Most 'Underrated' Aircraft of WW2?

[michael rauls]

The P-36 and P-40 both had a serious flaw, that being the lack of high altitude performance of the engines. They never did figure this out. The airframe was too heavy until two stage supercharged RR Merlin engines were available, and these were put on the (faster and longer-ranged) P-51 by the British, and later in an official capacity by NAA as we all know. Because of the relatively low altitude performance ceiling of the engines, both speed and range of the P-36 and P-40 series were limited (since the highest speed and the best cruise efficiency were reached at relatively high altitude, generally speaking) and it limited their effectiveness as an interceptor against Operational or Strategic bombers - that is to say specifically, against high-flying multi-engined level-bombers.

This made Generals, military planners and strategists deeply dislike the Curtiss Hawk family of fighters. The P-36 was not suitable for the defense of England during the BoB, because it wouldn't have been good fighting at 20,000 feet or more where the German medium bombers and their Bf 109 escorts were flying. The P-40 also had problems early on against Japanese long range medium bombers (G3M, G4M, Ki-21 etc.) in the Pacific though they were able to get around the performance ceiling issues by using clever tactics. It wouldn't be good for escorting bombers on those kinds of raids either, and had very limited Strategic value.

However, in Tactical combat, the P-36 and P-40 both rose to the occasion far better than expected (or that they should have a right to do on paper, so to speak) and continued to be effective throughout the War.

The P-36 was the most effective Allied fighter in the Battle of France - and this includes the Hurricane and Spitfire.

The P-40 was the most effective Allied fighter in the early period (roughly the first year) of the Western Desert in Commonwealth use. It was the best hands down in the CBI, and along with the Wildcat, was the best Allied fighter in the Pacific in the initial crucial stages. It was also one of the most effective fighters available to the Soviets in the pivotal and desperate year of 1942, though the Soviets had a lot of maintenance problems with them.

By 1942, the Hurricane, with which the P-40 is so often compared, had clearly slipped a notch. The British and Commonwealth had downgraded it beneath the P-40, the latter often providing escort for the former after 4 RAF, 2 RAAF and 4 SAAF Fighter Squadrons were converted over to the Tomahawk. The Soviets hated the Hurricane and phased it out of use in 1942, whereas they were still using P-40s in the front line for another year, and in the Baltic and PVO (air defense) squadrons until the end of the War.

The P-40 was continuously improved through 1943, including the use of License-built Merlin XX engines and various weight reducing programs, but even the Merlins were not high altitude engines and even with significantly boosted horsepower from the Merlis or much more powerful Allisons (V-1710-73 for example), the P-40 never made the magic cutoff line of 400 mph, and never became the Strategic Escort or high altitude interceptor that the Generals wanted. Curtiss Aircraft company arguably never made another successful major combat aircraft after the P-40 and had a series of ever more egregious and embarrassing scandals which made the War Dept dislike them even more.

However, the improvements, even though they appeared marginal on paper, continued to enhance the capabilities of the P-40 sufficiently to keep it in the game, and not just as a fighter bomber as is so often claimed in various summaries. The extremely maneuverable fighter had a very high dive speed and good high speed handling, enabling pilots to escape or disengage from combat when they needed to, a critical ingredient for a successful fighter which the Hurricane, for example, never managed, and which the Wildcat didn't really manage when facing German or Italian fighters. It was also able to outmaneuver enemy fighters in the MTO that attempted to dogfight, and catch enemy planes that tried to dive away.

The P-39, the ostensibly much more modern stablemate of the P-40, never worked out in US or Commonwealth use. Newer American types like the P-38 and P-47 were late to the game and had extended teething problems (the P-47 having to go from P-35, to P-43, through a series of early P-47 models before reaching maturity). Gnashing their teeth, the US Generals were forced to equip 5 Fighter Groups with P-40F/L for use in North Africa and Italy (57th, 33rd, 79th, 324th, and 325th Fighter Groups) plus the 99th FS of the Tuskegee airmen. During and right after the War they were often portrayed as doing poorly, but their records were actually very good, better than most MTO P-38 squadrons and competitive with the Spitfire V squadrons in terms of victories vs. losses.

