H2AIR-4+1: Hydrogen-hybrid VTOL UAV for long-range infrastructure inspection

Hydrogenera (Green Innovation AD, Sofia) develops and manufactures hydrogen production and storage systems, from alkaline electrolysers to metal-hydride storage. The company has completed industrial hydrogen installations and a hydrogen engine programme. It also designed, built and flew its own battery-electric VTOL UAV.

Battery VTOL drones are the standard inspection tool, but the best small models fly only 90 to 120 minutes, so long corridors need many bases and crews. Existing hydrogen UAVs fly longer, but they sit in the 25 kg class and are closed products.

H2AIR-4+1 is a lift-and-cruise aircraft with four lift rotors and one pusher propeller. An 800 W PEM fuel cell carries the cruise load, and a buffer battery covers the power peaks and holds a landing reserve. An energy management system divides the load between them. The demonstrator targets a take-off mass below 15 kg, a 1.2 kg payload and 120 minutes of endurance. It will be refuelled in minutes. Longer missions need only a larger cylinder, and a variant of about four to five hours stays well below 25 kg. The airframe is 3D-printed in-house around a carbon-fibre frame.

In 2027 the powertrain will be validated on a test bench, the aircraft will be tested on the ground, and the flight campaign will end with three consecutive two-hour missions. The project will deliver the TRL 7 aircraft, a reusable integration package and a cost model for an inspection service billed per kilometre.

We seek fuel-cell developers interested in airborne test data or a flying test platform. We also seek UAV and vehicle manufacturers willing to trial the integration package, and infrastructure operators interested in pilot inspections from 2028. In return, we offer flight and bench data, expertise in hydrogen production, storage and commissioning, and joint demonstration within the IH-MIE network.