The Amaurotean Capitalist wrote:

"Scott M. Kozel" wrote:

Given that over 15,000 P-51s were built by North American Aviation in
the U.S. and paid for by the U.S. government, it was predominently a
U.S. aircraft. Like you said, the later models did use the Merlin
engine.

The critical point is that the P-51 would not have been sustained in
production without the RAF championing the type on the basis of the
Merlin installation in mid-1942. It was never a part of USAAF
procurement until October 1942, and it took substantive British
efforts to get the USAAF to accept it as a major production type.

Given that with the Allison engine that the P-51 on the balance had
significantly better performance than previous U.S. fighters, even
with that engine it most likely would have been built in substantial
quantities and been a useful fighter aircraft.

So it's certainly a US aircraft, but it wouldn't have existed without
substantial British input both in technological terms, and production
advocacy from the initial Allison-engined British purchase contracts
to the Merlin conversion.

I would agree that there were "substantive British efforts" in the
preliminary design of the aircraft, and that the Merlin engine design
substantially increased the performance of the aircraft.

The main production version of the P-51 was powered by the Packard
V-1650-3, built by the Packard Motor Car Company of Detroit, Michigan,
USA, and it was a two-stage two-speed supercharged 12-cylinder Packard-
built version of the Rolls-Royce Merlin engine. The P-51 was armed
with six of the aircraft version of the .50 caliber (12.7 mm) Browning
machine guns.

I would give a lot of credit to British efforts in the preliminary
design of the aircraft and its ultimate engine.

When I said that the P-51 was a "predominently U.S. aircraft", that is
because its final design and production was in the U.S., that over
15,000 P-51 airframes were built by North American Aviation in the
U.S., powered by engines built by Packard in the U.S., with the raw
materials and labor provided from the U.S., and that the project was
paid for by the U.S. government.