P51 is P40's baby!!

[Professor Brensec]

I recall some discussion months ago about the way in which the P51 came about as a 'replacement' for the then 'overcommitted' Curtiss plants.

Just quickly, the British, who were looking for P40's to supplement their Fighters were told that Curtiss could not make any more than were already being made. They were sent to North American to see if they could make the P40 under license (something done by almost everyone and involving almost every American aircraft during WWII).

North American said they could design a better fighter than the P40 and in 'record' time.

Looking at the prototype, which was produced in 102 days, I (and most) can see the obvious P40 influence in the design. Also the 'belly scoop' was a known Curtiss design.

Here is an excerpt about this particular 'speedy design feat':

Curtiss had been ordered to turn over its design studies and other pertinent information on the XP-46. This included the radiator scoop originally intended for installation under the fuselage of the P-40. This scoop, which provided cooling air for glycol and oil cooling, was also to have a hot air exit ramp which would create thrust that more than offset the drag caused by the frontal cross-section for the scoop. Though never fitted operationally to the P-40, it held promise and was one of the features incorporated in the design of the NA-73. Just how much the data from Curtiss was used is subject to debate. Curtiss engineers state that it was almost total, while those at North American claim that little of the information was used. The truth is probably somewhere between these two extremes. Clearly, the NA-73 had a lot in common with the XP-46, and a rational analysis would indicate that the NA-73 could not have been engineered in such a short period of time without considerable use of the Curtiss data. But equally as clear is the original thinking added by the North American design team. Among the most important changes was the addition of the laminar flow wing.

The P40 (although it held the line till the other fighters arrived), may not have been a 'great performer', but it gave birth to one!!!!

[Rifleman]

You're gonna make me do some research here on this one Bren.....I thought the P-51 came along in 117 days ?.....I also have the Squadron Signal productions of " In Action " for both models, the 40 and 51 , so its time for me to start digging them up.....I gotta get to the bottom of this one now......

[Hagar]

I seem to remember discussing this at length in a previous thread. The designer of the P-51 always denied seeing the belly scoop data & it had several basic differences to the Curtiss design which made it successful. All designers worth their salt are aware of the latest work of their competitors & no doubt indirectly influenced by many things. This is not so much a direct copy, it's the way anything progresses. This is even more obvious now computers are involved. There's not a great deal of difference between vehicles designed for the same purpose by any of the major car manufacturers. Where one leads the others follow the trend. Whatever the truth of the matter, the P-51 turned out to be far superior to any variant of the P-40. Being a new design the P-51 was capable of future development while the P-40 was the last in a line of thoroughbreds, much like the difference between the Hurricane & Spitfire.

I've always thought that the Spitfire owed more to the Heinkel He 70 than the previous Supermarine seaplanes. This takes nothing away from the brilliance of RJ Mitchell. They might look similar but if it was that easy why didn't the Gunter brothers produce a Spitfire?

[randombeaner]

While Im at it, heres a picture of the development of the P-51 i found somewhere I cant remember


the P-51 also lead to the development of the F-82


just two aircraft I found on my "Planes" folder

[Professor Brensec]

Agreed all. Everyone is right here (as there is really no 'wrong' in these discussions).

[Hagar]

Mention of the F-82 leads to the question of whether it was an original idea or based on German research like many other post WWII projects. The Bf 109Z Zwilling (twin) was very similar being two Bf 109 fighters joined together.



The single prototype was badly damaged in an air raid in 1943 & the project was abandoned in 1944 when priority was given to the Me 262. http://www.luft46.com/mess/me109z.html

This idea had been used successfully before with the He 111Z (also named Zwilling). This was a 5 engined glider tug developed to tow the huge Me 321 transport glider.
http://www.unrealaircraft.com/hybrid/He111Z.php

Aircraft design is influenced by many different ideas & concepts. Even a comparatively simple WWII fighter has 1,000s of different parts & uses various construction methods. Although 2 different types might look very similar there is no reason to suspect that one is a direct copy of another. There are only so many ways of doing some things (like placing a radiator scoop) & they're bound to look similar in some respects. The need to keep up with competitors, especially in wartime, is the main reason for the rapid progression of aircraft design in the 20th century.

[Professor Brensec]

Hagar wrote:

Aircraft design is influenced by many different ideas & concepts. Even a comparatively simple WWII fighter has 1,000s of different parts & uses various construction methods. Although 2 different types might look very similar there is no reason to suspect that one is a direct copy of another. There are only so many ways of doing some things (like placing a radiator scoop) & they're bound to look similar in some respects. The need to keep up with competitors, especially in wartime, is the main reason for the rapid progression of aircraft design in the 20th century.

