Hermeus has completed the first supersonic flight of its high-Mach remotely piloted aircraft, Quarterhorse Mk 2.1.
The aircraft reached a top speed of Mach 1.21, the defence aviation company said in a statement on 26 May 2026.
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The flight took place during the aircraft’s third test at Spaceport America, operating over the White Sands Missile Range.
Hermeus noted that this milestone follows less than three months after Quarterhorse Mk 2.1’s first flight and comes 364 days after the debut flight of the company’s initial aircraft, Mk 1.
Hermeus CEO and co-founder AJ Piplica said: “Our customers at the Department of War are paying close attention to how fast this program is moving. This flight demonstrates a pace of execution that is extremely rare in modern aviation.
“Our country’s ability to deliver new asymmetric military capability at scale depends on teams that can solve hard technical challenges quickly. That’s exactly what we’re proving with each test flight we conduct and each new aircraft we build at Hermeus.”
Hermeus signed a $60m partnership agreement with the US Air Force (USAF) to flight test its first autonomous high-speed aircraft ‘Quarterhorse’ in 2021.
Quarterhorse Mk 2.1 is the first of three planned supersonic aircraft models, each similar in size to the F-16, according to Hermeus.
The aircraft is powered by the Pratt & Whitney F100 engine, with Pratt & Whitney operating as a business of RTX.
Hermeus describes its approach as designing, building, and flying aircraft rapidly, using results from each test flight to guide performance improvements and manage programme risks. This strategy is designed to accelerate development and scale up new capabilities in a shorter timeframe.
The company is already constructing and testing the next version, Quarterhorse Mk 2.2, with a further model, Mk 2.3, to follow.
Each aircraft within the roadmap has an aim of pushing performance and progressing towards continuous high-speed flight.
The recent test comes as the Pentagon increases interest in high-speed capabilities amid competition from countries such as China.
Hermeus plans to continue flying the Quarterhorse Mk 2.1 in additional test campaigns and to introduce further updates through subsequent aircraft models.
