Hermeus successfully flew its latest Quarterhorse aircraft, marking the company’s second first flight in less than a year. The flight kicks off a test campaign that will see the unmanned aircraft reach supersonic speeds.
Roughly the size of an F-16 and powered by a Pratt & Whitney F100 engine (Pratt & Whitney is an RTX business), Quarterhorse Mk 2.1 is nearly three times larger, four times heavier, and significantly faster than its predecessor, making it one of the largest unmanned aircraft ever built.
Hermeus Quarterhorse Mk 2.1 (as of March 2, 2026 — first flight announced today)
Roughly the size of an F-16 (~50 ft class length reference).
Engine: Pratt & Whitney F100 (RTX business. F100-229 variant confirmed in program updates).
Design features: Variable inlet + delta wing configuration for high-Mach performance.
Comparisons to Mk 1 (previous smaller vehicle flown May 2025): Nearly 3× larger, 4× heavier, and significantly faster. Mk 1 used a GE J85 engine and focused on high-speed takeoff/landing validation.
Weight & exact dimensions: Not publicly released (no length, wingspan, or MTOW numbers disclosed yet — common for early test vehicles in this program).
One of the largest unmanned aircraft ever built. Remotely piloted from a ground-based flight deck. First flight completed today at Spaceport America (New Mexico) over White Sands Missile Range airspace — validated systems, handling qualities, and operations.
Speed & Performance
Maiden flight was subsonic (systems checkout).
Test campaign goal is orogressive expansion to supersonic speeds (Over Mach 1) in the coming weeks/months.
Designed for high supersonic (Mk 2 series overall targets Mach 2+ class performance with the F100 engine and variable inlet). Mk 2.1 is the entry point. It is not yet hypersonic.
Updated Roadmap (Quarterhorse Program)
Hermeus runs a single aggressive program with four aircraft, each building rapidly on the last using real flight data. Goal is to compress decades of aerospace development into months and deliver operational hypersonic capability for the U.S. this decade.
Mk 0 — Completed (non-flying iron bird for subsystem validation).
Mk 1 — Completed (May 2025 first flight at Edwards AFB. high-speed takeoff/landing demo).
Mk 2 series (current phase — supersonic focus)
Mk 2.1 — Just flown (March 2, 2026). Starts supersonic test campaign.
Mk 2.2 — Already in build pipeline. Expected to fly soon and become the world’s fastest unmanned aircraft.
Later Mk 2 variants (2.3) — Further speed/performance expansion.
Next steps (post-Mk 2)
Ramjet integration for sustained high-Mach flight.
End goal is Mach 5 Darkhorse — operational hypersonic unmanned aircraft (Mach 5-class with Chimera II engine family).
Full hypersonic readiness targeted this decade.
This is the fastest aircraft development cadence in modern history — Mk 1 flew less than a year ago.
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