P-38 Question

[Marshall_Stack]

Why is that the P-38 had so many problems in the European theater but not in the Aleutians (as far as I know). I know that the British fuel was improperly blended but is that the only reason? Does using different RPM and manifold pressure settings account for the turbochargers problems?

[FLYBOYJ]

Good questions and yest to be answered especially by the ETO folks. Perhaps the Aleutians were so miserable that the heater situation didn't matter to the pilots?!?

You second question is correct. There were definitely operator difference in each theater of operation and IMO is the reason why the P-38 performed so well in the Pacific and was considered sub-par (by some) in the ETO.

[ccheese]

I think the fuel probably played a part in it. If you recall the Italians
"killed" the P-38 they captured intact by their poor fuel. It destroyed
the engines.

Charles

[renrich]

I believe that the P38 was operated at higher altitudes in the ETO which exacerbated the turbo problems and they also had the problem that at higher altitudes in a dive they would get into compressibility more quichly and lose control. Even though air temps were low in the Aleutians at the altitudes the P38s operated at they were not as low as in the ETO.

[drgondog]

Originally Posted by renrich

I believe that the P38 was operated at higher altitudes in the ETO which exacerbated the turbo problems and they also had the problem that at higher altitudes in a dive they would get into compressibility more quichly and lose control. Even though air temps were low in the Aleutians at the altitudes the P38s operated at they were not as low as in the ETO.

Renrich dead on

The ETO temps at 30,000 feet were frequently in the 60-70 below zero range and played havoc with the superchargers as well as unpressurized cockpits nearly freezing the pilots to death.

As you noted compressibility major problem. was just a few knots above top speed at that altitude and absent the dive brakes for the 38L it went into compressibility quickly after start of dive.

At medium altitudes the 38 was a beast in climb, turn and dive - so was well suited to MTO and PTO. 12th and 15th operated at lower altitudes in the MTO plus a lot more escort to medium bombers. Aleutians was all medium altitude also.

IMHO, if the first P-38 had not been destroyed in the crash landing after the speed run - the compressibility and turbo problems would have been discovered and fixed in time for the P-38 to be a major player in long range escort much earlier than the P-51. That stunt sent the P-38 program back two years at least (prototype with no production tooling)..

[Marshall_Stack]

"IMHO, if the first P-38 had not been destroyed in the crash landing after the speed run - the compressibility and turbo problems would have been discovered and fixed in time for the P-38 to be a major player in long range escort much earlier than the P-51. That stunt sent the P-38 program back two years at least (prototype with no production tooling).."



The XP-38 crashed because of carbeurator icing. I know they fixed this problem (carbeurator heater?).

Would they have needed to use the British fuel to find the problem. From what I have read, the British fuel was improperly blended and the lead would come out of suspension from the extreme cold weather and too-efficient turbocharger intercoolers.

[drgondog]

The report Kelsey wrote after the crash noted that he suspected Carb icing - but the combination of bad brakes, forced to land at low speed and high drag put him under the power curve - and engines didn't resond to increased throttle..he stated that 9 possibilities existed and he had eliminated five before the crash"

He noted that the problem was solved with a combination of fuel supply and carburator redesign - but I don't believe the precise root cause was determined.

Having said that, the future high altitude supercharger problems were not carburator icing but low/freezing lubrication issues mostly solved with redesign of intercooler from leading edge to radiator core-types with manual control available in cockpit.

I will check on that bold statement..

[SoD Stitch]

Yeah, it probably came down to the altitudes at which the aircraft was employed. Although the P-38 had turbo-supercharged engines, it actually performed better at low to medium altitudes, whereas the Merlin, with a 2-speed supercharger, performed better at higher altitudes, which is where a lot of the air combat in the ETO took place, particularly in the later stages of the War.

The P-38 also had a fairly high wing-loading compared to other single-engined fighters of the period (50 lbs.+ per square foot, versus about 30-40 lbs. per square foot); this would make it much less maneuverable at altitude, though a very stable gun platform at lower altitudes for strafing.

The reason it did so well in the Aleutians (IMHO) was due to the fact that it had exceptional range for the time period (no other fighter of the time could fly further), which was necessary considering the vast distances they had to patrol. It also had two engines, which was a considerable safety factor when most of your flying is done over the vast expanses of the North Pacific and the Bering Sea; I have no idea how many P-38's limped home to Unimak after losing an engine, but I'm sure it must've happened occasionally.

And, finally, the opposition (Japanese) aircraft tended to be inferior to the P-38; there weren't very many Zeros operating in the North Pacific, most of them were sent to the Phillipines and the South Pacific. What was left in the North Pacific were mostly flying boats and bombers, so the P-38 didn't have any real opposition.

[Cub Driver]

Because of the high-ranging "German 88" flak gun, bombers over Germany had to fly at higher altitudes than anywhere else in the world, at least until B-29s began operating over the home islands of Japan.

Japanese planes especially tended to fly at at medium altitudes--14,000 feet in the case of bomber formations over Rangoon in the winter of 1941-1942. That's why the P-40 was an effective fighter in the Pacific theater, months and even years after the RAF had turned it down as inadquate for the defense of England.

