P-63 King Cobra

[10thmd]

I think we can all agree that Stalin would not hold to any agreement that would mean less weapons to use against Hitler. In short he ordered the records Falsified.

[Karnak]

I think we can all agree that Stalin would not hold to any agreement that would mean less weapons to use against Hitler. In short he ordered the records Falsified.

I disagree.  Stalin held to some agreements and broke other.  We'd need evidence.

In any case, the P-63 cannot be argued for as anything other than an extremely low priority for AH.

[Unit791]

I believe the highest scoring allied pilot flew the P-39 and refused flying the P-63. 

Incorrect, he flew La-5/La-7

[Guppy35]

Yes. Alas that seemed to be the great ptoblem with P-63 records is the strange agreeement that said they couldn't use them in western front. Maybe that needs to be researched. Can that possibly be true?  and why whould it be so? I've accepted that wit hout seing any documentation on that which should be findable since it would be U.S. documents that say it. Hmmm. I smell research project.

There's these goofy things called books

Two great resources no the 39 and 63.  Both on my shelf at home

"Cobra's over the Tundra" by Everett Long.  Covers the lend lease stuff.  Nice shots of Russian 39s and 63s on their way to Russia

http://www.abebooks.com/servlet/BookDetailsPL?bi=1245337842&searchurl=kn%3DCobras%2Bover%2Bthe%2BTundra%26sts%3Dt%26x%3D46%26y%3D12

"Cobra! The Bell Aircraft Corporation 1934-46" by Birch Matthews.  Covers development of both the 39 and 63 with all kinds of stats on performance, might have beens, which birds went where, etc.

http://www.abebooks.com/servlet/BookDetailsPL?bi=1245337842&searchurl=kn%3DCobras%2Bover%2Bthe%2BTundra%26sts%3Dt%26x%3D46%26y%3D12

[Timofei]

I have seen test data for the XP-39..

I would like to see it also.

Test pilot Jimmy Taylor reported 390 mph (corrected airspeed) on April 6, 1939. He also stated that XP-39 had gone even faster later in the flight test program (he estimated 398 mph).

Source ?

Whitney also states that the P-63 was "an enlarged version of the P-39 fitted with a laminar flow wing." This is incorrect as the two aircraft were similar in layout, but even more different than the P-47 was from the P-43. Virtually no commonality of airframe components.

Trying to shoot the messenger here ?
 Pretty childish.

[Widewing]

I would like to see it also.
Source ?Trying to shoot the messenger here ?
 Pretty childish.

A copy of the factory test data is available in the National Archives, College Park, Maryland. Another copy on microfilm is available in the New York City NARA Microfilm Research Room, where I read it and took notes in 1995.

You can also check Dean, page 192 (America's Hundred Thousand). Bodie and Bowers also reference the same test data. Bowers had interview notes with Larry Bell as well. 390 mph @ 20k is well documented.

NACA and the Army's Fighter Branch were far from infallible. NACA's speed estimates for the XP-39 were far off of reality. They were responsible for the useless mass/balances on the P-38's elevators when the cause was actually turbulence from the wing to fuselage mating. Fillets were the actual cure for the incorrectly diagnosed "tail flutter".   

Let me ask you a question, Timofei... Why are you dogging every post I make? You puffed out your chest on the P-40 discussion and were proved wrong. When I asked that you post a document that proves your claim, you stated the copy was too poor...

Thus, in the ignore list you go...

[AWwrgwy]

Let me ask you a question, Timofei... Why are you dogging every post I make? You puffed out your chest on the P-40 discussion and were proved wrong. When I asked that you post a document that proves your claim, you stated the copy was too poor...

Thus, in the ignore list you go...

He doesn't know your pedigree.   

wrongway

[Widewing]

He doesn't know your pedigree.   

wrongway

He's simply a troll... Read his various posts. With few exceptions, they're trolls, looking to generate heat rather than light. Thus, I placed him into my ignore list.


My regards,

Widewing

[Timofei]

Daniel D Whitney's "Vees for Victory - The Story of the Alison V1710 Aircraft Engine 1929-1948" pp79-988 has a bit to say on the development of the P-39 and the removal of the turbo.

