Hypersonic aircraft startup Hermeus unveiled its Quarterhorse aircraft on Thursday at its Atlanta factory where the company is preparing the vehicle for its first flight test this summer.

The aircraft, dubbed Mk 1, is the second version of Quarterhorse, a high-speed test platform Hermeus is developing iteratively with a goal of demonstrating autonomous, reusable, near-hypersonic flight by 2026. The company’s initial vehicle, Mk 0, completed its ground-based test campaign last November. Mk 1 will be the first to take flight.

Hermeus’ goal is to build one test vehicle per year, and CEO AJ Piplica told C4ISRNET that as Mk 1 prepares for flight in the next few months, refining the company’s processes for quickly building and testing aircraft is just as important as the capability it will demonstrate in flight.

“That’s something that is very different about the approach we’re taking to aircraft development — being this iterative and really pushing to do one aircraft per year,” he said in a March 28 interview. “I think this particular problem requires it. High speed airplanes and pushing the bounds of what’s been done before really requires it.”

While Quarterhorse in its multiple iterations serves as a stepping stone toward the company’s larger goal of developing hypersonic aircraft — which can reach speeds of Mach 5 or higher — for defense and commercial customers, the Pentagon is interested in using the aircraft to help test its own systems.

The Defense Department lacks the flight test infrastructure to support the more than 70 hypersonic development programs being pursued by the military services. In recent years, the department has been working to increase its flight cadence by funding commercial systems like Quarterhorse and developing flying testbeds for advanced materials and components.

The Air Force Research Laboratory was an early investor in Quarterhorse, awarding Hermeus a $1.5 million contract in 2020 and another $60 million the following year. Last November, the Defense Innovation Unit selected the aircraft for its Hypersonic and High-Cadence Airborne Testing Capabilities program, or HyCAT, which aims to increase DOD’s flight testing capacity.

Hermeus had planned to fly Quarterhorse in 2023, but its decision to build Mk 0 as a ground test platform pushed that target to this year. Piplica said the delay was disappointing, but noted that spending more time wringing out the technology and processes on the ground has started to payoff as the company shifts its focus toward flight.

Following a 204-day build process, Mk 1 will now move through ground testing in Atlanta before it is shipped to Edwards Air Force Base in California for additional tests, Piplica said.

‘Push the envelope’

The goal of the first flight, which will take off from Edwards, is to demonstrate high-speed takeoff and landing. Piplica declined to detail specific speed and altitude targets but said Mk 1 is designed for a “pretty limited” flight envelope. Once Quarterhorse achieves those objectives, the company will see if it can move beyond those limits.

“We’ll push the envelope, get as much data as we can, and we’ll certainly take technical risk in doing so,” he said. “One of the key pieces to our approach is to really push learning as far to the left as early as you can.”

Hermeus will provide data from the flight to AFRL, DIU and other customers. The test will also inform Mk 2, which is set to fly next year and achieve supersonic speeds.

A key difference in that vehicle is that it will feature Hermeus’ Chimera II propulsion system, which includes Pratt & Whitney’s F100 engine. That engine is what will ultimately fly in Hermeus’ first hypersonic aircraft, Dark Horse.

“We’ll be flying that engine about three years earlier than we had originally planned in our roadmap,” Piplica said.

Mk 3 will follow in 2026, and Piplica said he expects that’s the timeframe in which Quarterhorse will start supporting Defense Department testing. As for how or when future vehicles may be incorporated into DOD aircraft fleets, Piplica declined to speculate, though he compared Mk 2 to an F-16-scale, autonomous aircraft.

“How does that play into the future force roadmap of the Air Force and the Joint Force writ large?” he said. “For us, it’s an aircraft on a roadmap that we have to do anyway. That alignment, I think, is really powerful.”

Courtney Albon is C4ISRNET’s space and emerging technology reporter. She has covered the U.S. military since 2012, with a focus on the Air Force and Space Force. She has reported on some of the Defense Department’s most significant acquisition, budget and policy challenges.

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