Breitling Classic AVI Chronograph 42 P-51 Mustang A233803A1B1X1. The Classic AVI P-51 Mustang honours one of those legends. When the aircraft was built in a mere 120 days, even its developer North American Aviation, didn't anticipate what a powerhouse it had on its hands. The P-51's low-drag wings and engine-cooling system--considered experimental when the single-seat fighter first took off in 1940-gave it unprecedented speed and range. The addition of a Merlin engine, expanded the plane's performance to high altitudes, making it the best all -purpose fighter of its time.