Radian Aerospace completes ground tests of prototype space plane

Radian Aerospace has moved one step closer to achieving the “holy grail” of spaceflight: a reusable space plane that can take off from an airfield and land on a runway like a conventional airplane. The startup just announced completion of a series of ground tests in Abu Dhabi earlier this summer.

The tests were completed with a subscale prototype flight vehicle that the company is calling PFV01. The main purpose of the testing was to generate data on how the vehicle would fly and handle and to compare this data to simulations the company’s been doing over the last several years. While the vehicle did not fly, it did perform a series of small hops on the runway, executives told TechCrunch in a recent interview.

PFV01 is much smaller than the final vehicle at around 15 feet long, but the data still helps inform key pieces of the final design and flight control systems, like where the landing gear should be located, or where the center of gravity should be to maximize stability midair, co-founder and CTO Livingston Holder explained.

“This vehicle gives us the ability to adjust the center of gravity forward and aft, up and down, it gives us the ability to adjust the location of the landing gear. Those adjustments give us real-world feedback into what our analytical data says,” he said. “Wherever there's ambiguity … that's one of the things that the PFV really gives us the opportunity to do, is drive uncertainty down so that we have better fidelity with our analytical processes as we go faster with the vehicle and do more flights.”

The plan is for the Radian One space plane to take off from a roughly two-mile-long rail sled, ignite engines on orbit, then return to Earth back on a normal runway. The concept is considered a holy grail because removing the necessity for a launch vehicle makes space, in a way, as accessible to space vehicles as the upper atmosphere is to airplanes.

The economics are promising, too: A reusable space plane could take trips to and from space on a daily basis or even more frequently, and with better margins to boot. It's been tried before; one of the most notable examples is NASA's X-33 program to develop a suborbital space plane. Holder led Boeing's X-33 effort.

“The least interesting thing this system has the potential to do is launch satellites,” Radian co-founder and CRO Jeff Feige said. “What's really impressive about Radian is that it's a system that can do a wide, wide range of missions so it basically accesses a much larger market than a traditional rocket. Not only could you potentially launch something, but you can service it, you can recover it. We can bring entire payloads or satellites down from space. We can carry people up. We can dip in the atmosphere and theoretically, either drop things or observe things on the planet. So there's just a much wider range of capability.”

The design is dramatically different from a vertical rocket, and this means the development process differs as well, noted Feige: “You have to retire a lot of risk early." So while rocket companies must build full-scale vehicles, the stepwise fashion of spaceplane development more closely resembles how an airplane is developed.

The Seattle-based startup isn’t disclosing any technical specs of the tests, like the top speeds of the vehicle or how long it was taxiing for, but Holder did say PFV01 “reached its velocity for takeoff.” Now the company will spend some time analyzing all the data it collected from the tests before embarking on a series of higher-speed taxi tests and the start of actual flight testing. Parallel to that, the company will be working on getting regulatory approval to operate out of a different UAE-based airport and fly there.

Company executives say they are hoping to start full-scale flights of the Radian One space plane in 2028. The company has raised $32 million to date from investors, including Fine Structure Ventures, EXOR, The Venture Collective, Helios Capital, SpaceFund, Gaingels, Private Shares Fund, Explorer 1 Fund, and Type One Ventures.

The story has been updated to reflect that Radian has raised $32 million.