U.S. Army successfully tests 3D-printed heavy-fuel hybrid drone engine

Researchers at the U.S. Army Combat Capabilities Development Command (DEVCOM) Army Research Laboratory have successfully demonstrated a flight test of a 3D-printed heavy-fuel rotary-engine series-hybrid system. The propulsion system was integrated into the VICTOR, a mid-sized vertical takeoff and landing (VTOL) unmanned aircraft system developed in collaboration with industry partners including Griffon Aerospace.

The project utilized advanced computational fluid dynamics modeling and 3D metal printing to address the challenges of burning heavy fuels, such as JP-8, in a rotary engine. This approach improved fuel atomization and vaporization while minimizing leaks. The use of 3D printing allowed for rapid redesigns and the implementation of an air-cooled design, which eliminates the need for bulky liquid cooling systems and reduces the overall size of the propulsion system.

The hybrid architecture features a 400-volt motor-generator system, allowing the engine to drive the generator while the electric motor handles propulsion. This setup enables the engine to operate at its most efficient speed independently of the propeller requirements. The technology aims to allow drones to fly longer, carry heavier payloads, and operate in extreme environments while reducing the logistical burden of supplying multiple fuel types in the field.