Boom Supersonic's XB-1 Breaks Sound Barrier In Two Historic Test Flights

On January 28, 2025, XB-1, an experimental aircraft built by US company Boom Supersonic, became the first privately built jet to fly faster than the speed of sound. To prove this was not a fluke, test pilot Tristan Brandenburg flew around for two more supersonic runs over California’s Mojave Desert before returning to land.

He repeated the feat with another test flight on February 10, 2025. Once again, the aircraft broke the sound barrier three times. Even more impressive, the single-seat, three-engine aircraft reached supersonic speed on both test flights without producing the usual sonic boom.

Supersonic speed refers to any speed faster than the speed of sound — about 768 mph (1,236 km/h). When an aircraft breaks this sound barrier, it produces an intense sound that can shake buildings and even crack windows. This noise was a major factor in the failure of the Concorde, the world's first supersonic passenger airplane. The aircraft was only allowed to fly at its top speed over the ocean. This limited its travel routes, eventually leading to its retirement.

Boom credits XB-1's "quiet" supersonic flight to physics. At high altitudes, where the air is thinner, sound travels more slowly. When a jet breaks the sound barrier up there, it creates a loud boom. As the boom moves downward, it enters denser air, where sound travels faster. This speed difference bends the sound waves upward. This prevents the boom from reaching the ground.

The February 10 flight was XB-1's 13th and final test flight. Boom will now focus on developing Overture, a commercial supersonic aircraft that can carry 64 to 80 passengers. The company expects to begin testing the plane in three years. If all goes well, Overture will take to the skies in 2029, cutting travel time by half or more. For instance, a flight from New York to London will take just three and a half hours instead of the current seven.

Resources: Boomsupersonic.com, Space.com, PCmag.com