A supersonic drone that will be propelled by a revolutionary new engine has taken to the skies for the first time. When Venus Aerospace's aircraft does go supersonic on a later date, it will be powered by a Rotating Detonation Rocket Engine (RDRE).
Supersonic drones may sound like something bleeding edge, but they're surprisingly old hat as a basic concept. As far back as the early 1950s, the US Air Force was fielding remote-controlled supersonic jets for targets to test air defenses, as platforms for reconnaissance in dangerous areas, or as weapons armed with conventional or nuclear warheads.
However, the one thing they've all had in common over the past 75 years was a jet engine for propulsion to boost them past Mach 1. In recent years, advances in avionics, aerodynamics, and autonomous systems have allowed uncrewed aircraft to expand their roles, but at their heart, they were still jet propelled.
Now, Venus Aerospace is taking things a step further by installing a RDRE in its latest drone. When the prototype was airdropped at an altitude of 12,000 ft (3,700 m) on February 24, the eight-feet (2.4-m), 300-lb (140-kg) robotic aircraft only managed a top speed of Mach 0.9. This is because it was powered by a hydrogen peroxide monopropellant engine running at 80 percent thrust for a range of 10 km (16.1 km) to keep it under the speed of sound. But alongside it was the RDRE system that will take over in later flights to boost the craft past Mach 1.
An RDRE is essentially a way of overcoming the limitation of a rocket or jet engine by relying on a much more novel principle without moving parts. An RDRE consists of two coaxial cylinders with a gap between them. Into this gap a fuel/oxidizer mixture is introduced and ignited. If this is done right, this generates a closely coupled reaction and shock wave that speeds around inside the gap at supersonic velocity that generates more heat and pressure.
The result is a lighter, simpler engine that is at least 15% more efficient than conventional engines. This means bigger payloads or higher speeds. Venus showed off a sustained burn of its RDRE a few weeks ago.
"Using an air-launched platform and a rocket-with-wing configuration allows us to cheaply and quickly get to the minimum viable test of our RDRE as a hypersonic engine," said CTO & Co-Founder Andrew Duggleby. "The team executed with professionalism and has a wealth of data to anchor and tweak for the next flight."
Where does all this go? Well, Venus says it plans to create a reusable, hypersonic spaceplane capable of moving passengers at upwards of Mach 9 (6900 mph / 11,000 km/h). Stargazer, as it's currently named, would take off and "gently" propel itself to an altitude of 170,000 ft – a little over halfway to the Karman line – then go hypersonic to make bulk progress in that thin air.
Venus bandies about the idea of trips like Houston to London, or San Francisco to Tokyo in one hour. Clearly, that's a long shot, and way off in the future with a frightening amount of red tape standing between Stargazer and reality. Closer to Earth, the company is developing this engine for various defence applications and that's the bulk of where we'd expect to see it in the short to medium term.
Source: Venus Aerospace
