Sometimes a technological revolution can be captured in a few simple figures. In this case, those numbers would be five kilowatts per kilogram. What these figures express is the power/weight ratio of a new electric motor from the Electric Aircraft Unit at Siemens Corporate Technology. “With a weight of 50 kilograms, it delivers around 260 kilowatts of continuous output,” explains Dr. Frank Anton, head of the electric aircraft team. “That’s a world record for this power class. Powerful electric motors used in industry have a power/weight ratio of, at most, one kilowatt per kilogram, and in the automotive industry they reach two kilowatts per kilogram at best.”
For the applications that are of interest to the Siemens team, the power/weight ratio is a crucial metric. After all, their aim, long term, is to revolutionize the aerospace industry. Back in 2011, Anton’s researchers, working together with Airbus Group and Diamond Aircraft, notched up a world premiere with the maiden flight of the first ever aircraft powered by a electric hybrid drive. 2013, the same plane flew with an optimized drive system. The electric motor used in this setup had a power/weight ratio of around 5 kilowatts per kilogram, which at the time was unsurpassed, but it only delivered a relatively modest 60 kilowatts of continuous power — enough for a single-engine light aircraft at most.
Anton’s goal is therefore to develop an even more powerful electric motor of minimal weight, since this is precisely the precondition for being able either to replace completely the internal-combustion or jet engines currently used in aircraft and helicopters or to combine those engines with an electric drive within a hybrid system.