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

I never understood the reason for that oil tank. Was the extra oil meant to cope with dust?

I think they underestimated the effects of the faring on drag. It had a streamlined shape but it's just too large, anything that sticks out into the slipstream has a cost in drag. And that Vokes filter is a lot.

The extra oil was to allow for the extra range of drop tanks.
The Spitfires and Hurricanes had been designed for short range and their oil tanks had been designed accordingly for the size of their fuel tanks.
The Photo recon Spits had extra large oil tanks.
Hurricanes had an oil tank in the leading edge of the left wing but it wasn't big enough for long flights with drop tanks.

Tank is inboard of the guns. Exposed tank also acted as an oil cooler. Changing the wing tank may have meant modifying the ribs on either side or some other problem?





P-40s had been designed for 160-180 US gallons of fuel originally and had oil tanks designed accordingly.
I don't know what they did for ferrying. There may have been different amounts of oil consumption per hour of cruise flight vs oil consumption per hour of high speed or combat power?

I would assume you consume less oil flying at lower RPM and boost

ThomasP said:

I believe that all of the air intakes for the Bf109 series were on the left side.

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The DB6xx engine intakes were to port, the Jumo2xx intakes were to starboard.

The early DB intakes were angular and later versions had more of a radiused design.

Thumpalumpacus said:

All that nose armor.

I'll get my jacket.

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Don't forget the cast iron cockpit heater!

NTGray said:

I used to think that the P-40 was basically a mediocre plane that could get good results in the hands of exceptional pilots like the Flying Tigers, but I have been revising my opinion upward in recent years. Note the assessment given in Wikipedia:



Given that more P-40s were produced than any other American army or navy fighter other than the P-47 and P-51, it would seem that the people in charge had a high opinion of the plane at the time.

Your thoughts?

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You have to look at timespan - in 1940 the P40 was near the top of it's game and needed to be lightened by Gipsy Rose Lee to stay competitive. It is a time game.
Hampdemon

HP52 said:

You have to look at timespan - in 1940 the P40 was near the top of it's game and needed to be lightened by Gipsy Rose Lee to stay competitive. It is a time game.
Hampdemon

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People at NAA, Suprermarine, MTT, Macchi etc used a superior way i order to keep their fighters competitive, namely by installing the engines with condiderably more power for all altitudes.
Worked very well; not so much what the P-40 received.

tomo pauk said:

People at NAA, Suprermarine, MTT, Macchi etc used a superior way i order to keep their fighters competitive, namely by installing the engines with condiderably more power for all altitudes.
Worked very well; not so much what the P-40 received.

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P-40 got a double whammy.
They crammed too much stuff into it in the D & E models and they didn't have enough Merlin engines to keep making the F & L versions into 1943.
Or rather Allison spent too much time screwing around with the two stage engine and not enough time making a better single stage supercharger.

A lightened P-40 with a Merlin 24 engine (18lbs of boost) might have been very interesting
Not a P-51 by any stretch but having several thousand ft of altitude over a 'normal' P-40N might have been interesting.

The Us should have decided wither they wanted a P-40 or B-40 (one 1000lb under each wing and 500lb under the fuselage) and designed the wing/landing gear accordingly.
An 8300-8700lb fighter clean (no drop tank) is going to need an hell of engine to compete with 7100-7500lb fighters.

<Homer Simpson's voice> "mmmmm . . . P-40F/Ls with Merlin 24s . . . & 4-blade props"

and 400-500lbs lighter

And paddle prop blades.

Shortround6 said:

P-40 got a double whammy.
They crammed too much stuff into it in the D & E models and they didn't have enough Merlin engines to keep making the F & L versions into 1943.
Or rather Allison spent too much time screwing around with the two stage engine and not enough time making a better single stage supercharger.

A lightened P-40 with a Merlin 24 engine (18lbs of boost) might have been very interesting
Not a P-51 by any stretch but having several thousand ft of altitude over a 'normal' P-40N might have been interesting.

The Us should have decided wither they wanted a P-40 or B-40 (one 1000lb under each wing and 500lb under the fuselage) and designed the wing/landing gear accordingly.
An 8300-8700lb fighter clean (no drop tank) is going to need an hell of engine to compete with 7100-7500lb fighters.

