The FAA Clears Hermeus to Fly a Second Quarterhorse Drone Faster Than Sound

The Federal Aviation Administration has authorized Hermeus to fly its Quarterhorse Mk 2.2 uncrewed aircraft faster than the speed of sound, according to a notice published in the Federal Register on September 11, 2026. The special flight authorization took effect on August 20.

The Mk 2.2 is the second of Hermeus’s fighter-sized Quarterhorse test aircraft. Its predecessor, the Mk 2.1, went supersonic in May, and the new approval, first reported by FlightGlobal, clears the next airframe to follow it.

What the FAA approved

Hermeus petitioned the FAA on May 22, 2026, and filed its final revision on August 20, the notice says. It asked to run developmental flight tests of the Mk 2.2 inside restricted airspace over the US Army’s White Sands Missile Range in New Mexico.

The authorization covers up to six supersonic test flights through August 20, 2027. The flights are to take place at or above 24,000 feet during daytime hours.

For its environmental review, the FAA adopted the Army’s own determination for the Quarterhorse program at White Sands and concluded the flights would not significantly affect the human environment. It found the request “well within the intent” of its rules and granted it.

The terms are close to those the Mk 2.1 received in April. That earlier authorization allowed up to seven supersonic flights by the end of 2026, at or above 30,000 feet.

Why a drone over a missile range needs FAA permission

Quarterhorse is backed by Pentagon money, but Hermeus flies it as an experimental aircraft, and the FAA notice treats it as a civil aircraft. That puts it under the same speed rule as an airliner or a business jet.

Under 14 CFR 91.817, civil aircraft have been barred from flying faster than Mach 1 over the United States since 1973. The exception is a special flight authorization under section 91.818, which the FAA issues case by case.

That section is narrow. It allows supersonic flight only for purposes such as proving airworthiness or measuring sonic booms, and each applicant must explain why the testing cannot be done over the ocean instead.

The permit system may not last. In July the FAA proposed repealing the overland ban and replacing it with a sonic-boom noise limit, a supersonic overland rule that has drawn criticism over how it measures boom loudness. Comments closed on August 17, and no final rule has been published.

Where the Mk 2.2 fits in Hermeus’s plan

The Mk 2.1 reached Mach 1.21, about 930 mph (1,497 km/h), on its third flight from Spaceport America in May, Aerospace Testing International reported. It is powered by a Pratt & Whitney F100 afterburning turbofan, the engine family used in the F-15 and F-16.

Hermeus designs each Quarterhorse to push further toward sustained high-Mach flight. The company has said it is targeting Mach 3 in 2027 and wants a hypersonic Quarterhorse Mk 3 flying before 2030, powered by its Chimera turbine-based combined cycle engine.

The program is funded in part by the US Air Force, which awarded Hermeus $60 million in 2021, and by a Defense Innovation Unit contract with a ceiling of $219 million. The company has not announced a first flight for the Mk 2.2.

Quarterhorse is also meant to become a launch platform. On September 9, Hermeus unveiled Ramjet-X, an expendable ramjet test vehicle it plans to release from a Quarterhorse at about Mach 3, AeroTime reported, with integrated vehicle testing planned for 2027.