How good a plane was the P-40, really?

pbehn said:

I agree, plus most of the issues with the P-40 stem from its engines supercharger, not from the airframe itself.

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Actually, some of the issues in 1943/44 are because the airframe first flew In May of 1935 (Hawk 75/P-36) The airframe was beefed up, but aerodynamics and construction was pretty much the same. The real problem was not actually the airframe itself, it was that the P-51 airframe was over 5 years newer. The FW 190 was about 4 years newer and the New Hawker (Tornado/Typhoon) was 4-4 1/2 years newer ( engines delayed the airframe).
The P-40 was not only up against the other countries fighters, it was up against the P-47 and P-51 and P-63 for production priorities.

Shortround6 said:

Actually, some of the issues in 1943/44 are because the airframe first flew In May of 1935 (Hawk 75/P-36) The airframe was beefed up, but aerodynamics and construction was pretty much the same. The real problem was not actually the airframe itself, it was that the P-51 airframe was over 5 years newer. The FW 190 was about 4 years newer and the New Hawker (Tornado/Typhoon) was 4-4 1/2 years newer ( engines delayed the airframe).

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As we can see with Fw 190, and especially by Typhoon, is that being of newer design was not a guarantee of having aerodynamics better than the 'legacy' fighters of the day. Construction of the P-40 allowed it to loft around a good-sized weapon+ammo set-up, as well a good deal of fuel and/or bombs.

With a competitive engine in the nose, P-40 was competitive. Despite being with a bigger wing, the XP-40Q-2 was about as fast as the Fw 190D-9, and faster than the Antons.

Shortround6 said:

The P-40 was not only up against the other countries fighters, it was up against the P-47 and P-51 and P-63 for production priorities.

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Agreed all the way.
Although, if there was a choice of installing the 2-stage V-1710s on a fighter, I'd rather see these on P-40s, than on the P-63s.

Shortround6 said:

Actually, some of the issues in 1943/44 are because the airframe first flew In May of 1935 (Hawk 75/P-36) The airframe was beefed up, but aerodynamics and construction was pretty much the same. The real problem was not actually the airframe itself, it was that the P-51 airframe was over 5 years newer. The FW 190 was about 4 years newer and the New Hawker (Tornado/Typhoon) was 4-4 1/2 years newer ( engines delayed the airframe).
The P-40 was not only up against the other countries fighters, it was up against the P-47 and P-51 and P-63 for production priorities.

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The war changed too, out went N Africa as a "front" and in came the requirement for bomber escorts.

tomo pauk said:

With a competitive engine in the nose, P-40 was competitive. Despite being with a bigger wing, the XP-40Q-2 was about as fast as the Fw 190D-9, and faster than the Antons.

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tomo pauk said:

Although, if there was a choice of installing the 2-stage V-1710s on a fighter, I'd rather see these on P-40s, than on the P-63s.

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There was a trade-off. The P-63s didn't carry as much fuel. But they carried more weight of guns and were faster on the same power.
The P-40Q did hit 420-422mph, trouble is that it needed a crap load of power to do it.
The test planes carried 4 guns and 235rpg which is lot less than the P-51B carried. P-63s carried the 37mm and four .50s for about the same speed.
P-51B in the mid 20,000ft area could climb as well using 67in of boost as the P-40Q did using 75in, water injection and running at 3200rpm.
The P-51B had room for growth, the P-40Q was running into a wall. It was better than any other P-40, it was not as good as the alternatives. In 1944 the US built 14,000 P-47s and P-51s.
They didn't need P-40s.

Curtiss proposed six .50s or four 20mm but even if it didn't do much to the speed it would have hurt climb. The Prototypes held about 160 US gallons (159? like the P-40Ns they built out of?). Perhaps it could have been changed. Without the P-51 wing the P-40Q was always going to be a bit slower and carry less fuel without a significant redesign.

P-40Q whad a substantially new (smaller) wing, new cooling layout, new rear fuselage, new tail... I'm not sure how much of a P-40 it still really was. I'm also not sure if it would still have the agility that was kind of the saving grace of P-40s

P-63 was only good for the Russians due to it's very short range. And by the time it appeared the war was almost over.

