New research aircraft “Do 228” D-CEFD handed over to DLR A brief portrait of the DLR institutes

DLR at a glance

The German Aerospace Center (DLR) is the research center of the Federal Republic of Germany for aerospace.

At the COP26 UN climate conference in Glasgow, numerous countries recently reaffirmed their goal of making aviation climate-neutral by the middle of the century. An important step in this direction will be the development of electric drives for feeder and regional aircraft. In the future, the DLR research aircraft "Do 228" D-CEFD will be used to test electric propulsion technologies. In mid-November 2021, it was handed over to the German Aerospace Center (DLR) by the aviation company General Atomics Aerotec Systems (GA-ATS). At the DLR site in Oberpfaffenhofen, preparatory work is now beginning to expand the flying technology platform. A first extensive project has started together with the industrial partner MTU Aero Engines. The research partners want to replace one of the two conventional powertrains with an electric 600kW powertrain powered by a fuel cell. This is to be developed by the middle of the decade and tested on the aircraft in flight.

“A fundamental test of the suitability and efficiency of different propulsion options in combination with sustainable energy sources for all aircraft classes is the prerequisite for achieving zero-emission aviation. All of the technologies underlying this goal require a boost in research and development, to which DLR is making its contribution," says Dr. Markus Fischer, DLR Head of Aviation. “The use of electric drives combined with fuel cells is a promising concept for feeder and regional aircraft. With the new test platform 'Do 228' D-CEFD, we want to decisively advance this technological concept.” The use of electric drives and fuel cells in aircraft places particularly high demands on the performance, reliability and safety of the overall system. The new research aircraft now makes it possible to test a wide variety of components and entire propulsion systems in detail under real operating conditions.

Neues Forschungsflugzeug „Do 228“ D-CEFD an das DLR übergeben DLR-Institute im Kurzporträt

On behalf of MTU, Barnaby Law, Chief Engineer Flying Fuel Cell, said: “A liquid hydrogen and fuel cell system can power future aircraft and produces no emissions other than water. And that is exactly our goal: zero emissions.” For an engine manufacturer like MTU, the development of an airworthy fuel cell is a great opportunity because: “The experience and data gained, including in the areas of control and qualification under aviation law, are important for our further product development is crucial.”

Very reliable aircraft with striking livery

The "Do 228" is known and appreciated as a very reliable aircraft in its category. After the machine handed over to DLR had been in service as a passenger aircraft for many years, it was completely renovated for its new use and given a particularly striking paint finish by General Atomics Aerotec Systems in accordance with DLR specifications in order to enable quick and accurate recognition. "Our 'Do 228' aircraft is already in use around the world to protect countries from coastal pollution using precise reconnaissance and surveillance technology," explains Harald Robl, CEO of General Atomics Aerotec Systems, and adds: "Based on the project by DLR and MTU we are using our opportunity to make our own contribution to environmental protection with new propulsion technologies in the future and thus counteract the climate crisis support the progress of the project.

Electric drive train with effective cooling

The research aircraft will initially be used in the joint technology project by DLR and MTU to test individual system components and will later be extensively modified to test the entire electric drive system developed by MTU. The aim is to develop an aviation-grade, electric drive train (power line) with liquid hydrogen as the energy carrier and all the necessary additional systems such as cooling (cooling line). During the extensive conversion of the aircraft, the left-hand turboprop engine was removed and replaced with an electric motor. Fuel cells housed in the fuselage supply the power needed for the drive train. There is also a tank there that provides the necessary hydrogen for the operation of the fuel cell. With the exception of water, fuel cells do not cause any emissions and are characterized by a high degree of efficiency. However, these generate a lot of heat, which is why the development of an efficient cooling system is also crucial. The partners are aiming for the first flight of the flying laboratory “Do 228” D-CEFD in the middle of the decade. Extensive ground tests and preliminary tests are necessary beforehand.

Cooperation for the first electric flight

The planned research project on the "Do 228" D-CEFD is managed by DLR, which is providing the research aircraft and carrying out the flight experiments. DLR is also responsible for integrating the powertrain into the new research aircraft. DLR contributes know-how in numerous research areas, such as aerodynamics and aeroelasticity. As a partner to industry, DLR is contributing to the joint technology project with its overall system expertise. MTU's task is to develop the entire hydrogen-powered fuel cell powertrain, including the liquid hydrogen fuel system. All work and integration is carried out jointly and in close coordination. Up to 80 experts will be involved.

The procurement of the "Do 228" D-CEFD is partially subsidized with funds from the Bavarian State Ministry for Economic Affairs, Regional Development and Energy (StMWi). The planned research work is financed by funding projects in the aviation research program of the Federal Ministry for Economic Affairs and Energy (BMWi) and by funding from the StMWi. Further funding applications have been applied for and are being processed.