The P-40 itself was able to remain competitive, in the sense that they could still fly 'armed recon', fighter sweeps, escort Tactical bombers (frequently A-20s and B-25s) and strafing runs on enemy fighter bases with a reasonable probability of survival all over the world, well into 1944. In the CBI this continued into 1945. The reason was the maneuverability and the means of disengaging, as well as the oft mentioned ruggedness and firepower of the type. Those qualities tend to be overemphasized though since with the increasing firepower of late-war fighters meant that no amount of armor or sturdy construction could be counted on to save you in a fight, at best they increased the chances of survival incrementally. The real reason P-40 pilots so often survived combat was the maneuverability and high dive speed.

Even in 1943 and 1944 you get experienced pilots flying P-40s shooting down Bf 109s, MC 205s, Fw 190s and Ki43s and A6Ms in large numbers, at favorable rates.

Details I have seen posted in other threads on this very forum show that P-40 pilots were actually holding their own very well even against late war types like the Ki-84 and Ki 61, and planes (like Zeros) flown by the most experienced crews.

The P-40 may not have been the most underrated but it's still very negative reputation is at odds with it's admittedly uneven but often very good combat record.

S

Verry informative post. Just one question or comment if you will, I have read about( they have a website) the 450th RAAF using p40s till ve day. At ve day they were bassaed out of an airfield on the northern most tip of Italy. About 350 miles from Berlin. This would seem to indicate p40 uasage in that theater until rhe end although I can't find any info on missions or kills even on there site. If anyone knows anything more about this i would surely appreciate it.

 

[Schweik]

Verry informative post. Just one question or comment if you will, I have read about( they have a website) the 450th RAAF using p40s till ve day. At ve day they were bassaed out of an airfield on the northern most tip of Italy. About 350 miles from Berlin. This would seem to indicate p40 uasage in that theater until rhe end although I can't find any info on missions or kills even on there site. If anyone knows anything more about this i would surely appreciate it.

Yes they definitely did and they were not the only Commonwealth Squadron to do so. 450 RAAF used P-40s until August 1945 though they also got Mustang IIIs in May 1945

No. 450 Squadron RAAF - Wikipedia

There is a bit more about the operational History of 450 RAF here:

No. 450 Squadron RAAF | Wikiwand

250 Sqn RAF also used P-40s until August of 1945 (when they converted to Mustangs) - some of the South African squadrons also stuck with P-40s to the end of the War.

Most Commonwealth squadrons used P-40s until mid 1944 or a bit later (for example 3 RAAF Squadron switched to Mustangs in November 1944)

You won't find a lot of victories after around fall 1944 because the Luftwaffe was in decline in Italy and the Balkans where they were fighting and because they were mostly flying fighter-bomber sorties by then.

They always did fly a lot of fighter-bomber sorties but up until the Battles of Anzio and Monte Cassino they were also doing a fair amount of fighter sweeps, bomber escort and CAP missions. After that it was basically exclusively ground attack. For 450 RAAF in particular they were almost exclusively doing ground attack from around mid-1943.

It's the same incidentally for most of the P-47 squadrons stationed in the Med after 1944.

This is why I didn't mention P-40s in the Med after 1944 because by then they were no longer being used as fighters there so much, though in part this was due to lack of enemy air activity.

S

 

[Shortround6]

Just that it shows the p40 is 1934/35 design that was still fairly effective at what it was originally designed to do right up until the end of hostilities in 1945. Like all pre war amy designs( the p38 being an exception) it was designed to provide air cover for and direct support to ground forces. Such was the mission that was envisioned for army fighters at the time. Sort of low altitude air superiority and support.The thinking was the bomber would get through and there was no need for escorts. So I would submit in the p40 we have 1934/35 design that remained reasonably effective at the mission it was originally designed for right up until vj day.

IN regards to the bolded part. This assertion has been made in a lot of books/articles but NEVER with any supporting documentation (to my knowledge).
Like an official Army mission statement or quote from the initial or later requirements or a section of an Army tactics/doctrine manual.

The P-40, in it's initial form, was actually a pretty lousy airplane for providing support for ground forces. Two slow firing .50 cal machine guns with only 200rpg and little or no bombload (even though the P-36 could carry some small bombs and export Hawks could carry around 800lbs).
The wing .30 cal guns and the increased ammo for the cowl guns came later.
The single engine attack planes were carrying four .30 cal guns with 500-600rpg and around 600lbs of small bombs.

The older biplanes, the P-26 and even the P-35 all carried bombs, somewhat in proportion to the size of their engines. the P-26 could carry five 30lb bombs or two 100/116lb bombs so the complete lack of mention of bombs for the P-40, P-40A and P-40B is a bit puzzling if it was designed for ground support. The P-40C could carry a bomb instead of the drop tank. There were under wing racks but these get very little mention in US accounts which confuses things.

