On Wed, 3 Oct 2007 15:34:25 -0600, "Daryl Hunt"
wrote:

Keeping it in the whatif department. Whatif they had installed decent
Turbos and Supers on the Allisons.

The turbo required a large amount of plumbing that was accomodated in
the tail booms of the P-38 and the enormous fuselage of the P-47.
There wasn't room for it in the P-39 or P-40.

Improving the supercharger efficiency of the Allison would have been
the feasable alternative, as the better supercharger largely explained
the contemporary single-stage Merlin's advantage over the Allison.
Having said that, Allison didn't manage to do what Hooker did with the
Merlin 20/45 series Merlins despite the need to do so; the closest
they seem to have come was adapting the supercharger gearing on the
V-1710-E4 used in the P-39 to raise the full-throttle height by a
couple of thousand feet, which was too little too late.

What would that have done for even the
P-40. Afterall, later productions on the P-38 and the P-47 would have had
equal or more range and speed of the P-51C and the P-40 would have had near
identical performance and speed.

The P-40 was marginally slower than the Spitfire with a similar
engine, and relative aerodynamic efficiency (largely down to wing
thickness) and weight meant that the Spitfire outperformed it above
full-throttle height. The P-39 and P-40 were the most obsolete
airframes in the US single-engined fighter inventory by 1942, when
two-stage Merlin production was being mooted for Packard and the P-38
was in production with the P-47 to follow shortly. It made more sense
to put the engine with the best potential in the fighter with the best
potential. Out of the three options of the P-39, P-40 and P-51 the
Mustang was clearly the best airframe.

Improving the altitude performance of the Allison in 1941 - in time to
be relevant for 1942 - would have been more useful if you wanted a
better P-39 or P-40. But even then the available engines (the Packard
Merlin 20 series in the P-40F and L) still couldn't overcome the
constraints upon high altitude performance which made the P-40
inferior to the Spitfire at altitude, so unless Allison could out-do
the Merlin 20 series without turbocharging there wasn't much prospect
of them achieving anything better.

Now imagine instead if the US had agreed to begin production of the
Spitfire in 1940 when the British originally raised the issue....

Gavin Bailey

--
Solution elegant. Yes. Minor problem, use 25000 CPU cycle for 1
instruction, this why all need overclock Pentium. Dumbass.
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