Sketched out in a New York city hotel room in April 1940, the North American Aviation Corporation NA73X went on to become one of the best fighters to come out of World War 2. The U.S. Army Air Corps gave it the title of P (for Pursuit) 51 and it was named Mustang by the British. Of the several variations of the Mustang, the P51-D is considered the definitive version and was the first to have the bubble canopy. More "D" models were built than any other variant, with a total of 9,603 being produced.