-During 1937 when Alison had sold only 15 V1710 they pushed to develop altitude rated rather than turbo versions as they felt that their sales problems were partly due to Air Corps focusing on inadequately developed turbo charging.
-XP-39 Flight testing was delayed several months while Alison fixed vibration problems, resulting from torsional vibration of the extension shafts, found during ground running tests. This had "been only partially alleviated by first flight so certain RPM had to be avoided.
-He says "It is clear from recently located NACA test reports on the XP-39 that it was not meeting the contracted performance guarantees. While it has been reported that the aircraft was able to climb from takeoff to 20,000 ft in five minutes, and that the maximum speed at that altitude was 390mph, with the airplane weighing 5550 lbs the data does not show it.
...
"Furthermore, given that General Arnold was hurriedly arranging to hava NACA put the airplane in its wind tunnel for drag reduction tests only a month after the first flight, suggests that all was not well."
-The XP-39 was 10% overweight at 6104 lb on official weigh in versus a contracted 5550 lb.
-Flight testing had shown inadequate cooling of oil, Prestone and intercooler. NACA found for example the radiator required 10,250 scfm and that during climb at 160mph only 7,880 scfm was provided.
NACA tests showed that the various air inlets were badly arranged with internal constrictions from the way the aircraft had been packaged (wing spars, landing gear obstructions etc) reducing air flow.
A table of drag breakdown is given showing turbo charger related drag (Turbo + waste gate + intercooler)was about 16.4 % of the aircraft total.
Intercooler air flow was ony 1,600 scfm at high speed while 5,000 to 7,000 was required if the engine was to achieve full power without detonation.
External arrangement of air inlets was causing asymetrical stalling with the left wing root stalling at several degrees angle of attack before the right.
As received by NACA they estimate speed to be 340mph at 20,00ft with 1150bhp
Following testing of modifications recommened by NACA drag was reduced to a level where it was estimated that 392mph at 20,000 if 1150 bhp was provided by the engine.
NACA considered an altitude rated V1710 and and with the other changes this was expected to give about 402mph at 13,200 feet with the elimination of the drag from the turbocharger and intercooler even before allowing for the reduction in weight from the removal of the turbo. NACA estimated that the performance at 20,000 feet would be "about the same" as the turbo version
NACA recommendations were
- Improve streamlining of wheel well doors
- Lower the canopy
- Remove turbosupercharging due to high installation drag.
- Relocate carburettor scope from left side of fuselage to just behind the canopy.
- Install the altitude rated engine.

To me this indicates the 390 mph at 20,000 ft is a probably a myth, being the NACA predicted value if the sum of all recommendations had been applied and that the V1710 provided 1150 bhp at that altitude.

Other aviation writer Ray Wagner:
http://www.americancombatplanes.com/p39_1.html

"The original X-609 specification called for a minimum top speed of 290 mph at sea level and 360 mph at 20,000 feet, but 400 mph was the desired goal. Bell guaranteed a top speed of 330 mph at sea level and 400 mph at 20,000 feet, climbing to that altitude in five minutes, but this was for a weight of 3,995 pounds empty and 5,550 pounds gross.


After the XP-39 was moved to Wright Field in December 1938, Army inspectors listed the actual prototype weight as 4,545 pounds empty and 6,104 pounds gross. Air intakes protruded behind the engine, the left side to cool the oil radiator, the right side for the carburetor and for the turbosupercharger intercooler, The first test flight was made at Wright Field by James Taylor on April 6, 1939. Drive shaft vibration curtailed tests and excessive airframe drag limited speed to nearer the minimum than the desired level. While detailed reports are not available, one Army chart stated top speed was 365 mph at 20,000 feet."

The above quotes from two known aviation authors.
I see Widewing has dedicated a whole  webpage to the "P-39 USAAF/NACA -conspiracy".
But the only actual proof he presents is "I took notes". For me it is easy to decide who to believe.

And no, I'm not troll, but I admit I'm a graduate from John McEnroe Charm School.

[Widewing]

A few facts...

NACA's estimates didn't come close to reality. The much modified XP-39 (now the XP-39B) barely reached 375 mph, but could not sustain it due to overheating. The YP-39, fitted with the "altitude rated V1710" managed only 368 mph at 13,600 feet. A far cry from their estimate of 402 mph at 13,200 feet. As to performance being equal to the XP-39 at 20,000 feet... Delusional. The YP-39s could do no better than 332 mph at 20,000 feet.

Larry Bell specifically stated in an interview with Pete Bowers that, "We expected that NACA's wind tunnel testing would help up clean up the airframe. We didn't expect that NACA would recommend what amounted to a complete redesign. We were appalled, to say the least. We objected to NACA's findings, my Engineers finding that much of their calculations were based not upon actual test data, but mathematical models. We argued back and forth for weeks with no result. The political reality was that the staff at Wright Field had cast their lot with NACA. That left me with two choices; redesign according to NACA's recommendations or have the plane canceled. This could not have come at a worse time for us. We had to reassign most of the Engineering staff working on the XFL-1 to the XP-39B. I feel that this was a great contributor to the failure of the XFL-1 as we simply didn't have the depth of resources to devote to both aircraft. The elimination of the turbosupercharger was a heartbreak. We had hoped that the Army would fund further development, instead they ordered us to remove it, which meant that the core of our effort was for no gain."

From Peter Bower's interview of Larry Bell, October 1953.

Again, I'll point to Whitney as being an Engineer who writes history of engines. His research into the aircraft is spotty at best. You put much credence in Whitney's research, so let's look at one example where he gets it all wrong.

Whitney has written, "As a way to expedite development of both the V-1710 and turbosupercharger the Army then issued a new requirement for an in-line powered, turbosupercharged Pursuit, the Curtiss XP-37. This airplane preceded a contract for 13 YP-37s, intended to introduce the high-speed, high-altitude fighter type aircraft to the US military, along with its integrated engine and turbo installation. As a group these aircraft were successful, although the primary lessons learned were that combining the turbosupercharger with a high performance engine/airframe required a much more sophisticated control system than was available at the time."