Please note the P-40 used the highest altitude rated engine available (or on offer) at the time (spring 1939). Allison had engines with lower supercharger gears for the P-38 would would give more power at low altitudes without the turbo.

Problem with 1934-35 fighters is that they didn't even have two speed superchargers so the gear chosen was always a compromise. Even in 1938-39 this was true, one P-36 being tested with a higher gear ratio driving the supercharger, it did give better performance at altitudes over 10,000ft or so but cost 100hp at take-off and at low altitudes.

Please note the A-20 was the result of a competition for an attack plane that had four prototypes show up. The Army was interested in planes that could support the ground troops. Single engine fighters with liquid cooled engines were NOT what they wanted.

I would also note that the P-36 was pretty much designed for a MUCH smaller useful load than the P-40, especially the later ones. I don't know what the first Hawk 75 was designed for (using the first three engines it went through) but by the the time you get to the P-36A the "normal" load was 105 gallons of fuel.
The 57-58 gallon tank behind the pilot was an overload tank and flight maneuvers were restricted when it had fuel in it. From the P-36 to the later P-40s teh wing gained about 200lbs in weight. Going from a 6000lb airplane to 8000lb airplane requires beefing up the structure if you want to keep the same safety margins as far as "G" loads go.

 

[Shortround6]

Newer American types like the P-38 and P-47 were late to the game and had extended teething problems (the P-47 having to go from P-35, to P-43, through a series of early P-47 models before reaching maturity).

The P-47 had a superficial resemblance to the P-35 and P-43 but that was about it. Good luck trying to turn a P-43 airframe into a P-47. It is going to take a whole lot more than a spare R-2800 engine.
Yes teh P-47 had lot of teething troubles, in part because it was whole new airplane with a new engine and operating in areas of flight that had seen little practical experience.

 

[michael rauls]

Yes they definitely did and they were not the only Commonwealth Squadron to do so. 450 RAAF used P-40s until August 1945 though they also got Mustang IIIs in May 1945

No. 450 Squadron RAAF - Wikipedia

There is a bit more about the operational History of 450 RAF here:

No. 450 Squadron RAAF | Wikiwand

250 Sqn RAF also used P-40s until August of 1945 (when they converted to Mustangs) - some of the South African squadrons also stuck with P-40s to the end of the War.

Most Commonwealth squadrons used P-40s until mid 1944 or a bit later (for example 3 RAAF Squadron switched to Mustangs in November 1944)

You won't find a lot of victories after around fall 1944 because the Luftwaffe was in decline in Italy and the Balkans where they were fighting and because they were mostly flying fighter-bomber sorties by then.

They always did fly a lot of fighter-bomber sorties but up until the Battles of Anzio and Monte Cassino they were also doing a fair amount of fighter sweeps, bomber escort and CAP missions. After that it was basically exclusively ground attack. For 450 RAAF in particular they were almost exclusively doing ground attack from around mid-1943.

It's the same incidentally for most of the P-47 squadrons stationed in the Med after 1944.

This is why I didn't mention P-40s in the Med after 1944 because by then they were no longer being used as fighters there so much, though in part this was due to lack of enemy air activity.

S

Wow that is fascinating. It's amazing how many ww2 history books are wrong about this. All my life I have accepted that the p40 saw no more front line service after 1944 except one or two groups in the cbi. After all thats what the books say. At least the ones i have read then i stumbled across the 450th website about year ago but couldn't find any more info on it. Thanks you!

 

[wuzak]

The P-36 was the most effective Allied fighter in the Battle of France - and this includes the Hurricane and Spitfire.

The Spitfire wasn't widely used in the Battle of France. In fact, they really only appeared over Dunkirk.

And all Spitfire squadrons remained based in the UK throughout.

The P-40 was the most effective Allied fighter in the early period (roughly the first year) of the Western Desert in Commonwealth use.

So, basically, it was the best Allied fighter in North Africa until the Spitfire was deployed there?

It was the best hands down in the CBI, and along with the Wildcat, was the best Allied fighter in the Pacific in the initial crucial stages.

When it was the only thing around?

So, the P-40's greatest claim to fame is that it was there.

 

[Schweik]

The Spitfire wasn't widely used in the Battle of France. In fact, they really only appeared over Dunkirk.

And all Spitfire squadrons remained based in the UK throughout.

