Spit 5

[bozon]

The FW-190 had less DRAG.

Maybe some experts about aero-engineering could chime in on this, but what I know is that drag (viscos / parasitic - not induced drag) is a tricky business. with increase of the speed certain parts of the plane change from laminar to turbulant flow and change the drag behaviour. Also, the radiator is a big mystery. Engineers built a beautiful smooth airframe with minimal drag and then had to stick this thing in the airstream... ALOT of high speed drag can be reduced by a good design of the radiator (or radial's intake and tubing).

This makes the drag (NOT the induced drag) a very difficult problem.
Compressible, viscos, non-adiabatic, driven air flow on an irregular shape... I want to see this solved analyticaly...

bottom line - better zoom doesn't mean less drag overall. It could mean less drag at high speeds and/OR better mass/drag ratio.
take for example the P47 - it's twice as heavy as the spit V but not twice as draggie.

Bozon

[Nashwan]

The FW-190 had less DRAG.

I'd say the drag on the 190 and Spit IX is pretty similar.

With 1580 hp at sea level, the Spit IX did 335 mph.

With 1710 hp at sea level (1.42 ata), the Fw 190 A8 did 337 mph, according to the chart you linked to earlier. I've seen other docs that put the 190 as up to 350 at sea level on 1.42 ata.

Overall, those figures are pretty similar, and don't indicate much of a drag advantage for either aircraft.

The 190, being heavier, would have had a drag to weight ratio advantage.

[MiloMorai]

Originally posted by Crumpp
It is a standard FW-190A8, Milo.  It just is outfitted with the 115 liter internal tank kits and GM-1.  GM-1 uses LNOX.  
Clamshell doors are standard.

Only one of the graphs says GM1 fitted with no 115l tank. Very few, if any, A-8s had GM1 installed. GM1 was a high altitude booster.

"GM-1 uses LNOX." No kidding. Another word is laughing gas.

The ETC 501 was standard fit on the A-8.  This meant the removal of the wheel doors.

It's in the Pilots Manual and I sent Pyro a copy along with several other things from the Flugzeug-Handbook.[/b]

How many times do you have to say this?  

It is clearly labeled in the top right hand corner of tests.
 [/B]

Bloody metric.  That should be 63lb heavier than what your 'bible', the pilot handbook claims.


To suppliment your 'bibles' you should buy, Focke-Wulf FW 190a: An Illustrated History of the Luftwaffes Legendary Fighter Aircraft, ISBN: 076431940X.

[GScholz]

Originally posted by gripen
Partially right but because needed Cl for constant lift drops when the speed is increased, the Cdi drops too:

As an example the Spitfire (3400kg) flying level 200km/h and 400km/h near sea level:

200km/h Cl=0,782 => Cdi=0,0366
400km/h Cl=0,196 => Cdi=0,00229

In other words, when the speed douples the Cdi drops to one sixteenth.

If we look formula for the Cdi, this is pretty easy to understand:

Cdi = (Cl^2) / (pi * AR * e)

Value of the Cl is squared.

gripen

Now you've done it! You've confused me!

Your formula is not correct though.

The correct formula is: CDi = CL^2 / pi*AR

The "e" in your formula is the Oswald's efficiency factor, which is a constant. pi and AR are also constants (for a given aircraft with fixed wing geometry).

The total drag formulae use the "e", not the lift dependent drag formulae.

CD = CDmin + (CL^2 / pi*AR*e)

In this formulae the constants (for a given airplane) are CDmin, pi, AR and e.

Speed is not a factor in any of these formulae.

CL = CIa*(AR/(AR+2))*a

Where "a" is AoA, AR is wing aspect ratio, CL is the 3D wing lift coefficient, and the CIa is the 2D wing coefficient slope.


So you see that CL increases with AoA at a constant airspeed, this is obvious. However to stay in level flight you need to decrease speed as you increase AoA. So as you increase AoA both lift and induced drag increases, however because you reduce speed to stay in level flight both lift and induced drag remains fairly constant.

[Crumpp]

"GM-1 uses LNOX." No kidding.  Another word is laughing gas.

Point is Milo it is in Liquid form not a compressed gas.  It's heavy.

The ETC 501 was standard fit on the A-8. This meant the removal of the wheel doors.

The ETC 501 rack was delivered with FW-190 as standard equipment as were the clamshell doors.   Only one jagd-einsatz includes it to mount the 300 liter drop tank.  It could be mounted and dismounted in just a few minutes mission dependant.  Just like many allied aircraft could mount and dismount stores.

