Hermeus flies newest supersonic plane, delivering its second successful first flight in nine months

Hermeus, a venture-backed defense aviation company, today announced it 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.

The next-generation Quarterhorse builds directly on the successful first flight of Hermeus' first aircraft, Mk 1, in May 2025, which validated the company's rapid, iterative development approach. 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.

Flown within a year after the company's previous flight campaign, Quarterhorse Mk 2.1 shows how quickly the Hermeus team can build and field high-speed aircraft — compressing timelines that traditionally take decades into a single development cycle.

"Speed is the fundamental requirement for our flight systems and for our company," said AJ Piplica, CEO and Founder of Hermeus. "We're building and flying aircraft on timelines that match the urgency of the world we're in. Today's flight kicks off a critical flight test campaign that will ultimately get us to supersonic speeds, bringing the United States closer to having the high-speed capability it needs now, not decades from now."

The flight was conducted at Spaceport America over White Sands Missile Range airspace in New Mexico. Quarterhorse Mk 2.1 was flown remotely from Hermeus' ground-based flight deck, validating aircraft systems, handling qualities, and operational procedures.

Hermeus' Quarterhorse program follows a rapid, iterative development roadmap in which multiple aircraft are designed, built, and flown in quick succession — steadily increasing speed and performance. By continuously building and flying prototypes, the company uses real flight data to refine designs, reduce risk, and accelerate progress with each new aircraft.

The company is currently 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 of multiple planned aircraft in Hermeus' Mk 2 program, followed closely by Mk 2.2, which is expected to become the world's fastest unmanned aircraft.

Subsequent phases will continue to push towards Hermeus' end goal of unlocking sustained ramjet-powered flight for the United States — this decade.