drgondog
Major
Why? The P-51 performed just fine with a normal supercharger.
Dave - apparently it wasn't as simple as modifying the Merlin two stage design to the Pratt. The F6F-3 was the first attempt that I am aware of and certainly led the way to the -18 and -21 R2800 - but the latter two weren't ready for either the F4U or F6F until late in the war.