Hermeus Quarterhorse Mk 2.1 receives FAA experimental airworthiness certificate for supersonic flight testing

TRUTH OR CONSEQUENCES, N.M. - Hermeus in Atlanta has received a Special Airworthiness Certificate in the Experimental Category from the Federal Aviation Administration (FAA) for its uncrewed Quarterhorse Mk 2.1 aircraft, clearing the vehicle for flight testing as part of the company's high-speed aircraft development program.

The certification follows about a year of collaboration between Hermeus engineers and FAA officials during the aircraft's design, build, and inspection phases. The certificate allows the company to proceed with an expanded flight-test campaign aimed at demonstrating supersonic flight.

High-speed development

Quarterhorse Mk 2.1 is the largest aircraft in Hermeus' Quarterhorse development program, which advances high-speed flight by building and flying a series of progressively faster aircraft. Data gathered during each flight-test campaign feeds directly into the design of subsequent vehicles.

"We are thankful for the diligent work of the FAA," said Jay Wagemann, Hermeus' director of mission operations. "Their team conducted a rigorous inspection and gained real confidence in the aircraft; now, we will continue our flight test campaign, collecting vital data and pushing the limits of high-speed flight."

Flight testing is taking place at Spaceport America in New Mexico within White Sands Missile Range airspace. Engineers will test the unmanned aircraft at progressively higher altitudes and speeds as the company works toward achieving supersonic performance.

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Hermeus announced that the aircraft completed its first flight on 2 March, marking the company's second inaugural flight in less than a year. The flight began a test campaign intended to demonstrate sustained supersonic flight.

The vehicle builds on the first flight of the earlier Quarterhorse Mk 1 aircraft in May 2025, which validated the company's rapid, iterative development approach to high-speed aircraft design.

Roughly the size of a fighter aircraft and powered by a Pratt & Whitney F100 engine, Quarterhorse Mk 2.1 is nearly three times larger and four times heavier than its predecessor. The engine, developed by Pratt & Whitney in East Hartford, Conn., an RTX business, is a military turbofan widely used in fighter aircraft.

Engineers flew the aircraft remotely from Hermeus' ground-based flight deck during the first flight, validating vehicle systems, flight controls, and operational procedures.

Hermeus says its Quarterhorse program follows a rapid development roadmap in which multiple aircraft are designed, built, and flown in quick succession. The company uses flight-test data to refine aerodynamics, propulsion integration, and flight-control systems for each successive vehicle.

The current Mk 2 phase of the program focuses on achieving and expanding supersonic performance. Quarterhorse Mk 2.1 is the first of several planned aircraft in the Mk 2 series, followed by the Mk 2.2 vehicle, which the company expects will become the fastest unmanned aircraft in the world.

"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."