As part of the Green Aviation Technology (GATE) funding line, the project will realize a scalable hybrid-electric powertrain based on hydrogen as an energy carrier, leading to a technology that is ready for flight and certification. This will cover the range between drones in the 25kg class and ultralight aircraft with a take-off weight of 250kg. As a first step, a 25kg drone with gaseous H2 hybrid powertrain will be used. This demonstrator will be made to fly. A further development and scaling for a gas (or liquid) hydrogen powertrain for small aircraft in the 120 kg class is then the next step.