Hermeus secures regulatory approval for supersonic flights with Quarterhorse Mk 2.1

The US Federal Aviation Administration approved Hermeus to conduct non-military flights at speeds exceeding Mach 1 with the company’s experimental Quarterhorse Mk 2.1 vehicle as part of the effort to achieve hypersonic flight.

Hypersonic aviation start-up Hermeus has received regulatory approval to carry out supersonic flights with the company’s experimental Quarterhorse Mk 2.1 vehicle.

Civil aviation regulators at the US Federal Aviation Administration on 9 April authorised Hermeus to conduct Quarterhorse Mk 2.1 flights at speeds exceeding Mach 1. The test sorties will take place at or higher than 30,000ft over White Sands Missile Range in New Mexico.

Notice of the approval is set to be officially published in the US federal register on 13 April, though the decision was released on 10 April.

Hermeus had submitted a petition for a Special Flight Authorisation permit in January, specifically requesting permission to carry out up to seven supersonic test flights by 31 December 2026.

The Quarterhorse Mk 2.1 vehicle, which is Hermeus’ first aircraft capable of reaching supersonic speeds, logged its first subsonic flight on 2 March from the base in New Mexico. Hermeus received experimental type certification for the uncrewed jet just days later.

Hermeus is seeking to develop a reusable flight vehicle capable of breaking the M5 hypersonic barrier, while also taking off and landing under its own power. Rival hypersonic developer Stratolaunch achieved M5 flight with its reusable Talon-A aircraft in 2024, though that design uses a captive carry mothership to ferry the rocket-powered craft to cruising altitude.

By contrast, Hermeus plans to break the hypersonic barrier with a design dubbed the Quarterhorse Mk 3, which will feature a conventional turbofan integrated with a dual-mode ramjet to power the vehicle through the full envelope of take-off, subsonic, supersonic and hypersonic flight.

While that aircraft is still under development, Hermeus will use the Mk 2.1 to break the sound barrier and validate its aircraft design and autonomous flight control systems at high speeds. The type is powered by a Pratt & Whitney F100 fighter jet engine.

Within the Mk 2 series, the company has plans for three variants that will each push further toward the M5 threshold. The Mk 2.1 is to break the supersonic barrier, while the successor Mk 2.2 is to push into higher Mach speeds.

“Subsequent phases like… will continue to push toward Hermeus’ end goal of unlocking sustained ramjet-powered flight and delivering operational hypersonic capability for the United States this decade,” the company says.

Hermeus previously said its goal for the Mk 2 iteration is to reach flight speeds of M2.5.

The company says its development timeline puts it on track to deliver an operational, reusable hypersonic capability before 2030.

This month, Hermeus announced it is moving the company’s headquarters from Atlanta to Los Angeles, with the Atlanta site to focus on aircraft production.