bdk wrote:
Are you sure that the Spitfire was designed for a water cooled engine? Those radiators seem to be scabbed on as such an afterthought! No wonder you don't see many Spitfires racing at Reno, might as well have added some permanently extended speed brakes...
Hmmm.
Prototype and up to Mk.V had one (smaller) radiator and a circular section oil cooler. The design is a generation earlier than the P-51, but the ducting isn't
that different, in that the rad face is the full height of the wing and depth of the radiator, with the entry to the housing being about 1/2 that height, likewise the exit with a variable flap - just like the Mustangs' in principle, in fact (the Hurricane's, on the other hand was a radiator in a housing with no effort at taking advantage the venturi effect).
The two stage Merlin Spitfires had two radiator boxes, the oil cooler being 1/3 (or so) of one of them, while the Griffon jobs were bigger still.
Bob Jens' Spitfire XIV was raced, but no Spitfire has been heavilly modified for US racing - like everything else, the rads would be one item that would be addressed for that, but they aren't as 'barn-door' like as you think. What the speed-loss/gain is I don't know, but closer (behind) the Mustang radiator set up than you'd think.
Odd one out is the High Speed Spitfire which was aimed at the world air speed record - but wasn't in the right league once the Germans got going with the Heinkel and Messerschmitts.