“"Designed in 102 days. Perfected by a British engine."”
In 1940, the British Purchasing Commission asked North American Aviation to build Curtiss P-40s under license. NAA's James Kindelberger proposed something better: a clean-sheet fighter designed in 102 days. The NA-73X prototype first flew on October 26, 1940. But the American Allison engine lacked high-altitude performance. The breakthrough came in 1942 when Rolls-Royce Merlin engines were fitted to Mustang airframes at Hucknall, England. The result was transformative: speed jumped past 400 mph, and the aircraft could now escort bombers all the way to Berlin. The P-51B/C arrived in Europe in late 1943; the P-51D, with its bubble canopy and six .50-caliber guns, became the most numerous variant. By war's end, Mustangs had claimed 4,950 aerial victories and 4,131 ground kills. The 15,000th Mustang rolled off the line during the war.
The P-51's laminar-flow wing design—rare in fighters of the era—reduced drag and extended range, a principle still used in modern high-performance general aviation aircraft.