Los Angeles – September 13, 2026 -- Hermeus is developing Ramjet-X, an expendable, ramjet-powered test vehicle designed to be launched from its reusable Quarterhorse aircraft, aiming to make high-Mach airbreathing flight testing cheaper and more repeatable.
Quarterhorse aircraft eliminates need for costly disposable boosters
Ramjet engines require substantial initial speed before they can operate, historically forcing test programs to rely on large, expensive, single-use boosters. Hermeus instead uses its reusable Quarterhorse aircraft to accelerate Ramjet-X to the required speed and altitude before release, after which the vehicle enters ramjet-powered flight while Quarterhorse returns for subsequent missions.
New system to launch Flight Test as a Service business line
Ramjet-X will underpin a Flight Test as a Service (FTaaS) offering, giving external customers and partners access to sustained high-Mach flight conditions that have traditionally been difficult and costly to reach. Clients will be able to integrate payloads, sensors, communications and compute systems, autonomy software, material samples, and propulsion technologies onto Ramjet-X rather than building bespoke high-speed test vehicles for each experiment.
"High-speed flight testing is extremely expensive, and you don't get many shots at it," said Zach Shore, CEO of Hermeus. He said Ramjet-X allows the company to place new systems into sustained high-Mach environments without constructing a one-off test program for every trial, combining speed, sustained flight, and scalability into a single platform.
Engine testing underway in Florida, integrated flight set for 2027
Hermeus is currently testing the Ramjet-X engine at its HEAT facility in Jacksonville, Florida, while high-temperature structural components are being developed at company headquarters in El Segundo, California. Integrated vehicle testing is planned for 2027.