P40 Vs all other fighters in Europe

[Schweik]

Didn't matter how they were mounted, the guns were tested with the plane flying straight and level, RAAF .50's didn't work and neither did the same guns fitted to FAA F4 Martlets, we have covered this in other threads.

They had a lot of problems with the .50s in the first few months (for several reason, both aircraft and ammunition), though this was starting to dramatically improve by mid 1942 (not every unit sorted it out at the same time).

They also had quite severe issues with the Hispano cannons particularly in the Tropical conditions, around the same time.

 

[PAT303]

They had a lot of problems with the .50s in the first few months (for several reason, both aircraft and ammunition), though this was starting to dramatically improve by mid 1942 (not every unit sorted it out at the same time).

They also had quite severe issues with the Hispano cannons particularly in the Tropical conditions, around the same time.

In 1939-40 the .30's from all nations were a proven gun yet the .50 and 20mm were described by the RAF as underdeveloped, including the ammunition.

 

[Schweik]

In 1939-40 the .30's from all nations were a proven gun yet the .50 and 20mm were described by the RAF as underdeveloped, including the ammunition.

It's kind of the perpetual dilemma of the war (and speaks to the circumstances of aircraft like the P-40 and the Hurricane) do you go with what you know works or gamble on something new and potentially much better?

 

[Brent]

Yeah, it did get a Merlin in a couple of models.



As a boy, I read and absorbed the idea that the P-40 was quite craptastic, but in the many intervening years I seem to get that like many overlooked airplanes, in the hands of a decent pilot using good tactics it was a dangerous opponent. Relatively maneuverable, good dive characteristics, limited in altitude performance in most cases, but well-armed and rugged.

Maybe not the prom queen, but a good date to dance with if that's what you've got.

I love that not the prom queen line!! I talking to a EAA chapter about my own P40k project and I'm gonna use it for sure!

Was it the hottest airplane we had? Maybe at first but certainly not by the end. But what 1935 design (think P-36) would still hold up by 1943? Not many other than the 109 and the P-38.

The Brits and Aussies in North Africa and the AV G showed how capable it could be with proper handling and strategy. Saburo Sakai said that down low the P-40 was one of his roughest opponents

But is it really too draggy to ever be updated to P-51 levels. A fat wing and a whole lot of airframe drag kept even the updated versions from getting real fast. It's kinda like comparing Babe Ruth to modern ballpayers training and equipment. For me personally the tradition and the style of the P-40 will always be an icon like the Colt 1911 and the Fender Stratocaster IMHO of course!

 

[Thumpalumpacus]

But is it really too draggy to ever be updated to P-51 levels. A fat wing and a whole lot of airframe drag kept even the updated versions from getting real fast. It's kinda like comparing Babe Ruth to modern ballpayers training and equipment. For me personally the tradition and the style of the P-40 will always be an icon like the Colt 1911 and the Fender Stratocaster IMHO of course!

Right, it was an important waypoint on the road to more-modern fighters, and in its day was nothing to sneeze at. The Kiwis were using them creditably in 1944 in the Solomons, some American units were using them in that year in the MTO, and while the airframe was flawed by its older design and provenance, it was still able to cut a bit of mustard. It ain't a P-51 or Spit, never will be, but it hung in for a long time giving creditable service against enemies of its era.

 

[SaparotRob]

Most perfectly adapted airframe for a shark's mouth. We were all thinking it.

 

[Schweik]

And in some roles it was more suitable than a P-51 or Spit. But it was just not as generally useful especially for what were thought of as the most important roles (escorting heavy bombers and point defense / interceptor duties especially for England).

I think the short-hand on the P-40 was that it was originally a shock how poorly it held up to Axis aircraft, but then as we scrambled to train pilots, develop suitable tactics, and make a lot of minor improvements, it turned out that the P-40, in spite of it's one major flaw (altitude) remained surprisingly effective in almost every Theater of the war - except NW Europe - till surprisingly late. Not only the Kiwis but the Aussies and the Americans were still using them in the Pacific in 1944, the Americans used them into 1945 in Burma, the Americans used them as fighters through the middle of 1944 in Italy, and the British continued to use them (as fighter bombers) right up to the end of the war. The Soviets also used them until 1944 at least and they played an important role in key battles in 1942 (at Moscow and Leningrad).

