Commercial supersonic flight sped closer to returning as the Boom Supersonic XB-1 prototype reached a transonic speed of Mach 0.95 during Test Flight 11 on January 10, 2025, in the skies over the Mojave Desert in California.
It's been over 21 years since the last Concorde supersonic aircraft retired, marking the first time that humanity completely lost a technological capability. In this case, a commercial aircraft capable of sustained supersonic cruising. In part, this was a matter of economics. In part, it was political. And a large part was a matter of running ahead of what the state of the art could support in a practical fashion.
It's a high-risk venture and while some companies have fallen by the financial wayside, a shrinking number have been pushing the envelope in hopes of developing a 21st century airliner that is not only capable of supersonic cruising speeds but can do so economically and without being trailed by the dreaded sonic boom.
At the moment, the leader seems to be Boom, which has completed 11 test flights as it works in increments to reach supersonic speed. During the latest 44-minute flight at an altitude of 29,481 ft (8,986 m) with Chief Test Pilot Tristan “Geppetto” Brandenburg at the controls, the prototype aircraft reached transonic speed. That is, flight so close to Mach 1 that some areas of airflow over the airframe exceed the speed of sound.
It's also the point where the XB-1 was subjected to a maximum dynamic pressure of 383 Knots Equivalent Air Speed (KEAS), which is a pressure on the fuselage and wings greater than what it would experience when flying supersonic at Mach 1.1.
In short, XB-1 pushed what was once called the Sound Barrier.
According to Boom, this was a key milestone in the test program because this dynamic pressure has a serious effect on aircraft performances and especially flight controls. If the data from Flight 11 proves promising, the company's engineers will be able to decide if another subsonic test flight is required before the final assault on the supersonic realm later this year.
Source: Boom
