The United States Defense Innovation Unit (DIU) has successfully completed an unmanned stores separation flight test with Atlanta-based aerospace company Hermeus under the Pentagon’s Hypersonic and High-Cadence Airborne Testing Capabilities (HyCAT) programme, marking another significant step in the development of next-generation hypersonic military aircraft.

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The stores separation test verified that Hermeus’ Quarterhorse test aircraft can safely release an external payload, such as a weapon, sensor pod or other equipment, without compromising the aircraft’s stability or risking a collision after release. According to the DIU, the achievement came during Quarterhorse’s fifth flight since spring 2026, a pace it said is four times faster than conventional hypersonic flight-testing programmes. “Another huge HyCAT milestone, a successful unmanned stores separation flight test with Hermeus. This was only the programme’s fifth flight since the spring. Tests like this usually take years. We’re moving four times as fast,” the agency said.

Quarterhorse is an uncrewed, quarter-scale aircraft designed to advance technologies for a future full-sized hypersonic platform. Powered by Hermeus’ Chimera turbine-based combined cycle engine, the aircraft previously reached Mach 1.21 (about 930 mph or 1,497 km/h), with the company aiming to expand its flight envelope to Mach 3 by 2027. Hermeus first joined the HyCAT programme in 2023 under a $23 million contract, which was expanded in May 2026 with a $159 million agreement to continue flight testing and share performance data with the U.S. Air Force and Navy.

Hermeus said the Quarterhorse programme is laying the foundation for Darkhorse, a planned unmanned hypersonic military aircraft intended for strike and reconnaissance missions. The successful payload release test is considered a critical milestone because aircraft capable of hypersonic speeds must also demonstrate they can safely deploy weapons or other external payloads under extreme aerodynamic conditions. The DIU said the HyCAT initiative is accelerating the development of hypersonic technologies by partnering with private-sector innovators, reducing testing timelines and helping shape future high-speed combat aircraft for the U.S. military.