Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained)

[FLYBOYJ]

What irks me is we clearly identified what manuals were being used and then he jumps back and forth from the N to the Q when the charts suit the discussion, then adds 120 gallons of fuel into the equation.

 

[buffnut453]

Questions that have been asked before but need to be asked again.

Yes, Kenney decided the P-39/P-400 was a dud. However, that was after some of the Pacific theatre airframes had the wing guns removed...and still the performance didn't cut it. If it had, and if the mod was worth doing, surely Kenney would have ordered all his P-39s and P-400s to be so modified? And yet, instead, he bins the P-39 in favour of the P-38. That screams to me that, for all the coulda-woulda-shoulda, the P-39 lacked performance for that theatre.

As for Europe, you'd definitely need the IFF...so no weight saving there. My observation that the early cannon-armed Spits retained 4x303s in the wings was blissfully ignored. Now we learn that the supposedly world-beating P-39N had a critical altitude some 5K below that of the Spitfire MkV which entered service in early 1941.

I'm willing to accept that the P-39 may have been a better performer than previously credited. However, it was NOT a world-beater. It could not compete in western Europe and, despite having the opportunity, it failed in the Pacific. Yes, the Soviets loved it and it was great for that theatre. It does not mean it was useful anywhere else.

 

[Marcel]

It could not compete in western Europe and, despite having the opportunity, it failed in the Pacific. Yes, the Soviets loved it and it was great for that theatre. It does not mean it was useful anywhere else.

Last part, isn't that true to an extent for most fighters in WW2? Like the Spitfire, it performed greatly in Europe, but didn't have the same impact on the Pacific arena. Other way around for the Hellcat and the Corsair etc.

 

[FLYBOYJ]

Questions that have been asked before but need to be asked again.

Yes, Kenney decided the P-39/P-400 was a dud. However, that was after some of the Pacific theatre airframes had the wing guns removed...and still the performance didn't cut it. If it had, and if the mod was worth doing, surely Kenney would have ordered all his P-39s and P-400s to be so modified? And yet, instead, he bins the P-39 in favour of the P-38. That screams to me that, for all the coulda-woulda-shoulda, the P-39 lacked performance for that theatre.

100% and if you read about Kenny, he was a stickler about performance and logistics. Look what he did to his medium bombers! If any mod "would have" helped the P-39 perfom better in the SWP, it "would have" been done.

As for Europe, you'd definitely need the IFF...so no weight saving there. My observation that the early cannon-armed Spits retained 4x303s in the wings was blissfully ignored. Now we learn that the supposedly world-beating P-39N had a critical altitude some 5K below that of the Spitfire MkV which entered service in early 1941.

Agree

I'm willing to accept that the P-39 may have been a better performer than previously credited. However, it was NOT a world-beater. It could not compete in western Europe and, despite having the opportunity, it failed in the Pacific. Yes, the Soviets loved it and it was great for that theatre. It does not mean it was useful anywhere else.

Agree 100%. I also believe that during it's development and early deployment the CG issues and false performance claims eventually pissed off the AAF. As we both know having worked a bit around aircraft, if you have an aircraft that is naturally tail heavy, this could be easily adjusted with ballast, but it seems that Bell initially refuse to accept the fact that the aircraft had C/G issues.

Although from Wiki and probably previously posted, sources are identified:

The weight distribution of the P-39 was supposedly the reason for its tendency to enter a dangerous flat spin, a characteristic Soviet test pilots were able to demonstrate to the skeptical manufacturer who had been unable to reproduce the effect. After extensive tests, it was determined the spin could only be induced if the aircraft was improperly loaded, with no ammunition in the front compartment. The flight manual noted a need to ballast the front ammunition compartment with the appropriate weight of shell casings to achieve a reasonable center of gravity.

Soon after entering service, pilots began to report that "during flights of the P-39 in certain maneuvers, it tumbled end over end." Most of these events happened after the aircraft was stalled in a nose high attitude with considerable power applied. Concerned, Bell initiated a test program. Bell pilots made 86 separate efforts to reproduce the reported tumbling characteristics. In no case were they able to tumble the aircraft. In his autobiography veteran test and airshow pilot R.A. "Bob" Hoover provides an account of tumbling a P-39. He goes on to say that in hindsight, he was actually performing a Lomcovak, a now-common airshow maneuver, which he was also able to do in a Curtiss P-40. An informal study of the P-39's spinning characteristics was conducted in the NASA Langley Research Center 20-foot Free-Spinning Tunnel during the 1970s. A study of old reports showed that during earlier spin testing in the facility, the aircraft had never tumbled. However, it was noted that all testing had been done with a simulated full ammunition load, which drew the aircraft's center of gravity forward. After finding the original spin test model of the P-39 in storage, the new study first replicated the earlier testing, with consistent results. Then, the model was re-ballasted to simulate a condition of no ammunition load, which moved the aircraft's center of gravity aft. Under these conditions, the model was found to often tumble when thrown into the tunnel.