I never said anything otherwise. But they were involved a bit more than just Dunkirk - 67 of them were lost during the Battle of France. There were also some Recon Spitfires based in France.

So, basically, it was the best Allied fighter in North Africa until the Spitfire was deployed there?

Basically yes. But still needed due to the limited range of the Spitfire, and later, problems with the P-38.

When it was the only thing around?

So, the P-40's greatest claim to fame is that it was there.

That it was there and able to shoot down enemy aircraft at a decent clip As you are aware, the record for the P-40 in the Pacific is actually better than the Spit.

S

 

[Milosh]

"During this period 67 Spitfires were lost over France, most of them in the attempt to prevent the Luftwaffe from bombing the evacuation beaches at Dunkirk."

Now what did Wuzak say?

 

[Schweik]

"During this period 67 Spitfires were lost over France, most of them in the attempt to prevent the Luftwaffe from bombing the evacuation beaches at Dunkirk."

Now what did Wuzak say?

He said "only" that says "most" - a subtle but significant distinction. And more to the point, I never suggested the Spitfire was widely used in France.

However using this old Thread as a source, for context with the 67 Spitfires lost mostly over Dunkirk, the Germans only lost 235 Bf 109s in the whole Battle of France. Per that thread the RAF lost 944 planes in the field (to all causes), out of which 67 were Spitfires and 386 were Hurricanes. Hurricanes claimed 299 victories.

By comparison the French had 4 squadrons of P-36 with a total of 300 aircraft of various subtypes, which claimed 220 victories and ~70 probables, losing 33 pilots KiA.

I couldn't find numbers for the Spitfire claims or the Hawk 75 losses other than the number of pilots killed. I know they had enough Hawk 75s left to put a dent in the US Navy during Operation Torch.

S

 

[Schweik]

The older biplanes, the P-26 and even the P-35 all carried bombs, somewhat in proportion to the size of their engines. the P-26 could carry five 30lb bombs or two 100/116lb bombs so the complete lack of mention of bombs for the P-40, P-40A and P-40B is a bit puzzling if it was designed for ground support. The P-40C could carry a bomb instead of the drop tank. There were under wing racks but these get very little mention in US accounts which confuses things.

In actual combat, fitting P-40s with bombs - initially one 500 lbs and then later up to three 500 lbs bombs, proved to be very easy and was done in the field in China, Russia, the Pacific and North Africa. The Russians also armed them with rockets.

In fact the P-40 series of fighters carried as heavy or larger larger bomb load than most of the dedicated bombers available at the beginning of the war - Fairey Battle (max 1500 lbs, realistic 1000), Bristol Blenheim (1,000 lbs), Ju-87 (990 lbs), Aichi D3A "Val" (550 lbs), TBD "Devastator" (1,000 lbs) etc. Gun armament of six .3 inch (Hawk 75) or two .5 in and 4 .3 inch (P-40 B / C) armament was similarly superior to all of the above bombers. Some were upgunned later but this was not the case in the early war let alone design phase.

Similarly, incidentally, the Hurricane was also easily adaptable (including in the field) to carrying a fairly heavy bomb load.

S

 

[Shortround6]

Nice try on the last post.
Battle and Blenheim could carry their admittedly small (1000lb) bomb loads 1000 miles and carried 3 man crews. They were misused as tactical support aircraft and had never been intended for that role.
The Val and the Devastator were carrier aircraft, something the P-40 was never going to be.
P-40s did not perform 90 degree dives or anything approaching 90 degrees no matter how many write ups you can find about them dive bombing. Some people consider anything over 30-45 degrees as dive bombing.

Many aircraft were pressed into service as close support aircraft. Some with greater success than others. Some had little or no modifications and some had a number of modifications.
No matter how successful some of these aircraft turned out to be that does not mean they were designed/intended for the close support role at the early stage of their careers.
Like the Hurricane, you might easily convert a MK II in the Field to a fighter bomber in 1941/42 but trying to convert a MK I in 1938 with it's fabric covered wing and Merlin III with fixed pitch prop wasn't going to go very far.
Likewise the P-40, any evidence the early long nose planes carried three 500lb bombs? Or what might have been left out of the planes that did carry 1500-2000lbs of bombs (like fuel or ammo for guns).

 

[Schweik]

Nice try on the last post.

Lol right back at you.

