how did the f4u have such a low CD,0

[F4UDOA]

Bolillo_loco,

I think you are refering to the chart in the back of "America's hundred thousand". That would explain what you mean by last place.

FYI, that chart was done by the authors calculation not by flight test results. The error in the chart is that many of the Max Cl's given are with flaps even though the chart says without. The F4U is without. You can check the Cl max of the F4U with flaps on page 534 of "AHT" where it describes the spoiler strip and the change in max CL or lift coefficient.

Also check this NACA doc that list the max Cl of the F6F, F4U, P-51, P-40 and P47.

 http://naca.larc.nasa.gov/reports/1945/naca-report-829/

look at page 20 that shows the max cl no flaps of the F4U being 1.48 and page 21 where you can see the P-51 is about the same with no flaps. Almost all WW2 fighters had a max no flap cl of about 1.50. If you use 1.88 in the chart in AHT for the F4U it then falls between the F6F and P-51 in turn performance which is where it should be.

This is not a flame attempt on my part. I had the same questions until I learned from Wells and others about some basic Aerodynamic theory.

If you know the level stall speed of an A/C you can determine the Max Cl very quickly.

Cl = Lift  * 391 / (V^2 * WingArea)
   = 12000 * 391 / (100^2 * 314)
   = 1.49

The 12,000 is the gross weight of the F4U.
391 is to correct for air density at sea level I believe. And the 100 is the stall speed in MPH at that weight.

Hope this helps.

[Citabria]

hmm

this new exciting plane (insert favorite uber ride) will:
1. out turn everything
2. outclimb everything
3. outdive everything
4. outrun everything
5. outgun everything


this new exciting plane will give me personal satisfaction because:

1. I have no desire for fair play
2. I am not looking for a challenge
3. I want easy kills and lots of them
4. I want the airplane to overcome deficiencies in my flying ability.

when I have an epihpany about online a2a games I will realize:
1. playing a game that isnt challenging gets boring quickly


 

[niklas]

i look at page 20 of this report and see 2 charts, one (fig. 15) for airplane 5 which is NOT the F4U, and one for the F4U- chart 14.

And maybe you need better glasses f4odoa but chart 14 says max lift coefficient for F4U in service condition ONLY ~1.18. Do you finally accept this??? Even WORSE than a laminar wing of a P51 with 1.3 (a naca flight test confirms this clmax value of the p51 btw in a 180° turn test). And without spoiler


And concerning your other numbers: Stall speed numbers are useless without knowing when the test was done- at the beginning of a flight i.e, or at the end with almost empty fuel tanks.
Clmax values also depend on Reynolds number.
I can show you naca documents with Clmax numbers up to 3.0 flaps down power on (Hurricane when i remember myself correctly)

[F4UDOA]

Niklas,

Accept what? That you have an agenda?

That 1.2 figure is with the propeller removed. With the prop wash over the wing it is 1.48 as all the A/C stall speed are measured . The stall speeds quoted are from the pilots manuals of these A/C. And you know how to calculate max Cl.

Look at page 15 and 16 for the big print.
Propeller operating max Cl reduced from 2.33 to 1.88 with 50degrees flap.

From the F4U pilots manual.

Weight 11,300lbs clean no flaps stall 84 Knots or 96.66MPH. Stall speed with flaps 66knots or 75.95mph.

If you don't like my numbers do the math yourself.

[juzz]

F4U-4 would not be the fastest a/c up to 25k. Tempest V, Fw 190D-9, and probably La-7 would be quicker at low-medium altitudes.

[F4UDOA]

Juzz,

You may be right on any of those birds. I was just comparing it to the one's already in AH.

Although I am certainly not aware of any off those birds being any faster than 380MPH at sea level and just under 440MPH at 20K. If you have speed and climb charts for the LA-7 or Tempest V I would luv to see them.

Cit,

Relax man. Nobody is introducing any uber planes. The F4U-4 is a possible perk plane. This conversation has nothing to do with Aces High FM's. This is about real flight characteristics. Pyro may  never put this bird or the P-47M/N in the game. Regardless of this they are still some of the finest of WW2.

