To test new propulsion systems, Deutsche Aircraft is converting a twin-engine D328 into the four-engine D328 Alpha. The test aircraft therefore has an external electric motor on each wing, which is powered by onboard fuel cells. The power of the electrical system is approximately 1.5 MW. However, the two conventional turboprop engines run on kerosene propulsion as before.
Deutsche Aircraft is showing a model of the test aircraft at the ILA. The concept for the four-engine test aircraft has been in development for three years. The goal is to be able to test fuel cell electric drive systems in combination and in flight to accelerate development and allow technologies to mature faster. The test aircraft will be tested in flight starting around 2025/2026. Numerous industrial and research partners are involved.
The advantage of converting the existing D328 is that an existing aircraft with a wide range of speeds and altitudes can be used as a base platform. By downsizing the kerosene tanks you can save the mass added by the additional engines. Test flights require no significantly longer operating time than a good two hours.
Like the Airbus with the A380, whose prototype is currently being converted into a test vehicle with a fifth hydrogen engine, Deutsche Aircraft also wants to measure water vapor emissions behind the fuel cell units in flight. The Oberpfaffenhofen DLR, which operates its own atmospheric research measurement aircraft, is helping with this.
Adjustments are also required for the electric motors and propellers. Since electric drives respond very quickly and with high torque, gears, adjustable pitch propellers and other mechanical assemblies must be designed for the new load peaks. The shape of the propeller blades has also changed.