Boom Supersonic, the Colorado startup at Centennial Airport that hopes to build the next generation supersonic airplane, unveiled a team of partners to design powerful engines for the sleek craft, according to a Tuesday news release.

Boom has taken commitments from American Airlines and two other carriers for a 65-to-80 passenger supersonic airliner.

In September the company parted ways with engine maker Rolls Royce, builder of engines for the Anglo-French Concorde. That was the airliner that pioneered supersonic passenger flight decades ago and that bears a strong resemblance to Boom’s “Overture” design today.

The falling-out between the companies had drawn wide concern from aviation experts as to the viability of the project, which envisions test flights in just a few years.

Boom announced Tuesday a new propulsion system for Overture called Symphony. It’s to be designed in conjunction with Florida Turbine Technologies — a manufacturer with team member experience on the engines developed for the Air Force’s F-22 and F-35 supersonic fighters. FTT was acquired in 2019 by San Diego-based Kratos Defense & Security Solutions.

The engine team will also draw on the experience of GE Additive, an affiliate of GE Aerospace and one of the world’s big-three passenger engine makers, as well as Arizona-based StandardAero, an engine maintenance provider.

According to Boom, the Symphony engine will resemble current fan-jet passenger engines that get part of their power from a turbine fan. The engine would create up to 35,000 pounds of thrust at takeoff — around 25% more than the engine that powers newer Boeing 737 Max airliners coming into widespread use now.

Unlike the engine on the Concorde, the four engines powering an Overture would need no noisy afterburners to take off and to push the plane past the sound barrier. Symphony will have a new kind of air intake and stronger turbines for the pressures of supersonic flight, according to Boom, along with a new exhaust nozzle designed to keep the noise down.

The Symphony engines will burn 100% sustainable aviation fuel, according to the release. Sustainability has been a prominent component in Boom’s marketing for the craft, maintaining that it would fly 100% carbon neutral by using sustainable aviation fuel rather than conventional jet fuel.

Boom is developing a 70,000-square-foot facility at Centennial to house a non-flyable testbed that will mimic the controls and avionics for the craft.

Meanwhile, ground tests are continuing nearby for a prototype XB-1 “Baby Boom” single-pilot test plane that will experiment with the flight dynamics of the design. Boom’s Aubrey Scanlan told The Denver Gazette that the test craft is scheduled to be transported to California next year for its first flights.

“Developing a supersonic engine specifically for Overture offers by far the best value proposition for our customers,” Blake Scholl, founder and CEO, said in the release. “Through the Symphony program, we can provide our customers with an economically and environmentally sustainable supersonic airplane — a combination unattainable with the current constraints of derivative engines and industry norms.”

In August, American Airlines announced it was making a non-refundable deposit on up to 20 Overtures, and United Airlines had previously committed to 15 supersonics. Defense aviation contractor Northrup Grumman has a partnership with Boom for “special mission” variants of Overture.

Boom maintains it will fly the first Overture by 2026. Sized just a little smaller and slower than Concorde, the jet would carry passengers from New York to London in three-and-a-half hours.

Scholl, in a prior interview with the Denver Gazette, underscored the value of relying on time-tested components for the new craft, rather than creating a totally novel design. Nonetheless, Boom says the new engines could deliver a 25% increase in “time on wing” — a metric of how much time an engine needs to be out of service for maintenance — along with reduced airline operating costs.

“United and Boom share a passion for making the world dramatically more accessible through sustainable supersonic travel,” Mike Leskinen, president of United Airlines Ventures, said in the release.

While development of the plane continues in Colorado, Boom is making plans for a “super factory” in Greensboro, N.C. where it would build the production versions. Boom has mentioned 2029 as a possible date it hopes to see Overture enter service.

Aviation analysts have closely followed the Overture project as it strives to overcome barriers to supersonic passenger flight, some of which hastened Concorde’s departure from service in 2003.

Chief among those were operating costs, which kept ticket prices at stratospheric levels and kept airlines from widening the number of routes. That route potential was further confined because Concorde was restricted from supersonic flight over land, to avoid the sonic boom that jets create as the shock wave passes over the earth behind them.

But with almost 50 years of intervening progress with lighter composites, newer electronics, and more experience with supersonic design, the Colorado aircraft maker hopes to cut costs for carriers, while achieving the much better environmental performance that is seen as critical now.