Remember Pyro may or may not model any of these birds but if he does he has access to the same data that we do. And if he is incorrect he has corrected mistakes in the past. Nobody on these boards tells HTC what to design.

[juzz]

Uhhh, since when does a real WW2 combat F4U-4 do 380mph at sea level? Only if you remove all the pylons and use high octane fuel...

Tempest V does 392mph at sea level.
La-7 if it was put in AH, would be around 380mph I guess.

[Torgo]

But what happens when we have "perk" planes that were in combat longer in WWII and in larger numbers than the F4U-1C?

This  is true of a variety of suggested perk planes....the Tempest, the Spit XIV, the F4U-4...

[niklas]

who is interested in a flight condition with flaps down??

In the whole report, there is only one example with flaps down and power on, and this is for the F4U. Where do you want to know from that 1.88 is good?? Itīs pretty bad for a flaps full down power on condition imo.

How do you want to know whatīs the effect of propwash without flaps?? Flaps allow maybe a much higher increase in Cl with power on.

I just compare 2 EQUAL conditions: power off, no propeller.
Clmax F4U 1.18
Clmax P51 1.28

There is only ONE test for flaps up and power on in the whole report.
page 17 shows only a slight increase in Cl for another aircraft with flaps up and power on btw. In the 180° turn test the XP51 reached with cruising power a Clmax of 1.25-1.30. Again only a slight increase in Clmax compared to the 829 number without propeller

and what do you think f4udoa, does this spoiler also reduce Clmax in a flight condition with flaps up?

niklas

[This message has been edited by niklas (edited 12-13-2000).]

[This message has been edited by niklas (edited 12-13-2000).]

[F4UDOA]

Niklas,

1. That is no prop condition. What does the chart show with the prop? 1.48
What does it show with 50degrees of flap? 1.88

I am calculating from stall speed and getting the same answers. What does it matter what the max cl is without a prop?

Yes the spoiler reduces cl max with or without flaps.

How many times do you think the aircraft was flight tested without a prop? The spoiler was meant to effect the flying characteristics on or near stall with or without flaps.


2. The only reason I am answering this question is for Bolillo_loco who read a chart in America's hundred Thousand that list most A/C Max Cl with flap and some without. I was trying to explain that most WW2 A/C have a Max Cl of Approx. 1.5(with propeller). The chart he is reading shows the P-51 with a Max Cl of 1.89. I am trying to tell him that 1.89 is to high for a wing with no flaps. Maybe you would like to explain it to him since you don't like my explanation.

Here is a list of the max Cl's in the chart.

1. FM-2=  2.38
2. P-63A= 2.38
3. P-61=  2.54
4. F6F-5= 2.27
5. P-51D= 1.89
6. P-38L= 2.17
7. P-47D= 1.93
8. F4U-1D=1.48

So are these numbers right? Flaps, no flaps?
Are they to high?

[F4UDOA]

Juzz,

My F4U-4 speed chart comes from "America's Hundred Thousand" and is not from the PDF file that you have. In fact the power curve from my chart looks nothing like the one in the PDF. The chart I am using shows the initial climb at 3850Fpm and max sea level speed being 380MPH. Also the critical alt is much higher than the PDF doc. It reaches 446MPH at 26,000FT. The PDF shows max critical alt being 20K which doesn't sound right anyway.

F4UDOA

[niklas]

F4udoa, i canīt find in the 829 no number with 1.48. Even on page 20 thereīs only a 1.38 number, but this is for aircraft 5 (F6F)

Where do you see in the 829 report the number 1.48 ????????

[Zigrat]

all those figured are flapped, cept for the hog

[F4UDOA]

Thanks Zig,

That's all I wanted to explain to bolillo_loco but I got sidetracked.

Niklas,

What's your point?

[wells]

DOA,

The lower critical height in the PDF is further indication that higher manifold pressures were used in that test.  The higher the manifold pressure, the lower the critical height.