XP-39 and the Claims

I suggest some people go back and read the title of the thread and the first post.

What the P-39 could or could not do in 1942 doesn't have a lot to do with what the XP-39 could do in the spring of 1939.

or at least any more to do with each other than the P-40N had to do with XP-40 in it's original configuration

With it's different radiator setup, different airscoops, machine gun tubes/fairings and so on. XP-40 was supposedly incapable of exceeding 300mph in it's orginal configuration.

drgondog said:

Bell's time to introduce what the field commanders wanted was early 1942 before the field commanders knew what they wanted. The War Plans Division in late 1941 and 1942 posited battlefield air superiority while performing Fast Attack role - the reason the Mustang in the form of A-36 snuck its big nose in the AAF tent - despite Oliver Echols' resistance to NAA getting in the Pursuit game.

The limiting known factor for the P-39 was never speed or maneuverability at low/medium altitude - it was the lack of range and external stores. It was already 'written off' as a primary AAF Pursuit (as was the P-40) in 1942 for future procurement. Bell and Curtiss survived in 1942-43 because we had to fight with what we had and there weren't enough P-38/P-47s to backfill the battlefield CAS requirements. They also were augmented by Lend Lease to USSR and our Allies while improvements kept them competitive for low to medium altitude use.

The final straw was the success of the Merlin 'experiment' in mid 1942 when the CAS acolytes viewed the Merlin Mustang as the answer to the fast, load carrying, maneuverable, long range CAS fighter that could achieve air superiority - the reason it was painted in to replace the P-39 and P-40. Only a few visionaries understood the escort potential of the P-51B until early 1943 so there was no fight by Strategic Air proponents until mid 1943 after Blitz Week - all were destined to be TAC CAS and Recce in ETO.

The achilles heel for the P-39 from the inception was the wing. It was never conceptualized in 1937-1938 as anything but interceptor - and therefore had no room for growth for either internal fuel or external load and very little for internal armament. Price's decisions to encourage Bell to add wing armament capability was a desire to improve CAS effectiveness - not 'kill the program'

It is kind of silly to suggest that Maj/LtC Price, the AAF Materiel Command P-39 Project manager wanted to kill the P-39.

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Bell, like all other manufacturers, built what the AAF/Navy ordered, presumably what they wanted. The A-36 Apache was a simple placeholder to keep the production line running while the Merlin P-51B/C was being developed.

The only reason the P-39 (and P-40) were pruduced at all was to give the AAF modern fighters before the P-38 and P-47 were ready for combat in December '42 and May '43 respectively. After that these planes were kept in production to supply our allies under lend-lease.

There was no "escort" of the 8th AF in England until the P-47. Okay a few Spitfires which could actually get across the channel before they had to turn back. The P-47 had NO PROVISION WHATSOEVER for drop tanks until August of that year when they got a single 75 gallon drop tank for a plane that burned 190gallons per hour at cruise. By October P-38s were in England and two months later the Merlin P-51 was arriving. So the P-47 had about two months for any meaningful escort duty.

To address post #134 a small bit, I don't believe anybody said the British were making "improper" fuel. At least, I didn't. I also haven't read it anywhere in here. I said it was not formulated the same as ours early-on (1941 - 1942-ish into early 1943), and it wasn't. There was nothing "improper" about it and the British were never less than technically savy. ... it was just different from the fuel supplied to domestic engine manufacturers, and the increased output of 100-Octane gasoline didn't happen overnight because someone planned 35+ new refineries in late 1941.

They actually DID have to build them, get them running, and figure out how to maintain production in the presence of ever-increasing demands for higher PN gasoline, which by itself tended to decrease volumetric output by as much as 26% unless ways could be devised to mitigate that reduction. Higher PN meant less gasoline from existing refineries. The introduction of aromatic additives (mainly cumene [mid 1942], xylidine, and napthas) largely helped defray this capacity reduction. In mid-1943 the Petroleum Administration of War approved the construction of a cycloversion facility (using napthas), but Borger didn't begin operations until July 1944. So, exactly when did the higher-aromatic fuel start to be seen in combat fuel tanks? I have not found anything stating that yet, but the FIRST cycloversion plant wasn't even operating until mid-1944 (Phillips Petroleum). Therefore, a DECISION made in Nov-Dec 1941 was implemented by mid-1944, and between those dates, the fraction of higher-performance fuels ramped ever-upward. I don't know exactly when a particular fighter group saw 115/145 or 105/150 fuel, but it wasn't likely until late 1943 - early 1944 in larger quantities. Certainly AFTER early ETO P-38 escort missions, anyway. Even the Early P-38Js were still being flown with fuels not best-suited for them.

