On its 12th test flight, the Boom XB-1 prototype broke the sound barrier three times and achieved a top speed of Mach 1.1. On its 12th test flight, the Boom XB-1 prototype broke the sound barrier ...

Boom Supersonic achieved Tuesday its goal of breaking the sound barrier on its first attempt with the XB-1 prototype of its Overture aircraft — and then repeated the feat two more times.

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 ...