In 1940, the British offered North American Aviation the opportunity to produce the P-40 fighter for Great Britain under license from Curtiss, but North American representatives proved that they could quickly develop and produce a more advanced aircraft of their own design. In late 1940, the prototype of the new NA-73 fighter was built, and in April 1941, the first production aircraft was produced, known in Great Britain as the Mustang I.

The main drawback of the aircraft soon became apparent, related to the low-altitude Allison engine installed on it: having excellent characteristics at low levels, the aircraft lost all its advantages as it climbed higher — so the first aircraft were used as attack and reconnaissance aircraft. But high-altitude fighters were needed, and so it was decided to install a high-altitude British Merlin engine on the Mustang. The Americans, having learned of this work by the British, decided to do the same and purchased a license to produce these engines. As a result of the installation of this engine, the P-51B/C modification was introduced. As production continued, the aircraft was improved and as a result, the most famous modification of the Mustang was introduced — the P-51D (NA-111/122).

The P-51D-15 was a single-seat, single-engine, all-metal cantilever monoplane with low laminar wings. Externally, the aircraft differed significantly from previous modifications with a teardrop-shaped bubble canopy with the complete absence of rear framing to improve visibility to the rear. This modification to a reduction of the lateral surface of the rear fuselage, which negatively affected the directional stability. To counteract this phenomenon, later modifications of the aircraft had a dorsal fin, which was also installed on earlier models during planned modifications or repairs. Pilot protection included armored glass in the front and an armored seat back with a headrest.

The P-51D-15 was equipped with a Packard V-1650-7 engine that developed 1,720 horsepower in emergency combat mode.

The armament of this modification consisted of six heavy machine guns in the wings, the ammunition feed was changed, and the machine guns were installed without tilting, which prevented them from jamming. The aircraft could carry two underwing bombs up to 1,000 pounds (454 kg) or external fuel tanks with a capacity of 75 to 110 gallons or unguided rockets.

After landing on the continent, the Mustangs were used for strike missions, and as the resistance of the German Luftwaffe weakened, such use of the P-51 became more frequent, but initially, they were used primarily as escort fighters. In general, the formation of American bombers called the "combat box" provided a serious defense, hitting the enemy with heavy machine gun fire from all directions. The tight formation made it possible to concentrate the fire of several planes on one enemy fighter, so for the Germans, the primary task was to destroy the "box." Then everything was easier: several Messerschmitts or Focke-Wulfs attacked the bomber from different sides and often succeeded. Thus, the losses of the bombers were significantly reduced in the presence of an escort that repelled the attacks of the German fighters.

The P-51D is considered one of the best fighters of the war and the "classic" variant of the Mustang. 900 aircraft of the D-15 series were built.

1. “American Warplanes of World War II” by David Donald, 1995
2. S. Ivanov “P-51 Mustang”, “War in the Air” No. 124 2005
3. Materials from the site airwar.ru