USAF funds testing of what will be the world's fastest reusable aircraft

The US Air Force has awarded US$60 million to aerospace startup Hermeus to finance flight testing of its hypersonic Quarterhorse aircraft intended for military and commercial applications. Capable of flying at Mach 5 with a range of 4,600 miles (7,400 km), the new aircraft will use a Turbine-Based Combined Cycle (TBCC) engine built around a commercial GE J85 turbojet engine.

Since the retirement of the Anglo-French Concorde supersonic airliner in 2003, the aerospace world has been divided roughly into two classes. On the one hand, there are the military air fleets that include a variety of supersonic aircraft, and the civilian lines, which are restricted to the subsonic realm.

But that's changing. Not only are there a number of private and public initiatives to usher in a faster, greener, more affordable era of civilian supersonic flight, but also under development are hypersonic passenger aircraft intended for both the civilian and military markets.

Founded by former members of SpaceX, Blue Origin, and Generation Orbit, Hermeus is looking to fly a demonstrator aircraft this decade that could become the fastest reusable aircraft in regular service. Called the Quarterhorse, there aren't a lot of technical details available, though it's slated to feature a titanium construction to withstand ultra-high speeds, and a highly streamlined delta wing design. It's also set to be the first aircraft of its kind to boast a turbine-based combined cycle (TBCC) propulsion system.

TBBC engines are similar to those used on the famous SR-71 Blackbird. They use a conventional turbojet to accelerate the craft to a high enough speed for a ramjet or scramjet to take over, which makes for a simpler and more efficient design. The trick is to produce an engine where the turbojet doesn't just sit there and produce drag while the aircraft is in supersonic or hypersonic mode.

In recent years, the US Air Force has shown interest in such high-speed commercial aircraft, not only for their military applications, but also as a potential long-term replacement for the President's Air Force One, which acts as both the Chief Executive's personal transport and a command-and-control center in the event of nuclear war or a national emergency.

“While this partnership with the US Air Force underscores US Department of Defense interest in hypersonic aircraft, when paired with Hermeus' partnership with NASA announced in February 2021, it is clear that there are both commercial and defense applications for what we're building,” says Hermeus CEO and co-founder, AJ Piplica.

The Mach 5 flight testing of small autonomous aircraft in 2023 is the first stop on Hermeus' roadmap to commercial hypersonic flight. It then plans to move onto flights of mid-size autonomous aircraft intended for time-critical cargo and reconnaissance in 2025, and ultimately hypersonic commercial passenger aircraft in 2029.

The video below gives an overview of the Quartermaster and the funding announcement.

Source: Hermeus