The one hundred million gallons of high-performance aviation fuel came between 24 Dec 1942 and Aug 1945. One thousand 4-engine bombers making a six-hour flight used up 1,850,000 gallons of high-octane fuel. We flew that more than a few times in the last year and half of the war; never before that time. On a smaller scale, in the Pacific, 18 planes on one mission burned 11,600 gallons. To train ONE pilot, we used 12,500 gallons.

The production capacity for US fuel in late 1941 was small when compared with 1944. I believe that has been established. They built some 35+ refining plants between Dec 41 and mid-1944, maybe closer to 50.

Seems like TEL went from 2g/gal to 3 g/gal to 4 g/gal (May 42 is when the change was agreed upon ... not sure when it hit actual combat gas tanks) to some 6 g/gal (Feb 44 to produce 104/150 fuel) that managed to run well at high power settings, but separated and fouled plugs and had other bad effects at low power settings. They DID manage to come up with additives, as stated above. They settled on 115/145 fuel (4.6 g/gal TEL?) after trying the 150 out and finding the increased maintenance requirements from the use of 150.

P-39 Expert said:

...
The P-47 had NO PROVISION WHATSOEVER for drop tanks until August of that year when they got a single 75 gallon drop tank for a plane that burned 190gallons per hour at cruise. By October P-38s were in England and two months later the Merlin P-51 was arriving. So the P-47 had about two months for any meaningful escort duty.

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Already the P-47C have had a provision for a belly tank; 1st delivered on Spet 14th 1942. 1st The P-47Ds were self-deployed to UK via Iceland in August 1943 (two wing drop tanks each). The only P-47 without any external tankage was the P-47B, none of them being deployed away from CONUS.

It was far easier to turn the P-47 into a long range fighter than to try to do that with P-39.

P-39 Expert said:

The P-47 had NO PROVISION WHATSOEVER for drop tanks until August of that year when they got a single 75 gallon drop tank for a plane that burned 190gallons per hour at cruise

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Source for the bolded part? Why on earth would the P-47 cruise at the maximum continuous rating of the engine?
The US tactical planning charts assume a speed of 210 IAS at 25,000ft which is about 315mph true depending on which calculator or formula you use.

P-47s with R-2800-21 engines were rated at 225IAS (337.5mph true) at 25,000ft using 145 gallons an hour and 200 IAS (300mph true) at 25,000ft burning a mere 95 gallons an hour. Granted this is for a clean air plane ( I don't believe the chart is correct when it says either clean or with empty 200 gallon ferry tank)

I would note that when the P-47D got the extra 65 gallons of internal fuel it's "radius" in the planning charts went up 100 miles with no drop tanks at all. Apparently "cruise" was using about 1 gallon for every 3 miles instead of the 1.9 miles per gallon you are claiming.

tomo pauk said:

Already the P-47C have had a provision for a belly tank; 1st delivered on Spet 14th 1942. 1st The P-47Ds were self-deployed to UK via Iceland in August 1943 (two wing drop tanks each). The only P-47 without any external tankage was the P-47B, none of them being deployed away from CONUS.

It was far easier to turn the P-47 into a long range fighter than to try to do that with P-39.

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The book "Thunderbolt" by Warren Bodie states that the 75 gallon tank was first used in combat on August 7, 1943. The 200+ gallon "udder" tanks were tried briefly but were unpressurized and didn't work at escort altitudes.

The "Iceland" tanks were P-38 tanks and were for ferry (from US to England via Greenland and Iceland) and were jerry-rigged attachments since Republic had not yet devised pylon mounts. From the same book.

Combat radius for the P-47 and P-39N at 25000' were about the same with both having a 110 gal external tank.

Shortround6 said:

Source for the bolded part? Why on earth would the P-47 cruise at the maximum continuous rating of the engine?
The US tactical planning charts assume a speed of 210 IAS at 25,000ft which is about 315mph true depending on which calculator or formula you use.

P-47s with R-2800-21 engines were rated at 225IAS (337.5mph true) at 25,000ft using 145 gallons an hour and 200 IAS (300mph true) at 25,000ft burning a mere 95 gallons an hour. Granted this is for a clean air plane ( I don't believe the chart is correct when it says either clean or with empty 200 gallon ferry tank)

I would note that when the P-47D got the extra 65 gallons of internal fuel it's "radius" in the planning charts went up 100 miles with no drop tanks at all. Apparently "cruise" was using about 1 gallon for every 3 miles instead of the 1.9 miles per gallon you are claiming.

