Rolls-Royce will acquire the electric and hybrid electric aerospace propulsion activities of Siemens under an agreement announced on June 18.
Based in Germany and Hungary, Siemens’ eAircraft business employs around 180 specialist electrical designers and engineers. The eAircraft team has already worked with Rolls-Royce on the E-Fan X demonstrator project with Airbus, which is intended to demonstrate hybrid electric propulsion at the scale required to power regional aircraft.
In announcing the acquisition, Rolls-Royce Electrical director Rob Watson stated, “We have already made significant strides in realizing our strategy of ‘championing electrification’ and this move will accelerate our ambitions in aerospace by adding vital skills and technology to our portfolio. It brings us increased scale and additional expertise as we develop a product range of hybrid power and propulsion systems.”
Rolls-Royce expects to complete the acquisition later this year, following a period of employee consultation.
The announcement comes a little less than a year after Rolls-Royce revealed a hybrid electric VTOL concept at the 2018 Farnborough International Airshow. Incorporating a modified version of the company’s M250 gas turbine engine, the concept features six electric propulsors and could carry four or five passengers at speeds of up to 250 miles per hour (400 kilometers per hour) for 500 miles (800 km), the company said.
In March of this year, Rolls-Royce reported successful ground tests of the hybrid version of the M250. Tests were carried out across three system configurations: series hybrid, in which the engine operates as a turbo-generator that charges an on-board battery system, and does not contribute to aircraft thrust directly; parallel hybrid, in which aircraft thrust is provided by a combination of the engine and electrical system; and turbo-electric mode, in which the battery system is redundant.
Rolls-Royce is now working toward integrating the system on an aircraft for experimental flights in 2021. With an expected power range from 500 kilowatts to 1 megawatt, the M250 hybrid power pack complements the AW 2100 2.5-megawatt system being developed for the E-Fan X demonstrator.
According to Rolls-Royce chief technology officer Paul Stein, “We believe that pure electric, or all-electric, propulsion will power smaller aircraft in the foreseeable future, while larger aircraft will rely upon hybrid electric solutions that combine electrification with evolutions of the gas turbine.”
Stein pointed out that Rolls-Royce is simultaneously working on other ways to make aviation more sustainable, including by increasing the fuel efficiency of its gas turbines and encouraging the development of environmentally friendly aviation fuels. As part of its agreement with Siemens, both companies will look for opportunities to work together “to support national and international goals of CO2 emission reductions for the benefit of society.”