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Be that as it may, the Kittyhawk III-IV series proved to be quite excellent fighters and interdictors in the MTO during this period. And while not as glamorous as the duties served in the ETO, these were still sterling records which manifestly contributed to victory in the War.

Yes, their altitude performance suffered, though in these theatres the effect of this mattered far less. Instead, you had an aircraft with good speed at low altitude (noting that if one compares a P-40N-5 series from 1943 to a Bf-109G-6 from the same period, the P-40 comes out with a slight advantage in 'on-the-deck' speed, and this is neglecting any filters which would accentuate this performance difference...), and a generally-superior combat radius compared to its in-theatre contemporaries.

Combine this with the other characteristics which made the type and excellent interdictor: Maneuverable and responsive controls, decent armament, rugged and well-protected airframe, sizable bombload (especially for the later P-40N / Kittyhawk IV types, which were cleared for a 2,500-lb ordnance load) and it becomes no surprise why the P-40 series was well-regarded by the USAAF and RAF alike in this region, among many other Allied nations abroad in other theatres.

The type was uniquely well-suited to the kind of isolated pursuit, escort and interdiction duties that were required in the desolate sands of North Africa, or the rugged hills of Italy. It was superb at the kind of low-altitude dogfights and logistical attrition which was necessary to bleed the Axis of their supply lifelines into these theatres.

So, in truth, I am not sure I agree that the US needed to "pick a horse" in this case. Having the type as a flexible and adaptable airframe was what allowed it to remain relevant until the War's conclusion. There were many improvements to the type I would've loved to see, though by the time of the 1944 Fighter Conference you see the general perception among USAAF staff as "Why fix what isn't broken, especially when we have other types to fulfill the more 'first-rate' duties?"

Now, of course, I personally still would love to see the fruition of Don Berlin's fantasies of sticking a two-stager Merlin in a P-40 airframe in 1940...but that wasn't feasible at the time considering the military realities of the RAF, and the political realities of a neutral US.

Think Tanker said:

Now, of course, I personally still would love to see the fruition of Don Berlin's fantasies of sticking a two-stager Merlin in a P-40 airframe in 1940...but that wasn't feasible at the time considering the military realities of the RAF, and the political realities of a neutral US.

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Everyone would have loved a two stage Merlin in 1940, but it wasnt there. The first two stage Merlin Spitfires came in service in spring 1942 and were almost exact contemporaries of the Allisson engined Mustang Mk I (P-51A). There were approx 6 squadrons of each at Dieppe in August 1942.

Think Tanker said:

The type was uniquely well-suited to the kind of isolated pursuit, escort and interdiction duties that were required in the desolate sands of North Africa, or the rugged hills of Italy. It was superb at the kind of low-altitude dogfights and logistical attrition which was necessary to bleed the Axis of their supply lifelines into these theatres.

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I think that on this forum, the P-40 usually gets a fair assessment.
Most of us here will acknowledge it's good sides (that were many of), as well as it's shortcomings (that IMO are mostly connected with the engines it received being behind the curve).

Think Tanker said:

Now, of course, I personally still would love to see the fruition of Don Berlin's fantasies of sticking a two-stager Merlin in a P-40 airframe in 1940...but that wasn't feasible at the time considering the military realities of the RAF, and the political realities of a neutral US.

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Reality with the 2-stager Merlin was that it was not being installed even on it's premier user - Spitfires in the UK - before mid-1942, mostly since there was not any to have (bar prototypes).
US production of 2-stager Merlins was lagging behind the forecasts in 1943 in such a measure that hundreds of future P-51 aircrafmes were gathering the dust in summer of 1943 waiting for the engines. Believing the recollections of the people can be ... tricky, since "Berlin left Curtiss-Wright in December 1941", meaning that it is very much possible that he had no information about the 2-stager Merlins in the 1st place before it was too late for him to do anything to improve the P-40 in such a fashion.

tomo pauk said:

I think that on this forum, the P-40 usually gets a fair assessment.
Most of us here will acknowledge it's good sides (that were many of), as well as it's shortcomings (that IMO are mostly connected with the engines it received being behind the curve).



