Hermeus unveils Ramjet-X air-launched expendable hypersonic testbed

Hermeus, the California-based hypersonic aircraft company, has unveiled Ramjet-X, an expendable, ramjet-powered flying testbed that will be launched in mid-air from the company's reusable Quarterhorse aircraft. Because ramjets need a high initial speed to operate, Quarterhorse will carry Ramjet-X to launch speed and altitude before releasing it to fly under ramjet power at high-Mach speeds, while Quarterhorse returns to fly again.

The vehicle is meant to support what Hermeus calls "Flight Test as a Service," allowing customers to mount payloads, sensors, communications and compute systems, autonomy software, materials samples and propulsion technologies for evaluation in sustained high-Mach conditions. "High-speed flight testing is extremely expensive, and you don't get many shots at it," said Zach Shore, CEO of Hermeus. "Ramjet-X gives us a way to put new systems into sustained high-Mach environments without building an expensive one-off test program every time."

Development is under way, with the engine being tested at Hermeus's HEAT facility in Jacksonville, Florida, and high-temperature structures being developed at its El Segundo headquarters. Integrated vehicle testing is planned for 2027. The launch aircraft, Quarterhorse, is Hermeus's reusable uncrewed testbed; its Mk 2.1 version reached Mach 1.21, about 930 mph, earlier this year in what the company called the first supersonic flight by a privately developed uncrewed jet, and Hermeus is targeting Mach 3 in 2027 and a hypersonic Mk 3 before 2030.

Ramjet-X and Quarterhorse join a growing field of reusable and air-launched hypersonic testbeds aimed at cutting the cost of high-speed flight testing, alongside Stratolaunch's rocket-powered, reusable Talon-A, which is air-launched from its Roc carrier aircraft and has flown more than 10 hypersonic missions.