Diamond Aircraft, Partners Launch H2EDT Hybrid Hydrogen VTOL Testbed
Plus, a look at its Chinese partner on the program.
Diamond Aircraft and a group of Austrian research institutions are working together on a major new project to advance hydrogen as a fuel for hybrid-electric propulsion in general aviation.
The initiative, known as H2EDT (Hydrogen-based Twin-engine Electrification and Digitalization Testbed), is supported by the Austrian Research Promotion Agency (FFG) and runs through the end of 2025.
The project is based at Diamond Aircraft’s facility in Wiener Neustadt and brings together key partners: FH JOANNEUM (Institute of Aviation and Electronic Engineering), TU Graz (Institute of Thermodynamics and Sustainable Propulsion Systems), hydrogen research center HyCentA, and sustainable aviation consultancy Institute of Engineering, Sciences, Technologies and Arts (IESTA).
Together, they are designing and building a scaled testbed aircraft to explore the technical challenges of using hydrogen in aviation powertrains.
According to Diamond Aircraft, the H2EDT platform will combine multiple energy sources—batteries and a hydrogen fuel cell—into a parallel hybrid system capable of powering up to ten electric motors.
Originally envisioned as a twin-engine general aviation testbed, the design was later adapted to support VTOL operations, reflecting growing industry interest in advanced air mobility.
To address hydrogen’s unique storage and integration hurdles, and the limited power-to-weight ratio of current fuel cells, the H2EDT system leverages a hybrid architecture. Battery packs and the hydrogen fuel cell can each directly power any motor in the system, offering redundancy and improved efficiency, Diamond Aircraft stated.
A key innovation in the testbed is its digital power management system, developed by FH JOANNEUM. This includes a custom-designed power distribution board and a sensor network that dynamically manages power from the two sources.
In addition, TU Graz is contributing a digital twin of the platform—a high-fidelity simulation model paired with CAD geometry. The model will be calibrated with real-world test data and used to simulate failure scenarios and various operating environments, including high-altitude and high-temperature conditions.
As part of the project, Diamond said the research team will evaluate energy management strategies, thermal performance, and the reliability and safety of hydrogen storage and distribution systems.
The findings will inform future certification and design guidelines, particularly for larger-scale applications on Diamond Aircraft platforms such as the DA40 or DA42.
Final results from the H2EDT test campaign are expected to be presented in the first half of 2026.
The H2EDT program is funded under Austria’s Take Off research and innovation program, administered by the Ministry for Innovation, Mobility, and Infrastructure and managed by the Austrian Research Promotion Agency (FFG).
The platform builds on earlier hydrogen initiatives by Diamond Aircraft, including the integration of a fuel cell system in a Diamond HK36 in cooperation with Boeing Phantom Works, and ongoing research into dual-fuel engines with Austro Engine (part of the Diamond Aircraft Group) and TU Wien.
The China Connection
Diamond Aircraft did not explicitly name a Chinese partner in its April 29 press release. However, additional research points to a collaboration on the H2EDT program with a high-tech Chinese enterprise specializing in fuel cell R&D and applications.