How the XB-1 aircraft became supersonic without a sonic boom

When the experimental XB-1 aircraft broke the sound barrier three times during his first supersonic flight on January 28, it did not produce a Sonic Boom Audible from Earth, according to the US company Boom Supersonic.

“This confirms what we have long thought: Supersonic Travel can be affordable, sustainable and friendly to those on board and on the ground,” said Blake Scholl, founder and CEO of Boom Supersonic, in a press released.

As an aircraft pushes through the atmosphere at a high speed, it changes the air press surrounds it and creates sound waves. And when a supersonic flight exceeds the sound speed – Mach 1, or approx. 1224 kilometers per hour – combine these sound waves to form a shock wave that spreads away from the flight road. This sonic boom can travel far enough to reach the group where it can produce an extremely high noise, rattle buildings and even break glass.

Sonic Booms Over Land is so disruptive that they have helped to try again by the legendary commercial Airliner Concorde in 2003 and spurred many countries to ban commercial supersonic aircraft. Since then, space engineers have been trying to develop flight design that can go supersonic without the accompanying boom.

In this case, the XB-1 utilized a physics phenomenon called Mach Cutoff. Becuse Sound moves slowly to higher heights, a plane that breaks the sound barrier at these heights will produce a boom that cannot reach the ground – if the boom moves downwards, the rising sound speed will divert it and push its shock waves upwards.

The trick is that temperature and wind also affect sound speeds, so the ideal height and speed of a supersonic aircraft depends on atmospheric conditions. “The actual challenge is to become very accurate atmospheric forecasts for temperature and about the wind computer, as the practical Mach-Cutoff aircraft speed is pretty straightforward from there,” says Bernd Liebhardt in the German Aviation Center.

Boom Supersonic says XB-1’s latest and last test flight on February 10 also reached supersonic speeds without producing a boom. Now the company is using what it learned from the test flights to help its future commercial aircraft, overture, achieve the same business. Supersonic overland flights would be up to 50 percent faster than today’s commercial carriers. It could shorten the flight time from New York to Los Angeles by 90 minutes.

Flying with supersonic speeds below shorter overland routes could also burn less fuel than flying at the “aerodynamic worst speed” – just below the sound barrier – says Liebhardt. But he travels that Tinging benefit of Mach Cutoff is probably more of a niche use box for “Supersonic Business Jet users”. It would provide less of a financial payment for a commercial airline service.