Battle and Blenheim could carry their admittedly small (1000lb) bomb loads 1000 miles and carried 3 man crews. They were misused as tactical support aircraft and had never been intended for that role. The Val and the Devastator were carrier aircraft, something the P-40 was never going to be.

You were comparing them to bombers. Those were all bombers. And all were, incidentally, also used for CAS. The fighters I mentioned were just better at CAS in the long run for a variety of reasons. Some like the Blenheim or the Battle, ultimately proved to be pretty useless by say, the end of 1941.

P-40s did not perform 90 degree dives or anything approaching 90 degrees no matter how many write ups you can find about them dive bombing. Some people consider anything over 30-45 degrees as dive bombing.

I tend to agree with you that there is a difference between the 'true' close to 90 degree dive bomber like the D3A, SBD, Ju 87 and the 45 degree (etc.) like the Ju 88 and most fighters, but that didn't mean they were ineffective at CAS. Clearly they were - these fighters were the most effective the DAF had in fact.

Many aircraft were pressed into service as close support aircraft. Some with greater success than others. Some had little or no modifications and some had a number of modifications. No matter how successful some of these aircraft turned out to be that does not mean they were designed/intended for the close support role at the early stage of their careers.

I never spoke about the intention of the design - I'm saying the success of the designs often hinged on flexibility and versatility. I've pointed out a few times before, pre-war planning (or even mid-war planning) rarely survived without the need to change once the actual machines reached the battlefield.

Like the Hurricane, you might easily convert a MK II in the Field to a fighter bomber in 1941/42 but trying to convert a MK I in 1938 with it's fabric covered wing and Merlin III with fixed pitch prop wasn't going to go very far.

It would surprise me a little if they never did put bombs on Hurricane Mk 1s, since they still had a lot of them in the field in North Africa ~ 1942 and even into 1943, and were using them mainly for ground attack. But I'm not an expert on the Hurricane.

Likewise the P-40, any evidence the early long nose planes carried three 500lb bombs? Or what might have been left out of the planes that did carry 1500-2000lbs of bombs (like fuel or ammo for guns).

I didn't say "early long-nose" P40s carried three bombs. In North Africa they didn't start using them as fighter-bombers until 1942 when they had the later model Kittyhawks. Same in China from what I understand. The Russians probably the same. In all three zones the need for the fighter was more urgent in the first few months.

Here is a Kittyhawk carrying 6 x 250 lbs bombs, which is a 1,500 lb bomb load by my count.

Here is another with 3 bombs (don't know what size but one very large and two smaller)

And another with 3 bombs

and another

They did have Tomahawks in the field for a long time so I would be surprised if they didn't modify some of them to carry bombs as well, but I don't know. I was always more interested in the Air Superiority type missions personally so it's not something I paid much attention to.

But the larger point is (I think) there were no major changes between the Tomahawk and the Kittyhawk which would prevent you from putting bomb-shackles on the former. In many parts of the world they were probably phased out before the switchover to emphasis on fighter bombers. But it's not like the Tomahawk had a fabric wing or anything.

The P-40 design in general, like the Hurricane, P-39, F4F, LaGG-3, Yak-1, Bf 109, Fw 190 and many others, was capable of carrying bombs. Some carried more than others and some were more or less effective (Fw 190 was a much more effective bomber than a Bf 109) but they were all pressed into service that way anyway and were able to do the job because the design was good enough to allow such versatility.

S

 

[Schweik]

According to "Americas Hundred Thousand" (page 241) the RAF started putting bombs on (Kittyhawk) P-40s in March of 1942, specifically this was done in the field by 112 Squadron. Clive Caldwell claimed this was his idea since he thought it was safer for the fighters to carry bombs than to escort Blenheims at 100 mph.

Same book (pp 235-236) also shows the 'useful load' for a P-40C (equivalent to Tomahawk IIb) as 2,246 lbs, P-40E (Kittyhawk Ib) as 2,221 lbs... i.e. essentially the same.

 

[Brent Jones]

The OS2U Kingfisher. Underpowered and had serious design flaws, but an absolute workhorse in the Pacific. Saved many lives.

 

[Ole Bill]

The A20 Havoc or Boston never gets the credit for what it achieved from the early days of the war until the end.
When thinking of light bombers, the USA tend to think of the B25 or B26, the British the Mossie, the Russians the IL2 or Pe2, but all used the A20 to great effect.

This is true. But as a child during the war (born in 41) most toy FIGHTER aircraft we had were P-40s (of course) and BOMBERS were A-20s. This simple fact of war history lead me many years into a long time friendship with and old A-20 Crew Chief!

