North American's NA-73X prototype flies, beginning the P-51 Mustang's careerIn 1940 the NA-73X, prototype of the North American P-51 Mustang, made its first flight, 86 years ago today.
In 1940 the NA-73X, prototype of the North American P-51 Mustang, made its first flight, 86 years ago today. North American had proposed the design to the British Purchasing Commission in place of license-built Curtiss P-40s and completed the prototype in 102 days. The Allison engine was weak at altitude until the British fitted a Rolls-Royce Merlin in 1942, which with the laminar-flow wing gave the range to escort Eighth Air Force bombers to the target and back. 12,776 were built during the war, and about 150 still fly.



