Boom Supersonic XB-1 breaks the sound barrier, a major milestone

Ten months after its maiden flight, Boom Supersonic’s XB-1 prototype has achieved a significant milestone, breaking the sound barrier three times during its 12th test flight. This achievement marks a crucial step towards the company’s goal of developing the Overture airliner, a supersonic passenger jet capable of Mach 1.7 speeds.

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Taking off from the Mojave Air & Space Port, Chief Test Pilot Tristan Brandenburg piloted the XB-1 to an altitude of 34,000 feet, reaching a top speed of Mach 1.1 (approximately 844 mph) for about four minutes.  This flight not only represents the XB-1’s first supersonic journey but also marks the first time a privately developed civil aircraft has broken the sound barrier.  The Concorde, the only previous supersonic passenger jet, was a joint venture between the British and French governments.

The XB-1 repeated its supersonic feat twice more during its descent. The 34-minute test flight took place in the Bell X-1 Supersonic Corridor, named after the first aircraft to break the sound barrier.  The 63-foot-long prototype is currently powered by three General Electric J85-15 turbojet engines. However, Boom plans to develop its own four engines for the larger Overture airliner after its partnership with Rolls-Royce ended in 2022.

This supersonic flight is a substantial leap forward from the XB-1’s initial test flight in March 2024, where it reached only 283 mph.  The most recent previous test flight, in January 2025, saw the XB-1 achieve Mach 0.95 at an altitude of 29,481 feet.

Despite this breakthrough, Boom Supersonic faces a long road of development and testing before Overture can take its first flight, currently targeted for 2030.  The company has raised over $700 million and secured orders for 15 aircraft from United Airlines (with options for 35 more) and 20 from American Airlines. This successful supersonic test flight provides significant momentum as Boom Supersonic works towards bringing supersonic passenger travel back to the skies.