How good a plane was the P-40, really? (3 Viewers)

[Jabberwocky]

It's important to remember that the 20mm ammunition used over Darwin was Australian made and woefully out of spec as it was made in a brand new factory and rushed into service before the quality control standards were in place.

Do you know where the ammunition was being produced? I can't find anything from the official sources, nor various histories of CAC or Lithgow Small Arms.

 

[Wild_Bill_Kelso]

The ammunition being used by 1st Air Wing was Australian made

 

[PAT303]

Do you know where the ammunition was being produced? I can't find anything from the official sources, nor various histories of CAC or Lithgow Small Arms.

St Mary's, Funny thing is I later worked for TRW and we had the stamping presses from the ammunition factory but used them to make car parts. There was a great website with heaps of information on it but I can't find it now.

 

[Thumpalumpacus]

Au Contraire.View attachment 760300

That looks scared, not scary. "Eek! A mouse!"

 

[GrauGeist]

That looks scared, not scary. "Eek! A mouse!"

Dunno, considering the size of the Tiffy's cowling as well as it's ability to scour the earth, I'd say that it's sharkmouth is most appropiate.

 

[bf109xxl]

Dunno, considering the size of the Tiffy's cowling as well as it's ability to scour the earth, I'd say that it's sharkmouth is most appropiate.

It's a shark's mouth, too! Honestly!

 

[Thumpalumpacus]

Dunno, considering the size of the Tiffy's cowling as well as it's ability to scour the earth, I'd say that it's sharkmouth is most appropiate.

It's just that that particular iteration doesn't look fearsome, it looks fearful. It's the eyes.

 

[GrauGeist]

It's just that that particular iteration doesn't look fearsome, it looks fearful. It's the eyes.

Anglophobe!

 

[GTX]

As a slight diversion, it is interesting to speculate if the XP-60 developments might have taken the P-40 family further if the P-51 never eventuated.

 

[Shortround6]

The thing with the P-40 is that it sort of stagnated.
It did improve from the fall of 1940 to the spring of 1943 but it was an increase in capability (firepower and protection) rather than performance.
Gaining 20mph in speed over 2 1/2 years and only picking up a few hundred FPM in climb (using WEP) was certainly done by other aircraft but not the first rank ones.

This was not helped by less than forward tactics used by a lot of it's users (not all) and poor training by many. It is not enough to be able to fly and not crash. Air to air gunnery was sorely neglected by many Air Forces for far too long. This means that some of it's service record was spotty but not due the aircraft itself.
Due the limited supercharger on the P-40 better fuel and WEP ratings only really helped out in a narrow altitude band, Unlike the P-38 which got almost a 40% boost in power from sea level to 27,000ft over 3 years. (it did take quite a bit of work).

 

[Shortround6]

As a slight diversion, it is interesting to speculate if the XP-60 developments might have taken the P-40 family further if the P-51 never eventuated.

Nope.
The US Army helped screw that up, Between the Army and Curtiss they came up with a P-47 wannabe with eight .50 cal guns with a smaller wing although larger than the P-40 wing. When the Army's fair haired boy engine failed it became an air frame in search of engine, too big for a Merlin or modified Allison and too small for an R-2800, They tried using a version of the navy two stage supercharged engine.

 

[GTX]

Nope.
The US Army helped screw that up, Between the Army and Curtiss they came up with a P-47 wannabe with eight .50 cal guns with a smaller wing although larger than the P-40 wing. When the Army's fair haired boy engine failed it became an air frame in search of engine, too big for a Merlin or modified Allison and too small for an R-2800, They tried using a version of the navy two stage supercharged engine.

Remember though that there were multiple XP-60 developments:

XP-60A with Allison V-1710-75 engine:

XP-60B in flight test with Allison V-1710-75 engine and a Wright SU-504-1 turbo-supercharger:

XP-60C with R-2800 engine:

XP-60D with Merlin 61 engine:

I suppose my thinking is that if the P-51 never developed (say the British Purchasing Commission rejected NAA's proposal to design a more modern fighter and instead stuck with the request for P-40s...) then perhaps more effort would have gone into making developments such as the one of the XP-60 series to work. We know that in the real world the need wasn't there because of the other designs but an alternate reality might have been different. Just saying.

 

[Wild_Bill_Kelso]

The thing with the P-40 is that it sort of stagnated.
It did improve from the fall of 1940 to the spring of 1943 but it was an increase in capability (firepower and protection) rather than performance.
Gaining 20mph in speed over 2 1/2 years and only picking up a few hundred FPM in climb (using WEP) was certainly done by other aircraft but not the first rank ones.

