Aerospace THWS Develops a Modular Fuel Cell Propulsion System for Hydrogen Aircraft

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Technische Hochschule Würzburg-Schweinfurt (THWS)

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The Technical University of Würzburg-Schweinfurt (located in Germany) is working together with the aerospace-specialised engineering firm Kasaero on a modular electric fuel cell propulsion system. This is intended to enable retrofitting of existing ultralight aircraft with a climate-neutral drive.

Climate-neutral flying without a guilty conscience—a team from the Faculty of Mechanical Engineering at the Würzburg-Schweinfurt University of Applied Sciences (THWS) has been working on this for several years. A new grant from the federal aviation research program contributes to continuing research on the self-developed touring motor glider “Taifun 17 H₂.” Around 890,000 euros (approx. 1.014.070 USD) can be allocated to this project at the university. Together with the aviation-specialised engineering firm Kasaero, THWS is developing a modular electric fuel cell propulsion system, which can also retrofit existing ultralight aircraft with a climate-neutral drive.

The "Taifun" is currently airworthy: The application for a flight permit and the necessary certifications are currently being reviewed by the Federal Aviation Authority. So far, the team has already conducted taxiing tests at the Haßfurt-Haßberge (located in Germany) airfield. This means accelerating up to take-off speed—"but before the wheels lost contact with the ground, braking was required again," explains Dean Prof. Dr. Johannes Paulus. Once the permit is granted, only a few more tests will be needed, and the aircraft could take off for the first time later this year.

Smaller, lighter, and more range

Thanks to the new funding program, the work for the team continues seamlessly. Everything is to become smaller, lighter, and more adaptable. A modular drive system could be installed in various similarly constructed light aircraft. Another goal is achieving high energy density to increase the range of the touring motor glider—which in turn is intended to boost acceptance of the new propulsion system. "The light aircraft has a dual drive—both directly electric with a battery and hydrogen-powered via a fuel cell," explains Prof. Dr. Paulus. "The fuel cell serves either as a range extender or as a booster." This allows for an increase in range and maximum propulsion performance.

To fit into the space of standard aircraft engines and undercut their weight, the electric fuel cell propulsion system now needs to be designed smaller and lighter. This is achieved primarily through a higher degree of integration in the power electronics, leading to size and weight reductions, as well as through the optimisation of cooling systems. Optimising the interaction between the electric and fuel cell propulsion systems provides additional opportunities to improve flight characteristics and increase range. All these efficiency improvements, in turn, make it possible to reduce the size of the buffer battery, which positively impacts the overall weight.

How does the project work proceed?

The work for the core team of the "Taifun" will not be ending anytime soon: Research associate Jan Hußlein is responsible for the test bench used to test the aircraft's fuel cell on the ground. Research associate Toni Schott mainly works on the powertrain and the integration of the propulsion system into the aircraft. Master's student Sebastian Stenger is currently developing a mobile hydrogen refueling station. With the electricity from the in-house photovoltaic system, the required hydrogen can be generated and stored. Laboratory engineer Tom Wollin handles the implementation of the designs and the assembly. The retired THWS professor and flight instructor Martin Hansen co-designed the aircraft and will also carry out the maiden flight.

Further third-party funded projects with industry partners are in the pipeline. Work is already underway to lighten the built-in battery and develop a new cooling concept for electrical components. Other side projects include the development of a lighter, more efficient propeller adapted to the propulsion of an electric motor, and the tank is still too heavy and is being optimised. (se)

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