Somethings not right in Mudsville part two

[F4UDOA]

Did some offline testing on straight ahead stall speeds. 100%fuel ammo sealevel no Flaps

FW190A-5 1G stall=100mphTAS sealevel

F4U-1D 1G stall=100mphTAS sea level

Using those stall numbers calculate the max CL

Cl = Lift * 391 / (V^2 * Area)

FW190A5 weight 8690Lbs wingarea 197sq ft
max Cl=1.72

F4U-1D weight 12000lbs wing area 314sqft
Max Cl=1.49 <==matches NACA documentation for Max Cl no Flaps.

Isn't 1.72 high for a WW2 fighter or anyplane for that matter without flaps?
If the stall speed is corrected to 110mph then the Max Cl drops to 1.42 which corresponds to the Max Cl data I have.

Also based on that correct the 3G stalls speeds to be
F4U-1D=173MPH
FW190A5=190MPH

Does this sound right?? Can anyone confirm my testing?

Thanx F4UDOA

   

[popeye]

This is a bit off topic, but why are these tests done with 100% fuel?  Is it assumed that all testing was (is) done with 100% fuel?

Just wondering.....

popeye

[wells]

I think you could be right.  110 mph sounds more reasonable.  Airfoil data shows the following

NACA 23015 - 1.64 @ 17 deg (root)
NACA 23009 - 1.16 @ 12 deg (tip)

Average is somewhere around 1.4

Compare the a8 to the a5 and see what you get?

[F4UDOA]

Yes, all test were done 100%fuel no flaps at sea level in TAS(true air speed).

I guess I'am looking for somone to perform the same offline test to confirm or give me some data to contradict my calcs.

Thanx
F4UDOA

[F4UDOA]

YES!!

WOOHOO, I'm right!!

Anyway thanks for checking Wells. Have you done any testing offline to verify 1G and 3G stalls?

Thanks again
F4UDOA

Wells, I have some more questions for you on accelleration. Will email you offline.

[wells]

I got 104 mph for the 190a5
109 mph for P-51 and P-38
107 mph for P-47

Those were in level flight with just enough power to maintain altitude (about 30")

Power off stall for a P-51 at 10000 lbs is 106 mph by the manual, so it could be tad high in the sim.  The P-47 is 115 mph 'clean'  so it could be a bit low.

[F4UDOA]

Wells,

Used your numbers to calculate accelleration between Fw190A-5 and F4U-1D. They are a virtual dead heat. FYI if you are just joining this conversation these numbers are real world physics model, not AH based.

(thrust-total drag)/mass=acceleration in m/s/s


FW-190A-5 weight =8535lbs(3875KG)
49 meters per second=110Mph and also is TAS 1g stall for 190A-5
49(110mph) accelleration =2.78Meters per Sec.
60(134mph) acclleration = 2.81MPS
80(179MPH) accelleration =2.30MPS
100(234MPH) accelleration=1.66MPS
120(268MPH) accelleration=1.02MPS
140(313MPH) accelleration=.38MPS


F4U-1D weight =12,000Lbs(5455Kg)
45Meters per sec is the TAS 1G stall for the -1D
45(100mph) accelleration =2.78meters per sec
60(134MPH) accelleration =2.80MPS
80(178MPH) accelleration=2.30MPS
100(234MPH) accelleration=1.71MPS
120(268MPH) accelleration=1.14MPS
140(313MPH) accelleration=.58MPS

The point here being that the accelleration between the F4U-1D and Fw190A-5 should be identical up until high speed were the F4U should gain by a slight margin. This corresponds exactly to the 1944 test results.

Wells, Pyro, Hitech,

If I am wrong please let me know. I have been pointing in this direction since well before the release of the A5. This just makes it stand out a little more. The thrust and drag numbers came from Wells(thanks again Wells). If your data is different than mine let me know. Also Wells your sustained turn for the F4U is 180MPH. In the Game it is somewhere aroung 130MPH. I think the accelleration would change that as well.

Thanx
F4UDOA

[funked]

How did you calculate total drag and thrust?

[F4UDOA]

Funked,

I was hoping you would reply. I didn't.
Wells did. I asked him about climb so he did two charts showing thrust, induced drag, Zero lift Drag and Total drag at various speeds. I took the calc for accelleration and their it is. I would post Wells graphs on my web page but they are his and I don't want to take credit. If he doesn't want to post them and doesn't mind I'll put them up.
I can email them to you in the mean time.
Are you surprised? It matches the flight test data right on.

Later F4UDOA

[Toad]

Thanks to all for this interesting thread.

IMHO, this is the way the "discussions" about the game should go. So far, what I'm seeing is an attempt to identify a perceived problem and provide some hard numbers supporting a position.

I'm NOT saying any of the stuff is right. I'm just saying I REALLY prefer to see things done in this manner. No acrimony, no finger pointing...just research, testing, calculating and team work to see "what's up".

This kind of discussion HAS to be more helpful to HTC than the unsubstantiated "did not..did so" approaches most threads end up using.

Thanks to all again.

[funked]

Looks good to me DOA - exactly what I would expect.  The -1D and A-5 have about the same power/weight ratio, and the -1D is a hair faster in top speed, so I would expect a close race until the very end where the -1D pulls away.

[F4UDOA]

Thanks Toad,

Trying to keep focused on issues and not the personalities.

Funked,

Wells did allot of work on those charts. Just doing the accelleration made my eyes bleed. Guess that's why I am not an engineer.
Do you think this corresponds to the game accurately. I think the accelleration may be the piece of the F4U puzzle that cures the sluggish characteristics of the -1D FM including sustained turning abilty.

Thanx
F4UDOA

[This message has been edited by F4UDOA (edited 06-27-2000).]

[wells]

DOA,

The sustained turn speeds in AH seem really low to me.  I'm sure they would be a tad lower than the charts with the drag being slightly higher at the higher angles of attack, but to go from 180 to 130 mph implies nearly double the overall drag.  Perhaps the thrust values are lower in the sim as well, I don't know.

[F4UDOA]

Wells,

So what do I do now that I think I found a flaw in the FM? I guess I'll try doing the
P-51D numbers too. Or I'll just wait for the FM fairy to come along and fix everything?

Have you done any offline testing to show the accelleration of the F4U and Fw190A5. I know Funked has, I have to find it. But I know it is not close to the calculated results. My test are done by counting so I need more accurate data. Am I out of line thinking that this is a problem that should be fixed?

Later
F4UDOA

[wells]

I think you'll find it very difficult to prove as a flaw.  You'll have to find some hard evidence to disprove the manual and AHT figures for climb rate.  What I've done offline can be found here..

Aces High Climb Tests