Researchers at the U.S. Army Combat Capabilities Development Command Army Research Laboratory in Adelphi, Maryland, flew a 3D-printed heavy-fuel rotary-engine series-hybrid propulsion system on a tactical unmanned aircraft. The Versatile Tactical Power and Propulsion program applied computational fluid dynamics and 3D metal printing so researchers could produce an air-cooled rotary engine that burns heavy fuel without liquid coolant. Combined with a 400-volt motor-generator, the setup powers the Group 3 VICTOR unmanned aircraft system built with Griffon Aerospace and shown near Huntsville, Alabama.

The work drew in more than 30 universities, more than 13 federal laboratories and more than 20 industry partners, generating hundreds of journal papers and training hundreds of scientists and engineers. Results will shape the PULSAR concept of multi-mission swarms of VICTOR drones now open to military partners for added testing.