And as mentioned earlier, Bell never learned from their mistakes:

In February 1944, the Soviet government sent a highly experienced test pilot, Andrey G. Kochetkov, and an aviation engineer, Fyodor P. Suprun, to the Bell factories to participate in the development of the first production variant, the P-63A. Initially ignored by Bell engineers, Kochetkov's expert testing of the machine's spin characteristics (which led to airframe buckling) eventually led to a significant Soviet role in the development. After flat spin recovery proved impossible, and upon Kochetkov's making a final recommendation that pilots should bail out upon entering such a spin, he received a commendation from the Irving Parachute Company. The Kingcobra's maximum aft CG was moved forward to facilitate recovery from spins.

Personally I believe that Bell engineers knew they couldn't get the speeds promised by their management to the AAF so they intentionally kept the aircraft tail heavy to squeeze a few more MPH out of the aircraft and that's why they were so reluctant to listen to the Soviets - this is just my personal opinion.

Now fast forward a bit - the post war Thompson Trophy Races. the P-39s and P-63s operated for racing did real well with a P-39 winning the 1946 race. Although you need the performance, there's a lot more pilot skill involved as you're flying "a line" without cutting a pylon. Aside from souping up engines and modifying airframes, the other thing you're going to do to get the aircraft to fly a little faster is make the aircraft tail heavy....

Low and tail heavy, the P-39 and P-63 made perfect racers!

 

[Peter Gunn]

Totally agree about Gen. Kenney, as I said in post #1612, I'm pretty sure he was aware of what changes had been made to any aircraft in the AAF inventory that were considered combat capable.

Also agree re: medium bombers, with that in mind and knowing that he was willing to innovate just about anything to get the job done, if there was a way to improve the P-39's performance he would have his "Kids" try it.

That he ditched the 39 in favor of the Lightning ASAP, well, if that doesn't speak volumes to you about the respective aircraft, I don't know what does.

 

[eagledad]

Gentlemen,

Let us look the high altitude performance of the P-39, by looking at the actual experience of the 350th FG. The group flew from England to North Africa with a mixture of P-400's and P-39L's and entered combat in North Africa in Jan of 1943. P-39N's appeared some time during April/May 1943.

The unit defended the coast of Algeria during the summer and fall of 1943. Yet despite the presence of some P-39N's, each squadron in the group was assigned two P-38s to intercept and destroy high-flying Luftwaffe reconnaissance aircraft sent to photograph the allied invasion fleet gathering along the North African coast for the invasion of Sicily..

If the P-39N had such sterling high altitude performance, why would the Air Force send the group 6 P-38's to intercept the high-flying German photo ships? Remember, we are not talking charts or theory, we are talking about what actually happened.

Sources
350th Fighter Group — Wikipedia Republished // WIKI 2
350thfghonor_roll (raf-112-squadron.org)

Eagledad

 

[buffnut453]

That he ditched the 39 in favor of the Lightning ASAP, well, if that doesn't speak volumes to you about the respective aircraft, I don't know what does.

It's all part of the great conspiracy against the P-39, which included Perfidious Albion and persists to this very day in all the negative press that the P-39 receives. We're all mistaken in our understanding of the P-39 but our resident expert, alone, has recognized the truth.

I'm off to check websites about 5G cell towers causing COVID 19!!

 

[special ed]

I understand it was really P-39s that intercepted Yamamoto but it was reported as P-38s to keep the P-39s ability secret.

 

[Peter Gunn]

I understand it was really P-39s that intercepted Yamamoto but it was reported as P-38s to keep the P-39s ability secret.

You left out its ability as a night fighter/bomber stopping battleship bombardments of Henderson Field on Guadalcanal, torpedoing Musashi off Leyte, mining Tokyo Bay and dropping both A bombs.

Just sayin'.

 

[SaparotRob]

I understand it was really P-39s that intercepted Yamamoto but it was reported as P-38s to keep the P-39s ability secret.

The P-38's just flew top cover over the P-39's on that interception. This was in case the IJN was flying P-39's captured from the Soviets.

 

[Marcel]

I'm off to check websites about 5G cell towers causing COVID 19!!

Old news, it's now believed that an American professor at Harvard created the virus and secretly sold it to China. Can't believe you're that outdated on your conspiracy theories

 

[pbehn]

It's all part of the great conspiracy against the P-39, which included Perfidious Albion and persists to this very day in all the negative press that the P-39 receives. We're all mistaken in our understanding of the P-39 but our resident expert, alone, has recognized the truth.

