Hermeus, a venture-backed aviation defense company, said it has completed the first flight of its newest Quarterhorse aircraft, a milestone the company described as its second successful first flight in less than a year and the start of a test campaign aimed at exceeding supersonic speeds.
The Atlanta-based defense company said it conducted the flight at Spaceport America in New Mexico, operating over White Sands Missile Range airspace. Hermeus flew the unmanned aircraft remotely from a ground-based command center and said the sortie validated aircraft systems, handling qualities, and operational procedures.
Hermeus described the aircraft, Quarterhorse Mk 2.1, as its largest and fastest vehicle to date. The company said the design builds on the first Quarterhorse aircraft, Mk 1, which it flew in May 2025. That earlier flight, Hermeus said, validated the company’s “rapid, iterative” development approach.
Quarterhorse Mk 2.1 is roughly the size of an F-16 and uses a Pratt & Whitney F100 engine. Compared with Mk 1, the company said Mk 2.1 is nearly three times larger and four times heavier, and is “significantly faster,” the company said.
Hermeus also called the Mk2.1 one of the “largest unmanned aircraft ever built.”
“Speed is the fundamental requirement for our flight systems and for our company,” AJ Piplica, Hermeus CEO and founder, said in a statement. He said the company is building and flying aircraft on timelines meant to match “the urgency of the world we’re in,” and described the flight as the start of a campaign that will “ultimately get us to supersonic speeds.”
Hermeus said its Quarterhorse program follows a roadmap in which it designs, builds, and flies multiple aircraft in quick succession, increasing speed and performance with each step. The company said it uses flight data from each vehicle to refine designs, reduce risk, and accelerate progress.
Hermeus said it is now fully in the Mk 2 phase of the program, a multi-aircraft series focused on achieving and expanding supersonic flight. Quarterhorse Mk 2.1 is the first aircraft in that series, the company said, and it expects to follow it with Mk 2.2, which Hermeus said is expected to become the world’s fastest unmanned aircraft.
Looking further out, Hermeus said subsequent phases will continue pushing toward an end goal of sustained ramjet-powered flight “this decade.”
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