Hermeus has begun testing its proprietary precooler technology with the F100 engine made by Pratt & Whitney. The precooler increases the max speed of the turbine engine by lowering the temperature of incoming air. This is the first major propulsion milestone for Hermeus' next aircraft, Quarterhorse Mk 2, which will utilise this engine configuration.

Testing took place at Edwards Air Force Base at sea-level static conditions. The data collected from these tests inform how the F100 handles the Hermeus precooler under a variety of loads and will lead into future testing with heated air, simulating high-Mach flight conditions.

Hermeus' turbine-based combined cycle (TBCC) engine, named Chimera, is a full-range, air-breathing hypersonic engine combining a turbine with a ramjet. At low speeds Chimera operates in turbine mode with the F100 engine, while at higher speeds the engine transitions to ramjet mode. The precooler helps bridge the gap between these two modes of operations by increasing the performance of the turbine.

"The F100 is one of aviation's most reliable engines having clocked more than 30 million flight hours," says Josh Goodman, senior director of the F100 Program at Pratt & Whitney. "The F100 is taking on new life as Hermeus extracts even more performance out of our storied engine."

Quarterhorse Mk 2 will fly with this precooler-F100 engine combination and be capable of hitting speeds greater than Mach 2.5. The entire Chimera engine, which includes a ramjet, will power Hermeus' following aircraft, Quarterhorse Mk 3. This will reach speeds close to Mach 4 and pave the way for future Hermeus aircraft that will fly at hypersonic speeds.

"Air-breathing engines are critical to Hermeus' goal of operationalising hypersonic aircraft," says co-founder and chief technologist Glenn Case. "By making a full-range, air-breathing hypersonic engine, Hermeus is setting the stage for aircraft that are capable of taking off from a regular runway and accelerating up to hypersonic speeds. No rockets or motherships required."