The size of the experimental airspace for today's flight limited how long the jet was able to fly above Mach 1. Boom Supersonic's XB-1 aircraft goes supersonic during a test flight on Jan.
Boom Supersonic's XB-1 demonstrator jet became the first U.S.-made civilian supersonic jet to break the sound barrier. The independently funded XB-1 reached a speed of Mach 1.122, or about 750 mph ...