Quarterhorse
DIU-funded Hermeus flight-test program building reusable high-speed demonstrator aircraft toward Mach 5.
Quarterhorse is Hermeus' reusable high-speed aircraft flight-test program, funded principally through the Defense Innovation Unit with US Air Force and Navy participation. It advances through Mk1 (first flight 2025), Mk2 (supersonic), and Mk3 (target Mach 5, unmanned) demonstrator variants using an iterative design-build-test approach. In May 2026 DIU scaled the effort to $219M cumulative to demonstrate high-Mach flight for the Department of War. On July 31, 2026, Quarterhorse (Mk 2.1) completed an unmanned stores-separation flight test under DIU's HyCAT program — its fifth flight since spring 2026, a pace DIU describes as roughly 4x faster than typical hypersonic test programs; an earlier 2026 flight reached Mach 1.21 (~930 mph).
Program detail
- Agency
- Defense Innovation Unit (DIU) / US Air Force
- Acronym
- QH
- Budget
- $219M (cumulative DIU value, May 2026)
- Phase
- Flight demonstration
- Domain
- Hypersonics / high-speed flight
Participants1
Contracts0
No linked records yet.
Frequently asked
- What is Quarterhorse?
- Quarterhorse is Hermeus' reusable high-speed aircraft flight-test program, funded principally through the Defense Innovation Unit with US Air Force and Navy participation. It advances through Mk1 (first flight 2025), Mk2 (supersonic), and Mk3 (target Mach 5, unmanned) demonstrator variants using an iterative design-build-test approach. In May 2026 DIU scaled the effort to $219M cumulative to demonstrate high-Mach flight for the Department of War. On July 31, 2026, Quarterhorse (Mk 2.1) completed an unmanned stores-separation flight test under DIU's HyCAT program — its fifth flight since spring 2026, a pace DIU describes as roughly 4x faster than typical hypersonic test programs; an earlier 2026 flight reached Mach 1.21 (~930 mph).
- Which agency runs Quarterhorse?
- Quarterhorse is run by Defense Innovation Unit (DIU) / US Air Force and is also known as QH.
- What is the budget for Quarterhorse?
- Quarterhorse has a budget of $219M (cumulative DIU value, May 2026), currently in its Flight demonstration phase.
Sources & citations2
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- 1
DIU scaled the Hermeus Quarterhorse contract to $219M cumulative to demonstrate high-Mach flight for the Department of War
Hermeus: Hermeus Scales DIU Contract to $219MVerified2026-05-28 - 2
Quarterhorse (Mk 2.1) completed an unmanned stores-separation flight test under DIU's HyCAT program on July 31, 2026 — its fifth flight since spring 2026, ~4x the pace of typical hypersonic test programs; an earlier 2026 flight reached Mach 1.21 (~930 mph).
Defence Blog: Pentagon's HyCAT program tests one of the fastest aircraft ever builtVerified2026-07-31