If no P-51, how would the P-40 have evolved?

[gjs238]

If the P-51 never happened, would evolved P-40's been fielded, and what sort of evolution might we have seen?

 

[michaelmaltby]

XP-40Q

 

[Shortround6]

A P-40 was a re-engined P-36. ANY development past 1943 was flogging a dead horse. The Hawk 75 first flew 6 months BEFORE the Hawker Hurricane. If not the P-51 then some other airframe would have come up in the 6 1//2 years between the Hawk 75s first flight and Pear Harbor let alone the another 2-3 years.

 

[wuzak]

I would suggest the XP-46, XP-53 and XP-60 would be a good guide.

The XP-46 was a smaller, lighter development with inward retracting gear and belly mounted radiator, but was cancelled in favour of improved P-40s (those already being in production).

Curtiss : XP-46 by San Diego Air & Space Museum Archives, on Flickr

Curtiss : XP-46 by San Diego Air & Space Museum Archives, on Flickr

The next development would have been the XP-53. his had a P-40 fusealge mounted to laminar flow wing with inward retracting main gears and 6 0.50s.

It was to be powered by the IV-1430, but problems with that engine caused delay and eventually led to one of the prototypes being fitted with a Merlin 28 and redesignated XP-60. Due to delays with production of Merlins it was proposed that the XP-60 then be powered by a turbocharged Allison, then a later variant was powered by an R-2800.

The wiki page says that this picture is of the

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

. It is clearly the Merlin XP-60.

The Allison turbo model (with GE turbo) looked like this

.

The XP-60B with the Wright turbo never flew.

 

[Shortround6]

With Curtiss themselves trying 2/3 different airframes by the end of 1941 (both the XP-46 and XP-60 flying for the first time in Sept 1941, design work stated much earlier) There is little doubt that both Curtiss and the USAAC felt that the P-36/40 had limited development potential.

 

[drgondog]

For the USAAF, absent P-51B, the only choice for escort was P-38 and continuously improved P-47.. big impact from Big Week through D-Day on 8th AF bomber crews, more US fighter losses, fewer LW casualties in that same period. Probably no start of May Oil/Chemical campaign because of deep penetration prohibitive losses until perhaps 6-7 P-38 Groups fully operational.

 

[wuzak]

For the USAAF, absent P-51B, the only choice for escort was P-38 and continuously improved P-47.. big impact from Big Week through D-Day on 8th AF bomber crews, more US fighter losses, fewer LW casualties in that same period. Probably no start of May Oil/Chemical campaign because of deep penetration prohibitive losses until perhaps 6-7 P-38 Groups fully operational.

Isn't that a different discussion?

I suppose the answer to the question in the OP "If the P-51 never happened, would evolved P-40's been fielded?" is no.

 

[davebender]

I agree. Curtiss needs to start with a clean sheet of paper for their next design.

 

[wuzak]

Well, the P-51 "happened" in 1940, so if i hadn't there may have been more of a push for the P-53/P-60. Curtiss were trying to develop new aircraft, but using parts of the P-40 to expidite development.

If the P-51 doesn't happen, NAA must have signed with the British Purchasing Comission to build P-40s and, presumably, whatever came next.

 

[The Basket]

The P-40 was an important in production aircraft so would have to assume that the P-40 derivatives would have been pushed forward.

One role of successful aircraft is they do stop other aircraft going anywhere. Why have a new Spitfire when the old Spitfire is working fine. Not sure when the Curtiss antipathy kicked in which would eventually end the maker.

But that P-40Q looks a fine machine.

 

[Shortround6]

The P-40 was an important in production aircraft so would have to assume that the P-40 derivatives would have been pushed forward.

One role of successful aircraft is they do stop other aircraft going anywhere. Why have a new Spitfire when the old Spitfire is working fine. Not sure when the Curtiss antipathy kicked in which would eventually end the maker.

But that P-40Q looks a fine machine.

Ah, P-40 "derivatives" include the XP-46, the XP-53 and the XP-60 (in five variations) Curtiss antipathy may have kicked in when none of these caught on and a number of other projects turned out to be duds. Or perhaps Curtiss was trying to do too much with too little talent?

Curtiss Seamew, Curtiss Seahawk, the XBTC-1, XBTC-2 and XBT2C-1, XF14C-2 and XF15C-1, XP-62 and XP-72 ( the latter a 40,000lb fighter with twin turboed R-4360 engines driving 8 bladed counter rotating pusher propellers) and the XSB3C-1 ( a stretched Helldiver using a R-3350, tricycle landing gear and a 4,000lb internal bomb load) Throw in the XP-55 and Curtiss had about 14 different aircraft or projects aside from the P-40 going during WW II. It doesn't sound like they were sitting back being fat, dumb and happy on P-40 profits like is sometimes claimed.

 

[KiwiBiggles]

=XP-72 ( the latter a 40,000lb fighter with twin turboed R-4360 engines driving 8 bladed counter rotating pusher propellers).

XP-71, I think. XP-72 was a Republic development of the P-47.

