At the end of January, the Boom Supersonic XB-1 became the first privately built plane to reach supersonic speeds. It reached 1,360 km/h in the Mojave Desert, USA, and will be the basis for the Boom Overture passenger plane that will operate by 2029. Now Boom has confirmed that the XB-1 is also the first plane to break the speed of sound without producing an audible sonic boom.
When flying at supersonic speeds at an altitude of 30,000 feet (9144 m), the sonic boom produced is reflected all the way up and will not be heard by people on the ground. The sonic boom is the reason why Concorde is banned from flying in populated areas. It not only startles residents but also causes windows to shatter as it explodes like a bomb.
Without the sonic boom, the XB-1 and Overture can operate in more airspace safely. Concorde failed to replace commercial jets because it was banned from flying over the United States and also Malaysian airspace while operating with Singapore Airlines more than 40 years ago.
In addition to Boom, NASA is also developing a “quiet” supersonic passenger plane under the QueSST project. The experimental Lockheed X-59 will fly at Mach 1.4 (1,510 km/h) at an altitude of 55,000 feet (16,800 meters) but produce only about 75 dB of noise, or about the same as a loud conversation and a dishwasher. Like the XB-1, the X-59 will also make its first supersonic flight this year.