P-39 and P-63 Data

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GregP

GregP

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Jul 28, 2003
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There is an article out on the net called "Aerodynamics of the Bell P-39 Airacobra and P-63 Kingcobra by David A. Lednicer" that has some data on the P-39 and P-63. In this article, he details how the prototype was modified with all the NACA-recommended changes and, after being so updated ands streamlined, managed to achieve the 391 mph mark we all know and love to hate.

The link is at: https://www.researchgate.net/public...of_the_Bell_P-39_Airacobra_and_P-63_Kingcobra

Not trying to say anything except it is the first time I have seen in print how the 391 mph that was stated in the books of the time was achieved using the engine they used.

Not trying to feed the troll or start anything. Just trying to pass along an article you might be interested in should you happen to be a P-39 fan ... not that there ARE any.

I am not responsible for numerous following posts about how we needed more P-39s and do not espouse such shenanigans. If nominated, I will not run and, if elected, I will not serve.

I'd say "Cheers," but maybe "watch out" is more appropriate.

Sic. Transit. Gloriosky.
 
GregP said:
In this article, he details how the prototype was modified with all the NACA-recommended changes and, after being so updated ands streamlined, managed to achieve the 391 mph mark we all know and love to hate.
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Thanks for the link, Greg.
From reading the article, at pg. 4, it was the AH 571 aircraft that did 391 mph at 14400 ft, not the prototype outfitted with turbocharger. The AH 571 using far more nip and tuck than it will bethe case with a series-produced machine.
 
Yes, and it's the first time I ever read how that speed was supposedly accomplished. I have a 1946 (James Fahey) book that lists 391 mph, but no explanation until I saw that. Funny, I was always interested but never came across it until today. Doesn't mean it is right, but does give some explanation for the change in speed. I'd bet there are some calculations around, somewhere ... maybe they'll turn up.

Cheers Tomo.
 
It's amazing how Larry Bell, in order to save his company, basically cheated with the silent acquiescence of the various authorities. Bell, like Curtis, managed to come up with airplanes that the US didn't want but was ready to pay for.
 
Big Jake said:
It's amazing how Larry Bell, in order to save his company, basically cheated with the silent acquiescence of the various authorities. Bell, like Curtis, managed to come up with airplanes that the US didn't want but was ready to pay for.
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There was nothing wrong with Curtiss airplanes (P-36, P-40, C-46). They were well-designed under the specs given pre-war and were robust. The problem with Curtiss was getting them to start a clean-sheet aircraft designed to new specs after Pearl Harbor. They were a quality company that suffered from very poor management decisions. Curtiss-Wright is still in business, but not in the aircraft business. C-46s are still flying today commercially as freighters.

Bell was trying anything to stay in business and had enough money into the P-39 that he could never bring himself to write off the P-39 and go another direction. He genuinely thought his airplanes were good ones, and the P-63 WAS a good one that never got accepted by the USAAF. Bell is still in aviation, but not in fixed-wing aircraft. Their helicopters are some of the best made anywhere. But, they really didn't help the war effort much, except for the Soviet Union. I'd bet they would argue that the P-39 was a good aircraft, considering their war record with it. We just never did fight a low-altitude, short-range, ground support war like the Soviets did, using the P-39.
 
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Reluctant Poster said:
The C-46 did have some detail design issues such as fuel leaks
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They did - as did the B-24.

Over 3000 were built, the design was generally successful although they did have issues, I think the government still got their money's worth with those purchased unlike all those other designs that went nowhere
 
Personal opinion is it was the mediocre performance of the production aircraft that ended Curtiss.
People don't expect every prototype to a winner, although the list of Curtiss failures was pretty impressive in it's own way.
A winner every once in a while can gloss over some failed prototypes.
Unfortunately For Curtiss the SB2C and the Seamew were not winners, they were not even 2nd place, they were well back in the pack at best.
The Navy got rid of the SB2C in 1947 and the reserve got rid of them in 1950.

The Curtiss Seahawk came way too late (June 1945 combat debut) and was too small a production run to change very many minds.

The Curtiss products were arriving late. Were trouble prone when they did show up and often didn't perform quite as promised even after modification/s.

How much longer do you keep giving them money?