Reality with the 2-stager Merlin was that it was not being installed even on it's premier user - Spitfires in the UK - before mid-1942, mostly since there was not any to have (bar prototypes).
US production of 2-stager Merlins was lagging behind the forecasts in 1943 in such a measure that hundreds of future P-51 aircrafmes were gathering the dust in summer of 1943 waiting for the engines. Believing the recollections of the people can be ... tricky, since "Berlin left Curtiss-Wright in December 1941", meaning that it is very much possible that he had no information about the 2-stager Merlins in the 1st place before it was too late for him to do anything to improve the P-40 in such a fashion.

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Additionally, even for a single stage Merlin, the UK ordered them from USA because they were short and knew they needed a lot more. The British Merlin factories were not in production in 1940, all BoB engines were made in the home factory. So, any Merlins put into P-40s would mean they werent put in a Hurricane. While the Allisson engine restricted altitude performance in places like N Africa the P-40 was superior in most roles to the Hurricane and its attraction for the British was it was extra not instead of what they had. I cant see a neutral USA putting Merlins in its planes while leaving Allisson without a market, even if Merlins could be found and shipped.

pbehn said:

Additionally, even for a single stage Merlin, the UK ordered them from USA because they were short and knew they needed a lot more. The British Merlin factories were not in production in 1940, all BoB engines were made in the home factory. So, any Merlins put into P-40s would mean they werent put in a Hurricane. While the Allisson engine restricted altitude performance in places like N Africa the P-40 was superior in most roles to the Hurricane and its attraction for the British was it was extra not instead of what they had. I cant see a neutral USA putting Merlins in its planes while leaving Allisson without a market, even if Merlins could be found and shipped.

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Between 1935 & 1939 the original RR Derby factory had its floor area expanded by nearly one third to 1.1 million square feet.

The first RR shadow factory was at Crewe. Ground for the new factory was broken on 6 July 1938. The first production engine was run on 16 May 1939 and delivered in June and production ramped up from there. Early production was of Merlin III engines for types including Spitfires & Hurricanes (2,012 built)

The next RR shadow factory was at Hillington on the outskirts of Glasgow. Construction started in June 1939. The first completed engine was delivered on 28 Oct 1940. But the factory had been supplying Merlin parts to Derby & Crewe for several months before that. By June 1941 production reached 200 per month and 400 per month was achieved by March 1942.

The Ford run Trafford Park, Manchester saw construction start in Spring 1940. Production of parts for incorporation in Crewe built engines began in Aug 1940 while the first complete engines were delivered in May/June 1941.

tomo pauk said:

I think that on this forum, the P-40 usually gets a fair assessment.
Most of us here will acknowledge it's good sides (that were many of), as well as it's shortcomings (that IMO are mostly connected with the engines it received being behind the curve).



Reality with the 2-stager Merlin was that it was not being installed even on it's premier user - Spitfires in the UK - before mid-1942, mostly since there was not any to have (bar prototypes).
US production of 2-stager Merlins was lagging behind the forecasts in 1943 in such a measure that hundreds of future P-51 aircrafmes were gathering the dust in summer of 1943 waiting for the engines. Believing the recollections of the people can be ... tricky, since "Berlin left Curtiss-Wright in December 1941", meaning that it is very much possible that he had no information about the 2-stager Merlins in the 1st place before it was too late for him to do anything to improve the P-40 in such a fashion.

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Absolutely a fair point, though from what I recall (a dangerous thing, a recollection of a recollection) it was a formal request to the RAF around that period. It may, indeed, more likely be a reference to the two-speed Merlins which were in service at that point in time.

However, on the whole I do agree with the consensus it was too late for him to have much effect in any two-stage powerplant at that point, I still do think it would be interesting to see the fruition of Berlin's "what ifs" in a circa 1941-1942 timeframe. As inferred in the original comment, it isn't a likely scenario in any event--the factors against the installation of such a engine at that point are simply too great--but it's still a point of curiosity.

Think Tanker said:

Combine this with the other characteristics which made the type and excellent interdictor: Maneuverable and responsive controls, decent armament, rugged and well-protected airframe, sizable bombload (especially for the later P-40N / Kittyhawk IV types, which were cleared for a 2,500-lb ordnance load) and it becomes no surprise why the P-40 series was well-regarded by the USAAF and RAF alike in this region, among many other Allied nations abroad in other theatres.

