Radian space plane on sled
A patent drawing shows Radian Aerospace’s concept for a space plane on a sled. (Radian via USPTO)

For years, Renton, Wash.-based Radian Aerospace has been working on a rocket project while holding its cards close to the vest. Now several of the big puzzle pieces have been put together to reveal what Radian’s executives and backers have in mind: a rail-launched space plane that could carry passengers to orbit and back.

The key piece, as reported by Business Insider, is a presentation that Radian CEO Richard Humphrey delivered to potential investors during a virtual conference in June. Citing the presentation, Business Insider said the venture was seeking $20 million in a Series A funding round. The money would fund further development of the orbital launch system, with an eye toward beginning flights to orbit as soon as 2025, Business Insider said.

The video presentation doesn’t appear to be publicly available, and Radian did not respond to GeekWire’s emailed request for more information. In fact, we’ve made inquiries with Radian executives numerous times — by email, by phone and in person at space industry conferences — ever since the venture reported raising $350,000 in a filing with the Securities and Exchange Commission in 2016.

Despite Radian’s stealthiness, there’s ample evidence that the venture’s plan is more than a pack of PowerPoint slides.

In 2017, for example, Radian struck a deal with the Port of Bremerton to lease a half-acre of land at Bremerton National Airport for a rocket engine test facility. A prototype engine has reportedly gone through many test firings, and Radian would like to expand the Bremerton facility.

Radian also is seeking a patent for a concept that calls for launching a winged single-stage-to-orbit craft with an initial boost from a rocket-powered sled on rails. One diagram that’s included in the application shows the plane docking with a space station, shuttle-style. At the end of each mission, the plane would make a horizontal, airplane-style landing on a runway.

Radian says the plane’s design was inspired by Boeing’s concept for a Reusable Aerodynamic Space Vehicle, or RASV, which was proposed in the early 1970s but never built.

This schematic lays out the flight plan for Radian Aerospace’s space plane, including a launch abort scenario and a landing. (Radian via USPTO)

Radian claims that such a plane could carry passengers to low Earth orbit and back more cheaply than, say, the space shuttle — or even SpaceX’s Falcon 9 rocket, which is now being used to launch astronauts to the International Space Station.

“Both the space shuttle and the Falcon 9 were designed to carry relatively heavy payloads of about 50,000 lbs. to LEO,” Radian’s inventors say in their application. “As a result, those vehicles do not present viable, relatively low-cost options for transporting crew and/or lighter cargo (e.g., about 5-10,000 lbs.) to LEO.”

The inventors listed in the application include Livingston Holder, who was part of Air Force’s Manned Spaceflight Engineer program in the 1980s and went on to become a Boeing program manager.

Dive into the details: Check out the patent application for Radian’s space plane

After spending more than a decade at Boeing, he became vice president for space systems at Seattle-based Andrews Space in 2002, and then co-founded a Renton-based consulting firm called Holder Aerospace in 2004.

Two of the other inventors, Gary Hudson and Bevin McKinney, are veterans of Rotary Rocket, a space venture that tested a rotor-equipped prototype launch vehicle in 1999 but fizzled out a couple of years later.

In September, Holder gave a pitch for two projects in the Air Force’s AFWERX Global Space Transport and Delivery Challenge. One project involves a cold-spray additive manufacturing technology for rapid, low-cost rocket engine production. The other proposes manufacturing linerless, carbon-composite tanks for cryogenic liquid-oxygen propellant.

“Our work to date has been highly proprietary, so please feel free to contact us at the information provided,” Holder, who identifies himself as Radian’s chief technology officer, says in his welcome video.

What are Radian’s chances of success? Historically, that depends on the ability to raise money and find a market — and two other Seattle space ventures show how challenging that can be.

Like Radian, Stratolaunch has been seeking to develop space vehicles for years. Stratolaunch had the advantage of being founded by a billionaire: Paul Allen, the co-founder of Microsoft. At one point, Stratolaunch envisioned building a whole fleet of air-launched, rocket-powered vehicles for a variety of purposes, including sending crews to orbit on a space plane code-named Black Ice.

After Allen’s death in 2018, Stratolaunch went through a round of layoffs and spent months in limbo. The venture was transferred to new ownership last year. Now Stratolaunch has pivoted to concentrate on developing an air-launched hypersonic test vehicle, with national security applications uppermost in mind.

The second example is EarthNow, a startup that attracted seed funding in 2018 from a set of high-profile investors including Microsoft’s other co-founder, Bill Gates. EarthNow’s vision was to provide real-time and on-demand video streams from an orbiting constellation of satellites.

EarthNow’s founder and CEO, Russell Hannigan, left the company in March 2019 and is now senior director for advanced exploration technology at Xplore, another Seattle space startup. “I am thrilled to be at Xplore,” Hannigan told GeekWire in a text message. Meanwhile, EarthNow’s website has disappeared into the ether.

By all appearances, Radian Aerospace isn’t yet at the website-building stage of its development, although RadianAerospace.com has been reserved since 2015. Even before it unveils its website, Radian will have to do something about its status on Google Maps — which has marked its listed headquarters on a Renton residential street “permanently closed.”

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