Hermeus has announced that its Quarterhorse Mk 2.1 uncrewed aircraft has completed its first supersonic flight, reaching Mach 1.21 during a test flight at Spaceport America in New Mexico.
The Atlanta-based defense aviation company shared news of the milestone on May 26, 2026, noting that the flight took place over White Sands Missile Range airspace.
Hermeus describes Quarterhorse Mk 2.1 as the world’s first privately developed uncrewed supersonic jet.
The aircraft reached supersonic speed on its third test flight. According to Hermeus, the milestone came less than three months after Quarterhorse Mk 2.1’s first flight and 364 days after the first flight of the company’s original Quarterhorse Mk 1 aircraft.
“Our customers at the Department of War are paying close attention to how fast this program is moving,” Hermeus CEO and co-founder AJ Piplica said. “This flight demonstrates a pace of execution that is extremely rare in modern aviation.”
Powered by a Pratt & Whitney F100 engine, Quarterhorse Mk 2.1 is the first of three F-16-sized supersonic aircraft in the company’s current development roadmap. Hermeus is using flight-test data from each aircraft to improve performance and reduce risk as it works toward higher-speed flight.
Hermeus has received US Air Force backing as it develops its high-speed aircraft roadmap. In 2021, the air force awarded the company a $60 million jointly funded contract to accelerate hypersonic aircraft and propulsion development. The award followed an earlier AFWERX contract in 2020 that explored how a future Hermeus Mach 5 aircraft could support the Presidential and Executive Airlift fleet. However, the company’s current work is focused on high-speed defense aircraft and test vehicles, rather than a formal Air Force One replacement program.
The company declared that it is already building and testing Quarterhorse Mk 2.2, with Mk 2.3 to follow, with each aircraft in the series intended to push performance further and move the program toward sustained high-Mach flight.
The Atlanta-based aerospace and defense firm is developing high-speed aircraft for military and commercial applications. Its roadmap starts with Quarterhorse, a series of uncrewed aircraft designed to prove out supersonic and high-Mach flight, before moving toward Darkhorse, a planned hypersonic military aircraft, and Halcyon, a proposed Mach 5 passenger aircraft.
Hermeus also plans to continue the Quarterhorse Mk 2.1 flight-test campaign while building subsequent aircraft for higher-speed test points. The company did not announce a date for the next flight or for the first flight of Quarterhorse Mk 2.2.