The U.S. Army’s Combat Capabilities Development Command Army Research Laboratory (DEVCOM ARL) has flight-tested a 3D printed heavy-fuel rotary engine aboard VICTOR, a Group 3 midsized drone flown near Huntsville, Alabama. The engine is a rotary-electric series hybrid paired with a 400-volt motor-generator, built under ARL’s Versatile Tactical Power and Propulsion research program with industry partner Griffon Aerospace.
The problem it targets is a fuel mismatch rather than a flight-performance one: most small drones run on gasoline, while militaries standardize on kerosene-based heavy fuel. Heavy fuel is harder to atomize and vaporize than gasoline, and rotary engines are already prone to leakage, so running one on heavy fuel compounds the failure modes.
ARL’s team used CFD modeling and a clean-sheet design to improve atomization and vaporization while cutting compressed-air and fuel-vapor leaks. Metal 3D printing was used as an iteration tool rather than a final-part shortcut: program manager Dr. Chol-Bum “Mike” Kweon said it let the team “rapidly redesign engine components based on lessons learned through experimentation,” and enabled an air-cooled architecture that drops the liquid coolant loop entirely. For a drone, removing that circuit means less weight and volume carried, which converts directly into endurance and payload.
No thrust, power output, fuel-burn, or endurance figures were published for the VICTOR flight itself. The program has involved more than 30 universities, more than 13 federal laboratories and more than 20 industry partners, producing what ARL describes as tens of patents and patent applications. Findings are reportedly already transitioning to industry partners, and lessons will feed PULSAR, a concept for swarms of VICTOR-class drones operating beyond line of sight. Both VICTOR and PULSAR are to be made available to military partners for further testing.