P-40Q had less than half the range of a P-51, and about 60% of the range of a P-38, 70% of a Corsair or an P-47D... a lot less than a P-47N I'm not sure how much precisely. But that alone made it less versatile.

The P-40's time had come by the time those planes were available and sufficiently 'debugged'. It continued until enough of the newer types became available in each Theater, that just took a little longer than I think most people realize.

Wild_Bill_Kelso said:

P-40Q whad a substantially new (smaller) wing, new cooling layout, new rear fuselage, new tail... I'm not sure how much of a P-40 it still really was

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They just clipped the wings on the P-40Q, despite may legends/rumors/myths about new air foils, laminar flow, etc.
The tail was pretty much standard P-40.
The rear fuselage was extended, helps counter act the longer nose (like the Fw 190 D), yes they cut it down to fit the bubble canopy.
Moving radiators was not that big a deal. Unless most the British planes with leading edge radiators were new planes?

tomo pauk said:

As we can see with Fw 190, and especially by Typhoon, is that being of newer design was not a guarantee of having aerodynamics better than the 'legacy' fighters of the day. Construction of the P-40 allowed it to loft around a good-sized weapon+ammo set-up, as well a good deal of fuel and/or bombs.

With a competitive engine in the nose, P-40 was competitive. Despite being with a bigger wing, the XP-40Q-2 was about as fast as the Fw 190D-9, and faster than the Antons.


Agreed all the way.
Although, if there was a choice of installing the 2-stage V-1710s on a fighter, I'd rather see these on P-40s, than on the P-63s.

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XP-40Q versus XP-63 is a hard call.

Though I LIKE the P-63, I tend to agree with Tomo that the XP-40Q could have been a better airplane. Without comparative flight tests, it would be hard to say, but either one would have been nice to get if you were flying a P-39 and had the chance to upgrade. My stance was that the P-40Q would have been better hands down than the the P-40s they were currently flying when it became a possibility for production. So, A P-40Q or a P-63 would have been a pretty decent step up from a P-40N.

Alert:
Yanks Air Museum at Chino Airport, CA, U.S.A. is flying their P-63A (freshly restored) on Saturday, 17 Feb 24, for the public. Welcome all. Come see it it.

Shortround6 said:

There was a trade-off. The P-63s didn't carry as much fuel. But they carried more weight of guns and were faster on the same power.
The P-40Q did hit 420-422mph, trouble is that it needed a crap load of power to do it.
The test planes carried 4 guns and 235rpg which is lot less than the P-51B carried. P-63s carried the 37mm and four .50s for about the same speed.

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P-63s on same power were faster if we believe Bell's figures. USAAF figures are more conservative, talk ~20 mph more conservative.
They (AAF) were in need of aircraft that carry more fuel by 1943/44, not the ones that can also carry 37mm.

Wild_Bill_Kelso said:

P-40Q whad a substantially new (smaller) wing, new cooling layout, new rear fuselage, new tail... I'm not sure how much of a P-40 it still really was. I'm also not sure if it would still have the agility that was kind of the saving grace of P-40s

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As noted by SR6, wing was the same as on the other P-40s but clipped. There was also one-off XP-40N with the bubble canopy, it looked like this; there is a photo at pg. 260 of the 'America's hundred thousand' book. There was also an XP-40Q with full-span wings, pg. 262 of the same book.

Here's an excellent video interviewing P-40 pilot Bobby Gibbes. Watching Gibbes' homemade videos from his time in the desert was fantastic.

View: https://www.youtube.com/watch?v=7Dojo57mUmw

The saga of the P-40Q is difficult to sort out. Many accounts do not agree.


Is pretty good and has a several pictures of the early one, Which is the one that was flying for most (all?) of 1943 when most of the decisions would have had to have been made.
It appears that the 1st airframe used two different radiator setups, used two different engines (the -101 and the -121), had the canopy changed from regular P-40 to a bubble top, had it's changed and had it's wings clipped in the 3rd (?) rebuild. It first flew in June of 1943 and after the 3rd (?) rebuild was flying in March 1944 when it suffered a nose over, was repaired and was flying again when it suffered a ground loop July 1944. The 2nd aircraft first flew in March of 1944, and the 3rd flew in April 1944. The -121 engine was plagued by problems. and was responsible for several crashes.
Most of the bubble top pictures are from 1944 and that means you have two prototypes being judged against P-51Ds that went into production in March of 1944. It is no longer a case of the P-40Q vs P-51B.
P-63 was having problems to but was in limited production in Oct 1943 with it's -93 engine.

