So far, at least, sustainable aviation fuel (SAF) is limited to the jet fuel set, which has kept most piston-powered aircraft out of the conversation. A notable exception is the fleet of Austro-Engine-powered Diamond Aircraft models, which burn jet fuel rather than aviation gasoline (avgas). Diamond has just announced a dedicated SAF development program for its aircraft powered by jet-fuel-burning (aka “diesel”) engines from sister company Austro Engine.
To this end, the company has developed a dedicated engine-test bench. It has the unique capability to measure “cylinder pressures in real time with crank angle resolution, the emission components of unburned hydrocarbons (HC), nitrogen oxides (NOx), GHG [greenhouse gas] carbon dioxide and carbon monoxide (CO2, CO).” Diamond clarified, “To validate and approve sustainable aviation fuels that will be available at airports in the future, turbocharged compression-ignition piston engines require not only chemical and calorific analyses but also investigations on component test stands, engine test stands and flight tests.” The company expects to receive its first batch of certified SAF to start the testing next month.
With electric-powered aircraft also in the planning stages for Diamond, Robert Kremnitzer, Diamond’s head of design organization, said, “Next to the all-electric eDA40, SAF will become a near-term available solution for sustainable aviation. In the piston engine segment, we have the big advantage that most of our existing fleet is already using jet fuel. With this program, we ensure that sustainable alternatives to these fuel types may be used as soon as they become available at airports with General Aviation fuel stations—with no, or only minor, adaptions to the aircraft.”
Diamond Aircraft said it expects to see D7566 SAF blends become increasingly available at GA airports as a seamless “drop-in” fuel. The company targets approval for the fuel mix across its entire fleet by year-end of 2025. Diamond said, “Significant market penetration of SAFs is expected by 2030 and availability of 100 percent pure SAFs without blending for 2050.”