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The First P-40N fighters were delivered in March of 1943. Which is a little late to considered as a reply to the Bf 109G or any Italian fighter.
They were ordered (first batch) in Jan 1943 which is well after the initial orders for the P-51B Mustang.
The US was not considering the P-40N as a first line fighter. Useful for a number of rolls but they already had the Merlin powered P-40s in stock, the P-38s, the Merlin Mustangs and the P-47 starting to show up in large numbers.
Please note that the P-40N-5 was the first rated for 1500lbs of bombs (500lbs on the underwing racks.) the 2500lb rating shows much later.

There is the mysterious P-40J. Sources do not agree and Curtiss sources and AAF documents do not list it.
There was supposed to have been a GE turbo charger delivered to Curtiss late 1941 or 1942 but if it was this project or for one of the P-60s is not known. No metal appears to have been cut for for a turbo P-40 of any sort (letter). This would have been a 2 stage supercharged engine.
With Berlin gone by the end of 1941 it is quite a stretch for him to still be involved with major projects in late 1942 or into 1943.
It may also be that some writers confused two speed with two stage, a rather common mistake in many books/articles both during the war and after.

Basically the P-40, like the P-39, stayed in production to meet lend lease deliveries in 1943 and through 1944.

Shortround6 said:

The First P-40N fighters were delivered in March of 1943. Which is a little late to considered as a reply to the Bf 109G or any Italian fighter.
They were ordered (first batch) in Jan 1943 which is well after the initial orders for the P-51B Mustang.
The US was not considering the P-40N as a first line fighter. Useful for a number of rolls but they already had the Merlin powered P-40s in stock, the P-38s, the Merlin Mustangs and the P-47 starting to show up in large numbers.
Please note that the P-40N-5 was the first rated for 1500lbs of bombs (500lbs on the underwing racks.) the 2500lb rating shows much later.

There is the mysterious P-40J. Sources do not agree and Curtiss sources and AAF documents do not list it.
There was supposed to have been a GE turbo charger delivered to Curtiss late 1941 or 1942 but if it was this project or for one of the P-60s is not known. No metal appears to have been cut for for a turbo P-40 of any sort (letter). This would have been a 2 stage supercharged engine.
With Berlin gone by the end of 1941 it is quite a stretch for him to still be involved with major projects in late 1942 or into 1943.
It may also be that some writers confused two speed with two stage, a rather common mistake in many books/articles both during the war and after.

Basically the P-40, like the P-39, stayed in production to meet lend lease deliveries in 1943 and through 1944.

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In fairness, I am not of the mind to consider the P-40N as a 'reply' to the Bf-109G-6 (which, in truth, it wasn't), but instead a contemporary of the type in the MTO, which it absolutely was. Both the P-40N-5 onwards and the Bf-109G-6 (in its various sub-increments through this period) were common airframes over the MTO from 1943-1944, which is the relevant point I'd wager.

These airframes were ordered after the first P-51B series, yes, but it is also worth acknowledging the teething troubles the P-51B series was going through at this time (as is typical for any new production type), and that it was never going to be a primary service airframe in the MTO during this timeframe. Besides that, arguably, the P-51B-10 and similar were not especially well-suited to the MTO theatre, whereas the P-40 was never going to thrive in the ETO as a pursuit aircraft or escort.

The P-40N-5 were at-first rated for 1,500-lbs, though this is still quite a sizable payload which was often exceeded in practice--much like the P-40E and P-40Ks carrying the 1,000-lb munitions for bridge-busting operations despite this technically being in excess of the manual. P-40Ns had flown with 2,000-lb loads--typically one 500-lb per wing and a 1,000-lb on the centerline--before the official 'approval' for a 2,500-lb load around the time of the P-40N-20 in the Fall of 1943.

As for the P-40J, much like yourself I haven't found much information about the type through the years. I don't believe this is the variant which Don Berlin was referencing, but without a copy to reference at-hand I cannot rule it out either. The timing, however, I believe my recollection is more or less correct, as he discussed the Battle of Britain as interfering with his ambitions--whether that's a self-serving hindsight, a faulty recollection or something else...I leave up to individual interpretation.

Anyways, for a slight tangent, but I felt it might be worthwhile to share a general characteristics scan I took for a P-40N-1 several years ago. You'll have to forgive the low quality of the image, but I felt this may be an intriguing, if fairly banal, item for you folks.