Prior 1942: ideal fighters for USAAC

[Shortround6]

While there is no doubt what so ever that the US Aviation industry benefited enormously financially form the both the British and French in 1938-1940 I an not so sure that there was that big a technological benefit. French and British were pretty much buying standard American products. In some cases planes that the US government didn't want (no, not the Mustang, earlier). The expertise was more in the line of "yes, combat planes need armor and self sealing fuel tanks" and "No, a critical height for fighter engine can't be under 15,000ft."
I can't think of a single Aircraft made in the US (not Canada) that was designed by Britons in 1938-41. The only engine made in the US that was designed by Britons was the Merlin and that deal wasn't until the summer of 1940. No guns "designed" by Britons. It might be better if we had because the US sure made a hash of the Hispano.

 

[parsifal]

just to pick on one product....wasnt the f4f redesigned from a four gun broadside to a six gun broadside, on the basis of british advice and experience. There are a lot here that criticise this change, but given the relative advantages of the enemy pilots and equipment in 1939-42, giving the allied pilots the ability to unload a large amount of ordinance in a short space of time was probably the right thing to do at that stage......

 

[tomo pauk]

The F4F-4 received the folding wings in the same time (increasing weight), and that, coupled with added weight from new pair of hefty guns, is what made plane overweight compared with -3. As far as F4F's adversaries are concerned, the IJN/IJA planes were not that resistant to the original 4 guns , so perhaps sticking with them would've been the right choice - the climb rate wouldn't suffer as much. The FM-1 FM-2 reverted to 4, and I didn't read any complaints about low firepower of those.
The additional guns severely reduced firing time, too (IIRC 400 rpg -> 240 rpg).

 

[Shortround6]

just to pick on one product....wasnt the f4f redesigned from a four gun broadside to a six gun broadside, on the basis of british advice and experience. There are a lot here that criticise this change, but given the relative advantages of the enemy pilots and equipment in 1939-42, giving the allied pilots the ability to unload a large amount of ordinance in a short space of time was probably the right thing to do at that stage......

The only place/s I have see that is on internet forums. Maybe I don't own the right books. It may be true. What is really strange is that of all the Wildcats the British received, both paid for and lend lease, something like 2/3 or better had four guns. Apparently the British didn't get the benefit of their own expertise in this case. There are also timing issues to work out. The P-40D with four wing mounted .50s was ordered during the early part of the battle of Britain, The first one wasn't delivered until late spring of 1941. Only about 30 or so built because the contract had been amended to 6 guns. When and Why? it could take months for such a change to go from paper order to actual production model rolling of the line.
The Wildcat thing also points out that once lend lease started the British got what the US wanted to give them, not what the British themselves wanted. Case in point the M3 Lee and Grant tanks. Apparently the US was only going to listen to British expertise so much.

 

[Njaco]

well, no techno nut here - just limited knowledge - so my choices would the P-40 and P-43.

I do have to say my impression is this is somewhat hard to make a choice given the parameters of the discussion. The LW had numerous designs to choose from while the US had about half as many. Makes this interesting.

 

[tomo pauk]

Think it was the other way around - Germans have had 4 SE fighter types worth speaking of (109, He-100 -112, while 190 just manages it for 1941), while US produced P-36, -39, -40, -43, -66, F4F, Buffalo, CW-21. All for a 1939-42 time frame; even the prototype of F4U was flying long before Pearl.

 

[parsifal]

Whi;st i cant put my fingers on my paper source material, I am fairly certain that it is true that the decisions to incorporate armour, self sealing tanks, and a six gun broadside were at the request of the british purchasing commission. these were known in the RN as martlet II, whilst they were concurrently developed as the F4f-4 for the USN. The decision to build to this standard was a british one, however.

The reason why most of the early deliveries were not to this standard, is because the majority of martlets received by the RN were foreign orders, principally french and greek orders diverted to to the RN. The first mkIIs were not delivered to the RN until December, after earlier deliveries of the F4f-4 to the USN had revealed serious problems in the fuel systems (i think, in any event the F4f-4s delivered to the USN in 1941 were not airworthy).

Later, the majority of f4fs were FM-2s, which were cut down versions adapted for use from escort carriers. these FM-2s retained the same level of protection afforded to the martlet IIs, but reduced armament. by the time of their introduction, the main fleet types for the Rn had progressed to the Hellcat and the corsair, but even so, by the time of the introduction of the FM-2, I think the inferiority of allied pilots was passing. no longer was acquiring an enemy target such a fleeting desperate affair. allied pilots were better, axis pilots were worse, and the FM-2 was really trhere for convoy protection (though it was often pressed into servicce for more frontline duties anyhow).

The FAA website gives this description about martlet usage:

Versions
Mk I British version of the F4F-3; Four 05in machine guns
Mk II British version of F4F-4 with folding wings, armour, self-sealing fuel tanks and six 0.5in machine
guns
Mk III
Mk IV
Mk V General Electric built FM-1 with R-1830-86 engine, four 0.5in machine guns with provision for
underwing stores or: FM-2 with 1,350hp Wright R-1820-56 Cyclone, with taller vertical tail
surfaces and on some aircraft provision for six 5-inch rockets under the wings

In total the Fleet Air Arm received 1172 Wildcat 1940-1945. The first Wildcat used by the Fleet Air Arm were 53 Grumman G-36a Martlet I, and 6 Grumman G-36a Martlet III diverted from a French order which had not been delivered before the Fall of France in 1940. The aircraft were all delivered to the British Purchasing Commission on 23 August 1940 and transferred to the first FAA unit 804 Hatston on 7 September 1940 (eg AX827), 778 squadron at Arbroath in September 1940 (eg AX826), 759 squadron at Yeovilton in October and November 1940 (eg BJ555) and 802 squadron at Donisbristle on 23 November 1940 (eg AL237).

Further aircraft in 1940 were lost when 20 Grumman G-36a Martlet I diverted from an undelivered French orders sank with SS Ruperra which was torpedoed 500 miles NW of Ireland on 19 October 1940.

The next Wildcat to be received by the Fleet Air Arm were in Spring of 1941, when 30 Grumman F4F-3a Martlet III ordered by Greek Purchasing Commission in August 1940 for shipment to Greece reached Port Suez in April 1941, then diverted to the Royal Navy under Lend-Lease transfer on 4 April 1941. These aircraft were subsequently involved in convoy patrols, one Martlet piloted by Sub Lt R Griffon shot down a S.79, forced two others to jettison bombs, then hit by return fire attacking a fourth, dived vertically into sea 50m N of Ras el Milh on 28 December 1941.

Martlet II started to be delivered in December 1941, when 54 were shipped from New York to Bombay arriving in March 1942 (AJ100), this was closely followed by further losses of 10 Martlet III in HMS Audacity on 21 December 1941.

With this situation, 16 Grumman F4F-3 [Martlet III equivalent] were loaned from the US Navy to 890 and 892 Squadrons during work up at Norfolk, Virginia, USA from 18 July 1942 until 12 September 1942 after which the aircraft were returned to the USN. All these aircraft were from the USN squadron VF-9, and carried 9F codes (they kept their US Nos: BuAer Nos 1858-3873).

By February 1942, the first major delivery of 220 Wildcat IV (ex Martlet IV until 1.1.44) was made. 806 squadron was equipped with Martlet II from July 1942 on HMS Indomitable, whilst most were shipped to the UK in September 1942 onwards, first reaching 896 squadron in November 1942, and 312 Grumman FM-1 Wildcat V delivered in June 1943 to 787 squadron and C Sqdn A&AEE in July 1943, and 1832 squadron from August 1943.

The Wildcat was one of the FAA's primary naval fighter up till the end of 1942. However, during 1943 Wildcat squadrons started to be re-equipped with either the larger Grumman F6F Hellcat or the Chance-Vought F4U Corsair.

However, orders continued and 288 Grumman FM-2 Wildcat VI were delivered in May 1944, firstly to AHU Stretton, and 881 squadron in July 1944. Many of these latter aircraft remained in service with the FAA until 1946. The final 82 Grumman FM-2 Wildcat VI were delivered in August 1945 up until November 1945, and mainly being sent out to the Far East and Australia

 

[Shortround6]

Perhaps the request for armor and self sealing tanks was the request of the British and maybe not. At what point did the US army decide that any P-38 ,P-39, or P-40 without armor or self sealing tanks would be held in US territory as training aircraft and were not combat capable. Having observers in England might lead to the same conclusions being drawn. It also turns out that early American self sealing tanks were not compatible with British fuel.

