Initial concept art of the Quarterhorse aircraft, planned to be built by Hermeus Corporation. (Hermeus)

WASHINGTON — Hermeus unveiled its new high-speed, jet-powered Quarterhorse Mk 1 aircraft today, taking another small step toward the Atlanta-based startup’s goal of producing the world’s first reusable hypersonic plane.

The uncrewed Mk 1 aircraft is set to become the first Hermeus-produced aircraft to take to the skies during flight tests at Edwards Air Force base scheduled later this year, which are aimed at proving it can safely conduct high-speed take off and landings.

Hermeus ultimately seeks to build two types of mass-produced hypersonic aircraft: a multi-mission drone for the defense market called Darkhorse and a passenger plane known as Halcyon capable of flying from New York to London in 90 minutes.

But for now, as the company debuts the Quarterhorse Mk 1, it also intends to pitch the next iteration of the Quarterhorse, a faster supersonic Mk 2 version set to roll out in 2025, to the Pentagon as its first product.

“We’re building a capability that certainly fill some gaps, and I think having an operational capability earlier than Darkhorse — like a couple years earlier — really helps [the Pentagon],” said Hermeus founder and CEO AJ Piplica in an interview with Breaking Defense.

Piplica declined to comment on whether Hermeus will propose the Quarterhorse Mk 2 for the Pentagon’s Replicator program, which is seeking to field thousands of unmanned systems over two years, or the Air Force’s collaborative combat aircraft program that aims to build autonomous drone wingmen that will be commanded by fighter pilots. (Hermeus is not among the first five primes participating in the early stages of the Air Force’s collaborative combat aircraft project.)

However, Hermeus views the Quarterhorse Mk 2 — billed by the company as “the world’s first purpose-built high-Mach drone” — as a unique offering among the systems currently operated by the United States military like the RQ-4 Global Hawk and MQ-9 Reaper, which operate at subsonic speeds.

Hermeus’s foray into high-speed unmanned aircraft isn’t the only one. Recently, fellow startup Anduril unveiled a high subsonic rocket-powered platform to act as an air defense system, and higher-flying Stratolaunch plans to conduct its own test flight of a recoverable hypersonic vehicle later this year.

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A path to hypersonic speeds

As a bridge to hypersonic aircraft that travel in speeds in excess of Mach 5, the company plans on constructing four Quarterhorse test vehicles, culminating in the Mk 3 aircraft that Hermeus executives say will fly faster than the Mach 3.3 speeds clocked by the legendary SR-71 spyplane built by Lockheed Martin.

In parallel, Hermeus is developing its Chimera II propulsion system that will be tested aboard the Quarterhorse Mk 3 and produced en masse for Darkhorse. The Chimera II uses a Pratt & Whitney F100 engine as its base, but replaces the afterburner with a ramjet afterburner, and modifies the engine with a precooler and bypass system manufactured in house, Piplica said.

The Mk 1 aircraft, powered by a General Electric J85 engine and operated by remote control, is a subsonic craft and will be put through subsystems, ground station, operations, and human factors testing before making its first flight later this year.

Piplica acknowledged Hermeus had initially hoped to get a plane off the ground in 2023, but said the company “reframed” its plans to do additional testing with its Quarterhorse Mk 0, which completed remote taxi tests in November.

For the Mk 1 aircraft, “its requirements were set in September of last year, and it’s being unveiled today about 200 days later,” Piplica said. “It’s a pace of development we haven’t seen in this country for a very long time.”

Next year’s Mk 2 aircraft will transition to the F100 engine used by the F-15 and F-16, allowing the aircraft to fly at supersonic speeds. The engine will be modified with the Hermeus-built precooler, which is designed to allow the engine to reach higher speeds than what the F100 had previously accomplished, Piplica said, but a full-up Chimera II engine will not be installed in Quarterhorse until Mk 3.

Piplica said Hermeus could manufacture about “a dozen or so” Mk 2 drones per year in its current facility in Atlanta, but will have to expand if it gets a “clear demand signal” that the Defense Department wants to buy more. In the meantime, the company is “building up the supply chain relationships” that will be necessary to start producing Mk 2 drones if the Pentagon signs on as a customer.

The Defense Department has not publicly revealed a program of record for a hypersonic aircraft, but has made several investments in Hermeus as it develops Quarterhorse.

The Air Force in 2021 awarded Hermeus a three-year, $60 million jointly funded contract to build and test three Quarterhorse aircraft, as well as to flight test a reusable hypersonic propulsion system. At the time, Air Force leaders said a commercial-built hypersonic aircraft could have viability for the US military as a transport or surveillance plane.

Under a contract inked last November with the Pentagon’s Defense Innovation Unit, the Quarterhorse will take part in tests for DIU’s Hypersonic and High-Cadence Airborne Testing Capabilities (HyCAT) initiative, which seeks to boost the department’s high-speed flight test capacity.

RTX’s venture capital arm announced in 2022 that it would invest an undisclosed amount in Hermeus.

The Defense Department is interested in reusable hypersonic aircraft, as they would allow the US military to conduct surveillance and strike missions much faster than its current bomber fleet, said James Weber, the department’s principal director for hypersonics, during a congressional hearing earlier this month.

However, “there’s a lot of work that we have to do in the science and technology world to address the materials and structures for reusable hypersonic aircraft,” he said.