The P-63 had a drag coefficient of .0203 and was the 2nd lowest after the P-51. It had a lower flat plate equivalent than the P-40.
How they used the P-63 from a design stand point (armament/fuel load, etc) may be a different story but it was another indication that the P-40 airframe was falling behind.

Even with a single stage singe speed supercharged V-1710 the P-40E-N was a much better fighter bomber than the Spitfire or Hurricane, and probably better than the Typhoon. The RAF saw no need to replace P-40's still flying on the Northern Italy front with anything else and neither did the Aussies or Kiwis in the Pacific theater. The RAF did replace Hurricanes in the CBI with P-47's.

Wildcat said:

Here's an excellent video interviewing P-40 pilot Bobby Gibbes. Watching Gibbes' homemade videos from his time in the desert was fantastic.

View: https://www.youtube.com/watch?v=7Dojo57mUmw

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Gibbes is a wonderful character, really a hero to me. Little guy, seemingly very humble in demeanor, but hard as nails when it came down to it. He's very candid in his interviews. I have transcripts of two other long interviews he gave. I admire this fellow and like his gap toothed grin. He was part of this wonderful cadre of working class Aussies (at one point he worked as a 'jackaroo') who really added a great deal to the personality and tenacity of the Desert Air Force, counterbalancing the (mostly more aristocratic leaning) British pilots and commanders.

That video is also interesting because there is footage I haven't seen before.

I think in that clip it actually shows 3 RAAF Kittyhawk IIs (P-40F or L) flying by, you can tell for example at 02:21 because there is no air intake scoop on the top of the nose. At 03:52 I think that might be a P-40K. 3 RAAF was one of only two Commonwealth squadrons which ever got the Merlin-engined Kittyhawk IIs, a bone of contention between the US and British leadership. The US at one point was flying 16 squadrons of them in Theater.

Gibbes himself for a while led 3 RAAF squadron while it was armed with Kittyhawk II, though for a while he was flying a Kittyhawk III / P-40K (that he says he 'stole' from another unit) which he liked because it was apparently a fair bit faster below about 8,000 ft. While flying his Kittyhawk III on one occasion he famously shot down one of three Bf 109s flying above their formation at very long range. A self confessed bad shot, Gibbes was annoyed that they threw him a party because he says he was actually aiming at the lead aircraft, but hit the last one.

Earlier in the fighting in North Africa, Gibbes was part of another famous battle, flying a Tomahawk against Bf 109Fs, the British fighters shot down 6 German planes, also losing six, over the course of an hour. I think this is the fight he talks about at 9:35 in the video. Both sides were shaken by the outcome, Gibbes himself seems to have scored at least one, maybe two of the victories, but they thought they had by far gotten the worse of it. They actually underclaimed. Gibbes says he was terrified, but he was a very brave man. Gibbes is also, like James Edwards of Canada, one of that unusual species of fighter ace who appears to have underclaimed his victories. He had 10 confirmed victories but it looks like he probably got 12.

After being sent from North Africa back to the Pacific, he was part of the "Morotai Mutiny" led by his fellow North African Ace, Clive Caldwell, which required another type of courage, but which I also personally find admirable. I have a model kit of his Spit VIII which I plan to build and paint one day when I'm caught up on my backlog.

I love how in the interview he keeps apologizing for being too wordy etc. Such a cool guy.

At 26:00 in that interview, Gibbes says something interesting. (Paraphrasing) - "...for this reconnaissance mission we put on the long range tanks, because we wanted to go more than the 180 miles there and back"

So that sounds like it might be the standard real world operational radius for Kittyhawks without external tanks. Or it might just be the distance to that particular Axis airbase, but it sounds like he felt he needed the external tanks to go past it.

tomo pauk said:

P-63s on same power were faster if we believe Bell's figures. USAAF figures are more conservative, talk ~20 mph more conservative.
They (AAF) were in need of aircraft that carry more fuel by 1943/44, not the ones that can also carry 37mm.



