The US Army research laboratory DEVCOM ARL has flown a drone powered by a metal 3D printed rotary engine that runs on heavy fuel and drives an electric generator in a series-hybrid layout. The Army calls it the first printed engine of its kind. Printing let the team redesign parts quickly after each test and build an air-cooled engine without liquid coolant.
Key facts
Flight demonstration in a Group 3 unmanned aircraft
Air-cooled engine paired with a 400-volt motor-generator
Aircraft named VICTOR, built with Griffon Aerospace
Programme spans 30+ universities and 20+ industry partners
Context A series-hybrid drive uses the combustion engine only to turn a generator, which powers electric motors, rather than driving the propulsion directly.
How was the engine developed?
ARL started from a blank sheet and used computational fluid dynamics to improve how fuel atomizes and vaporizes, and to cut leakage of air and vapor. Metal printing allowed components to be redesigned fast as test results came in, and enabled an air-cooled design that makes the propulsion unit smaller.
What flew, and what comes next?
The engine was paired with a new 400-volt motor-generator for a vertical takeoff concept. With Griffon Aerospace and other partners, ARL built the midsized VICTOR drone around it. The programme involved over 30 universities, 13 federal laboratories and 20 industry partners. Findings feed into PULSAR, a swarm concept. VICTOR and PULSAR will go to military partners for further experiments.
What it means
For European manufacturers this is a research milestone, not a product. It shows printing used for fast design iteration on thermally and mechanically demanding engine parts, a pattern relevant to small and mid sized firms in propulsion supply chains. No part cost, qualification route or production volume was disclosed, so timelines for series use remain open. Industry partners still have to mature the technology.
Frequently asked questions
What did the Army fly?
A Group 3 drone called VICTOR powered by a metal 3D printed, air-cooled heavy-fuel rotary engine in a series-hybrid setup.
Why was printing used?
It let the team redesign engine components quickly based on test lessons and build an air-cooled engine without liquid coolant.