I generally agree - it did certainly 'stagnate', or reach it's design limits by 1943, though I think the big innovation was not so much top speed it was altitude. There was a brief moment of enthusiasm for the P-40F, that was why they brought it into the Pacific and there was even some pressure on the Navy to figure out how to adapt it for carriers, though that was never going to happen because A) the Navy was never going to use an army plane, and B) the P-40, as you noted, had a fairly long takeoff run. They did manage to launch some from the Wasp etc. but it was never going to be suitable as a Navy aircraft.

There was always a significant flaw with the P-40 design, and that was altitude performance, and the P-40F/L improved that but not enough. I think for the Anglo-Americans at the planning level - i.e. generals and admirals, and some civilian bureaucrats, they were looking at short summaries, and wanted a very high performance, so they looked at it the exact way you articulated above - top speed and maybe rate of climb. Range was a factor too.

Speed was in part a function of altitude. Aircraft with a critical altitude below 20,000' is going to need a LOT of horsepower and very low drag to go over 400 mph. They don't care about the speed at Sea level or 10,000 ft, and the data card doesn't have a convenient way to summarize maneuverability. But it turned out in the operational history that faster planes like the P-39, P-51A, and early P-38 were not necessarily better in combat in terms of outcomes. Which is why the P-40 lingered. Same is true for some other types we've been discussing lately, like the Ki-43.

This was not helped by less than forward tactics used by a lot of it's users (not all) and poor training by many. It is not enough to be able to fly and not crash. Air to air gunnery was sorely neglected by many Air Forces for far too long. This means that some of it's service record was spotty but not due the aircraft itself.

I think if you really look at the operational history, it's record was fairly good to good. Not superb in the sense of a major advantage over adversaries like the Hellcat, the P-51 or Spit IX, but even in the earliest days when the pilots were untrained, P-40 units all over the world managed near parity in outcomes with enemy fighters, as we now know from reading the Axis losses. This at the same time as units using other types, like Buffalo, Hurricane, and P-39, were suffering losses at rates like 1-3 or 1-4. When training and tactics improved, P-40 units all over the world - South Pacific, China, India, Egypt, Tunisia, Ukraine - were doing a little bit better than 1 for 1, as you would generally expect fighter units to do. And this continued in those theaters right through 1943. That is why they kept them on the front lines so long - and as a fighter not just as a fighter bomber.

The P-40 just got very bad press after (and a little bit during) the war, partly because of the Truman hearings on Curtiss.

Due the limited supercharger on the P-40 better fuel and WEP ratings only really helped out in a narrow altitude band, Unlike the P-38 which got almost a 40% boost in power from sea level to 27,000ft over 3 years. (it did take quite a bit of work).

That's partly because it had a critical altitude closer to that 27,000 ft. Unfortunately the other issues related to engine cooling, diving etc. somewhat negated that advantage for a while.

 

[Wild_Bill_Kelso]

Remember though that there were multiple XP-60 developments:

XP-60A with Allison V-1710-75 engine:

View attachment 760738

XP-60B in flight test with Allison V-1710-75 engine and a Wright SU-504-1 turbo-supercharger:

View attachment 760739

XP-60C with R-2800 engine:

View attachment 760740

XP-60D with Merlin 61 engine:

View attachment 760741

I suppose my thinking is that if the P-51 never developed (say the British Purchasing Commission rejected NAA's proposal to design a more modern fighter and instead stuck with the request for P-40s...) then perhaps more effort would have gone into making developments such as the one of the XP-60 series to work. We know that in the real world the need wasn't there because of the other designs but an alternate reality might have been different. Just saying.

The one with the R-2800 looked the most plausible, and IIRC had the best performance of the lot. The first one had contra-rotating prop which never seemed to work, and I think the close cowl was giving them problems too. But as Shortround6 noted, it was DOA due to bad decisions both by Curtiss and the War Dept, and some bad luck. All the other variants had that 'designed by committee' look, even the P-60C/E did as well, and I don't think that shape was ever going to be as low drag as a P-51.

 

[Wild_Bill_Kelso]

Also, the P-40 while it could perform well with higher boost at low altitude, it was not really a low altitude fighter, so it didn't own that niche either. It was really a 'middling altitude' fighter, probably best at 5,000 - 15,000 ft.

The low altitude niche was better owned by LF / clipped wing Spitfires, Tempest, and some of those very small Soviet fighters like the Yak-3.

 

[Wild_Bill_Kelso]

P-40E and some P-40Ns had fuel system quirks. The linings of the fuel tanks on P-40Es and some P-40Ns delivered to the RAAF broke down when using high octane fuel. So, lots of RAAF Kittyhawks were plauged with leaky fuel tanks after a certain amount of time.

