P-400 Airacobra In North Africa

[mjfur]

Robert Davidson's P-400 was BX385. He had a taxing accident on Jan.19, 1943.
I found this thread relatively late, but here's a small addition. In a site I'm following since ...e-e-eh....long time (RAF 112 squdron) there is a Honour Roll of the 350th FG. with many serials and additional data about the P-400 in the MTO. Interesting are the landings in Portugal, en route to North Africa.
Cheers!

Spun in while taxiing?

It's a P-400. Anything is possible.

My photo shows the P-400 after being stripped of usable parts and abandoned. FYI - the photo is dated July 1943.

 

[MIflyer]

That tank looks like the 'flat' 150-gallon tank developed for the P-47 in the ETO.

It does, and also resembles that smaller flat tank used on the belly of the P-47. The author said it was a 185 gallon tank, and I'd say the one in that photo looks about right for that size.

One thing I wonder is that if all 675 Airacobra I/P-400 aircraft were delivered to the UK and then dispatched to the USSR and the South Pacific and eventually to North Africa or if some never made it to the UK and were dispatched from the US.. 54 were lost at sea during transport and 212 went to the USSR. I suspect that all of the P-400's made it to the UK and were sent elsewhere from there, mainly by sea.

In addition to the 675 aircraft purchased by the UK, another 494 were bought with lend lease funds and equipped with 20MM cannon instead of 37MM for commonality reasons. So there were both P-400's and P-39D-1's with 20MM guns.

Here is a picture of what must be a recovered Soviet P-400, based on the RAF color scheme.

 

[varsity07840]

Note that he refers to the "1165 HP unsupercharged engines." This is more traditional BS. The P-400 had a single stage mechanical supercharger, which essentially was invisible to the pilots, since he had no control over it. The earliest models of Spitfire featured the the pilot's ability to engage and disengage the supercharger, so he knew it was there. On the P-39, P-400, P-40, and Mustang Mk I the pilot had no control over the supercharger except by moving the throttle, but they had just as much of a supercharger installed as did the Spitfire I, II and V. Thus the oft repeated old nonsense that "the Air Corps deleted the supercharger from the P-39 in order to emphasize its low altitude performance." In reality the supercharger for the P-39 typically was optimized for 10,000 - 15,000 ft. The turbosupercharger was deleted from the P-39 because the increased drag associated with it made the airplane SLOWER than just the single mechanical supercharger.

 

[varsity07840]

Note that he refers to the "1165 HP unsupercharged engines." This is more traditional BS. The P-400 had a single stage mechanical supercharger, which essentially was invisible to the pilots, since he had no control over it. The earliest models of Spitfire featured the the pilot's ability to engage and disengage the supercharger, so he knew it was there. On the P-39, P-400, P-40, and Mustang Mk I the pilot had no control over the supercharger except by moving the throttle, but they had just as much of a supercharger installed as did the Spitfire I, II and V. Thus the oft repeated old nonsense that "the Air Corps deleted the supercharger from the P-39 in order to emphasize its low altitude performance." In reality the supercharger for the P-39 typically was optimized for 10,000 - 15,000 ft. The turbosupercharger was deleted from the P-39 because the increased drag associated with it made the airplane SLOWER than just the single mechanical supercharger.

How could an aircraft such as the Spitfire Mk 1 with a single speed supercharger have the option to disengage it? And, for what purpose?

 

[varsity07840]

Note that he refers to the "1165 HP unsupercharged engines." This is more traditional BS. The P-400 had a single stage mechanical supercharger, which essentially was invisible to the pilots, since he had no control over it. The earliest models of Spitfire featured the the pilot's ability to engage and disengage the supercharger, so he knew it was there. On the P-39, P-400, P-40, and Mustang Mk I the pilot had no control over the supercharger except by moving the throttle, but they had just as much of a supercharger installed as did the Spitfire I, II and V. Thus the oft repeated old nonsense that "the Air Corps deleted the supercharger from the P-39 in order to emphasize its low altitude performance." In reality the supercharger for the P-39 typically was optimized for 10,000 - 15,000 ft. The turbosupercharger was deleted from the P-39 because the increased drag associated with it made the airplane SLOWER than just the single mechanical supercharger.