In fact the P-40 proved just good enough to still bite at the nadir for the Allies all over the world in 1942, and then as things improved into 1943 was one of the key types which helped take out a lot of those elite aircrews. It was crucial at the hinge-point and lasted in a useful role a bit beyond that.

 

[tomo pauk]

Right but my real point is that they weren't slow compared to their opposition. I would also say, 360 mph in early 1942 (once they are pushing the engines a bit harder) is not slow, it's about average for a fighter. Some were faster but not necessarily in the field.

If the opposite side has aircraft doing 400 mph, like the Luftwaffe had in 1942 in the field, the 360 mph fighter is a slow fighter. Granted, not as slow as 320-330 mph Hurricane II or F4F.

My understanding is that the -33 had a slightly higher ratio, I'd have to go pull down some books to check. But for example according to this Sept 1941 data sheet, it had a critical altitude at military power of 13,600, where it is producing 1040 hp, and performance is usually still pretty good for another 2,000 feet above that. Which puts you at about 15,600

This similar chart from Dec 1942 for the P-40D/E shows a critical altitude at military power of 11,800 ft. Which puts you at 13,800 (but I think that was pushing it!). It's interesting though that the chart does show 56" Hg WEP setting for 1470 HP at Sea Level. I don't think a lot of units in the field got that memo until a bit later (like March).

The -33 impeller was turning at 8.77 times the crankshaft speed, the -39 impeller was turning at 8.80 times. A power of 1040 HP at 13600 ft is always 1040 HP at 13600 ft, whether made by the -33 or the -39.

My understanding is that there were different types of the later generation Allisons, and the variant they put on the 'Interceptor' configurations of the P-40N was the higher boost type, however the 'Fighter Bomber' type P-40N and the P-40Ms were limited to lower boost, this chart for a P-40M with the V-1710-81 shows 1360 for WEP and 1200 for takeoff. The infamous Allison Memo also mentions this, that the higher geared Allisons were going to have more trouble with high boost (due to heat, from what I gather).

Note the altitude for the WER there - sea level. It will be making more high up, as can be seen at the chart I've previously posted. The ram effect adds another 2500 ft for the rated altitude for WER power setting (57 in Hg at 3000 rpm). The Alison memo indeed warns for not over-boosting the new engines (the ones where impeller turns at 9.60 times the crankshaft rpm), and the power tables and chart show that, the new engines making ~100 HP less at low level vs. 'old' versions that could be run at 60 in Hg down low with blessing from Allison and USAAF. The 'old' S/C will also consume less power to drive, so more power is left to turn the prop.
There was no such thing as "this is a F/B P-40N, so easy on the throttle, fellas".

Right but without the second speed it would then be relatively a dog down low. As it was the P-40K was considered much faster than the P-40F below 4,000 ft.

As it should be, it had more power there. Trick was finding the answer how to gain performance, altitude and situational advantage over the enemy at all combat altitudes: the P-40 was lacking in that domain vs. the Luftwaffe, and could get at best the parity in Asia/Pacific.

But all the single speed superchargers had that problem - you pick where you want to go fast. Down low means poor at high altitude, up high means the reverse. It's just a bit less of an issue with a Spitfire because that is a much lighter aircraft (at least pre-Griffon)

Easy pick - the higher, the better.
FWIW, I was trying to note that 2-speed S/C is not be-all end-all qualifier, when we talk about 1-stage supercharged engines.

 

[Shortround6]

Tomo has covered just about all of the technical changes to the Allison engines.

Some of the pilots manuals don't quite line up with the Allison factory specifications. But some of the pilot manuals tend to get a little sloppy with ram and no ram altitudes
There were some refits with changes with the backfire screens, too. But the superchargers and gear ratios stayed the same. until the 9.60 gears came along.

But the main impeller when driven with a 8.80 (or 8.77) supercharger was only going to do so much and it didn't matter if you had the plain steel crankshaft, the shot peened crankshaft or the shot peened and nitrided crankshaft. The engine would hold up longer without breaking at low altitude but it was not going to make any more power at 12,000-15,000ft. (aside from changing out the backfire screens).

