The Air Force conducted the first ground test of the combined ramjet-scramjet engine being developed under the DARPA-led Falcon hypersonic research program April 9 at the Arnold Engineering Development Center on the grounds of Arnold AFB, Tenn. The dual-mode engine, dubbed the Falcon combined cycle engine test article, or FaCET, was successfully run in its “first hot-flow test” at the center’s aerodynamic and propulsion test unit, said Matthew Bond, APTU manager. This was the first use of APTU since it underwent an extensive multi-year upgrade, he said. The Falcon program will use the test unit to verify that FaCET’s flow paths are designed correctly to manage subsonic and sonic airflow as the engine transitions to higher speeds. Such an engine, combined with turbine propulsion, could one day be used to power an air vehicle from takeoff out to hypersonic flight and back. The APTU is only able now to test the FaCET engine at a fixed Mach number, so different engine runs are required to examine performance at different speeds. Bond said the goal for APTU is eventually to have the capacity to offer a real-time variable Mach capability. (Arnold report)