On the C-46 the fix wasn't that hard. Whose fault it was?
Installing vents in the wing root area usually cleared out the fumes and/or leaked fuel and I believe most or all the surplused aircraft in commercial service had the modification/s done?
I don't know if Curtiss didn't want to pay or the government didn't want to pay or somebody didn't want to delay deliveries or????????
 
Shortround6 said:
Personal opinion is it was the mediocre performance of the production aircraft that ended Curtiss.
People don't expect every prototype to a winner, although the list of Curtiss failures was pretty impressive in it's own way.
A winner every once in a while can gloss over some failed prototypes.
Unfortunately For Curtiss the SB2C and the Seamew were not winners, they were not even 2nd place, they were well back in the pack at best.
The Navy got rid of the SB2C in 1947 and the reserve got rid of them in 1950.

The Curtiss Seahawk came way too late (June 1945 combat debut) and was too small a production run to change very many minds.

The Curtiss products were arriving late. Were trouble prone when they did show up and often didn't perform quite as promised even after modification/s.

How much longer do you keep giving them money?

On the C-46 the fix wasn't that hard. Whose fault it was?
Installing vents in the wing root area usually cleared out the fumes and/or leaked fuel and I believe most or all the surplused aircraft in commercial service had the modification/s done?
I don't know if Curtiss didn't want to pay or the government didn't want to pay or somebody didn't want to delay deliveries or????????
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I think the same could be said for the other local Buffalo fighter-builder, Bell.

All good points - IIRC the C-46 vent issue was addressed with post war airworthiness directives and modification kits. The C-46 was a gas hog but it was able to haul a lot.
 
FLYBOYJ said:
I think the same could be said for the other local Buffalo fighter-builder, Bell.

All good points - IIRC the C-46 vent issue was addressed with post war airworthiness directives and modification kits. The C-46 was a gas hog but it was able to haul a lot.
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The C-46 was good at carrying a full load, but it's cross over point from profit to loss with passengers may have been too high.
Most of the C-46s went into air freight fairly quickly and the different weight/payload limit vs seats worked to it's advantage.

If you needed to move a lot of cargo you might need 2 (or more) C-47s for each C-46.
But is was easier for the small C-47 operators to fly less than full and stay in business.
 
Shortround6 said:
The C-46 was good at carrying a full load, but it's cross over point from profit to loss with passengers may have been too high.
Most of the C-46s went into air freight fairly quickly and the different weight/payload limit vs seats worked to it's advantage.

If you needed to move a lot of cargo you might need 2 (or more) C-47s for each C-46.
But is was easier for the small C-47 operators to fly less than full and stay in business.
Click to expand...
I had an instructor when I was in A&P school who flew the hump in both C-46s and C-47s, he said the C-46 was a beast, I remember his words, "you needed some muscles." He loved the C-47.
 
The main Curtiss product, the P-40, did not have maintenance issues that were a problem. It was rugged and robust. Still is today.

When Curtiss DID produce a good one, the XP-40Q, they didn't buy it. It would have been head and shoulders above the standard P-40s that WERE being flown, but was too late and didn't quite have enough range to have a useful mission. Still, it had useful performance gains over other P-40 variants. To be fair, I likely wouldn't have bought it by time it came out, but the performance wasn't bad, and the mechanics were already trained and out there. I'm pretty sure it would have a welcome change from a standard P-40 by the pilots and mission planners, but it would have been MUCH more useful had it been available a year to two sooner.

I'll say I generally liked Curtiss better than Brewster or Bell (except for the P-63), but that doesn't give them much of a leg up on things like P-47s or P-51s.
 
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I have a photo of a C-46 freighter, NMF , no name or logo, except the word "FISH" on the fuselage near the cargo door. All doors and windows were open, it was July, parked waaay out on the transient ramp at the New Orleans Lakefront Airport. Photography was done upwind with a long lens.
 
The C-46 had TWO jump doors, vs. the C-47s one door, but the fuel leaks meant it caught fire a heckuva lot easier than the Dakota/Skytrain. It was only used for one combat jump in Europe that I'm aware of, Varsity (the jump over the Rhine), where they took a lot of casualties. It was a lot better freighter than a combat jump aircraft.
That's not my opinion, but the opinion of the US AIrborne troops.
 
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