The 9.60 supercharger gears increased the temperature of the mixture and the higher temperature is what caused the caution in restricting the Pressure. An engine running 9.60 gears was always going to be operating closer to the detonation limits.

I would note that the WER were also what the engine should make no RAM (like climbing or coming out of a steep turn)

The P-40 also got lucky. How many threads do we have on things the Japanese could have done differently. (or what the Italians could have done differently)
If the Japanese had looked around and realized that the Ki-43 needed to be retired at the end of 1942 then a lot of the P-40 saga against the Japanese facing Ki-44s ( or Ki-44s with big wings) would have been way different.

The P-40N (and the L) were both attempts to lighted the plane up when they realized they weren't going to get much in the way of increased power. But with the N the difference in performance wasn't great and the trade-offs limited the actual utility of the airplanes. There were thousands of P-40Ns built (over 1/2 the production run)and no more of the 400 were hotrods were built, if that many and a number of them were converted back to normal Ns, at least somewhat. The Japanese and Italians and to some the extent the Germans, were not able to come up with next generations fighters (or even good improvements to existing generation fighters) that would have knocked the P-40s out of the feild.

 

[K5083]

How many threads do we have on things the Japanese could have done differently. (or what the Italians could have done differently)

Got a big engine? Use it. Not got one? License it. Can't license it? You're screwed. Power is the key.

 

[tomo pauk]

Got a big engine? Use it. Not got one? License it. Can't license it? You're screwed. Power is the key.

Japanese answer to the 1st question was 'yes'. However, the 'use it' part of the deal was not exactly followed through, especially for the Navy fighters.
Italian engine policy past 1935-ish was a hot mess, leaving them to a late start by 1940s, despite the licence deals with DB.

 

[drgondog]

Didn't matter how they were mounted, the guns were tested with the plane flying straight and level, RAAF .50's didn't work and neither did the same guns fitted to FAA F4 Martlets, we have covered this in other threads.

Actually it mattered significantly in P-51B/D. The solution to the B was addition of booster motor (from B-26 top turret IRC) to assist feed continuity uner high G, but realigning the 50 cal upight in the D solved the feed issue

I do know that RAF had to exert some cycles to sort out both feed chutes and mounts for the Mustang I and IA to solve issues with early Mustang 50 cal and 20mm.

 

[PAT303]

It's kind of the perpetual dilemma of the war (and speaks to the circumstances of aircraft like the P-40 and the Hurricane) do you go with what you know works or gamble on something new and potentially much better?

The Merlin only had about 1100hp available in 1938/39 so weight was a big issue.

 

[BiffF15]

Got a big engine? Use it. Not got one? License it. Can't license it? You're screwed. Power is the key.

Or you can do like the one communist country I know of, and build stuff without a license. Currently houses the birthplace of the Wuhan Flu...

 

[drgondog]

Or you can do like the one communist country I know of, and build stuff without a license. Currently houses the birthplace of the Wuhan Flu...

Amen

 

[PAT303]

Or you can do like the one communist country I know of, and build stuff without a license. Currently houses the birthplace of the Wuhan Flu...

Oh you mean that virus of unknown origin

 

[BiffF15]

Oh you mean that virus of unknown origin

Yes, it still hasn't been confirmed which room it escaped from in the Wuhan Institute of Virology.

 

[pbehn]

The Merlin only had about 1100hp available in 1938/39 so weight was a big issue.

With a twin blade fixed pitch prop, only around 66BHP was available on take off, revs had to be limited or the prop was stalled.

 

[Peter Gunn]

The P-40 is in my honest opinion the most under rated fighter in the entire war...and there were lots of under rated fighter...F4F anyone? Considering it held the line before the war even started...its kill ratio is amazing...and it was flown against other nations at their peak by inexperienced American airmen unlike the P-51D that got to hold the trophy after the p-47 and Spitfires had already demolished the Luftwaffe.

*SNIP*

I hope you don't actually believe this do you?

That's trope has been debunked more times than your average politician lies.