As noted by SR6, wing was the same as on the other P-40s but clipped. There was also one-off XP-40N with the bubble canopy, it looked like this; there is a photo at pg. 260 of the 'America's hundred thousand' book. There was also an XP-40Q with full-span wings, pg. 262 of the same book.

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XP-40N with bubble canopy. Nice-looking bird. I wonder if, had it been adopted, it would have needed a dorsal fin like the P-51D got to "restore" stability lost when the rear fuselage was cut down. The vertical fin doesn't LOOK larger than a standard P-40 (below), but that is only a qualitative look at it, not measured. I also wonder if the carburetor airscoop is different or just looks smaller due to lighting. I suspect the latter.

GregP said:

Nice-looking bird. I wonder if, had it been adopted, it would have needed a dorsal fin like the P-51D got to "restore" stability lost when the rear fuselage was cut down.

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The fin on the later F models and subsequent versions had been moved aft to correct for what was asserted to be a directional instability, but the designer, Berlin, said that in reality they had made the nose intake too large and the air was spilling out the front and causing the instability. Compare the E and later models intake with the earlier models (seen below) and the difference is huge, with not that much of an increase in engine power. So the P-40 probably already had too much fin and too much rudder authority. One of the quirks of the later models is that while you had to hold Right rudder on takeoff to correct for P-factor and torque you had to hold Left rudder in a dive to get rid of the built in fin offset when you did not have the power turned up to High.

Wild_Bill_Kelso said:

I love how in the interview he keeps apologizing for being too wordy etc. Such a cool guy.

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Bill, if you haven't already got them, I can recommend these books dealing with RAAF pilots flying P-40's in the desert.



Also keep an eye out for this two-volume history of 450 sqn supposed to be released this year. A Catch-Up, No. 450 Squadron Status Update and a Chat - Air War Publications

I have two of those. The Russell Brown book is kind of famous, but famously hard to find in the US. I never had any luck.

MIflyer said:

The fin on the later F models and subsequent versions had been moved aft to correct for what was asserted to be a directional instability, but the designer, Berlin, said that in reality they had made the nose intake too large and the air was spilling out the front and causing the instability. Compare the E and later models intake with the earlier models (seen below) and the difference is huge, with not that much of an increase in engine power. So the P-40 probably already had too much fin and too much rudder authority. One of the quirks of the later models is that while you had to hold Right rudder on takeoff to correct for P-factor and torque you had to hold Left rudder in a dive to get rid of the built in fin offset when you did not have the power turned up to High.
View attachment 761134View attachment 761135View attachment 761136

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The lengthening of the fuselage was done to offset the greater horsepower at higher boost settings and during steep dives. Initially, they put in the big fin on the P-40K, which only partly worked... then they lengthened it by 33". It was apparently effective and only added a little bit of weight. The need to adjust rudder trim during dives was a well-known issue with the P-40s. There were jokes about having one leg twice the size of the other etc.

MIflyer said:

The fin on the later F models and subsequent versions had been moved aft to correct for what was asserted to be a directional instability, but the designer, Berlin, said that in reality they had made the nose intake too large and the air was spilling out the front and causing the instability. Compare the E and later models intake with the earlier models (seen below) and the difference is huge, with not that much of an increase in engine power.

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Don't forget that the P-40D,E,K and N used an engine that raised the prop up 6 inches from it's location on the earlier versions.
Merlin engine was close or maybe identical?
Merlin used different radiators and oil coolers and used the scoop underneath for the carb air instead of the over the nose scoop. The scoop on the Merlin powered versions was bigger than the one on the D,E,K and N. Maybe they didn't take as much time as they should have?
But they had a limited amount of space to work with, and a limited amount of time.

Note the spacing of the top of the prop spinner and the exhausts and note the spacing of the bottom of the spinner from the bottom of the engine.

Now note the height of spinner in relation to exhausts and the bottom of the engine. Note the radiators in both pictures. The scoop is about the same size, the opening got bigger but then they moved the upper lip of the scoop higher.