The origins of the P-51 began in early 1940. Great Britain’s Purchasing Commission, interested in acquiring Curtiss P-40s, approached North American Aviation to build them under license for the RAF. Instead, North American pitched an alternative consisting of a completely new fighter that would outperform the P-40. The British accepted the offer and placed an order for 340 of the new aircraft in March 1940. On September 9th, the NA-73X was rolled out 102 days after contract signature.
Early Mustangs entered production in May 1941 and went into combat with the RAF 11 months later. These were powered by Allison engines and were typically equipped with two .50-calibre nose-mounted and four .30-calibre wing-mounted machine guns. RAF Mustang Marks I and II were soon followed by the improved P-51As, Bs, and Cs operated by the USAAF and the RAF. British experimentation with the supercharged Merlin powerplant provided for outstanding high-altitude performance, and by mid-1943, Packard-built Merlin engines became standard for new build P-51s.
During WWII, P-51s saw action in the European, North African, Mediterranean, and Pacific theaters. Mustangs claimed 4,950 air-to-air kills. In USAAF service, P-51s, with their very long range, escorted bomber formations over Europe beginning in 1943 and as ground attack and close air support aircraft following D-Day. The definitive P-51D was fitted with a Plexiglas bubble canopy providing excellent 360-degree visibility, and the aircraft could reach around 440 MPH while its service ceiling was just shy of 42,000 feet.
By the start of the Korean War, the Mustang had been re-designated as the F-51 and it served as the front-line fighter until the F-84 and F-86 arrived on the scene. The “Cadillac of the Skies” served with Air National Guard Units until 1957 and the last Mustang in USAF service was retired in 1978. In foreign service, the Dominican Republic retired its last operational P-51 in 1984. Today, a handful of P-51s still fly as warbirds with private owners.