190 vs SpitIX

[Vermillion]

Better yet, get him hooked up to this BBS and ask him to drop in and say hi  

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Vermillion
**MOL**, Men of Leisure
"Real Men fly Radials, Nancy Boys fly Spitfires"

[F4UDOA]

Actually gents my plan is to scan everything he has. And he is so nice he may let me do it. I'm trying not to be a pest but I have emailed him several times and I plan to visit him again shortly. He has volume after volume of original flight data that no Museum will ever have. It is breath taking. 40 years of research.

And yes Vermillion I did just that. I gave him the URL to the message board. I even Emailed him a copy of a P-38L flight model thread that was interesting about rate and radius calculations. I think we should get him to the next AH convention what do you think. He can tell you the story about how when he was 17yrs old in 1943 and he and his friend went to enlist in the Army Air Corps. But his mother wouldn't let him go because he was to young. A year later his friend was sending him pictures of himself flying P51's over Europe. If that were me I would wake up at night screaming for the rest of my life.
Anyway he did serve in the Navy in the South Pacific but not as an aviator. Oh well, next war right.

See Ya's
F4UDOA

[wells]

F4UDOA,

That's cool that you know Dean!  

I suspect he used the information in the flight manual to come up with that 173 mph figure and 1.48 max Cl.  Also, check out page 15 of that report on the F4u, that 2.3 lift coefficient comes with full flaps.  Check out every other plane in that test.  Lift coefficients don't exceed 2.0 unless flaps are used and rarely exceed 1.4 without flaps.

[F4UDOA]

Wells,

He is a great guy too.

Anyway I think I got you on the lift coefficient. I think it is without flaps as a matter of fact. Just check AHT for lift coeffients of all A/C tested at 3g's. Most are at or near 2.0. Especially carrier A/C.

FM-2=2.38
P-63=2.38
P-61=2.54
F6F-5=2.27
P-51D=1.89
P-38L=2.17
P-47D=1.93
F4U-1D=1.88 reduced from 2.30

Which would make sense considering the Hellcat has approximatley the same size wing.
In fact it has the second largest wing of any single engine fighter.

Were on page 15 does it say that flaps are down?

See Ya
F4UDOA

[wells]

There's a symbol at the bottom for flap deflection, says = 50 degrees.

Then, check out page 20, max lift coefficient is about 1.4 with flaps up (=0 degrees).  
Part of the problem here could be propwash.  I don't think there's a difference between power on and power off stalls in AH, which would make a big difference in a tight turn.  A 5-10 mph reduction in 1G stall speed would account for 10-20 mph in a 3G turn.  This may be also what allows a Spit XIV to turn with a Spit IX, while being heavier.

[Hooligan]

Funked:

Thanks for posting the information!

F4UDOA:

Thanks for obtaining and distributing it!

I'd really like to see the flight tests between the P-51/F4U and the FW-190 comparisons vs. Allied fighters.  Could you please send them to me.  I have some WEB space and I will post the information there.

thanks,

Hooligan



[This message has been edited by Hooligan (edited 05-12-2000).]

[Vermillion]

F4UDOA, you should get Ronni to consider asking him to be guest speaker at the Con this fall in Texas.

I couldn't think of anyone better  

Oh, and ask him about the fabled 427mph Ki-84 tests in 1946 at Wright Field and Middletown Air Depot in PA. Maybe he knows something about them. My quest continues!

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Vermillion
**MOL**, Men of Leisure
"Real Men fly Radials, Nancy Boys fly Spitfires"

[funked]

I hope they get Mouse Shaw too.  

[F4UDOA]

I know this thread is getting kind of long so I may start a new one under Aircraft and Vehicles. Anyway I just finished scanning the report of the P-51B vs the F4U-1(modified) and F4U-1A(service condition).

Wells,

If you look at the top of the page on the AHT table that list lift coefficients under a 3g' stall it say's "no flaps". Also the 50% indication you saw is really 50 degrees represented as a tangent I believe. Look at the top of the page and it reviews the equation. It is for propeller efficiencey and thrust. Again 2.30 and 1.88 would put it right in mid range with the other A/C with no flaps used.

By the way, what equation are you using to calculate stall speeds at different G force?

F4UDOA  

[wells]

Stall speed varies with the square root of the G factor.  If you know the 3G stall speed, you can get the 1G stall by dividing the corresponding speed by 1.732.  I still disagree with the flaps.  df looks alot like flap deflection to me.  Tc is thrust coefficient, I see that...

I've done alot of airfoil analysis and I haven't found one yet that exceeds a Clmax of  1.7 without flaps, but as I mentioned before, the added airflow from propwash makes for a higher effective airspeed than what is indicated, so the lift force is also higher.  If you use indicated airspeed in the lift equation, you will get a higher lift coefficient than if you were to use a 'corrected' airspeed to account for the propwash velocity.  Given that pilots only have indicated speed to go by, this, I believe accounts for the rather high lift coefficients listed in AHT, which were seemingly calculated from the 1944 fighter conference results in a turn at full power.

For example,

An F6f stalls at 79 knots (power off) and 72 knots (power on).  Why is this?  Is the lift coefficient greater?  no...the wing will stall at the same lift coefficient, just that there is more airflow over the inner portion of the wing than there is outboard, where the pitot tube is.  But if you plug 72 knts into the lift equation, you will get a higher lift coefficient.  Does that make any sense?

So much for the Spit vs 190 thread....heheh

[F4UDOA]

Wells,

In some strange way I think we are actually agreeing. I can see that the lift-coefficient goes up with a prop spinning in front of the wing. But that doesn't change the fact the the coefficient has been incresed. All fighters listed in AHT are without flaps at a 3g turn. Of course they would only ever need to make a 3g turn with a propeller. A Hellcat is a great example. The lift coefficient is roughly proportional to the wing dimensions. Very close to the F4U. By comparision the 3g stall speed I have listed is 121knts and the power on stall is 69knts. Using your figure of 1.732 it works perfectly giving me a 1g stall of 69.86. Remember this was an actual flight test averaging results from approx. 30 pilots in 1944. Pretty amazing accuracy I think. Then take the F4U-1D test resultsof a power on 1g stall of 76Knts and a 3G stall of 150knts. According to those numbers 3g stall should be at 131.63knts. So my the 150Knts figure is actually conservative. In AH however the number is closer to 200knts IAS giving it a 1g stall of 115knts. The Navy would have let C-47's take off from it's decks before an A/C with such a high speed stall. Remember the F4U had a take of run of 700Ft. 300ft shorter than a P51, P-38. This is before catapults and JATO you know. How else would one ever make it off the deck with such a high stall?

By the way were does the number 1.732 come from? I ask a lot of questions. Hehe.

F4UDOA

[wells]

1 knot = 1.15 mph

The AHT figure of 172.5 mph = 150 knts.  Perhaps that is where the confusion lies?

1.732 is the square root of 3 (the G-factor).

The Carrier planes had 30 knts of wind (ship velocity) + the actual wind velocity as a head start!


[This message has been edited by wells (edited 05-13-2000).]