Stoke Space fires its ambitious main engine for the first time

Stoke Space fired its first-stage rocket motor for the first time earlier this month, briefly igniting for about two seconds, Stoke Space announced Tuesday. The company declared the June 5 test a success because the engine’s performance was nominal and it would be running again soon.

“The first data point is that the engine is still there,” Andy Labsa, CEO of the Washington-based launch company, said in an interview with Ars.

Testing was conducted at the company’s facilities in Moses Lake, Washington. Seven of these methane-fueled engines, each designed for 100,000 pounds of thrust, will power the company’s Nova rocket. This launch vehicle will have a lifting capacity of about 5 metric tons into orbit. Lapsa declined to announce a target launch date, but based on historical development programs, if Stoke continues to move quickly, it could fly the Nova for the first time in 2026.

Big ambitions for a small company

Although still relatively new to the startup scene, Stock has attracted a lot of attention for its bold ambitions. The company intends for the two-stage Nova rocket to be fully reusable, with both stages returning to Earth. To achieve vertical landing, the second stage features a new design. This oxygen-hydrogen engine relies on a ring of 30 thrusters and a regeneratively cooled heat shield.

Lapsa and Stoke, which now have 125 employees, have also turned to an ambitious first-stage engine design that was tested earlier this month. The engine, with the placeholder name S1E, is based on full-flow staged combustion technology in which liquid propellant is burned in the engine’s primary burners. Because of this, they reach the engine’s combustion chamber in fully gaseous form, resulting in more efficient mixing.

Such an engine — the technology has only previously been demonstrated in flight by SpaceX’s Raptor engine, on a Starship rocket — is more efficient and should theoretically extend the turbine’s life. But it’s also technically demanding, and is among the most complex engine designs a rocket company can begin with. This is not rocket science. It’s very difficult rocket science.

It may seem like Stoke is biting off a lot more than it can chew with the Nova’s design. Getting into space is difficult enough to launch, but this company is seeking to build a completely reusable rocket with an entirely new second-stage design and first-stage engine based on full-flow staged combustion. I asked Labsa if he was crazy for taking up all this.

Are these guys crazy?

“I’ve been here long enough to know that any missile development program is difficult, even if you make it as simple as possible,” he answered. “But this industry is moving toward complete reuse. To me, that’s the inevitable end state. When you start with that North Star, any other direction you go is diversionary. If you start designing anything else, it’s not something where you can go back to possibility.” “Full reusability at any time, meaning you’ll have to stop and start over to climb the mountain.”

This may sound like happy talk, but Stoke appear to be fulfilling their ambitions. Last September, the company completed a successful “jump” test for its second phase in Moses Lake. This validated its design, propulsion vector control and avionics.

After this test, the company turned its focus to developing the S1E engine and put it on the test stand for the first time in April before launching the first test in June. Going from zero to 350,000 horsepower in half a second for the first time had a “very high wrinkling factor,” Labsa said of the first integrated test of the engine.

Now that this initial testing is complete, Stock will spend the rest of the year developing the engine design, conducting longer firing tests, and beginning development of the flight stages. Next will come stage tests before the Nova is fully assembled. Meanwhile, Stoke is also working with the US Space Force on the regulatory process to renovate and modernize Launch Complex 14 at the Space Force’s Cape Canaveral Station in Florida.