North American manufactured two airframes. They flew a total of 129 flights between 1964-1969. The joint program among North American Rockwell, the Air Force, and NASA featured the world’s largest experimental aircraft with a delta wing and hinged wing tips that could be folded down to a 65° angle to improve stability at the aircraft’s supersonic speeds of up to Mach 3, a speed at which the Valkyrie was designed to ride its own shock wave. The program used the Valkyrie to conduct fundamental flight research at high speeds for use in designing future supersonic aircraft, both military and civilian. The aircraft produced a significant quantity of information on supersonic flight at up to Mach 3 speeds in areas such as noise (including sonic booms), potential flight corridors, validation of wind-tunnel data, flight control, operational problems, and clear-air turbulence.