Siemens Aviation Motor Achieves New Electric Motor Power/Weight Benchmark

April 28, 2015 - Last month Siemens AG, Berlin, Germany, announced a new, lightweight electric motor expressly built for aviation propulsion weighing in at a mere 50 kilograms and delivering continuous output of about 260 kilowatts. That approximately 5-to-1 power-to-weight ratio is five times higher than comparable drive systems and more than any other motor before.

That would provide the propulsion necessary to lift larger aircraft (MTOW up to two tons) for the first time, the company stated. Comparable motors used in industrial applications deliver less than one kW per kg and drive systems used in electric vehicles are about two kW per kg, so this indeed appears to be a breakthrough. In addition, the new motor’s 2500 rpm means it can drive propellers directly without the use of a transmission.

“This innovation will make it possible to build series hybrid-electric aircraft with four or more seats,” said Frank Anton, head of eAircraft at Siemens Corporate Technology, the company’s central research unit. Plans are set to begin flight-testing the motor before the end of the year.

In the next step, the Siemens researchers will boost output further. “We’re convinced that the use of hybrid-electric drives in regional airliners with 50 to 100 passengers is a real medium-term possibility,” Anton said.

The development of this motor was supported by the German Aviation Research Program LuFo in a collaboration of Grob Aircraft and Siemens.

In 2013, Siemens, Airbus, and Diamond Aircraft successfully flight-tested a series hybrid-electric drive in a DA36 E-Star 2 motor glider for the first time. The test aircraft had a power output of 60 kW.