nope, its because USA started building their fighters years after the spit and 109 were first built so there was less time to produce different variants. up to the end of WWII the production runs of US aircraft were years shorter than either the spit or 109.
also the US industrial machine was geared more towards cheaper more efficient mass production of mil hardware than the european manufacturers, who could therefore respond to tactical requirements quicker, albeit at the expense of production numbers and cost. european production was also far more widely dispersed than US production too, because our factories had bombers flying over them. eg. RR mostly hand-built Merlins vs Packards mostly line-built Merlins. spits largely hand built wings vs P-51 line-built wings. etc etc.
Strange, I could have sworn the 109 and Hurricane were introduced in 1937, Spitfire and P-36 1938 and the P-40 in 1939...not years of difference there. High performance fighters weren't necessary until the U.S. was dragged into the war, at which time the industrial machine developed such "cheap" aircraft as the P-40, F-4U, P-47, P-38, P-51, B-17 and B-24, none of which used wood or fabric in their airframes unlike the Spitfire, Hurricane and Mosquito. And, I guess you could consider low production numbers of 13,000 P-40s with only 9 operational variants, 16,000 P-51s with only 4 operational variants, 16,000 P-47s with only 6 operational variants and 10,000 P-38s with only 7 operational variants, all produced in shorter time periods from concept to retirement, to be low production numbers compared to 20,000 Spitfires with more than 25 operational variants produced over a 10 year span. Didn't realize the U.S. was the only country using assembly line production, that would account for the aircraft manufacturing facilities in Britain, Russia, Germany and Japan.
There are enough Spitfires in AH.
