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omissis
What changes could have been made? I had actually thought of creating a thread about theoretical ways WWII airplanes could have been made better with the knowledge of the time.
Even if the mass distribution was OK, if you change the engine substantially it isn't and you need a new airframe.No changes, unfortunately. No matter how pretty P-39 could have been, the mass distribution was flawed, and there were no modifications that could have improved the design.
USAAF was more than happy to get rid of it at the first useful opportunity, giving them as a present to a low-ranking Allies...
I was thinking more along the lines of fitting the Merlin, most allied aircraft had some engine change or other, with the P-39 it required a complete re design to do it.Even without the turbocharger P-39 had a C.G dangerously aft, so I can imagine how it could be with turbocharger in the rear of the fuselage.
I'm inclined to think that stripping P-39 of the turbo was a technique to get an aeroplane "more or less" flyable at the expense of high flying performance.
But it is not only , as I stated before, just a matter of "static balance" but also of "dynamic balance".
Could you just slot a Griffon or Sabre in there Mr Bell.I don't know why people want to reinvent the wheel.
The P-63 was a redesigned P-39. It solved the handling problems.
it also used no parts in common with the P-39 except screws and rivets.
Even without the turbocharger P-39 had a C.G dangerously aft, so I can imagine how it could be with turbocharger in the rear of the fuselage.
I'm inclined to think that stripping P-39 of the turbo was a technique to get an aeroplane "more or less" flyable at the expense of high flying performance.
But it is not only , as I stated before, just a matter of "static balance" but also of "dynamic balance".
The turbo was below the engine, not in the aft fuselage.
Why didn't the USAAF buy the P-63?The P-63 was a redesigned P-39. It solved the handling problems.
So that was about friction reduction?Pratt & Whitney 2 stage engines used a hydraulic clutch to change supercharger drive gears.
Okay, I got youThe torque converter/fluid coupling drove the supercharger directly.
So that was about friction reduction?
I'm confused...No, it operated like a friction clutch.
To replace what? Months before the start of the jet age?Why didn't the USAAF buy the P-63?
Who do you think paid for over 3300 of them?Why didn't the USAAF buy the P-63?
I'm confused...
By my personl point of view, P-39 was a mess not for aerodynamics, but for the distribution of the masses, expecially consumables.
That affected quite a lot Static balance (Moment of first order, expecially after ammunition expended) but even more the Moment of second order, namely the "Moment of inertia" of the airplane, making handling tricky, to say the least.
Moment of inertia - Wikipedia
Might have been faster at high altitude, was 30mph slower at low altitudes. This was a mock up.
P-39s were running on the margin for cooling both the glycol mixture and and the oil as it was. Trying to cool an 1150-1425hp engine at 25,000ft needs bigger radiators or a lot of attention to the radiators and ducts.
The space in the outer wings doesn't work well for fuel if you are using self sealing tanks. the tanks wind up rather thin and spread out for the amount of fuel they hold meaning even the empty tanks are rather heavy.
You are also forced into using under wing tanks/bombs, perhaps not a bad thing but that much more stuff to sort out.
The P-39 was already a pint and a half (750ml) in a pint (500ml) bottle, trying to stuff the turbo in means you are going for the full quart (1000ml) in the pint (500ml) bottle.