ZeroAvia and Marshall Aerospace have signed a collaboration agreement to explore hydrogen-electric propulsion and power systems for defence aircraft.
The work will assess applications across uncrewed aerial systems, intelligence, surveillance, and reconnaissance aircraft, logistics, training, and special-mission platforms. The companies will examine propulsion integration, certification, hydrogen fuel systems, thermal management, and aircraft-level power architecture.
ZeroAvia brings hydrogen-electric propulsion technology, while Marshall Aerospace contributes experience in military aircraft modification, integration, complex fuel systems, and certification. The combination gives the agreement both a propulsion development route and an aircraft engineering route, which is essential if the technology is to move beyond isolated demonstration flights.
Hydrogen-electric propulsion offers a possible route to lower-emission flight while addressing some of the endurance limitations associated with purely battery-electric aircraft. Fuel cells convert hydrogen into electricity to drive electric motors, but the aircraft challenge extends well beyond the stack. Storage, distribution, venting, safety systems, redundancy, thermal control, certification evidence, and maintenance procedures all have to be designed around the whole platform.
Defence aircraft present a different set of constraints from early civil demonstrators. Military and special-mission platforms may operate from dispersed locations, carry mission equipment, require rapid turnaround, and demand availability under conditions that are less controlled than commercial trial environments. In uncrewed and ISR applications, endurance, acoustic profile, electrical power availability, and maintenance burden can influence mission performance as much as headline propulsion efficiency.
The agreement comes as the UK is paying closer attention to autonomy, uncrewed systems, and domestic defence production depth. The same issues are evident in current scrutiny of drone funding and UK manufacturing capacity, where airframes, propulsion, sensors, control systems, and production scale all shape whether policy ambition becomes deployable capability.
Hydrogen infrastructure will be as important as propulsion hardware. A defence platform using hydrogen-electric power needs an operational model for fuel supply, storage, refuelling, safety procedures, maintenance, and deployment away from fixed facilities. Aircraft performance on its own is not enough if the support system cannot travel with the mission or be established at reasonable cost.
Marshall Aerospace’s involvement is therefore significant. Retrofitting or modifying aircraft for hydrogen-electric operation requires structural assessment, systems integration, revised weight and balance analysis, updated maintenance documentation, safety cases, and certification evidence. Even where new aircraft are designed around hydrogen from the outset, those same engineering disciplines remain central.
The collaboration also reflects a wider sorting of technologies across future aviation. Sustainable aviation fuel is likely to dominate near-term decarbonisation for larger commercial aircraft, while battery-electric propulsion is better suited to smaller aircraft and shorter missions. Hydrogen-electric systems occupy a space where longer endurance may be possible, provided infrastructure and certification can be brought into line with the aircraft design.
Defence applications may provide a useful early pathway because mission value is often judged across endurance, payload, resilience, and supportability rather than fuel cost alone. A quieter or more electrically capable aircraft may offer operational advantages even before a wider commercial market is ready.
The next phase will depend on whether the companies can identify aircraft classes where hydrogen-electric benefits justify the engineering and infrastructure burden. If that balance can be achieved, hydrogen-electric propulsion could become part of a broader defence aviation mix, particularly in missions where endurance, onboard electrical power, reduced emissions, and acoustic performance carry operational value.
