The North American XB-70 was the largest Mach 3 airplane ever flown. It had a 105-foot wingspan and cruised at 72,000 feet. Powered by six 30,000-pound-thrust General Electric YJ-93 engines, it had a range of 4,288 miles at an altitude of 77,350 feet. The second prototype crashed when its wing was clipped by a chase plane. The first XB-70 continued to provide supersonic flight test information until it was retired to the Air Force Museum at Wright-Patterson Air Force Base, Ohio.