As society's awareness of the environment has increased, and inspired by political will like the European Green Deal, there is growing interest in climate-friendly propulsion solutions for aviation. To illustrate the tremendous potential for hydrogen as a propulsion option in flight, Bosch Aviation Technology, a subsidiary of Robert Bosch AG located in Vienna, has converted a conventional aircraft engine to run on hydrogen as part of an innovation project.

The basic unit is a four-cylinder gasoline engine, supplied by the Austrian manufacturer BRP-Rotax, which has been developing and producing powertrains for the leisure and powersports industry for decades. Christian Grim, Managing Director of Bosch General Aviation Technology GmbH, has worked in transferring products, services, and technologies from the automotive to the aviation sector for over 15 years. Grim explains:

“Instead of developing an entirely new engine, we opted to modify an established engine design as we anticipate strong demand for this pioneering approach in future customer projects due to the time, cost, and approval advantages,”

As part of a feasibility study, Bosch experts successfully carried out the required alterations for hydrogen operation on the 1.4-liter turbo engine in a period of about four months. With their development work on the engine test bench, they could already improve the hydrogen engine performance considerably. All components for the hydrogen system are based on volume-production developments at Bosch.

In this stage of the project, the engine already offers 115 kilowatts of maximum power and thus comes within approximately 2% of the base gasoline sector. Through a specific future development of a prototype, power will be able to improve further.