The North American Aviation P-51 Mustang is an American long-range, single-seat fighter and fighter-bomber used during World War II and the Korean War, among other conflicts.

Although first designed for the British as a medium-altitude fighter, the Mustang excelled in hedge-hopping strafing runs and long-range escort duty. It gained acclaim for firing on trains, ships and enemy installations in Western Europe.

The Mustang was designed in April 1940 by a team headed by James Kindelberger[5] of North American Aviation in response to a requirement of the British Purchasing Commission. The Purchasing Commission approached North American Aviation to build Curtiss P-40 fighters under license for the Royal Air Force (RAF). Rather than default to an old design by another company, North American Aviation proposed the design and production of a new more modern fighter.

The Mustang was the first single-engine plane based in Britain to penetrate Germany, first to reach Berlin, first to go with the heavy bombers over the Ploiesti oil fields in Romania, and first to make a major-scale, all-fighter sweep specifically to hunt down the dwindling Luftwaffe.
One of the highest honors accorded to the Mustang was its rating in 1944 by the Truman Senate War Investigating Committee as “the most aerodynamically perfect pursuit plane in existence.”
The North American prototype, NA-73X, was first flown on Oct. 26, 1940. At least eight versions of the Mustang were produced.

The Mustang was designed to use the Allison V-1710 engine, which had limited high-altitude performance in its earlier variants. The aircraft was first flown operationally by the RAF as a tactical-reconnaissance aircraft and fighter-bomber (Mustang Mk I). Replacing the Allison with a Rolls-Royce Merlin resulted in the P-51B/C (Mustang Mk III) model, and transformed the aircraft’s performance to capabilities of altitudes above 15,000 ft while maintaining its range allowing it to compete with the Luftwaffe’s fighters.

The definitive version, the P-51D, was powered by the Packard V-1650-7, a license-built version of the two-speed, two-stage-supercharged Merlin 66, and was armed with six .50 caliber (12.7 mm) AN/M2 Browning machine guns.[10]

At the start of the Korean War, the Mustang, by then redesignated F-51, was the main fighter of the United States until jet fighters, including North American’s F-86, took over this role; the Mustang then became a specialized fighter-bomber. Despite the advent of jet fighters, the Mustang remained in service with some air forces until the early 1980s. After the Korean War, Mustangs became popular civilian warbirds and air racing aircraft.