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MOJAVE, California—High-speed airliner developer Boom took a major leap toward the development of its Mach 1.7 Overture transport with the successful supersonic flight of its XB-1 demonstrator, the first independently developed faster-than-sound aircraft.
The XB-1, flown by Boom Chief Test Pilot Tristan “Geppetto” Brandenburg, exceeded Mach 1 on three separate occasions during its 12th test flight on Jan. 28, hitting a top speed of Mach 1.12 at around 11 min. 30 sec. into the flight. The aircraft accelerated through the transonic regime while flying at 34,000 ft. in the Mojave Desert’s Black Mountain supersonic corridor within the area’s restricted R-2508 test airspace complex.
Accompanied throughout by two chase aircraft, a T-38 and a Mirage F1, the specific test points targeted by Boom for this XB-1 test flight included accelerating to Mach 1.1 while also evaluating flutter. Testing for flying and handling qualities at KEAS (knots equivalent airspeed) 360 was also undertaken during three fast dashes along the supersonic corridor before the XB-1 returned to Mojave, where it landed at 8.55 a.m. PST after a 34-min. flight.
The supersonic flight marks the culmination of a steady test campaign in which the XB-1 has flown higher and faster since making its first flight on March 22, 2024. On the aircraft’s penultimate pre-supersonic flight, conducted on Jan 10, the XB-1 reached an altitude of 29,481 ft. and Mach 0.95. However, the main objective of that flight was to expand the dynamic pressure envelope to 383 KEAS, higher than the pressures the aircraft experienced on the Jan. 28 Mach 1.1 flight.
“It was smooth, it was predictable, and it felt great,” says Brandenburg, who is now the first pilot to fly an independently developed, purpose-designed civilian supersonic aircraft. Once the aircraft transited through Mach 1.07-1.09 to Mach 1.12, “it was the smoothest that airplane has flown, and I’d expect it to get even better as we fly faster,” he says.
Although the XB-1 delta wing trijet does not represent the final configuration of the Overture airliner, Boom says the supersonic milestone caps a valuable development and test effort that will help pave the way for the much larger follow-on project. Aside from a safety-based test culture established through the program, the company stresses several specific technologies that will apply to the Mach 1.7 transport. These include the XB-1’s augmented reality vision system, the digital optimization techniques used to define the aircraft’s aerodynamics, supersonic inlet design experience and composite airframe structural knowledge.
Commenting on the supersonic flight, Blake Scholl, Boom founder and CEO says: “Today is a day that I’ve been looking forward to for more than a decade. Today, we get to celebrate. Tomorrow, we’re back to work because it’s time to go big. It’s time to take this little airplane made out of airliner technology and scale it up. It’s time to bring back supersonic flight.”
Boom expects to conduct one more supersonic flight with XB-1 in early February and may attempt to go to Mach 1.3 depending on the results of data analysis from the Jan. 28 flight. The company is working with NASA to utilize the final flight in a potential attempt to capture a schlieren image of the XB-1 that will visualize air density gradients caused by aerodynamic flow. The attempt will be made using an image processing technique called Background-Oriented Schlieren using Celestial Objects, or BOSCO, in which the XB-1 will fly between a camera on the ground and the Sun.
“After next week’s final flight of XB-1, our attention goes back on the Overture, so we will be advancing that. Where we are today is that it’s about time to break the engineer’s pencils, meaning that we have a design that accomplishes what we need to accomplish, and it’s ready. The next thing we’re looking forward to is the Symphony engine,” Scholl says. The first prototype engine is due to make its initial run “later this year,” he adds. Referring to the airframe, Scholl says: “We are about 18 months away from starting to physically build the first Overture.”
The 201-ft.-long Overture is designed to carry up to 80 passengers on ranges over more than 4,250 nm and is ambitiously targeted to enter service around the end of the decade.
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