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We continue to disagree on how much time the P-47 spent on normal (maximum cruise) power on escort missions in the ETO. During late '43 and early '44 when the Luftwaffe held air superiority I believe the P-47s spent the vast majority of their time at normal power for survival.

The P-47D-25 with the extra 65 gallons of internal fuel wasn't available overseas until May '44 after air superiority had been won. These later D models had the wider propeller blades and had somewhat better climb numbers but were now relegated to the ground attack role.

I see, you just believe? with nothing to back it up?

The poor old obsolete fuel hog P-47 needs to run (cruise) at max continuous just survive over Europe at 25,000ft while the neglected( If not outright conspired against) P-39 can't fly as fast at full military power (5 or 15 minute rating) as the P-47 can cruise at. (unless we use the super N numbers)
Something seems a bit off in that logic.

Reason for bringing in the later P-47 was just to show what a difference 65-75 gallons of fuel made. I did say there were no drop tanks involved in the change of radius.

[P-39 Expert, post: 1549345, member: 73913"]Bell, like all other manufacturers, built what the AAF/Navy ordered, presumably what they wanted. The A-36 Apache was a simple placeholder to keep the production line running while the Merlin P-51B/C was being developed.

Nope - the A-36 was proposed in Dec 1941and accepted by AAF April 1942 - one month before the Rolls-Royce experiment was approved. The P-51A ordered in June 1942 was the placeholder for the P-51B and so covered in the contract which provided for 'conversion of the order to the P-51B-1.

The only reason the P-39 (and P-40) were pruduced at all was to give the AAF modern fighters before the P-38 and P-47 were ready for combat in December '42 and May '43 respectively. After that these planes were kept in production to supply our allies under lend-lease.

Nope- the P-39 and P-40 were in production before the P-38D, but the F-4 were in combat in May 1942. All of the P-38E and Fs initially went to 1st FG on west coast, then to ETO - first combat ops Aug 1942 from UK. The P-47C first combat was April 1943 in ETO. It was a simple matter of fight with what ya have, and when the P-47 and P-38 produced numbers to backfill specific combat units there weren't enough until 1944 to retire both from active AAF units. In May 1943 for example, there were only 3 P-47 groups operational, and four P-38 group plus several 'mixed P-40/P-38 FGs

There was no "escort" of the 8th AF in England until the P-47.
Nope - The 1st (P-38 Aug 42), 4th (Spit Sep 42), 14th (P-38 Oct 42), 31st (Spit Aug 42) were flying escort. The 350th FG (P-400) and 82nd FG (P-38) and 78th FG were in training in UK when all were transferred to North Africa.

Okay a few Spitfires which could actually get across the channel before they had to turn back. The P-47 had NO PROVISION WHATSOEVER for drop tanks until August of that year when they got a single 75 gallon drop tank for a plane that burned 190gallons per hour at cruise. By October P-38s were in England and two months later the Merlin P-51 was arriving. So the P-47 had about two months for any meaningful escort duty.

The first combat mission with the 200gal Ferry tank was 4th FG July 28, 1943. That said, from April 1943 through October 15th (when 55th FG P-38s went operational, there were seven operational P-47C/D FG in 8th AF - prior to the centerline tank conversions the 4th, 56th, 78th were flying escort and sweeps into Holland, Belgium and France. With the 75gal tanks in August the combat radius of the P-47 was 230 mi, with the 110 in October it was extended to 275mi - Despite your presumption that the P-47 performed only 'two months of meaningful escort duty', the victory totals in 1943 for each were P-47=402; P-38=29; Spitfire=7 P-51B=8 for 1943 ETO combat ops. The Spit and Mustang only flew one month respectively in 1943.

P-39 Expert, post: 1549473, member: 73913"]We continue to disagree on how much time the P-47 spent on normal (maximum cruise) power on escort missions in the ETO. During late '43 and early '44 when the Luftwaffe held air superiority I believe the P-47s spent the vast majority of their time at normal power for survival.

Max Continuous Cruise Power was Not the setting for escort operations. The cruise throttle and RPM were at much lower to target max cruise radius.

The P-47D-25 with the extra 65 gallons of internal fuel wasn't available overseas until May '44 after air superiority had been won. These later D models had the wider propeller blades and had somewhat better climb numbers but were now relegated to the ground attack role.

