Overview
- Hermeus confirmed its uncrewed Quarterhorse Mk 2.1 exceeded the speed of sound, reaching Mach 1.21 during its third test flight over Spaceport America and White Sands restricted airspace.
- The Mk 2.1 is roughly the size of an F-16, uses a delta-wing layout for high-speed stability, and relied on a modified afterburning Pratt & Whitney turbofan to achieve supersonic speed.
- The flight came less than three months after the Mk 2.1's first flight and about a year after the original Mk 1’s debut, illustrating the company’s fast build-test-iterate approach.
- Hermeus is already developing Mk 2.2 to incorporate its Chimera II turbine-based combined-cycle engine with Mk 2.3 planned next, and the Quarterhorse program is being advanced in partnership with the U.S. Department of Defense toward the Darkhorse hypersonic concept and the Halcyon civil transport idea.
- Leadership will shift on June 1, 2026, with Zach Shore becoming CEO and co-founder AJ Piplica moving to executive chairman, and observers should watch upcoming Mk 2.2 tests for sustained high-speed performance and the Chimera II engine’s behavior.