25 April 2023
Diamond Aircraft’s engine subsidiary, Austro Engine, is taking part in a project to develop a bivalent hydrogen engine – that’s an engine which can burn two types of fuel.
The two types of fuel Diamond is interested in are hydrogen and kerosene – also known as Jet-A, paraffin or diesel fuel.
Felix Zahradnik, Chief Technology Officer at Austro Engine, explained:
“Hydrogen is regarded as the energy storage medium of the future. Undoubtedly, many challenges in the production and especially handling as well as infrastructure are not yet clarified.
“In addition to highest efficiency with lowest emissions, factors such as operating costs, safety and worldwide availability have been decisive in determining the strategy of future propulsion concepts.
“We see our long-term future not only with sustainable aviation fuels, but also believe that hydrogen direct combustion might be a good propulsion system for General Aviation.”
Three of Diamond’s Jet-A burning aircraft, the DA40, DA42 and DA62
There are two different methods for the direct combustion of hydrogen in a piston engine, said a statement from Austro. The initial ignition of the air/hydrogen mixture can be done either by a spark plug or an ignition jet.
Initiating combustion by spark plug is ideal for a constant 100% hydrogen operation. However, if the ignition jet method is chosen, the hydrogen can be mixed with kerosene in part or 100% replaced. That’s useful with the current lack of availability of pure hydrogen in some regions of the world.
The project is expected to take until the end of 2024 and will also consider engine durability and EASA certification.
Diamond is working with Austrian Federal Ministry for Climate Action, the Federal Ministry for Digital and Economic Affairs, Vienna University of Technology and Bosch General Aviation Technology.
Collaboration is essential : Representatives of the Vienna University of Technology, Austro Engine and Bosch General Aviation Technology in front of the engine test bench of the university
“Partnerships across industry borders are crucial to achieve sustainability in aviation,” said commented Christian Grim, General Manager at Bosch General Aviation Technology.
“We are convinced hydrogen will play a major role in regard to sustainable aviation solutions if used with fuel cells or in hydrogen engines. To face decarbonisation as a major challenge for General Aviation, it will become increasingly important to search for alternative propulsion systems.”
Diamond Aircraft and Austro Engine, together with Lufthansa Aviation Training, are also working on Sustainable Aviation Fuel options for the Austro Engine powered aircraft line.
“We believe the coexistence of several technologies as strategically sensible for General Aviation,” added Felix Zahradnik.
“Diamond Aircraft is currently developing the eDA40, an all-electric training aircraft, which will be certified in the near future.
“In addition to further innovations in the field of material science and combustion process development, the key to sustainability lies in the type of fuel used. By using regeneratively produced fuels, not only can the existing infrastructure be utilized, but also the CO2 balance significantly and directly influenced.”
Diamond Aircraft and Austro Engine anticipate increasing availability of ASTM D7566 SAF blends as a ‘drop-in’ fuel for General Aviation in the coming years and plans to release the entire fleet for this fuel mix by the end of 2025. Significant market penetration of SAFs is expected by 2030 and availability of 100% pure SAFs without blending for 2050.