 

[Schweik]

If the opposite side has aircraft doing 400 mph, like the Luftwaffe had in 1942 in the field, the 360 mph fighter is a slow fighter. Granted, not as slow as 320-330 mph Hurricane II or F4F.

But the Luftwaffe didn't have any 400 mph aircraft flying in the Med in 1942. With Trop filters their 109F and early G (toward the end of the year) were doing about 370-380 mph at their highest operating altitude. MC 202 was about the same or a little less. They got one squadron of Fw 190s briefly in 1943 but they were in Theater only for a short time.

The -33 impeller was turning at 8.77 times the crankshaft speed, the -39 impeller was turning at 8.80 times. A power of 1040 HP at 13600 ft is always 1040 HP at 13600 ft, whether made by the -33 or the -39.

As indicated on the charts I linked, the Tomahawk types were showing a higher critical altitude at military power.

Note the altitude for the WER there - sea level. It will be making more high up, as can be seen at the chart I've previously posted. The ram effect adds another 2500 ft for the rated altitude for WER power setting (57 in Hg at 3000 rpm). The Alison memo indeed warns for not over-boosting the new engines (the ones where impeller turns at 9.60 times the crankshaft rpm), and the power tables and chart show that, the new engines making ~100 HP less at low level vs. 'old' versions that could be run at 60 in Hg down low with blessing from Allison and USAAF. The 'old' S/C will also consume less power to drive, so more power is left to turn the prop.

Allison didn't give that blessing until Dec of 1942, the power issues with the Kittyhawks were already resolved by then (for several months) as acknowledged in the memo. But in early 1942 they did not know how far the engines could safely be pushed, and the improved bearings, crank shaft and crank cases were not delivered yet. Hence the problems with the early Kittyhawks starting in Dec 1941.

This is the way 11 victory P-40 Ace and Squadron Leader Bobby GIbbes put it:

"Well it was basically the same aeroplane. We were a little disappointed when we first got the Kitty, we thought it'd be way ahead of the Tomahawk. In actual fact, it was a little bit better. One thing I personally didn't like about it was the Tomahawk had fairly high sides and you'd be sitting behind a thin sheet of metal but you felt safer. The Kittyhawk had perspex coming way down and you felt as if you were sitting up, very vulnerable, because you could see out so much. That was one feature I do remember. However, later when we got our Kittyhawks running properly - were getting better performance - they were a better aeroplane."

There was no such thing as "this is a F/B P-40N, so easy on the throttle, fellas".

I believe there was though I don't know if this was just a bureaucratic thing (i.e. orders / policy) or literally a throttle limitation. Some of them had a wire which had to be broken to exceed a certain boost pressure. As Shortround6 often points out, the crew chief would typically know if they had been overboosting the engines (or just using WEP) when the plane landed due to scorch marks, oil leaks etc.

As it should be, it had more power there. Trick was finding the answer how to gain performance, altitude and situational advantage over the enemy at all combat altitudes: the P-40 was lacking in that domain vs. the Luftwaffe, and could get at best the parity in Asia/Pacific.

With the P-40, in all Theaters, they had to figure out how to contend with being attacked from above and carrying the day anyway. That is a very tall order, and it's the reason why the P-40 was considered so flawed. They worked out very specific tactics for this in the MTO, starting with just flying in pairs / figure 4 flights (which for some reason lagged in that Theater until around mid-1942) then flying in squadron formation and turning into the initial attacks as a unit (on the word of the squadron leader). And of course, using their escape maneuvers when they got into trouble.

Tactics in the Pacific and China were actually somewhat similar, except that they could extend more easily at or near co-altitude without doing a dramatic split S escape manuever and zoom climb.

Easy pick - the higher, the better.
FWIW, I was trying to note that 2-speed S/C is not be-all end-all qualifier, when we talk about 1-stage supercharged engines.

Well, generally I agree, but not always. In an Allison P-40, the higher critical altitude is a tradeoff to the much higher power down low. There were definitely more Aces made flying P-40K than M. This also depended where the fighting was taking place, which is a reflection of what kind of bombers were active and what kind of targets they were going for. In the Pacific with dive and torpedo bombers the fighting was often lower, similar in the Med and Russian Front. There is a reason why they made those LF Spitfires.