It seems to me that bombers, not fighters, determined the altitude at which combat took place.

My two cents (pennies, pfennig, yuan, sen) anyhow!

Blue skies! -- Dan Ford

Coming August 21: Flying Tigers: Claire Chennault and His American Volunteers, 1941-1942

[JoeB]

Originally Posted by SoD Stitch

...it probably came down to the altitudes at which the aircraft was employed. Although the P-38 had turbo-supercharged engines, it actually performed better at low to medium altitudes,

...The reason it did so well in the Aleutians (IMHO) was due to the fact that it had exceptional range for the time period (no other fighter of the time could fly further)

...And, finally, the opposition (Japanese) aircraft tended to be inferior to the P-38; there weren't very many Zeros operating in the North Pacific

I agree with all those points. I'd add that there were no landplane Japanese fighters ever within range of P-38's in the Aleutians. When the Japanese invaded Kiska their occupying force included a detachment floatplane Zero's (A6M2N, 'Rufe'), that detachment and reinforcements were it for fighters. The Japanese never built operational airfields on Attu and Kiska before losing and abandoning those islands respectively. The float Zeroes actually had some successes v P-38's, but soon the Allies (including one Canadian P-40 sdn) had bases from which P-40's and P-39's could also strike Kiska, heavily outnumbering the Japanese floatplanes, and the floats also slowed a Zero down quite a bit, and the Japanese suffered their own heavy operational losses to the Aleutian weather like the Allies (in the two months from July 1942 16 Rufes lost operationally, 6 in combat including bombed/strafed on the water). So, air opposition dwindled to almost nothing long before the islands were retaken in 1943. The first P-38 claims ever were 4 August 1942 against 2 of 3 'Mavis' flying boats attacking Atka, but Japanese accounts indicate just one a/c was hit and none lost (the first P-38 kill confirmed in opposing accounts was later in August, an Fw200 off Iceland). Later on when US bases were extended further west, P-38's downed some unescorted Betty's flying all the way from the Kuriles. The situation in the Aleutians was overall just not very comparable to 8th AF operations over Germany.

Joe

[Marshall_Stack]

Another question somewhat related...

I have heard that at high altitude the P-47 was the queen of the sky with its turbocharger. But, I saw on TV a Tuskegee airman saying that the P-47 was only good at medium altitude, maybe up to 28,000 ft and then the P-51 was better.

Which is true?

[drgondog]

Originally Posted by Marshall_Stack

Another question somewhat related...

I have heard that at high altitude the P-47 was the queen of the sky with its turbocharger. But, I saw on TV a Tuskegee airman saying that the P-47 was only good at medium altitude, maybe up to 28,000 ft and then the P-51 was better.

Which is true?

The P-51/Packard Merlin 1650-7 was designed for peak speed and performance at 25,000 feet whereas the P-47D and M were targeted for peak performance at 30,000 feet.

He was wrong in the context of P-47 performance 'falling off' at 28,000 feet.

As to Better, in my opinion the Mustang was a better air superiority fighter than the P-47 or P-38 and on par with an F4U. The Mustang had far better results aginst the Luftwaffe.

[renrich]

What youall are saying is interesting to me because the tubocharger was supposed to give better high altitude performance at high altitudes( above 25000 feet or so) and apparently it did with the P47 but perhaps not with the P38. Somewhere on this site there was a report published which showed that in tests conducted in Australia a Spit 9 with a 2 stage supercharger had a higher Vmax at 30000 ft than a P38. The turbochargers on the P38 must not have been very effective.

[SoD Stitch]

Originally Posted by renrich

What youall are saying is interesting to me because the tubocharger was supposed to give better high altitude performance at high altitudes( above 25000 feet or so) and apparently it did with the P47 but perhaps not with the P38. Somewhere on this site there was a report published which showed that in tests conducted in Australia a Spit 9 with a 2 stage supercharger had a higher Vmax at 30000 ft than a P38. The turbochargers on the P38 must not have been very effective.

I'm not an aircraft powerplant engineer, but I do know two things:

1. The turbo-superchargers on the P-38 were first-generation turbo-superchargers (we just call them turbochargers nowadays, but back then the word "turbocharger" had not been invented yet, so they were originally called exhaust-driven superchargers, as opposed to the mechanically-driven superchargers on the Merlin) developed by General Electric. GE was approached to develop them because GE had experience in building high-temp steam-driven turbines for industrial powerplants. As I said, these were first-generation turbochargers, so they probably weren't very efficient.

2. The Allison V-1710 engines were not originally designed to operate with a turbo-supercharger bolted onto them; every other application of the Allison engine up to the P-38 was in naturally-aspirated form (meaning no forced-injection of the air/fuel mixture). In fact, the P-38's that got shipped to the UK in '41 didn't have any turbochargers on them per Britain's request (dumb move). The Merlin, on the other hand, was designed from the outset to operate with a supercharger.

[renrich]

Thanks Stitch, good info. Makes sense.