Looking for something completely different I just noticed this interesting quote by GregP in this post:

"A second problem was the European fuels. 100+ Octane fuel in the U.S.A. had 2% aromatics in it. European fuels had up to 20% aromatics, so the carburetors were jetted wrong right from the factory, but ran just fine on US fuel. Once the fuel issue and intake issue had been corrected, the P-38's ran just fine. By that time the P-51 was arriving and there was simply no need for two top fighters in the ETO with two logistics chains and two sets of mechanics, etc. The P-38's were mostly transferred to the Pacific where they ran just fine ON AMERICAN FUEL. Our two top aces, Bong and McGuire, both flew P-38's."

I don't know what the correction was exactly, or how soon it was available, but IIRC one of the things that helped improve the P-40s in the Middle East was the availability of the richer / higher octane fuel, I think SR6 may know the details of when it arrived a bit better. Maybe GregP can tell us?

 

[Shortround6]

Remember though that there were multiple XP-60 developments:

XP-60A with Allison V-1710-75 engine:

Problem was that they were based on the XP-53.
Wing span 41' 5"
Wing area 275 dq ft
Prop 11' 2"
204 US gallons fuel
empty weight 7650lbs (est)
useful load 2325lbs (est)
design gross weight 9,975lbs (est)
Max weight ferry, 10,693 (est)
Eight .50 cal guns with 2000 rounds.
Engine.
Continental XIV-1430-3 with
1250hp for T-0
1600hp (military) at 15,000ft
1,300hp (normal) at 18,000ft.
And we know what happened to the Continental engine.
The Allison V-1710-75 engine was an off-shoot of the aborted P-38K series. and offered 1600hp WER not 1600hp Military. also the timing in a bit off.
also they were reducing the armament in an attempt to save performance. Six .50 cal guns with 1200 rounds was not all that exciting.

XP-60B in flight test with Allison V-1710-75 engine and a Wright SU-504-1 turbo-supercharger:

I believe this photo is a misidentified XP-60 (no letter) with a Merlin XXVIII (or Packard V-1650-1) and while it did rather well with this engine, the above airframe with same engine as the P-40F was never going to be a good production aircraft. empty weight was 7,060lbs, useful load was 2290lbs Normal gross of the aircraft was 9350lbs

XP-60C with R-2800 engine:

First flight Jan 27th 1943. The two stage supercharged engine was given counter-rotating propellers. Unfortunately, while the increase in power was considerable weight had ballooned to 8,600lbs empty, 1925lb useful load and gross weight 10,525lbs. For this the customer got four .50 cal machine guns and 225 US gallons of fuel. A poor bargain for a R-2800 engine.
414mph at 20,000ft was not enough to make up for the lower fire power and shorter range compared to an F4U or F6F using the same engine.

XP-60D with Merlin 61 engine

Another misidentified photo. This is the XP-60 with the original Merlin engine. both by designation in the photo and by the date and then the color scheme.
Now this airframe (same serial number) was used to house a Merlin V-1650-3 in the summer of 1942.
But now we have the Engine from a P-51B trying to drive the larger airframe that had a gross weight of 9,980lbs and did not have the P-51 radiator installation.

I suppose my thinking is that if the P-51 never developed (say the British Purchasing Commission rejected NAA's proposal to design a more modern fighter and instead stuck with the request for P-40s...) then perhaps more effort would have gone into making developments such as the one of the XP-60 series to work. We know that in the real world the need wasn't there because of the other designs but an alternate reality might have been different. Just saying.

If they had more production for two speed Merlins or had gotten a decent two speed supercharger on an Allison engine and used just four .50 cal guns they might have gotten a more useful fighter in late 1942 and 1943. The super 1942-43 German and Japanese planes that people feared would show up in 1940-41 planning seemed to be slow showing up.
It is one thing to use four guns in an 8,000lb fighter, sticking 4 guns in a 10,000lb fighter seems a little skimpy

 

[Shortround6]

Looking for something completely different I just noticed this interesting quote by GregP in this post:

"A second problem was the European fuels. 100+ Octane fuel in the U.S.A. had 2% aromatics in it. European fuels had up to 20% aromatics, so the carburetors were jetted wrong right from the factory, but ran just fine on US fuel. Once the fuel issue and intake issue had been corrected, the P-38's ran just fine. By that time the P-51 was arriving and there was simply no need for two top fighters in the ETO with two logistics chains and two sets of mechanics, etc. The P-38's were mostly transferred to the Pacific where they ran just fine ON AMERICAN FUEL. Our two top aces, Bong and McGuire, both flew P-38's."

I don't know what the correction was exactly, or how soon it was available, but IIRC one of the things that helped improve the P-40s in the Middle East was the availability of the richer / higher octane fuel, I think SR6 may know the details of when it arrived a bit better. Maybe GregP can tell us?