The 56th, 78th, 350th, 356th FG - all of which were first to receive the bubble canopy/370 gal internal tank would be greatly surprised at that comment. All continued escort duties well into October and the 56th through VE Day.

drgondog said:

With the 75gal tanks in August the combat radius of the P-47 was 230 mi, with the 110 in October it was extended to 275mi

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radius without the tanks (clean) was supposed to be 125 miles, so again, the implication that the 75 gallon drop tank wasn't of much use or that the P-47 cruised using 190 gallons an hour does not seem to be supported by either documents or operational use.

P-39 Expert said:

The book "Thunderbolt" by Warren Bodie states that the 75 gallon tank was first used in combat on August 7, 1943. The 200+ gallon "udder" tanks were tried briefly but were unpressurized and didn't work at escort altitudes.
The "Iceland" tanks were P-38 tanks and were for ferry (from US to England via Greenland and Iceland) and were jerry-rigged attachments since Republic had not yet devised pylon mounts. From the same book.

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The official manual for the P-47C notes that external tank facility is there. That in the ETO the intended user took a few months to took advantage of that was no fault of P-47. The intended user in SWP jumped into the opportunity, while not wanting any P-39 long before P-47 arrived, due to the lack of range of P-39.

Combat radius for the P-47 and P-39N at 25000' were about the same with both having a 110 gal external tank.

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Not if both of them are to fly at 300+ mph TAS at 25000 ft.
BTW - the drink is on me when you post a picture of a P-39 with 110 gal drop tank.

... With the 75gal tanks in August the combat radius of the P-47 was 230 mi, with the 110 in October it was extended to 275mi

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Bill - your figures seem to come short by 100 miles? 330 miles with 75 gal DT, 375 miles with 110 DT.

- Despite your presumption that the P-47 performed only 'two months of meaningful escort duty', the victory totals in 1943 for each were P-47=402; P-38=29; Spitfire=7 P-51B=8 for 1943 ETO combat ops. The Spit and Mustang only flew one month respectively in 1943.

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Bingo.

Shortround6 said:

I see, you just believe? with nothing to back it up?

The poor old obsolete fuel hog P-47 needs to run (cruise) at max continuous just survive over Europe at 25,000ft while the neglected( If not outright conspired against) P-39 can't fly as fast at full military power (5 or 15 minute rating) as the P-47 can cruise at. (unless we use the super N numbers)
Something seems a bit off in that logic.

Reason for bringing in the later P-47 was just to show what a difference 65-75 gallons of fuel made. I did say there were no drop tanks involved in the change of radius.

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P-47 max continuous cruise was 360mph (clean) per the pilot's manual while the P-39N max speed at the same altitude was 370-375mph depending on the test.

tomo pauk said:

The official manual for the P-47C notes that external tank facility is there. That in the ETO the intended user took a few months to took advantage of that was no fault of P-47. The intended user in SWP jumped into the opportunity, while not wanting any P-39 long before P-47 arrived, due to the lack of range of P-39.



Not if both of them are to fly at 300+ mph TAS at 25000 ft.
BTW - the drink is on me when you post a picture of a P-39 with 110 gal drop tank.



Bill - your figures seem to come short by 100 miles? 330 miles with 75 gal DT, 375 miles with 110 DT.



Bingo.

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I'm looking at the manual for the P-47B/C/D/G right now and there is no mention at all of any external tank other than the 200gal unpressurized tank that was proven unsuitable for high altitudes. None.

Regarding the 110gal external tank, it is quoted in both books by Edwards Park on operations in NG in '42 and '43. He was very specific. He was there as a P-39 pilot in the 8th fighter group.

duplicate

P-39 Expert said:

I'm looking at the manual for the P-47B/C/D/G right now and there is no mention at all of any external tank other than the 200gal unpressurized tank that was proven unsuitable for high altitudes. None.

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The P-47 in the field took advantage of the factory-made external tank facility, running contrary to the claim:
"The P-47 had NO PROVISION WHATSOEVER for drop tanks until August of that year..."

Granted, the 200 gal unpressurized tank was unsuitable for high altitudes, but it was there and could (and was) used to extend the range in combat ops until better and more refined solution was in the place.

Regarding the 110gal external tank, it is quoted in both books by Edwards Park on operations in NG in '42 and '43. He was very specific. He was there as a P-39 pilot in the 8th fighter group.

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I've offered a drink for a good reason.

tomo pauk said:

Bill - your figures seem to come short by 100 miles? 330 miles with 75 gal DT, 375 miles with 110 DT.