 

[Geoffrey Sinclair]

One thing I wonder is that if all 675 Airacobra I/P-400 aircraft were delivered to the UK and then dispatched to the USSR and the South Pacific and eventually to North Africa or if some never made it to the UK and were dispatched from the US. 54 were lost at sea during transport and 212 went to the USSR. I suspect that all of the P-400's made it to the UK and were sent elsewhere from there, mainly by sea.

In addition to the 675 aircraft purchased by the UK, another 494 were bought with lend lease funds and equipped with 20MM cannon instead of 37MM for commonality reasons. So there were both P-400's and P-39D-1's with 20MM guns.

Not all the P-400 went to the front via Britain, some were delivered to Britain then exported to the USSR, some were delivered to Britain and transferred to the USAAF, some were retained by the USAAF. Later British Lend Lease P-39 were sent to the USSR but charged to the British Account, "Britain For Russia"

Total of 675 P-400, accepted May 1941 to April 1942, exported June 1941 to April 1942 plus 1 straggler in July 1942. First order for 170, USAAF took 6, second order for 205, USAAF took 150, third order for 300, USAAF took 40, leaving 479 for Britain. Britain also received 3 P-39C, accepted in March 1941, exported in June. Britain records importing 480 Airacobra June 1941 to July 1942 and exporting 281 Airacobra November 1941 to September 1942. Air Arsenal North America reports 179 transferred to USAAF in Britain, which means 460 of the reported imports are accounted for. There are another 213 "exports" in May and June 1943 which seem to be accounting for some of the Britain for Russia P-39 plus at least 1 remaining P-39 from Britain.

150 P-39D-1 were on contract DA-32, plus 186 P-39D-1 and 158 P-39D-2 were on contract DA-156. DA-32 was 149 USA, 1 USSR, accepted April to June 1942, DA-156 D-1 were 184 USA, 2 USSR accepted April to August 1942, the D-2 were 61 USA, 97 USSR, accepted June to August 1942.

 

[MIflyer]

How could an aircraft such as the Spitfire Mk 1 with a single speed supercharger have the option to disengage it? And, for what purpose?

Disengaging it is easy. It is a device called a "Clutch" and the F4F, F6F, F4U, and P-61 had the ability to manually engage the supercharger speeds. The Merlin Mustang had the option to manually engage the high speed supercharger, but except for modified airplanes that switch was spring loaded and had to be held in position. As for the Spitfire having that option a friend of mine, who joined the RAF and went to the UK prior to Pearl Harbor, described that. But I have not checked the pilot's manuals.

 

[GrauGeist]

The P-51D's supercharger control switch was located at the lower-center of the instrument panel.
To the right of that control switch was the engine ignition switch, with a supercharger "high blower" warning light situated between.

 

[OldGeezer]

I think the Russians would be very surprised to hear that the 37mm cannon would only fire one round, or 2-3 at most, before jamming. I don't recall reading in any of their stuff that this was a problem. Maybe it was just another rumor that the author (flying 20mm-armed versions) heard from others, without any documentation?

 

[MIflyer]

Maybe it was just another rumor that the author (flying 20mm-armed versions) heard from others, without any documentation?

The RAF tested the 37MM equipped P-39 on a gunnery range for an anti-tank test to compare it to the 40MM equipped Hurricane IID. They found:
1. The 37MM would not crack a German tank, while the 40MM would.
2. It jammed after a very few shots. They modified the ejector mechanism and then it worked, but that was not for in flight firing.

In the book Cobra Combat the author, who flew a lot of P-39 missions in the Pacific said that the 37MM would jam if you were not very careful to fire with positive G's. It needed gravity to eject the empty shell casings. It worked Okay if you were sure that you were not firing it while starting a dive, which induced positive G's. You pushed the nose over, got it on the target and then fired it without increasing the dive.

 

[GregP]

The belly above tank was actually a bumper car body from Coney Island that was sealed up and used as a gas tank. It was still painted in amusement park colors and it wouldn't feed above 12,000 feet but, since they never went any higher anyway, it didn't really matter. The propeller was taken from a P-40 ceiling fan that was seen as a potential source of surplus aircraft parts. Shown below.

Nobody knew these thing came from China, so we used them by the thousands. Unfortunately, the chains to fire the armament couldn't be used since they would get tangled up in the prop.