 

[renrich]

According to Lundstrom the six gun package in the F4F4 was solely at the behest of the British Purchasing group and was strongly resisted by the USN. The armor, SS tanks and folding wings were installed because the USN had already retrofitted all but the wing fold in the F4F3, based on the advice of observers in England in 1940.. The USN wanted to carry more fighters on the carriers and the wing fold was needed for that. The addition of the two extra guns caused a lot of design problems for Grumman and a small number of F4F4s reverted to the four guns as well as the FMs. The six guns was obviously a mistake and my guess is that the British wanted it because they were accustomed to eight or even twelve guns and four just did not seem like enough. The USN, on the other hand, felt that pilots well trained in gunnery were better off in the carrier warfare environment with more ammo per gun and a longer firing time. Thach said, "If you can't hit with four you would miss with eight." (I think.)

Shortround, many thanks for posting the report about manufacturing of engines and airplanes. Most interesting and informative. I skimmed it and it answers a lot of questions about why certain models of US aircraft were produced when they were. I had always wondered about the long gestation period of the Corsair and my book by Boone Guyton did not adequately explain it. The rebuilt ( after a crash) XF4U attained a speed of 404 mph in October, 1940, and in November, 1940 the Navy requested a production airplane with certain changes. The first production airplane flew on June 25, 1942. Why the delay between prototype and production? Of course, the urgency was not there until December, 1941 which partially is an explanation. Another explanation obviously is that there is little use in producing airplanes if there are no engines for the aircraft.

However, there is another point which the report you posted does not address. We have all heard about the performance and reliability of the P&W R2800 engine but in 1940, 1941 and later, the R2800 was far from a finished and fine tuned product. In Guyton's book they continually had problems with the engine as well as the Hamilton Standard prop. In the production models of the F4U1, in 1942 and later there were a number of crashes caused by engine failures, one of which almost killed Guyton, putting him in the hospital for a number of months. Whether these were design flaws or production defects, letters between Vought and P&W (both owned by United Aircraft) were flying back and forth and redesigns and manufacturing process changes must have caused delays in R2800 production. Even when airplanes like the Corsair and Thunderbolt became operational, there were electrical problems with the engine which showed up during high altitude operation.

 

[tomo pauk]

The F4U was redesigned to accept more guns (4 -> 6), all now located in wings. That required deletion of wing tanks, necessitating installment of a large hull fuel tank to solve that. Therefore the hull too endured stretching. Quite a lot of redesign (coupled with peace time development) - no wonder it took time to execute properly.

It would've been interesting if XF4U entered production in second half of 1941 (and redesigned/historical version in 1943).
Perhaps 1850 HP (deliveries of B-26 commenced early in 1941, same power), 4 HMGs, lighter than historic F4U-1, shorter nose for better landing approach. An US La-7?
Doesn't solve the issues Navy examples of R-2800 had that early, though.

Or with R-2600 (1700 HP; wider, but lighter). *ducks for cover*

 

[renrich]

TP, as I am sure you know, not all the wing tanks were deleted in the F4U1. There were two unprotected wingtanks which could be purged with C02. They enabled the F4U1 to carry 361 gallons of fuel internally. One of the major problems with the F4F was it's short range. Early in the war there were no belly tanks for the Wildcat and it's combat radius of 150-175 miles severely limited it and probably caused some air to air combat losses at Coral Sea. The Wildcats escorting Torpedo Three were cruising at 105 knots to save fuel when they were jumped by Zekes. The Wildcats did not maneuver well below 130 knots and two were duck soup. The early Corsair had a substantial increase in range over the Wildcat which came in very handy.

 

[tomo pauk]

Ren, do you have any info about how much fuel XF4U carried?

 

[davparlr]

The F4U was redesigned to accept more guns (4 -> 6), all now located in wings. That required deletion of wing tanks, necessitating installment of a large hull fuel tank to solve that. Therefore the hull too endured stretching. Quite a lot of redesign (coupled with peace time development) - no wonder it took time to execute properly.

No production F4U was equipped with only four 50s. The F4U-1 and -1A had wing fuel tanks and six 50s. The wing fuel tanks were not removed until the -1D was delivered. I am not sure but I believe the wing tanks were removed on the -1D because by that time long range flight was not as important as earlier in the war. Renrich would probably know.

 

[davparlr]

Ren, do you have any info about how much fuel XF4U carried?

