Supersonic Hermeus Quarterhorse Mk 2.1 Starts Taxi Tests

COLORADO SPRINGS—High-speed aircraft developer Hermeus has begun taxi tests of its Pratt & Whitney F100-229-powered Quarterhorse Mk. 2.1 supersonic flight demonstrator at Spaceport America in New Mexico.

The remotely piloted aircraft is designed for high supersonic speeds, and “will be the world’s first high-Mach unmanned aircraft for national defense,” the Atlanta-based startup says. The aircraft, which arrived by road at the New Mexico site in early January, is similar in size to an F-16 and incorporates a variable inlet and an integrated precooler, the first element of the Hermeus-designed, Chimera turbine-based, combined-cycle (TBCC) propulsion system.

Although designed to evaluate performance at supersonic speeds, the Mk. 2.1 is also representative of the company’s first practical operational vehicle, a version of which has already been selected by Kratos Defense. The contractor will use the Mk.2.1 as part of its support work for the U.S. Navy and Missile Defense Agency’s Multi-Service Advanced Capabilities Hypersonic Testbed (MACH-TB) program.

Commenting on the start of low-speed taxi testing, Hermeus founder and CEO A.J. Piplica says the evaluation represents “a critical phase where we validate ground handling, braking, and systems integration ahead of flight. It’s a deliberate, methodical process, but an important one as we progress toward flight.”

Describing the testing on social media, Piplica says the campaign includes powering up the F100 to full thrust and validating propulsion hardware; drop tests to verify gear and structural performance; ground vibration testing and verification of vehicle-to-ground and ground-to-vehicle communication. “This work reflects a coordinated effort across manufacturing, structures, mechanisms, propulsion, avionics, software, flight test, and deployed operations. We’re moving hardware forward quickly and methodically,” he adds.

Flight tests of the variable inlet and pre-cooler will also provide Hermeus with insight into the design of the follow-on Mk. 3 version, which will be equipped with the complete TBCC propulsion system incorporating the pre-cooler, variable geometry inlet, F100 and a ramjet. The Mk. 3 is planned to demonstrate mode transition from turbine to ramjet power over speeds between Mach 2.5 and Mach 3.

Flight tests of the Mk 2.1 are expected to be more extensive than that of the Mk.1 demonstrator, which made a single short flight at Edwards AFB, California, on May 21.