 

[OldGeezer]

The RAF tested the 37MM equipped P-39 on a gunnery range for an anti-tank test to compare it to the 40MM equipped Hurricane IID. They found:
1. The 37MM would not crack a German tank, while the 40MM would.
2. It jammed after a very few shots. They modified the ejector mechanism and then it worked, but that was not for in flight firing.

In the book Cobra Combat the author, who flew a lot of P-39 missions in the Pacific said that the 37MM would jam if you were not very careful to fire with positive G's. It needed gravity to eject the empty shell casings. It worked Okay if you were sure that you were not firing it while starting a dive, which induced positive G's. You pushed the nose over, got it on the target and then fired it without increasing the dive.

Nikolay Golodnikov talked about the 37mm gun and the reasons why different users had different experiences with them: "The Cobras had interesting reloading and cannon trigger mechanisms -. hydraulic. At first, in the 'English version' of the 'cobras', they had a lot of trouble with them, the 'hydraulics' froze. Apparently, these 'cobras' were intended for Africa, because the slurry thickened and clogged the holes in the hydraulic cylinders. So our craftsmen replaced the slurry with a domestic one and increased the holes in diameter. The recharge started working normally... The M-4 was a very reliable gun. If this gun had failures, it was only through the fault of completely unqualified service." He was no fan of the alternative Hispano-Suiza 20mm: "Hispano demanded an incredible quality of service. The slightest dustiness, thickening of the lubricant or some other trifle, and that's all - a failure. Very unreliable." So like most things, reports on the M-4 gun seem to vary quite a bit between users.

 

[MIflyer]

The Soviets seem to have been impressed enough by the 37MM that they used a 37MM in the Mig-15. I wonder if that 45MM gun they used in that Yak-9 variant actually was used for anti-tank.

The USN found they could only get the 20MM Hispano to work reliably if they coated the rounds with wax. Even so they found that the F4U's with 20MM guns they deployed to Okinawa had problems with the guns working at altitude. Reportedly, the USN decided to dispense with the high altitude low temperature testing because the Japanese did not usually fly that high.

 

[GrauGeist]

Of course the M4 was really popular with the PT Boat guys.

 

[varsity07840]

Disengaging it is easy. It is a device called a "Clutch" and the F4F, F6F, F4U, and P-61 had the ability to manually engage the supercharger speeds. The Merlin Mustang had the option to manually engage the high speed supercharger, but except for modified airplanes that switch was spring loaded and had to be held in position. As for the Spitfire having that option a friend of mine, who joined the RAF and went to the UK prior to Pearl Harbor, described that. But I have not checked the pilot's manuals.

All those aircraft had two speed superchargers which could be shifted to high and low blower speeds. What would be the purpose of a single speed supercharger that could be disengaged?

 

[SaparotRob]

Bragging rights?

 

[Shortround6]

All those aircraft had two speed superchargers which could be shifted to high and low blower speeds. What would be the purpose of a single speed supercharger that could be disengaged?

Actually they didn't. and they did. The F4F, F6F, F4U, and P-61 all had a single speed supercharger that ran at all times, no disengagement.
However they all had an auxiliary supercharger with 2 speeds and a "Neutral". I believe the F4U had doors/flaps in the intake system that could bypass the auxiliary supercharger.
The F6F and P-61 drew their air through the auxiliary supercharger and the impeller "windmilled" as the air went through it. Not sure on the F4F.
Supercharger was pretty rugged. Engage the clutch and the impeller had to go from near zero to 17,400 rpm very, very, very quickly.
A very good reason why nobody else did it.

 

[Shortround6]

The Soviets seem to have been impressed enough by the 37MM that they used a 37MM in the Mig-15

They weren't impressed with the US M-4.
They were impressed with their own 37mm cannon

Used in the some Yak fighters and in some IL-2s. A little too much of a good thing.

 

[GrauGeist]

The Nudelman NS-37 was an upgrade from the Sh-37, which itself was developed from the 61-K 37mm AA cannon.
Postwar, the NS-37 was further developed to the N-37 (which was used in the MiG-15).

The only thing the Soviet 37mm had in common with the M4, was caliber.

 

[CATCH 22]

I was curious to check if P-39 did or didn't have a single-stage supercharger, just because I remembered reading about early US-engines being equipped with the latter. This is a quote from the first book about P-39 I opened: