European aerospace giant Airbus, British high performance power systems company Roll-Royce and German engineering and technology business Siemens have partnered to develop a hybrid-electric propulsion system for commercial aircraft. This is intended to be test flown in the near term, the three enterprises jointly announced at the Royal Aeronautical Society in London on Tuesday.

The flight demonstrator is designated the E-Fan X and will probably employ the airframe of the four-engine BAE 146 regional airliner. It is expected to fly in 2020.

Hybrid-electric propulsion is seen as one of the most promising ways to massively cut carbon dioxide and nitrous oxide emissions by the aviation sector. The European Commission’s Flightpath 2050 Vision for Aviation seeks to cut aviation carbon dioxide emissions by 60% and nitrous oxide emissions by 75%, targets which cannot be reached using current propulsion systems.

The plan is to replace one of the four turbofan (gas turbine) engines on the BAE 146 with a 2 MW electric motor. There will be a comprehensive programme of ground tests before the first flight is made. Later, once the maturity of the hybrid-electric power plant has been established, a second gas turbine engine will also be replaced by an electric motor.

The flight test programme will focus on questions such as electric thrust management, thermal effects, the impact of altitude and dynamic effects on electric systems, and electromagnetic compatibility. The aim is to drive the technology forward and mature it, assuring safety, reliability and performance, as well as to determine the requirements for the certification of future electric aircraft, in addition to training a new generation of designers and engineers. The desire is to accelerate the development, production and adoption of hybrid-electric airliners.

Airbus will handle the overall integration of the system into the test aircraft and provide the control architecture of the hybrid-electric propulsion system and batteries, as well as integrate it with the flight controls. Rolls-Royce will provide the turboshaft engine, the 2 MW generator and the power electronics. Airbus and Rolls-Royce will jointly adapt the fan to the existing engine nacelle and to the Siemens electric motor. Siemens will provide the 2 MW electric motors, their power electronic control unit, the inverter, the DC/DC converter and the power distribution system.