How the XB-1 aircraft went supersonic without a sonic boom
When the experimental XB-1 aircraft achieved supersonic speeds on a test flight, it did not create a disruptive sonic boom – thanks to a physics phenomenon called the Mach cutoff
By Jeremy Hsu
10 February 2025
The experimental supersonic aircraft XB-1
Boom Supersonic
When the experimental XB-1 aircraft broke the sound barrier three times during its first supersonic flight on 28 January, it did not produce a sonic boom audible from the ground, according to US company Boom Supersonic.
“This confirms what we’ve long believed: supersonic travel can be affordable, sustainable and friendly to those onboard and on the ground,” said Blake Scholl, founder and CEO of Boom Supersonic, in a press release.
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As an aircraft pushes through the atmosphere at a high speed, it changes the air pressure around it, creating sound waves. And when a supersonic flight surpasses the speed of sound – Mach 1 – these sound waves combine to form a shock wave that spreads away from the flight path. This sonic boom can travel far enough to reach the ground, where it can produce an extremely loud noise, rattle buildings and even break glass.
Sonic booms over land are so disruptive that they contributed to the retirement of the fabled commercial airliner Concorde in 2003 and spurred many countries to prohibit commercial supersonic aircraft. Since then, aerospace engineers have been trying to develop aircraft designs that can go supersonic without the accompanying boom.
