*World War II had just started. Britain needed more fighter planes and was looking to the USA. The Curtiss P40 Warhawk seemed attractive, but the Curtiss facility was already working at full capacity. So the Brits asked James H. "Dutch" Kindelberger of North American Aviation (NAA) to produce it at his plant in Inglewood, Calif.
His reply was that, in the 120 days it would take to tool up, he could offer an all-new machine that would fly faster, higher and farther, with greater maneuverability and firepower. This was an ambitious claim, but NAA had already proved its worth by supplying the Harvard trainer to the British military, so Kindelberger got the AOK. The Royal Air Force (RAF) was looking for something exactly like this. Its strategy was to conduct a campaign of bombing raids on Germany, but the fighter plane escorts that protected the big bombers against enemy attack didn't have the range. They could fly as far as the German border and then had to turn back, leaving the bombers vulnerable. The subsequent losses were unsustainable. Edgar Schmued was put in charge of the design team and after 78,000 man-hours and 102 days, an engine-less, unpainted prototype was completed; 18 days later, it was fitted with an Allison V-1710-39 engine (making about 1,100 hp). On October 26, 1940, test pilot Vance Breese took the plane for its maiden flight. The name of the person responsible for calling it the Mustang has not been recorded, but it was someone working within the British bureaucracy.
Despite a conventional (for the time) appearance, the Mustang sported two new features-a new low-drag wing designed by the National Advisory Committee for Aeronautics (NACA), and an innovative cooling design with the characteristic belly scoop and a feature where hot air exiting from the radiator acted as a form of jet thrust (known as the Meredith Effect, named after a British aerodynamicist). However, the Allison engine was found to be wanting at high altitudes. In April 1942, a British test pilot, Ronald Harker, suggested an engine swap with the Rolls-Royce Merlin V12 that powered the Spitfire and Hurricane. This change transformed the Mustang and unlocked its full potential. A Merlin-equipped Mustang could hit a top speed of 440 mph at 30,000 feet, 100 mph faster than an Allison-engined model. The Packard luxury car company was tasked to produce Merlins under license at its Detroit factory. Early versions made 1,400 hp, but power grew to 1,900 hp during the course of its development. Taking off and landing could be tricky, but in the words of fighter ace Clarence "Bud" Anderson, the Mustang "was pleasant and forgiving to fly... it could turn on a dime. Best of all, it went like hell.