What's a precooler and why are they testing it? The Hermeus precooler increases the maximum speed of the turbine engine by lowering the temperature of incoming air. This is the first major propulsion milestone for their next aircraft, Quarterhorse Mk 2, which will utilize this engine configuration and fly at supersonic speeds.

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 aircraft will reach speeds close to Mach 4 and pave the way for future Hermeus aircraft that will fly at hypersonic speeds.