TechnologyHermeus flies larger Quarterhorse Mk 2.1 in second first flight within nine months
Hermeus has completed the first flight of its Quarterhorse Mk 2.1 unmanned aircraft, marking the company’s second new prototype to fly in less than a year and advancing its effort to achieve supersonic performance.
The flight took place at Spaceport America over White Sands Missile Range airspace in New Mexico. The aircraft was operated remotely from a ground-based flight deck. The initial sortie focused on validating systems, handling characteristics and operational procedures ahead of a broader test campaign that will target supersonic speeds.
Quarterhorse Mk 2.1 follows the Mk 1 prototype, which first flew in May 2025 from Edwards Air Force Base. The earlier aircraft, powered by a GE J85 turbojet, was used to validate design, systems and high-speed takeoff and landing performance.
The new Mk 2.1 is significantly larger and more powerful. Roughly comparable in size to an F-16, it is powered by a Pratt & Whitney F100 afterburning turbofan, the same engine family used in the F-15 and F-16 fighter aircraft. Hermeus said the Mk 2.1 is nearly three times larger and four times heavier than the Mk 1, positioning it among the largest unmanned aircraft built in its class.
https://twitter.com/hermeuscorp/status/2028545878160523333
The Mk 2 phase is structured as a multi-aircraft series aimed at expanding into sustained supersonic flight. Mk 2.1 is the first aircraft in this series, with Mk 2.2 already in development and intended to push performance further. The company’s longer-term objective is to demonstrate sustained ramjet-powered flight in a subsequent iteration, using its Chimera combined-cycle propulsion architecture.
Hermeus is pursuing a rapid, iterative development model in which multiple aircraft are designed, built and flown in quick succession. The approach is intended to use flight-test data to refine designs and reduce risk incrementally, rather than relying on a single long development cycle.
Beyond the Quarterhorse program, the company is developing the Darkhorse unmanned high-speed aircraft for defense applications and the Halcyon concept for a future Mach 5 passenger aircraft.
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