Hirth Engines and ePropelled team up on hybrid propulsion for UAVs
Hirth Engines and ePropelled have formed a strategic partnership to develop hybrid propulsion systems for UAV, aerospace and defence applications.
The collaboration combines Hirth’s two-stroke engine technology with ePropelled’s electric propulsion, starter-generator and power-management systems. The companies said the goal is to deliver lighter, more energy-efficient propulsion for demanding missions. They expect the hybrid architecture to improve fuel efficiency, extend endurance, increase payload capacity and cut lifecycle operating costs. The systems are also being designed to add reliability and redundancy for mission-critical operations while supporting tighter sustainability and regulatory requirements.
Hirth is contributing its 3508HF engine, a member of the Hirth 35 series of liquid-cooled, two-cylinder, in-line two-stroke engines built for UAVs and light aircraft. The 3508HF is configured for heavy fuel, a feature that can simplify operations where jet fuel compatibility is required. That makes it relevant for both military and commercial UAV programs. Paired with ePropelled’s intelligent electric systems, the engine is intended to support strong power-to-weight performance in difficult operating environments.
The companies said the partnership is aimed at a broad set of platforms, including UAVs and other uncrewed systems, advanced air mobility aircraft, defence and surveillance missions, and industrial aerial applications. Research, development and integration work are already underway. Prototype demonstrations are expected in upcoming project cycles, with a public showcase planned at UMEX in Abu Dhabi in January 2026. Hirth, based near Stuttgart in Germany, brings nearly a century of experience in two-stroke aviation engines. ePropelled, founded in 2018 and headquartered in Laconia, New Hampshire, says it holds 40 patents in smart propulsion and energy-management systems for uncrewed vehicles.
The deal highlights a broader push toward hybrid powertrains as UAV operators seek longer flight times, higher payloads and lower operating costs without sacrificing reliability. If the prototypes perform as planned, the partnership could strengthen the case for hybrid propulsion in defence, industrial drone and emerging air mobility programs.