Aviation startup Boom Supersonic took a major step today toward its goal of returning commercial supersonic aviation to the skies, after the company’s prototype aircraft, the XB-1, left the ground for the first time this week. The short, subsonic flight over the Mojave Desert came years later than expected, but it shows that Boom is at least still making progress.

The XB-1 took off Thursday at 7:28AM PT, reached a maximum altitude of 7,120 feet, and a top speed of 246 knots (283 mph). It landed 12 minutes later at 7:40AM.

Boom’s overall mission is to launch Overture, the first supersonic commercial aircraft since the Concorde ended operations 20 years ago. The company has secured contracts with major airlines like American and United, as well as manufacturing and development partnerships with Florida Turbine Technologies and GE Additive.

However, some of the most significant news lately has been the loss of partnerships, specifically with Rolls-Royce. The British manufacturer of jet engines parted ways with Boom in 2022, leaving the startup to develop its own engines.

Notably, those engines are not used in the XB-1. Boom’s demonstrator aircraft, originally scheduled to fly in 2017, relies on a trio of 1950s-era J85 turbojet engines, the sorts used to power vintage aircraft like the Northrop T-38 trainer or F-5 fighter. 

Overture, Boom’s full-size supersonic commercial airliner, will use four of the company’s own engines, which are still under development and will be called Symphony. 

In an interview ahead of the flight,  Boom CEO and founder Blake Scholl says that each Symphony engine will deliver roughly three times the combined output of the XB-1’s three J85 engines. 

Engine type is just one of many design differences between the XB-1 and the eventual Overture craft, not the least of which is size. Scholl calls the XB-1 a “one-third scale prototype demonstrator for Overture.”

Scholl says the XB-1 is helpful for validation of simulator data and that its development has already borne fruit in the design of Overture — despite the two looking nothing alike.

“If your prototype looks exactly like your production airplane, it actually implies you’ve learned nothing. And we’ve learned a lot of things from XB-1 through the design, development, manufacturing that have caused us to improve Overture,” Scholl says. 

The XB-1 also serves another significant purpose: fundraising. 

“The way ventures like this are always financed, you raise some capital, you prove some milestones. And flying this airplane here is a very important one of those milestones. That demonstrates the track record of execution, demonstrates that progress is being made, and enables access to capital and ever higher valuation,” Scholl says. “That’s how you look at SpaceX, any other kind of private aerospace venture, that’s how they all work.”

The current target is for the Overture airliner to take its first flight by 2030, but getting there will be expensive. Scholl says Boom has raised over $700 million so far, but that the overall development of Overture could cost upward of $8 billion.

Beyond finances, one of Boom’s most significant challenges might be right there in its name. 

Today’s regulations against sonic booms would mean subsonic Overture flights over most major land masses, throttling up only over ocean transits. The deployment of technologies developed on demonstrators like the NASA X-59, which could turn sonic booms into sonic “thumps,” might ease those regulations in the future. 

Even so, flying at Mach 1.7 only over water would roughly halve the duration of flights between New York to London or Seattle to Tokyo.

The other big missing piece is sustainability. Flying two times faster than a current jetliner necessarily uses a fair bit more fuel in the process. That situation is compounded by the Overture seating just 64 passengers compared to the 853 souls you can sling over the Atlantic in an Airbus A380. 

Sustainable aviation fuel, or SAF, could prevent supersonic travel from becoming an even bigger burden on the environment than today’s aviation industry. SAF is created using renewable sources and is ideally infused with carbon pulled out of the atmosphere via direct air capture. This would, in theory, create a genuinely carbon-neutral aircraft fuel.

The eventual availability and distribution of SAF is an industry problem. Boom’s next steps are proving that its engineers’ designs can not only fly, but that they can break the sound barrier.

Of course, that is the goal for the XB-1, but we have a ways to go before that thing’s sonic booms shake the Mojave sands. CEO Scholl says that XB-1 will undergo a series of up to 15 test flights throughout the year, so-called “envelope expansion” missions, which will eventually push that envelope through the sound barrier.

Boom is also making progress on its Greensboro, NC “superfactory,” which Scholl says is ahead of schedule and will open this summer. But Overture, the airliner that will be assembled there, is years away. 

“We’re still targeting being in the air around the end of the decade on Overture. There’s a lot of work to do between now and then on that airplane, and our goal is to do it safely but also with a sense of urgency because we want this airplane for ourselves, our friends, our family, and our customers,” he says. 

So, the dream of supersonic commercial air travel is still moving toward reality, but those hoping to move quickly through the air will have to sit patiently for a good while longer.