As far as I can tell it was the same as the F4U-1 or 237 gal in the fuselage tanks and 114 gals in the wing tanks for 351 gallons internally. For comparison, the Bf-109 carried about 106 gallons internally.

 

[renrich]

According to Guyton's book, the XF4U carried 273 gallons of fuel. Seems like a lot to me. It had three 50 cal mgs and one 30 cal mg. That seems odd but I recall that other US fighters at that time had one 50 cal and one 30 cal over the engine. One interesting thing about the crash of the XF4U in July, 1940, is that, at the most, the XF4U was carrying one of only 19 R2800s in the world, according to SRs info he posted. I don't know if the engine was ruined by that crash. Guyton got the fuel and ignition cut off before the airplane went into the ravine. The Vought company rebuilt the plane in three months.

 

[tomo pauk]

No production F4U was equipped with only four 50s. The F4U-1 and -1A had wing fuel tanks and six 50s. The wing fuel tanks were not removed until the -1D was delivered. I am not sure but I believe the wing tanks were removed on the -1D because by that time long range flight was not as important as earlier in the war. Renrich would probably know.

The redesign I've posted about was the redesign of XF4U to become F4U-1
Thanks for the info re. fuel tanks.

 

[renrich]

I believe the wing tanks were removed because they had started using drop tanks extensively. The Corsair could carry a maximum of two 150 gallon tanks. Another difference between the XF4U and the production models was that the XF4U had compartments in the wings to hold bombs. The were deleted in production F4U1s.

 

[Shortround6]

According to Lundstrom the six gun package in the F4F4 was solely at the behest of the British Purchasing group and was strongly resisted by the USN.

Ok, I guess I can Accept that.

The six guns was obviously a mistake and my guess is that the British wanted it because they were accustomed to eight or even twelve guns and four just did not seem like enough. The USN, on the other hand, felt that pilots well trained in gunnery were better off in the carrier warfare environment with more ammo per gun and a longer firing time. Thach said, "If you can't hit with four you would miss with eight." (I think.)

The timing may be an issue here. The Browning .50 cal cycled at 600rpm (10 rps) up until 1940/41 after which it was speed up to the nominal 850 rpm (14rps) so 6 X 10rps= 60 rps or 4 X 14 rps= 56rps. If the British made their request before the more rapid rate of the .50 was finalized it may not have been a mistake. If it was made later then it probably was. The British found that the Synchronized .50s on some of the planes they received had rates of fire as low as 450rpm. While Thach was a great pilot I am not so sure his quote is all that accurate, not that he didn't say it but didn't he join the navy in 1929? over 10 years flying experience, hundreds if not thousands more hours flying than many of the pilots joining up in 1941/42.

Why the delay between prototype and production? Of course, the urgency was not there until December, 1941 which partially is an explanation. Another explanation obviously is that there is little use in producing airplanes if there are no engines for the aircraft.

However, there is another point which the report you posted does not address. We have all heard about the performance and reliability of the P&W R2800 engine but in 1940, 1941 and later, the R2800 was far from a finished and fine tuned product. In Guyton's book they continually had problems with the engine as well as the Hamilton Standard prop. In the production models of the F4U1, in 1942 and later there were a number of crashes caused by engine failures, one of which almost killed Guyton, putting him in the hospital for a number of months. Whether these were design flaws or production defects, letters between Vought and P&W (both owned by United Aircraft) were flying back and forth and redesigns and manufacturing process changes must have caused delays in R2800 production. Even when airplanes like the Corsair and Thunderbolt became operational, there were electrical problems with the engine which showed up during high altitude operation.

I am not sure that the prototype XF4U was using a two stage supercharged R-2800 for it's first flights. Accounts differ and some of the power ratings don't make sense to me, although they do if you count one digit as a typo?
Some of those "electrical" problems also affected Wright R-1820s and Allisons (turboed R-1830s?) . The thinner air gets the less it acts like an insulator and the magnetos on high altitude engines tended to cross fire or short to casing and miss fire. Certain models of these engines resorted to pressurized magnetos and others changed to a low voltage ignition with booster coils near the plugs.

 

[tomo pauk]

XF4U nicely fits the bill for 'ideal fighter' for USAAC, late 1941. And for USMC.
Not that Navy wouldn't have something to say about that

 

[tomo pauk]

Here it is, (1943 variant though - 6 guns, 2000 HP):