Hermeus, the California-based hypersonic aircraft company, has revealed it is developing an expendable, ramjet-powered flying testbed called Ramjet-X, which will launch in mid-air from its reusable Quarterhorse aircraft.
Ramjets need a high initial speed to work, so rather than using a large expendable booster for each test, Hermeus will use Quarterhorse to carry Ramjet-X to launch speed and altitude before releasing it. Ramjet-X will then fly under ramjet power at high-Mach speeds while Quarterhorse returns to fly again.
The vehicle is intended to support high-Mach “Flight Test as a Service,” said Hermeus, letting customers mount payloads, sensors, communications and compute systems, autonomy software, materials samples and propulsion technologies for evaluation in sustained high-Mach conditions. According to the company a repeatable platform lets customers focus on the technology being tested rather than building a one-off vehicle for each experiment.
Zach Shore, CEO of Hermeus, said, “High-speed flight testing is extremely expensive, and you don’t get many shots at it. 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 of Ramjet-X is under way, with its engine being tested at Hermeus’s HEAT facility in Jacksonville, Florida, and high-temperature structures in development 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 930mph (1,497km/h) – 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. Stratolaunch’s rocket-powered, reusable Talon-A, air-launched from its Roc carrier aircraft, has flown more than 10 hypersonic missions and is the first reusable hypersonic-capable US aircraft to fly since 1968.
Hermeus, which works with the US Department of War and is part of the Defense Innovation Unit’s high-cadence hypersonic testing program, says rapid hardware iteration is central to lowering the cost and time of hypersonic de