That is the basis of the premise. If the British had accepted the P-39C instead of making up stuff to get out of a contract, the very similar slightly modified P-39N (which only had a different "impeller" whatever that is) could have won the Battle of Britain and gone on to be the saviour of the western world.

Stating the P-39N of 1943 had impressive performance is only in comparison to earlier P-39s, the Spitfire MXIV was in service in 1943. If a Spitfire IX needed extended wings, stripping out armour, some guns and its radio to get to 42,000ft I am not convinced any P-39 had a service ceiling of 38,000ft.

 

[Thumpalumpacus]

Old news, it's now believed that an American professor at Harvard created the virus and secretly sold it to China. Can't believe you're that outdated on your conspiracy theories

What virus?

 

[Marcel]

What virus?

The one that the professor sold to China of course..

 

[Thumpalumpacus]

The one that the professor sold to China of course..

Look, 600,000 crisis-actors can't be wrong!

 

[Schweik]

This one looked like 6 50's with only two firing on the left side like #3 was jammed.

Or they didn't have all the guns in there, or all the guns loaded

 

[P-39 Expert]

The reduction from 120 USG to 87 USG was to reduce weight, like you've been banging on about for years now.

The N and Q were produced with 87 USG from the factory. Kits could be applied in the field to bring them up to 120USG, but how many were fitted and where? The first 160+ N models had 120gal internal fuel. P-39Q had full 120gal fuel from the -10 model through the end of production -30 model. Don't know how many kits were fitted.

Did the wings have the facilities for extra fuel tanks where the guns were mounted? Wings had the SPACE to mount fuel tanks where the wing guns were mounted.

 

[Schweik]

Oh jeez time to unsub this thread again

 

[P-39 Expert]

So much to parse out, well...



So, you're guessing at the TAS? No, it's printed in the range chart. Just mislabeled as IAS.



Because it fits your narrative better? No, because it is what I believe.



Why should the range discussion be based on non-factual data? The plane did not have 120 gallons of internal fuel, it also had wing guns instead of any extra fuel in that space and therefore it weighed what it weighed, there's no getting around those two FACTS. Almost 4000 N/Q had full 120gal fuel.



Why do you suppose that was? You don't think a general in command of a numbered air force with responsibilities for the entire theater was unaware of any changes in hardware coming down the pipeline? I'd wage General Kenney was eminently aware of what aircraft with attending upgrades were in the works or on the horizon. Bottom line, the short ranged low altitude P-39 was not a viable asset for his command. Hell, he even had reservations about getting the P-47 because of range issues with the Thunderbolt. So when it came to the P-39 he correctly said Nyet. First N model test was in mid October 1942, Kenney may not have known their performance. P-38s were already ordered.



Why do you think the AAF ditched the Airacobra for the P-38 and the Thunderbolt? Perhaps AAF leadership was cognizant of realities you are not, like ETO ops required high altitude long range, and more importantly, high performance fighters, something the P-39 was incapable of achieving. You're saying your smarter than all the AAF gentlemen (and RAF) that tested, flew, examined etc. this plane and universally reached the conclusion that it was not suited for any combat EXCEPT short range low altitude ops? Also, the VVS fought a different war than did the AAF or the RAF, or are we forgetting this? Certainly I'm not smarter, but I do have benefit of hindsight that they did not have. N was not a low altitude plane. VVS fought a tactical war but the Luftwaffe was not limited to low altitude. N/Q were successful because they could operate at Luftwaffe altitudes.

 

[P-39 Expert]

And we still have the questions
a) How much weight is involved adding the extra fuel plus its tanks and plumbing 6 pounds per gallon of fuel and 2 pounds per gallon for tanks. 30 gallons = 240lbs.
b) If the N was so good why was it replaced with the Q which had less performance Absolutely no earthly idea. Why were the D/F/K/L so heavy for available power when they could have been easily and quickly lightened? Why add external gun pods that produce drag? Especially when the podded 50s weighed almost twice as much as the internal 30s? These are questions I can't answer.
c) You don't just rip out guns and add fuel No, you remove the guns, ammo boxes, chargers and heaters and replace them with wing fuel tanks. The P-38 removed wing intercoolers and replaced them with fuel tanks. Certainly could be done.
d) what is the performance of the N with the extra weight. My guess is that it will be very similar to the P39Q which was a very similar aircraft, which in turn knocks great holes in your claim for the P39N being such a wonder weapon Go to wwiiaircraftperformance.org and look up the P-39N and Q. Just reinforces my claim.

Please expand above.