The German Aerospace Center research supports early deployment of hybrid planes
After the first electrified small aircraft, the next big step in electric flying will be in the commuter class of 19-seater aircraft. The German Aerospace Center (DLR), together with the Bauhaus Luftfahrt, has now analyzed in the CoCoRe (Cooperation for Commuter Research) project what possibilities and potential there are in the area of hybrid-electric 19-seaters planes. This shows that electric drives for the frequently flown short distances of up to 350 kilometers can be used in this class in a CO2-saving manner. In the future, this area will also include flight taxi connections from airports in less well connected medium-sized cities, and of course all kinds of private flights.
Batteries on improved chassis
Today, around 3,000 Commuter-class aircraft are in use worldwide, with only a little more than a dozen 19-seaters being delivered in the civil sector in recent years. “In our study, we examined an example of a configuration that, with a few modifications, closely resembles the 19-seater Do-228 currently flying, and in particular Jetstream 31,” explains project manager Wolfgang Grimme from the DLR Institute of Airport Management and Air Transport. In their design, the researchers especially modified the landing gear nacelles, which were expanded above the wings to accommodate quickly replaceable battery blocks. “This means that we have the weight of the comparatively heavy batteries exactly where it is most conveniently located on the plane during takeoff and landing – directly above the landing gear. This means that empty batteries can be changed quickly and easily at an airport. ”
Limited by the weight of the batteries of two tons with a total take-off mass of 8.6 tons, the researchers assume in their concept a fully electric range of 200 kilometers. Depending on requirements, this can be extended to a range of over 1000 kilometers with two range extenders in the form of a gas turbine that can be coupled and decoupled with the respective propeller. “According to our research, 19-seaters fly 56 percent of the distances under 200 kilometers and 83 percent under 350 kilometers worldwide, so that this combination of fully electric flight, supplemented by a range extender, already avoids a large part of the CO2 emissions in the area of commuter aircraft would, ”explains Dr. Annika Paul from Bauhaus Luftfahrt. The range extender is also crucial for the safety of such an electrified aircraft, because in an emergency, if a distant alternative airport had to be reached in bad weather conditions, this enables the necessary additional range. The range extender therefore enables a longer fully electric flight because the battery does not have to be used for reserves, ”adds Georgi Atanasov from the DLR Institute of System Architecture in aviation.
With further improvements to the storage capacity of batteries in the future, a purely electrical range over 200 kilometers with the same battery weight is also conceivable. In addition, the particularly cost-intensive development of new aircraft configurations, for example with numerous distributed electric propellers on the wings in combination with a modern, lighter aircraft construction, would also extend the range of fully electric flight. For these reasons, fully electric flights of over 400 kilometers are conceivable in the future.
Connect medium-sized cities directly
In addition to analyzing the technical possibilities, the researchers in the CoCoRe project also carried out a market analysis of possible fields of application for electrical commuter aircraft. In addition to the widespread classic application as small feeder aircraft for remote regions with little passenger traffic, such as in Canada, the researchers also identified a need for medium-sized cities in Europe that have inadequate direct connections to large metropolitan areas, among others. An economically viable regional air taxi service from smaller airports would be conceivable for these cities. For such scenarios, the low number of approximately 1000 charging cycles of the batteries and the comparatively low CO2 prices have so far been economically challenging compared to conventionally operated commuter aircraft. If these factors increase in the future, the economic prospects of electric aircraft will also increase.