 

[swampyankee]

I think the contributions of many support aircraft are sorely undervalued: transports, maritime patrol aircraft, reconnaissance aircraft, observation, scout, and liaison aircraft, training aircraft, gliders, ......

 

[GrauGeist]

The OS2U Kingfisher. Underpowered and had serious design flaws, but an absolute workhorse in the Pacific. Saved many lives.

They (and the other seaplanes like the PBY, SOC, etc.) are truly overlooked.

Here's one such example of the Kingfisher in action at Truk Lagoon, 1 May 44. Launched from USS North Carolina (BB-55), they picked up downed aviators (nine aboard for this photo - two being inside) in the lagoon and not having enough interior room for the airmen in order to get airborn, "taxiied" instead with them riding on the outside, out of the lagoon to a waiting lifeguard sub, which in this case, was the USS Tang (SS-306).

 

[Venturi]

Don Berlin gets a lot of the credit. He designed the P-40 wing with five spars, to give it excellent torsional strength. The idea being that aileron deflection would remain effective even at high air speeds (the wing would not twist under the torque that the aileron would put on it). Although this was purely done for maneuverability's sake, you can imagine then why the P-40 was able to be loaded down with bombs on the wing without compromise. It's a little recognized fact that the P-40 achieved by a fair margin the best roll rates of any Allied fighter at speed.

Additionally, as a aside note, Berlin quit Curtiss in rage, when it was determined that up-engining the Tomahawk required a bigger radiator, and the brass decided that instead of moving the radiator to post wing ventral fuselage (ala Mustang, Hurricane, Tony) as Berlin desired, that it should just be enlarged at the chin. Berin believed this was the root cause of the Warhawk's lateral directional instability which developed subsequently. Later experimental variants of the p-40, which utilized high altitude engines and laminar flow wings achieved equal or greater aerodynamic performance with the P-51. These simply were developed too late by Curtiss to be of any use in the actual war. They were too busy making profits cranking out P-40Fs and Ms to attempt to take Berlin's masterpiece to its deserved next level.

Yes I'm biased, no I don't care.

 

[P-39 Expert]

They (and the other seaplanes like the PBY, SOC, etc.) are truly overlooked.

Here's one such example of the Kingfisher in action at Truk Lagoon, 1 May 44. Launched from USS North Carolina (BB-55), they picked up downed aviators (nine aboard for this photo - two being inside) in the lagoon and not having enough interior room for the airmen in order to get airborn, "taxiied" instead with them riding on the outside, out of the lagoon to a waiting lifeguard sub, which in this case, was the USS Tang (SS-306).

View attachment 501590

Fantastic photo, is the horizontal tail actually in the water as it appears?

 

[Shortround6]

Additionally, as a aside note, Berlin quit Curtiss in rage, when it was determined that up-engining the Tomahawk required a bigger radiator, and the brass decided that instead of moving the radiator to post wing ventral fuselage (ala Mustang, Hurricane, Tony) as Berlin desired, that it should just be enlarged at the chin. Berin believed this was the root cause of the Warhawk's lateral directional instability which developed subsequently. Later experimental variants of the p-40, which utilized high altitude engines and laminar flow wings achieved equal or greater aerodynamic performance with the P-51. These simply were developed too late by Curtiss to be of any use in the actual war. They were too busy making profits cranking out P-40Fs and Ms to attempt to take Berlin's masterpiece to its deserved next level.

Berlin left in Dec of 1941, which is after the P-40E was in production and after the P-40F prototype had flown. He may very well have been angry but the XP-40 prototype had flown with a radiator under the center of the fuselage or slightly aft and was slower than when using the radiator in the forward position.
I would note that the prominent "chin" on the P-40E and later was due, in large part, to the propshaft being moved up 6in compared to the Tomahawk with the engine and radiators/oil cooler staying in the same place.
The Curtiss XP-46 with rear radiator showed no increase in speed over the P-40E using the same engine despite being a smaller airplane (once fully equipped)
Curtiss did try several changes in the radiators of the P-40 but results of the experiments are lacking.

Original XP-40 configuration.

The XP-60 that used a Merlin engine was interesting in that it was faster than a P-40F using the same engine despite using a larger wing. 275 sq ft instead of 236 sq ft.

The P-40Qs did NOT use a laminar flow wing despite many articles and books saying they did. They were slower than the P-51 using the same amount of power.