P-39 - why only one mid-engined aircraft?

[KG45]

I've been curious as to why only one mid/rear piston engined aircraft was ever developed. don't recall ever seeing another like it. the P-39 seems like a workable design, since it was widely used, even appreciated, esp by the russians.

[Motherland]

I've been curious as to why only one mid/rear piston engined aircraft was ever developed. don't recall ever seeing another like it. the P-39 seems like a workable design, since it was widely used, even appreciated, esp by the russians.

The P39 had trouble with odd stalls due to the CoG issues when all of the forward ammunition was expended. Other than that, I imagine maitenence was quite a hassle.

[KG45]

well, after the P-39 was announced, alot of info was posted. don't recall reading anything about maintenance being a problem. anyway the maintence and flight characteristics and other issues are usually worked out as a design is developed.

I guess what i'm curious about is that going beyond the US, it seems none of the other major powers ever even attempted a mid engined design. the P-39 showed it could be a workable concept.

[FrodeMk3]

well, after the P-39 was announced, alot of info was posted. don't recall reading anything about maintenance being a problem. anyway the maintence and flight characteristes and other issues are usually worked out as a design is developed.

I guess what i'm curious about is that going beyond the US, it seems none of the other major powers ever even attempted a mid engined design. the P-39 showed it could be a workable concept.

There were others' on the drawing boards; The fisher XP-75, The curtiss' XP-55 Ascender, I believe there was an Me.509 drawn up. The Japanese had a Rutan-looking rear-engined plane. There were quite a few unorthodox planes' around.

[Greebo]

Compared to a conventional plane, the mid engine layout is likely to weigh more. You have the transfer gearboxes, driveshaft and an extra firewall. The original P-39 prototype had a conventional taildragger undercarriage, but it had problems getting the tail up on takeoff so they went with a tricycle layout which added yet more weight.

Having most of the guns in the nose caused a rearward centre of gravity shift as the ammo was used up. Another issue is where you put the fuel if the engine is occupying the centre of gravity, the P-39 and P-63 both suffered from small fuel tanks.

The German, French and Soviets all had inline engines that could accept a cannon firing through the propeller shaft, taking away one of the main reasons for the P-39 layout.

[Krusty]

Do-335
Me-309

Quite a few Luft '46 designs, and a Japanese design or two (I think).

The main problem is the gearshaft. It just introduces problems. Even the Japanese planes that just extended the prop a short distance to the engine had major problems with vibration and maintainence, and that's not counting going from engine to shaft along to gearbox and out to prop.


Why reinvent the wheel when it's already been around and proven for 50 years?


P.S. The major reason for it on the P-39 in the first place was just to make room for a large cannon. However, we see other designs with big cannons and the engine's still in front. It [mid mount engine to make room for a big gun] was a good idea at the time, but unnecessary.

[Lusche]

Another one, the He 119:



8 prototypes successfully flown and setting a few world records, but Luftwaffe wasn't interested.

[CAP1]

I've been curious as to why only one mid/rear piston engined aircraft was ever developed. don't recall ever seeing another like it. the P-39 seems like a workable design, since it was widely used, even appreciated, esp by the russians.

production.
all of the auto manufacturers were already tooled up for conventional aircraft designs, and i think it would've cost a LOT to retool for this type of design. remember.....we overwhelmed them more than anything...we had sheer numbers, along with the highest quality training for our pilots.....

<<S>>

[angelsandair]

There were others' on the drawing boards; The fisher XP-75, The curtiss' XP-55 Ascender, I believe there was an Me.509 drawn up. The Japanese had a Rutan-looking rear-engined plane. There were quite a few unorthodox planes' around.

The XP-75 actually went into production though as the P-75A just not many were built. Plus the P-75 is like the retarded son of the P-39 and the P-51. Man it looks like it fell out of the ugly tree and hit every branch on the way down  But 10 .50 caliber machine guns could make up for it.

[Old Sport]

The P-63 Kingcobra was the result of an attempt on the part of the Bell Aircraft Corporation to correct some of the deficiencies of the earlier P-39 Airacobra. Although the Kingcobra had a superficial resemblance to the P-39 which preceeded, it was, in fact, a completely new design and no parts of the two aircraft were interchangeable.

http://home.att.net/~jbaugher1/p63_1.html

[Soulyss]

Another issue with putting the engine in the middle of the A/C is it regulates pretty much the entire internal fuel capacity to wing tanks.  One of the primary faults of the P-39 in U.S. service was it's lack of range. 

[gripen]

There was quite many projected/prototype mid engined aircraft like Koolhoven FK 55, Fischer P-75, Rolls Royce project with Mustang wing and Griffon and IIRC the Russians had a prototype mid-engined fighter as well. In addtion there was Arsenal VB 10 having nose and mid-engine.

[BroncoSquid]

My grandfather would tell me a story about the p-39, his best friend was a p-39 test pilot. Anyway one of  the biggest problem they had was that the p-39 would easily go into a flat spin during a hard turn. My grandfather told me about a time where his friend was up testing the p-39 and had put it into a flat spin. (He would then go into telling me about the gyrations of the plane and "Prop walking"). His friend went to bail out of the plane, he slid the canopy back, let go of the stick, stood up, and all of the sudden the plane straightened up (cog change I guess). His friend sat down and flew the plane in for a landing. After he got out of the plane, all of the testing staff, and other assorted higher ups wanted him to "Do it again". Needless to say he said No way. But in a more colorful way...

[stroker71]

Another big factor was the coming of the jet age.  Why continue work on a prop plane?

[humble]

My grandfather would tell me a story about the p-39, his best friend was a p-39 test pilot. Anyway one of  the biggest problem they had was that the p-39 would easily go into a flat spin during a hard turn. My grandfather told me about a time where his friend was up testing the p-39 and had put it into a flat spin. (He would then go into telling me about the gyrations of the plane and "Prop walking"). His friend went to bail out of the plane, he slid the canopy back, let go of the stick, stood up, and all of the sudden the plane straightened up (cog change I guess). His friend sat down and flew the plane in for a landing. After he got out of the plane, all of the testing staff, and other assorted higher ups wanted him to "Do it again". Needless to say he said No way. But in a more colorful way...

The only problem with that is the P-39 has a door not a canopy that releases so he couldnt have "stood up"....at least from my understanding of the planes configuration.