Hermeus Unveils Ramjet-X, a Low-Cost Test Vehicle for High-Mach Flight

Launched from its Quarterhorse aircraft, the expendable test vehicle is designed to make high-Mach airbreathing flight test cheaper, faster, and more repeatable.

LOS ANGELES, Sept. 9, 2026 /PRNewswire/ -- Hermeus today announced it is developing Ramjet-X, a low-cost, expendable ramjet-powered vehicle designed for launch from its Quarterhorse aircraft. Once released, Ramjet-X will fly at high-Mach speeds.

Ramjets require significant initial speed before they can operate effectively. Instead of relying on a large, expensive, expendable booster for every test, Hermeus will use its reusable Quarterhorse aircraft to carry Ramjet-X to the speed and altitude required for launch. Once released, Ramjet-X will commence ramjet-powered flight, while Quarterhorse returns for future flight test missions.

Ramjet-X will also enable Hermeus to offer high-Mach Flight Test as a Service (FTaaS), expanding access to flight environments that have historically been costly and difficult to reach. Customers and partners will be able to integrate payloads, sensors, communications and compute systems, autonomy, material samples, propulsion technologies, and other experimental hardware and software onto Ramjet-X for testing in representative sustained high-Mach conditions. By providing a repeatable platform, launch architecture, and flight-test infrastructure, Hermeus can allow customers to focus on the technology being evaluated rather than developing a bespoke high-speed flight vehicle and test program for every experiment.

"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. Bringing speed, sustained flight, and scalability all into one system lowers the barriers to gathering extremely valuable data from these conditions and accelerates programs for both us and our customers."

Development of Ramjet-X is already well underway. Hermeus is testing Ramjet-X's ramjet engine at its HEAT facility in Jacksonville, Florida, while high-temperature structures are in development at its headquarters in El Segundo, California. Integrated vehicle testing is currently planned for 2027.

About Hermeus

Hermeus is a venture-backed defense aviation company reclaiming the lost art of rapid iterative prototyping to build the fastest aircraft in the world today. By prioritizing relentless hardware iteration, we deliver high-speed systems at the pace of the modern battlefield. We work with the Department of War to provide the high-speed capabilities our nation and its allies need to maintain a durable, asymmetric advantage.

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SOURCE Hermeus