Too true. However, the issue with these two aircraft is not so much the fact that these 'common' developments can be simply a result of 'industry trends' and 'natural progression' in engineering thinking. Rather it has more to do with the fact that Curtiss were 'ordered' to handover their drawings and data on the new 'Fighter' to North American.

This has been confirmed by NA, but they have maintained over the years that they 'conveniently' didn't need to refer to this valuable material to come up with a design which has some very obvious developmental and physical similarities. The fact that they had the material already 'nutted' out for them, can't be denied. It has been too well documented.

Having said this, I'm not meaning to take anything away from the P51. I love the plane, (although I think of myself as more of a P51 purist in that I prefer, in almost every way, the P51B to the D and onwards).  ;D Visability, I think, is the only real drawback in the B/C. And the British 'Malcolm' hood went a long way towards rectifying this.

I have also noticed that, while I'm on the visability subject, the 'new' NA73 has the two 'clear' rear quarter panels in the cockpit. A distinct feature of the P40. This is to me, a very obvious 'copying' of a better feature, which was not seen on previous or current NA planes (maybe???).

Incidentally, back to the original subject, if my dates and caculations are correct, the P51B (which also had the range to take the bombers to Germany), was also available at a time when it has been 'accepted' that there was no viable 'long range escort' for this job.
Is this a fact, or am I thinking the P51B (C/W Merlin) was not available in say........mid 1943  ;D

[Hagar]

it has more to do with the fact that Curtiss were 'ordered' to handover their drawings and data on the new 'Fighter' to North American.

This has been confirmed by NA, but they have maintained over the years that they 'conveniently' didn't need to refer to this valuable material to come up with a design which has some very obvious developmental and physical similarities. The fact that they had the material already 'nutted' out for them, can't be denied. It has been too well documented.

I don't deny the remarkable similarity. It's quite possible the NA designers & engineers used some of the Curtiss research along with all available data as any competent design department would do. There's no point in repeating research that's already been done & proven. What I'm not convinced of is that Curtiss was ordered to turn over its research data to NA alone. It's quite likely that all important research was published for the common good of the US aircraft industry. This is quite common in the UK where research data from the test facility at Farnborough was & is available to any interested party in the aircraft industry.

Curtiss is not alone in having a gripe about this sort of thing. It goes on all the time. Frank Whittle had to turn over the results of his experiments to the US Government & Miles Aircraft was forced to do the same thing with the data on its suddenly cancelled M.52 supersonic project. This was under a reciprocal technical research sharing agreement among the Allies. They got nothing in return as the US had little to give at the time. (Whether the US would have shared its latest top secret research is debatable anyway.) It's no coincidence that the Bell X1 (the first aircraft to break the "sound barrier") has a remarkable resemblance to the M.52. A scale model of the M.52 later did the same which proved the design was "sound" [pun intended].

[Felix/FFDS]

This was under a reciprocal technical research sharing agreement among the Allies. They got nothing in return as the US had little to give at the time. (Whether the US would have shared its latest top secret research is debatable anyway.)

THe US purposely did NOT share its nuclear research (in case the UK "lost" the war.

It's interesting how this was applicable later on when the Japanese were/have been "accused" of copying/using US technology and "improving" upon it (and not merely consumer products).  Technology sharing agreements are usually more one-way than a two-way road.

[randombeaner]

Here a pic of the gear



its got "quadrical" landing gear , (I JUST MADE UP A WORD!!!)

[Wing Nut]

I'm not sure what the issue here is, but I think we did decide that the Mustang WAS derived from the P-40, although all North American got was the wind tunnel tests for the Curtiss design.  

The picture of the side views are from the Squadron pub 'P-51 Mustang in Action' and is available in most hobby shops.

[Professor Brensec]

Hagar,

I think the word 'forced' (when mentioning the handing over of data), is probably a bit strong). As you say, there was probably alot of common knowledge, in so far as the "next logical step' type stuff is concerned.

Although, I can imagine a situation where the Army (or Air Force) may very well say something like:

(In a broad American drawl) - "Well, if you Goddamn guys can't get the Goddamn job Goddamn done, well you better Goddamn well give the Godddamn data that you Goddamn well have, to the NA boys, if you ever want to Goddamn make another Goddamn plane for the Goddamn U.S. Goddamn. A.A.F. ever a-Goddamn-gain"