According to the XP-37/YP-37 test pilots, the aircraft was a nightmare. One specifically told me that the turbo installation was horrible. The engine would routinely overheat. His first flight of a YP-37 nearly killed him at Langley Field. I had several conversations with this pilot, Erik Shilling (later of AVG fame) specifically about this aircraft. He described the YP-37 as "badly engineered." Erik was my friend and a mentor. He recounts his YP-37 experiences in his book, Destiny: A Flying Tigers Rendezvous With Fate. Only 1,000 copies were published. I have number 627, with a hand written dedication from Erik. Curtiss' Edward Elliott, who also flew the XP-40 on its first flight, stated that, "The XP-37 was the only Curtiss airplane I came to despise."(*related by Herb Fisher, Curtiss test pilot)

Maybe Whitney should have talked to the test pilots.... If the XP-37/YP-37 was successful, it would only be so as an example of how not to design a turbo installation. The fact is that the XP-37/YP-37 was an expensive failure. Whitney is an Engineer. Engineers routinely spin failure into a positive by claiming that lessons were learned. However, the reality is that the lesson learned was as simple as poor design, bad analysis and failure to anticipate. How do I know this? I'm an Project Engineer/Manager for a fast growing aerospace company.

As to Ray Wagner... He quotes Larry Bell as being glad the turbo was removed.. Too bad Bell states otherwise. I also looked at some of his other writing on WWII fighters on his web page. It's riddled with errors. Here's an example: "Two XF6F-6s with the 2,100-hp R-2800-18W and four-bladed propeller were first flown July 6, 1944, but this advanced power plant was reserved for the F4U-4."

Absolutely incorrect. The F6F-6 was not built for one very simple reason. Leroy Grumman and Bob Hall thought that the F8F-1 was far superior and that they could not get F6F-6s to the fleet before February of 1945 anyway. The Navy agreed and the F6F-6 was canceled.

Wagner also states: "Meanwhile, the expedited production contract hadbeen changed to the F6F-3 model, the first flying October 3 with an R-2800-10, three-bladed Hamilton propeller without spinner, a simplified landing gear, and six guns. Ten F6F-3s were delivered by 1942’s end, and production accelerated rapidly, the 2,545 Hellcats delivered in 1943 being enough to equip every fighter squadron on the fast carriers. There was little change in the basic configuration, although the R-2800-l0W with water injection for emergency power was introduced in January 1944."

Again, Wagner is incorrect. Beginning with BuNo 40634, delivered in October of 1943, all F6F-3 aircraft were fitted with the R-2800-10W and water injection. By January of 1944, the majority of F6Fs in service were either manufactured with the R-2800-10W or had been retrofitted with the engine and ADI tank kit in the field.

The fact is that Wagner doesn't do any original research (I don't see any), but relies on the work of others. Not unlike what Joe Baugher does. That's fine. They both produce general works that are aimed at the general market. These guys borrow from Bowers, Bodie, Tillman and others. I've worked with most of these guys, and I have done research for Eric Hammel as well. I count these and others such as Boyne, Rob Morris and Bob Dorr as friends. Hell, we all network through Facebook, where we have public and private groups.

Yet, you throw Whitney and Wagner out and tell me that, "For me it is easy to decide who to believe."

Pfftt.. I've wasted enough time on you.. We're done.

[lyric1]

Fascinating reading reminds me of Good Will Hunting & the THEM APPLES scene.

[Vinkman]

 The elimination of the turbosupercharger was a heartbreak. We had hoped that the Army would fund further development, instead they ordered us to remove it, which meant that the core of our effort was for no gain."

Wide,
The P-38 seems, to my limited and non-expert knowlege of the Warbirds of the era, to be the only V-12 Turbocharged engine in the American line up. I assumed this was the same Powerplant the XP-39 was supposed to use. Any info on why Bell had so many problems with it?  In looking at the Lightning, it would seem one boom houses An engine, Turbo, and intercoolers, and radiators. It also seems there would be enough room in the aft fuselage of P-39 to fit the same hardware. Interesting also that P-63, redisigned to be larger, still avoided the Turbo and went with the two speed Supercharger.

[Timofei]

A few facts...

Always a good way to start a post if you want to impress.

I count these and others such as Boyne, Rob Morris and Bob Dorr as friends.
..
Yet, you throw Whitney and Wagner out and tell me that, "For me it is easy to decide who to believe."
..

Yet, a long post just to discredit two of your "friends". Heck, I don't want to be your "enemy" near you.
The point of my original post was that  if the goal of 400mph/20k was only 10mph short as you claim, there would not have been any need for drastic design changes.
I'm done too. Pfftt...

[TnDep]

Just use the tape measurer 

[Timofei]

You puffed out your chest on the P-40 discussion and were proved wrong. When I asked that you post a document that proves your claim, you stated the copy was too poor...

Off topic, but I found a better copy of P40D&E:
http://www.zenoswarbirdvideos.com/Images/P-40/P-40FOIC.pdf
I also found that you have posted the same document before in this forum..