Crumpp

[GScholz]

Liquid gas is compressed gas. If released it to the air at normal pressure the liquid gas will revert to gaseous form. Just like in a butane gas lighter.

[Crumpp]

Yes Gscholz you are correct.  By the time it is fed into the engine it is back in gasous form.  

However it is loaded into the Aircraft as a liquid and stored in the tank as a liquid.  The Luftwaffe did the same thing with Oxygen.  One reason their O2 systems were the best in the world for the time period.

It allowed them to carry more gas in a smaller container but was much more vunerable to attack.

The Allies used compressed gas in a high pressure cylinder.

Got some great pics of the "black men" refilling LNOX and LOX in Me-109's.  Extremely dangerous time for them.

Crumpp

[GScholz]

Or extremely funny time for them.

[Crumpp]

Got that book Milo sitting on my shelf.


Crumpp

[gripen]

Originally posted by GScholz
Now you've done it! You've confused me!

Your formula is not correct though.

The correct formula is: CDi = CL^2 / pi*AR

The "e" in your formula is the Oswald's efficiency factor, which is a constant. pi and AR are also constants (for a given aircraft with fixed wing geometry).

Well, the formula is correct see here.

Your version of the formula is true only for the planes with ideal elliptic shape of the wing.

Originally posted by GScholz
Speed is not a factor in any of these formulae.

The speed is factor for the lift coefficient which must be solved first for wanted speeds:

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

Where:

Cl=lift coefficient
L=lift
r=density
V=speed
A=wing area

So in the case of my example we solve Cl values first with above formula for 200km/h and 400km/h, after that Cdi values can be easily solved.

BTW all this is told several times above.

gripen

[GScholz]

Don't you see by those formulas that both the lift and drag quadruples with the doubling of speed? I.e. if you double the speed you quadruple the lift the wing generates, and quadruples the induced drag. To keep in level flight you would have to lower the AoA to lower the lift ... thereby equally lowering the drag.

I hate this ... HATE THIS!  Gripen, promise me we will never do this again, NEVER!

[gripen]

Originally posted by GScholz
Don't you see by those formulas that both the lift and drag quadruples with the doubling of speed?

Yes, at given AoA. But the calculation I use does not use  AoA at all. We just calculate what Cl is needed for level flight at wanted speeds with known parameters (density, weight, speed and wing area). This calculation is very accurate if we have the right value for the efficiency factor and in the case of the Spitfire it's probably close to 0,9  due to  elliptic wing.

gripen

[Crumpp]

This calculation is very accurate if we have the right value for the efficiency factor and in the case of the Spitfire it's probably close to 0,9 due to elliptic wing.

No it is not.  NASA says without experimentation in a windtunnel it's just number that is meaningless.  Your attempting to find the prediction without anything real data to back it up.

The real data is out there probably on the Spitfire and maybe on the FW-190A.  One thing is for sure, you smokin that Texas Instrument's finest is only going to make YOU feel smart.  

It's the same thing as If I just though up some numbers and said "well my caluclations are this BLAH, BLAH, BLAH.  I started working the formulas myself and checking them against Foilsim.  Yes I have had Calculus I and II.  These Formulas though are basic Algebra and nothing more. Then I read Foilsims fine print.  Without a windtunnel to verify your figures they are meaningless.  So what is the point?

I've told you that like 4 times already Gripen.  Read what NASA says right under the cool little diagram explaining the formula.
You keep focusing on the mathmatical part that determines a "prediction".  The word "prediction" in English means "GUESS".

Here is a way to determine a value for the lift coefficient. In a controlled environment (wind tunnel) we can set the velocity, density, and area and measure the lift produced. Through division, we arrive at a value for the lift coefficient. We can then predict the lift that will be produced under a different set of velocity, density (altitude), and area conditions using the lift equation.

The lift coefficient contains the complex dependencies of object shape on lift. For three dimensional wings, the downwash generated near the wing tips reduces the overall lift coefficient of the wing. The lift coefficient also contains the effects of air viscosity and compressibility. To correctly use the lift coefficient, we must be sure that the viscosity and compressibility effects are the same between our measured case and the predicted case. Otherwise, the prediction will be inaccurate.

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

Crumpp

[Crumpp]

http://www.anycities.com/user/j22/j22/aero.htm

This is one source for the Drag information.  The charts are down at the bottom of the page.


This is who calculated those figures posted on that website:

http://www.anycities.com/user/j22/j22/lednicer.htm


Crumpp

[gripen]

Well, Crumpp still can't understand that the value of the Cl needed for flight is very easy to calculate for known plane and conditions. No wonder he sounds so angry...

gripen