Hermeus seems dead keen on fast-tracking its way to hypersonic passenger flight. Its uncrewed subsonic Quarterhorse Mark 1 prototype has completed its maiden flight in the skies over Edwards Air Force Base in California on May 21, 2025.
Hypersonic flight looks to be the flavor du jour of the aerospace world these days, which isn't surprising. Not only is it poised to revolutionize warfare, it also has the potential to alter civilian cargo and passenger travel in ways far beyond what Concorde and its kin promised but never delivered in the 1960s.
The tricky bit is how to, pardon the pun, get it all off the ground. Since its founding in 2018, Hermeus has been pursuing a novel development strategy. Instead of the conventional approach of working directly on a final aircraft preceded by, perhaps, a flying prototype or two that approximate the performance of the ultimate aircraft, the company has been working on highly specialized prototypes designed to specifically test various systems without any pretense of being anything like a hypersonic plane.
Back in the saddle. Time to fly. pic.twitter.com/YTkwGTKhi3
— Hermeus (@hermeuscorp) May 21, 2025
For example, in November 2023, Hermeus rolled out its Quarterhorse Mark 0. This looked like a bit of a joke because it had one obvious flaw: it couldn't fly. In fact, that was, as they say in software development, a feature, not a bug. The whole idea was to speed up progress while reducing risks and costs by working on a series of prototypes that were each a new iteration of the technology designed to operate in a particular realm – on the ground, then subsonic, supersonic, and hypersonic flight.
It's an approach that seems to be working, since the Mark 1 went from sketch to flight in under a year.
The purpose of the May 21 flight was to meet a series of objectives. Powered by a single General Electric J85 turbojet engine, the 40-ft (12.2-m) uncrewed aircraft lifted off from the dry lake bed under remote control to test its capacity to handle high-speed takeoffs and landings. This was a primary goal because the Mark 1's 12-ft (3.66-m) wingspan is designed for high speed, so it has low-aspect-ratio wings that have to deal with high wing loading and a low thrust-to-weight ratio.
Short version, the Mark 1 is one bugger of a kite to land without pranging it.
During the test, the Mark 1 made a stable flight and landed without incident and the company claims that the test validated the digital design and performance models used to build the prototype, including the aerodynamics, stability, and flight controls. In addition, thumbs up were given to the propulsion, fuel systems, hydraulics, power, thermal control, and other subsystems.
All this came after 21 days of ground tests of the Mark 1 in December 2024 that climaxed with 130-knot (150-mph, 241-km/h) taxi tests.
The data from the Mark 1 flights will be used to improve the Quarterhorse Mark 2, which will be a much larger prototype about the size of an F-16 and incorporate a Pratt & Whitney F100 engine modified to use Hermeus' proprietary precooler technology. It's already under construction and is scheduled to fly at the end of the year. While the Mark 2 will be only supersonic with a top speed of Mach 3, the following Mark 3 will take a shot at reaching speeds in excess of Mach 3.3 – possibly reaching Mach 5 in 2026.
"The real-world flight data from Mk 1 provides significant technical value that we’re rolling into our next aircraft," said Co-Founder and President of Hermeus, Skyler Shuford. "Moreover, the team has accomplished this milestone on a challenging timeline while operating within the overall aerospace ecosystem – all to support rebuilding America’s lost capability to quickly develop brand-new, full-scale jets."
Source: Hermeus
