P-40 Warhawk and P-51 Mustang (World Fighter Aircraft Collection)

A P-40 Warhawk and the P-51 Mustang "Glamorous Gal" in formation during the 2006 Yankee Air Museum "Thunder Over Michigan" airshow.

Near the start of World War Two the British asked North American aviation to build Curtiss P-40s under contract, but North American said that they could produce a superior aircraft in about the same amount of time, and so the P-51 Mustang was born.

Even at the start of the war the Warhawk wasn't completely competitive with the main German fighter, the Bf109, and as the war developed it lost more and more ground.   However it continued to serve in places with fewer first-line enemy fighters until the end of the war, and by that time it had served in more theaters of operation than any other American fighter.   Because of its more advanced aerodynamics, particularly its laminar flow wing, the Mustang was about 30 miles per hour faster than the Warhawk, even when using the same Allison engine.   However the Mustang didn't reach its full potential until its American Allison engine was replaced by a British Rolls-Royce engine, which turned it into the most valuable land-based fighter in the American arsenal.