Siemens' Record-Breaking Electric Aircraft Motor

14 Jul 2025

Siemens' Record-Breaking Electric Aircraft Motor

In a significant leap for electric aviation, Siemens developed a groundbreaking electric motor that shattered world records for its power-to-weight ratio.¹ This innovation paved the way for electrically powered aircraft to achieve new heights of performance and opened the door to the future of hybrid-electric regional airliners.²

The German engineering giant's prototype motor, weighing a mere 50 kilograms (110 lbs), produced a continuous output of approximately 260 kilowatts (348 horsepower).¹ This represented a power-to-weight ratio of five kilowatts per kilogram, a figure five times greater than comparable drive systems at the time. Industrial electric motors of similar strength typically delivered less than one kW per kg, while those in electric vehicles offered around two kW per kg. This remarkable achievement was the result of extensive research, advanced simulation techniques, and sophisticated lightweight construction, where every component was optimized to its technical limits.¹

The motor's design was also notable for its efficiency, operating at a rotational speed of just 2,500 revolutions per minute, which allowed it to drive propellers directly without the need for a heavy transmission.¹ This innovation made it possible for the first time to envision electric drives for larger aircraft with takeoff weights of up to two tons.

Record-Breaking Performance

To showcase the motor's capabilities, Siemens collaborated with Extra Aircraft to install it in an Extra 330LE aerobatic plane. This partnership led to a series of record-breaking flights. In March 2017, the electric aircraft set a new world speed record for an electric plane in its weight class, reaching a top speed of approximately 337.50 kilometers per hour (209.7 mph).³ The Extra 330LE also set a new record for the fastest climb to 3,000 meters, achieving the altitude in just four minutes and 22 seconds.³

In another impressive demonstration of its power, the Extra 330LE became the world's first electric aircraft to tow a glider into the sky.³ The nearly silent aerotow was a powerful visual testament to the motor's performance capabilities.

A Stepping Stone to Hybrid-Electric Flight

Siemens' ambitions extended beyond small aerobatic planes. The record-setting motor was seen as a crucial stepping stone toward developing hybrid-electric propulsion systems for regional airliners. The company entered into a partnership with Airbus in 2016 to jointly develop these technologies, with the goal of eventually powering aircraft carrying 50 to 100 passengers.² The development of this motor was seen as a key enabler for this vision.

The company also developed other electric propulsion systems, including the SP200D motor, which was designed for applications like the CityAirbus air taxi.

Transition to Rolls-Royce

In 2019, in a strategic move to ensure the continued development of this technology within an aerospace-focused company, Siemens sold its eAircraft business to Rolls-Royce.⁴ The acquisition included the team of approximately 180 employees who had pioneered these electric and hybrid-electric propulsion systems. Rolls-Royce, which had already collaborated with Siemens on projects like the E-Fan X demonstrator, saw the acquisition as a way to accelerate its own electrification strategy and play a major role in what it termed the "third era" of aviation.⁴

While Siemens stepped back from manufacturing aircraft motors, it continues to support the transition to electric aviation through its digital solutions portfolio. The legacy of its record-breaking electric motor continues under Rolls-Royce, which is building upon this technology to develop the next generation of cleaner and quieter air transport.