 

[Jabberwocky]

I think the XP-46 is a non-starter. The airframe/engine combination simply wasn't aggressive enough in design and performance was no improvement over those fighters already in combat in Europe (Spitfire II/V, Bf 109E-4 -7/F-2). If wiki is to believed, the bird had VERY short legs as well, about half the range of the already short-ranged Spitfire and 109.

The P-53/60 is more interesting and probably do-able by late 1941/early 1942, but the whole project appears to have suffered from a lack of management and wildly changing requirements on behalf of the end user. Only 4 airframes were built, but they managed to test eight major configuration changes, including 5 different engines/engine sub-types.

The V-1650-1 powered XP-60A (Model 90) reportedly made either 380 mph or 387 mph at 22,000 ft. That's marginally better than the similarly powered P-40F, which achieved about 364 mph at 20,500 ft in US tests and 354 mph at the same height in RAF tests. The light-weight P-40L was able to achieve 357-367 mph (depending on the test) at 21,500 ft.

The XP-60s were quite portly though, so the extra speed would come at the price of a lower RoC. Empty weight was 450 lbs heavier than equivalent P-40Fs and loaded weight almost 700 lbs heavier. Climb to 15,000 ft is reported as 7.3 minutes (online source admittedly).

I say, get the XP-60 into service ASAP, and then follow it up with a V-1650-3 powered version in 1943. Add the airframe improvements when production switches over to the new engine.

I believe a two-speed Merlin powered P-60 is going to be more competitive (even marginally so) than the Allison-powered P-40 or P-39 during 1942/43 while the USAAF get the P-47 and P-38 sorted. Convert the P-40 into a dedicated fighter bomber and be done with it.

 

[wuzak]

With the XP-53/60 the radiator was found to be a major source of excessive drag.

So if they get the go-ahead for the P-60 (the P-53 being the one to be powered by the IV-1430) I expect there would have been a bit of refining in that area.

One XP-60 (the XP-60A I believe) flew with an Allison and turbocharger (B-series). That may have continued in development alongside the XP-60/60B Merlin variant.

 

[wuzak]

Double post

 

[Shortround6]

XP-71, I think. XP-72 was a Republic development of the P-47.

Thank you for the correction.

 

[Shortround6]

Part of Curtiss's problem was that they were designing to USAAC (and Navy) requirements and the USAAC (and Navy) had some rather unrealistic ideas on what was possible. TO be fair they were trying to guess what would be needed 2-3 years in the future and were trying to push the envelope. For example the XP-46 was to have a pair of .50 cal guns in the cowl PLUS eight .30 cal guns in the wing. The XP-52 and first XP-60 were supposed to have EIGHT .50 cal guns. P-47 armament in a smaller wing with a lower powered engine. AS the P-60 program advanced though one change after another the armament was reduced to 6 guns and then to 4 guns with just 250 rounds apiece in an apparent effort to lighten the aircraft.
The Specification for the XP-62 was issued in January of 1941 and Curtiss had a proposal ready by April 29 41. Powered by an R-3350 with turbo supercharger, equipped with a pressure cabin and armed with either EIGHT 20mm cannon or TWELVE .50 cal MGs.

Some of the Navy Specifications were about as bad, in the sense they sometimes just doubled the bombload of an existing aircraft while asking for more speed and more range at the same time. Even with R-2800. R-3350 and even R-4360 engines there is only so much that could be done.

 

[zoomar]

The P-40 was at the end of its development potential, and Curtiss seemed to have lost its grasp altogether providing a sucessor. Planes like the P-60 or P-62 would have been inferior to both the P-47 and P-38. Had the P-51 never materialized, AAF procurement strategy would have focused on the P-47 and P-38 (and potential successors like the P-72 and P-49 (which what what I believe the "improved P-38" was designated).

Alternatively, if this left a hole needing to be filled by a 2nd high performance single engined plane, why not look at dedicated land-based derivatives of the Corsair and Hellcat?

 

[Shortround6]

Curtiss was trying to supply what the customer said it wanted. If the customer says it wants a plane with eight 20mm cannon in the wings powered by a an R-3350 radial Curtiss only has a few choices. Design according to specification or prepare two detailed proposals, One to the customers spec and one that Curtiss thinks will work better and why and then show both to the customer and try to persuade the customer they are wrong.
In 1942-43 The USAAC was NOT proposing new fighters armed with just six machine guns and having speeds/ranges only 10-20% higher than existing fighters. They wanted massive increases in armament, speed, range and ceiling and all at the same time in the same airplane.

 

[spicmart]

The P-40 was at the end of its development potential, and Curtiss seemed to have lost its grasp altogether providing a sucessor. Planes like the P-60 or P-62 would have been inferior to both the P-47 and P-38. Had the P-51 never materialized, AAF procurement strategy would have focused on the P-47 and P-38 (and potential successors like the P-72 and P-49 (which what what I believe the "improved P-38" was designated).

Alternatively, if this left a hole needing to be filled by a 2nd high performance single engined plane, why not look at dedicated land-based derivatives of the Corsair and Hellcat?

At what point can one say that a certain design's development potential is used up. How can one measure that? Looking at the airframe one can get the impression that if given a powerful enough engine and maybe a relocating of the coolant radiator that the P-40 might be competitive with the Spitfires which also were not low-drag-wonders. At least why shouldn' it be?