North American P-51 Mustang

Ultimately the greatest long-range fighter of World War II, the P-51 Mustang took some time to find its war-winning final shape.
Designed in 1940 to meet an urgent British requirement for an airecraft to equip RAF Fighter Command, it initially proved a partial
failure. The advanced laminar-flow wings and streamlined all-metal fuselage made the aircraft fast in low-level flight, but its Allison
engine performed poorly at higher altitude. Although the RAF deployed the Mustang as a ground-attack aircraft, it found it useless
as an air-superiority fighter. Hoping to improve the aircraft’s high-altitude performance, the British finally thought to test it with a Rolls-Royce Merlin engine.
The results were spectacular. When the US aircraft company North American fitted a Packard-built Merlin engine as standard in 1943,  a great aircraft was born.
The Merlin-engined Mustang answered Allied bomber crews’ prayers for a really effective fighter that would protect them in the dangerous skies over Germany. With fuel drop tanks, the Mustangs could escort
bombers all the way to Berlin and back. Fast and agile, they could outfight any German interceptor sent up against them, even when
operating at extreme range. The Mustang was still the US’s frontline fighter at the start of the Korean War in 1950. More than 15,000of
the aircrafl were built in total.