matches the computer similation almost exactly.


Cl (your calculation run through downwash effect) = .1296
Cl (as computed by the computer simulation) = .1295

This is for NACA 23009 at 0 degrees and 300km.

"The data obtained by wind-tunnel testing of NACA families of airfoil sections is two-dimensional data. This means that since the airfoil was suspended in the wind tunnel from wall to wall, it essentially had no wingtips and simulated a section of a wing of infinite span. The data obtained is associated with just the airfoil and has no association with the span of the wing. "

The aspect ratio is the square of the span s divided by the wing area A.
Show me were the span is factored in anywhere else except AR.
Area is not the same as span.

Again I think your full of crap.  I am waiting on the answer from the engineers who run the site.

Crumpp

[Angus]

From Crumpp:
" It's a fact though that Merlin Powered Spits could not zoom with a 190 and have any hope of catching it from a co-energy state."

True, for almost all variants, I'd however not make a bet on a 190A vs a Mk VIII or a IF w. 25 boost. Truly the 190 will presumably outzoom them, but after zoom comes climb you see, and at some altitudes the difference can be up to 1500 feet a minute in the Spits favour.

And some couple of words on A of A.
Detch01 basically has it perfect.
Lower wingloading (as well as the shape) basically gives you a lower A of A at low speeds, hence less drag at low speeds, hence better acceleration at lower speed bands. Explains the Spitties as well as Zekes perormance in a stallfight.

[Crumpp]

True, for almost all variants, I'd however not make a bet on a 190A vs a Mk VIII or a IF w. 25 boost. Truly the 190 will presumably outzoom them, but after zoom comes climb you see, and at some altitudes the difference can be up to 1500 feet a minute in the Spits favour.

No doubt in a sustained climb that 190A will lose.  Good example is Robert Johnson's mock dogfight with a Spitfire in his P47C.

If he zoomed, he left the spit behind.  If he held the climb after he slowed down the spit caught up with him and quickly left him behind.  I think he described it as "Shot by him".  He had to enter a shallow dive, gain speed, and then zoom overhead.  While the spit was struggling to follow him in the dive/zoom, he reversed and came down in a classic hammerhead on top of him.

Read the P47 vs FW-190 tactical trials.  For Dive accelleration and zoom the FW-190 was better than the P47D4.  It took 7000 feet in a 65 degree dive for the much heavier P47 to catch the 190 due to it's accelleration.  Up to about 300 mph the 190 was a dragster.  After that it was unremarkable.

That pretty much follows the classic Spitfire Mk IX 66 (+25) vs FW-190A8 fight.  

Wasn't the Mk VIII a Griffen powered model? Have to check it out but If I remember the specifics on this one right, I think your right.
Crumpp

[MiloMorai]

The Spit VII and VIII were Merlin powered.

The Griffon powered the XII, XIV, XVIII, XIX, 21, 22, 24.


Can anyone see that Fw data sheet I posted. If yes please post again so crumpp can see it.