Seattle-based Radical says it has raised $4.5 million to support the development of solar-powered, autonomous airplanes that can beam down connectivity and imagery during long-duration, high-altitude flights.
The seed funding round was led by Scout Ventures, with additional funding from other investors including Inflection and Y Combinator. According to Pitchbook, Radical previously received $500,000 in pre-seed funding from Y Combinator.
Radical’s co-founders are CEO James Thomas and chief technology officer Cyriel Notteboom. Both founders are veterans of Prime Air, Amazon’s effort to field a fleet of delivery drones. They left Amazon in mid-2022 to found Radical — and the aerospace startup is just now coming out of stealth.
Thomas told GeekWire that Radical will use the newly announced investment to expand its team, which currently amounts to four people.
“We’re still a small team, but we’re growing very quickly,” he said.
Thomas said Radical’s mission is to develop autonomous, solar-powered, propeller-driven aircraft that can fly continuously in the stratosphere without landing. The lightweight aircraft could carry payloads for a wide range of applications including imaging, remote sensing and telecommunications.
“You could really think about what we’re developing as a technology for persistent airborne infrastructure,” he said. “The possibilities that this opens up are really enormous, and we’re excited about what that means. … Ultimately, a yearlong flight is definitely a possibility.”
Last October, Thomas and Notteboom flew an ultralight 13-pound prototype with a wingspan of 20 feet for more than 24 hours nonstop, at a site near Seattle. “It wasn’t too far from here,” Thomas said. “It was out in the mountains. We can’t talk too much about this.”
Thomas said the test flight was an important milestone. “Integrating the solar cells, having that battery endurance, autonomous flight — all these key aspects of our system, we’re proving them at subscale,” he said. “We like to be hands-on and hardware-rich with our development, and then iterate toward a solution. So we’re getting out there, proving the systems, and now moving on to full scale.”
The added funding should accelerate the drive toward building and testing that full-scale aircraft, with a projected wingspan in the range of 110 feet and the ability to fly as high as 70,000 feet. “We’re 100% focused on that now,” Thomas said. “In the next 12 months, we’ll be flying.”
The plane is already taking shape at Radical’s home base in Seattle’s Ballard neighborhood, Thomas said. “We’re building things right now, like big wing sections, and iterating from that. You know, better design, better prototyping. There’s lots of interesting development going on,” he said. “Seattle’s a great area to be building a company like this.”
Thomas said long-duration flights in the stratosphere could offer a “lot of opportunity” for commercial or government applications. Among the possibilities: continuous real-time monitoring of weather systems, wildfires or illegal fishing; high-resolution imaging and mapping; mobile cellular service and broadband direct-to-device internet access. The fact that the solar-powered flights involve zero carbon emissions is an added benefit.
Radical’s vision has similarities to the flight concept that Facebook pursued in a project that was known as Aquila. Facebook’s high-altitude, solar-powered drones were intended to serve as relay stations for internet access to remote areas. Flight tests were conducted in 2016 and 2017, but internal development of the aircraft ended in 2018, amid reports of formidable technical challenges.
Thomas said he and his teammates have learned from previous work on the frontiers of autonomous flight. Thomas spent five years as a research scientist at Amazon Prime Air, and Notteboom has nine years of experience as a hardware development engineer on Amazon’s drone development team. Lucas Campbell, a mechanical engineer who joined the Radical team in January, lists four years of experience at Amazon — plus internships at SpaceX and Zipline.
“I think the team is key,” Thomas said. “We have a really good team at Radical, bringing experience from programs like Amazon. What we learned there is really important, and how we apply that now to continue to address our customers’ needs is what we’re focused on.”
