Hermeus has reached a new stage in its high-speed aircraft initiative, with the Quarterhorse Mk 2 prototype now structurally assembled and supported by its tricycle landing gear. The startup company shared images confirming the airframe’s mounting as it prepares for the integration of the Pratt & Whitney F100 turbofan engine at its Atlanta facility. Quarterhorse Mk 2 represents the company’s first platform capable of supersonic flight, following the Mk 1’s maiden flight in May 2025, which focused on validating aircraft design and performance models. The Mk 2 introduces a delta wing configuration and a variable nose-mounted air intake, distinguishing it from its predecessor. Unlike the planned Mk 3, which aims to exceed Mach 5 and incorporate the Chimera turbine-based combined cycle (TBCC) propulsion system, the Mk 2 uses a modified version of the well-know F100 engine. The key innovation for this stage is a proprietary pre-cooling system, designed to allow the turbojet to operate efficiently at higher speeds by reducing inlet air temperature. Hermeus’ step-by-step development approach involves using each prototype to validate critical technologies before advancing to hypersonic speeds. The Mk 2 will be essential for testing and refining the pre-cooling system, which is seen as a prerequisite before integrating the scramjet-based TBCC engine in future models.

Full report : Quaterhorse Mk 2 Prototype shows structural progress as Hermeus prepares for engine integration and aims for first flight by year-end.

For more see the OODA Company Profile on Hermeus.