U.S. Army Flight-Demonstrates VICTOR With 3D-Printed Heavy-Fuel Rotary Engine

On Nov. 2, 2026, the U.S. Army announced the successful flight demonstration of a series-hybrid propulsion system using a 3D-printed heavy-fuel rotary engine. The propulsion system was integrated with a 400-volt motor-generator and installed on the VICTOR unmanned aircraft, developed by the Army's DEVCOM Army Research Laboratory (ARL) with Griffon Aerospace and others. VICTOR is a medium-sized unmanned aircraft system classified as Group 3.

Demonstrating in flight on VICTOR a system that generates electricity with a heavy-fuel engine and propels the aircraft with an electric motor addresses power and propulsion challenges the Army has identified for unmanned aircraft. The Army's description of an air-cooled design that does not require liquid cooling provides a specific design consideration for evaluating the propulsion system's configuration, but measured flight-performance and operational benefits would need to be confirmed with publicly released data.

The technical significance is not simply the presentation of a 3D-printed engine, but the integration of a heavy-fuel rotary engine, a 400-volt generation and electric-drive system, and a vertical-takeoff-and-landing aircraft, followed by a flight demonstration on VICTOR. The engine does not drive the propeller directly; instead, it sends power through a generator to an electric motor, separating the combustion system from the propulsion motor. The flight demonstration shows that the system integration was tested on an aircraft, but the announcement provided no measured figures for flight duration or speed, so this should be distinguished from a stage at which operational performance can be assessed. The design changes described by the Army include improvements to fuel atomization and vaporization to enable the rotary engine to burn heavy fuel efficiently, as well as redesigning parts after testing using metal 3D printing. The engine was also designed to be air-cooled, eliminating the need for a liquid-cooling system. The focus of evaluation therefore shifts from the manufacturing method itself to combustion stability, the overall weight and reliability of the system, including the generation and electric-drive components, and how the configuration without a cooling system performs under actual flight conditions. The Army's announcement did not provide quantitative results on these points. The development path runs from ARL's basic research to aircraft integration with Griffon Aerospace and other partners, additional experiments by military partners, and modifications to VICTOR for specific uses by industry partners. PULSAR is positioned to extend VICTOR beyond use as a single aircraft to an operational concept involving multiple aircraft. However, the announcement did not describe specific control methods or experimental conditions for group operations, and the flight demonstration does not mean that PULSAR was demonstrated. The next points to watch are measured flight-duration, speed and payload figures; the aircraft configuration used for the demonstration; reliability when operating on heavy fuel; and details of further tests by military partners. The Army cited a technical data package and design methods among the research outcomes, but did not announce production volumes for VICTOR or specific operational deployments. What is confirmed at this stage, therefore, is a flight demonstration of the propulsion system and plans to make it available for the next phase; operational performance and deployment timing require separate verification.

ARL said it used computational fluid dynamics modeling and new designs to improve heavy-fuel combustion efficiency, improve fuel atomization and vaporization, and reduce leaks of compressed air and fuel vapor. It redesigned parts based on experimental results using metal 3D printing and designed an air-cooled engine that does not require liquid cooling. Rather than directly turning a propeller, the engine drives a generator, which supplies electricity to the aircraft's electric motor in a series-hybrid configuration. The Army said it will provide VICTOR and the PULSAR concept, which involves operating multiple VICTOR aircraft as a group, to military partners for further experimentation and development. Industry partners plan to modify VICTOR for other uses.