Hermeus flies Quarterhorse Mk 2.1 at Mach 1.21
The unmanned aircraft exceeded the speed of sound on its third test flight over White Sands Missile Range.
Hermeus has flown its Quarterhorse Mk 2.1 unmanned aircraft at Mach 1.21, achieving supersonic speed on the vehicle’s third test flight. Announced on 26 May 2026, the flight operated from Spaceport America over White Sands Missile Range airspace. The milestone came less than three months after Mk 2.1 first flew and 364 days after the maiden flight of the company’s earlier Mk 1 aircraft.
Mk 2.1 is powered by a Pratt & Whitney F100 engine and is the first of three F-16-scale supersonic aircraft in the Quarterhorse development roadmap. The vehicle provides flight data for the design of subsequent aircraft, allowing Hermeus to test propulsion integration, vehicle performance and operating procedures through successive hardware builds.
The company’s March 2026 first-flight announcement described Mk 2.1 as nearly three times larger and four times heavier than Mk 1. It was flown remotely from a ground-based flight deck to validate aircraft systems, handling and operating procedures. The subsequent supersonic flight extends that initial envelope as Hermeus collects data for the next Quarterhorse vehicles.
Hermeus says construction and testing work is already under way on Mk 2.2, with Mk 2.3 planned to follow. Those aircraft are intended to extend performance toward sustained higher-Mach flight. The company will continue operating Mk 2.1 while developing the subsequent vehicles, maintaining an iterative flight-test programme across the Quarterhorse series.