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HI Tomo - until the D-15/-16 arrived in ETO in late winter/spring 1944, only the very lengthy depot mods on the wing enable pylon and fuel feed from the wing tanks. Until then all the single 75, 110 and flat 150gal were carried on C/L rack

drgondog said:

HI Tomo - until the D-15/-16 arrived in ETO in late winter/spring 1944, only the very lengthy depot mods on the wing enable pylon and fuel feed from the wing tanks. Until then all the single 75, 110 and flat 150gal were carried on C/L rack

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I know. The drop tank vs. range combinations are for a single, belly-mounted drop tanks as could've been found on P-47s in 1943 in the ETO.

drgondog said:

[P-39 Expert, post: 1549345, member: 73913"]Bell, like all other manufacturers, built what the AAF/Navy ordered, presumably what they wanted. The A-36 Apache was a simple placeholder to keep the production line running while the Merlin P-51B/C was being developed.

Nope - the A-36 was proposed in Dec 1941and accepted by AAF April 1942 - one month before the Rolls-Royce experiment was approved. The P-51A ordered in June 1942 was the placeholder for the P-51B and so covered in the contract which provided for 'conversion of the order to the P-51B-1.

The only reason the P-39 (and P-40) were pruduced at all was to give the AAF modern fighters before the P-38 and P-47 were ready for combat in December '42 and May '43 respectively. After that these planes were kept in production to supply our allies under lend-lease.

Nope- the P-39 and P-40 were in production before the P-38D, but the F-4 were in combat in May 1942. All of the P-38E and Fs initially went to 1st FG on west coast, then to ETO - first combat ops Aug 1942 from UK. The P-47C first combat was April 1943 in ETO. It was a simple matter of fight with what ya have, and when the P-47 and P-38 produced numbers to backfill specific combat units there weren't enough until 1944 to retire both from active AAF units. In May 1943 for example, there were only 3 P-47 groups operational, and four P-38 group plus several 'mixed P-40/P-38 FGs

There was no "escort" of the 8th AF in England until the P-47.
Nope - The 1st (P-38 Aug 42), 4th (Spit Sep 42), 14th (P-38 Oct 42), 31st (Spit Aug 42) were flying escort. The 350th FG (P-400) and 82nd FG (P-38) and 78th FG were in training in UK when all were transferred to North Africa.

Okay a few Spitfires which could actually get across the channel before they had to turn back. The P-47 had NO PROVISION WHATSOEVER for drop tanks until August of that year when they got a single 75 gallon drop tank for a plane that burned 190gallons per hour at cruise. By October P-38s were in England and two months later the Merlin P-51 was arriving. So the P-47 had about two months for any meaningful escort duty.

The first combat mission with the 200gal Ferry tank was 4th FG July 28, 1943. That said, from April 1943 through October 15th (when 55th FG P-38s went operational, there were seven operational P-47C/D FG in 8th AF - prior to the centerline tank conversions the 4th, 56th, 78th were flying escort and sweeps into Holland, Belgium and France. With the 75gal tanks in August the combat radius of the P-47 was 230 mi, with the 110 in October it was extended to 275mi - Despite your presumption that the P-47 performed only 'two months of meaningful escort duty', the victory totals in 1943 for each were P-47=402; P-38=29; Spitfire=7 P-51B=8 for 1943 ETO combat ops. The Spit and Mustang only flew one month respectively in 1943.

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What I read says the A-36 first flew in Sept '42 and entered combat in November. P-51A production (only 310 built) began March '43, switches to P-51B production in May '43. No P-51 series production occurred between October '42 and March '43 when the A-36 was being produced. Meaning the A-36 was a placeholder to keep production going until the P-51B could begin production.

Generally accepted dates of combat for the P-38 are very late '42 for Operation Torch and the SWP area. The earlier D/E models may have seen a little combat but had inferior performance to the later F/G models.

Regarding 8th AF escort the first P-47 escort mission is listed as April 30 and was the first 8thAF mission to use at least 100 bombers. I also said that prior to that they were escorted by Spitfires which had ridiculously short range. What escort missions did the P-38s fly before they were transferred to N. Africa for Torch?

Regarding the 200gal FERRY tank, it was just that. Not suitable for combat at escort altitude since it was unpressurized. Most don't consider escort missions to Holland, Belgium and a sliver of France to be meaningful. A Spitfire could take them that far. Even after getting the 110gal external tank they could only go 275 miles, about halfway to Berlin.

I stand by my original statements.

P-39 Expert said:

...

Regarding the 200gal FERRY tank, it was just that. Not suitable for combat at escort altitude since it was unpressurized. Most don't consider escort missions to Holland, Belgium and a sliver of France to be meaningful. A Spitfire could take them that far. Even after getting the 110gal external tank they could only go 275 miles, about halfway to Berlin.

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Make that 375 miles - map.