Hermeus Flies More Advanced Supersonic Demonstrator

Hermeus has made the successful first flight of its latest Quarterhorse Mk 2.1 prototype, kicking off a campaign the company said will see the uncrewed aircraft reach supersonic speeds. Flight testing of the Mk 2.1 builds on the original Mk 1, which took to the skies in May 2025. Atlanta-based Hermeus has plans to develop hypersonic aircraft for multiple military and civil applications that would include the 20-passenger Halcyon.

“Speed is the fundamental requirement for our flight systems and for our company,” said Hermeus CEO and founder AJ Piplica. He believes that capabilities developed through Quarterhorse’s “rapid, iterative development roadmap” will help in “bringing the United States closer to having the high-speed capability it needs now, not decades from now.”

The delta-winged Mk 2.1 prototype is four times heavier and three times larger than its predecessor. It is roughly the size of an F-16 fighter, which Hermeus claimed makes it “one of the largest unmanned aircraft ever built.”

Power is provided by a modified afterburning Pratt & Whitney F100 engine. Hermeus hopes its subsequent Mk 2.2 design will become the world’s fastest uncrewed aircraft, leveraging its proprietary air-breathing Chimera II engine. The company’s goal is to “unlock sustained ramjet-powered flight” this decade, collaborating with the U.S. Department of Defense to provide high-speed “novel operational defense capabilities.”