The real fuel miss-match was in 1939-40. They were working on getting a common fuel specification in 1941. By the Fall of 1942 they had come up with the 3rd joint speciation for 100/130 fuel. The difference between the 2nd and 3rd was pretty much the max allowable lead content? Some accounts do not agree. Now there may have been left over stocks of old fuel in some places in the world in 1942 but..........................
You can't make 100/130 with 2% aromatics unless you are using super rare components. The change from 3.0cc's of lead to 4.6cc's of lead allowed for over a 20% increase in 100/130 production.
Greg keeps bring this up. There was a miss-match in in the types of aromatics allowed in 1943 that gave a lot of trouble in P-38s compared to the older 100/130 fuel but the US had given up on the 2% stuff back in 1940. There was trouble with the fuel system parts (gaskets and seals) in addition to the early self sealing fuel tanks in 1940/41 with the up to 20% fuel but it was different trouble at different time and for different reasons.

 

[Wild_Bill_Kelso]

Problem was that they were based on the XP-53.
Wing span 41' 5"
Wing area 275 dq ft
Prop 11' 2"
204 US gallons fuel
empty weight 7650lbs (est)
useful load 2325lbs (est)
design gross weight 9,975lbs (est)
Max weight ferry, 10,693 (est)
Eight .50 cal guns with 2000 rounds.
Engine.
Continental XIV-1430-3 with
1250hp for T-0
1600hp (military) at 15,000ft
1,300hp (normal) at 18,000ft.
And we know what happened to the Continental engine.
The Allison V-1710-75 engine was an off-shoot of the aborted P-38K series. and offered 1600hp WER not 1600hp Military. also the timing in a bit off.
also they were reducing the armament in an attempt to save performance. Six .50 cal guns with 1200 rounds was not all that exciting.

I believe this photo is a misidentified XP-60 (no letter) with a Merlin XXVIII (or Packard V-1650-1) and while it did rather well with this engine, the above airframe with same engine as the P-40F was never going to be a good production aircraft. empty weight was 7,060lbs, useful load was 2290lbs Normal gross of the aircraft was 9350lbs

First flight Jan 27th 1943. The two stage supercharged engine was given counter-rotating propellers. Unfortunately, while the increase in power was considerable weight had ballooned to 8,600lbs empty, 1925lb useful load and gross weight 10,525lbs. For this the customer got four .50 cal machine guns and 225 US gallons of fuel. A poor bargain for a R-2800 engine.
414mph at 20,000ft was not enough to make up for the lower fire power and shorter range compared to an F4U or F6F using the same engine.

Another misidentified photo. This is the XP-60 with the original Merlin engine. both by designation in the photo and by the date and then the color scheme.
Now this airframe (same serial number) was used to house a Merlin V-1650-3 in the summer of 1942.
But now we have the Engine from a P-51B trying to drive the larger airframe that had a gross weight of 9,980lbs and did not have the P-51 radiator installation.

If they had more production for two speed Merlins or had gotten a decent two speed supercharger on an Allison engine and used just four .50 cal guns they might have gotten a more useful fighter in late 1942 and 1943. The super 1942-43 German and Japanese planes that people feared would show up in 1940-41 planning seemed to be slow showing up.
It is one thing to use four guns in an 8,000lb fighter, sticking 4 guns in a 10,000lb fighter seems a little skimpy

Agree with all that except I would say drag mattered maybe more than weight, P-51C weighed 9800 lbs up to 11800, but it was bloody fast. Fw 190A-8, also pretty fast, weighed 9,738 lbs according to one estimate I just hurredly googled.

 

[Wild_Bill_Kelso]

The real fuel miss-match was in 1939-40. They were working on getting a common fuel specification in 1941. By the Fall of 1942 they had come up with the 3rd joint speciation for 100/130 fuel. The difference between the 2nd and 3rd was pretty much the max allowable lead content? Some accounts do not agree. Now there may have been left over stocks of old fuel in some places in the world in 1942 but..........................
You can't make 100/130 with 2% aromatics unless you are using super rare components. The change from 3.0cc's of lead to 4.6cc's of lead allowed for over a 20% increase in 100/130 production.
Greg keeps bring this up. There was a miss-match in in the types of aromatics allowed in 1943 that gave a lot of trouble in P-38s compared to the older 100/130 fuel but the US had given up on the 2% stuff back in 1940. There was trouble with the fuel system parts (gaskets and seals) in addition to the early self sealing fuel tanks in 1940/41 with the up to 20% fuel but it was different trouble at different time and for different reasons.

I'm interested in that trouble, and when it was resolved...?