Airbus E-Fan X
| Company type | Partnership |
|---|---|
| Industry | Aerospace |
| Founded | 2017-11-28 |
| Fate | Project discontinued |
| Headquarters | Europe |
| Products | Hybrid electric aircraft demonstrator |
The Airbus/Rolls-Royce/Siemens E-Fan X represented a hybrid electric aircraft demonstrator created through a partnership between Airbus, Rolls-Royce, and Siemens. Revealed on 28 November 2017, the initiative sought to propel sustainable aviation forward in line with the European Commission’s Flightpath 2050 Vision. A BAe 146 test platform was planned to have one of its four Lycoming ALF502 turbofan engines replaced by a Siemens electric motor, which Rolls-Royce adapted and powered via its AE2100 turboshaft, integrated by Airbus alongside a battery system. The project was discontinued in April 2020 as a consequence of the COVID-19 outbreak.
Development
Introduced at the Royal Aeronautical Society in London on 28 November 2017, the E-Fan X was originally set to achieve its maiden flight by 2020. It followed earlier electric flight prototypes including the Cri-cri, e-Genius, and the E-Fan 1.2, aiming to demonstrate a hybrid single-aisle aircraft that is safe, efficient, and economically viable. Since April 2016, Airbus and Siemens have been jointly developing electric propulsion elements via the E-Aircraft Systems House initiative, conducting ground-based testing. The program also targeted establishing certification frameworks for electric aviation.
Current technology does not yet satisfy the European Commission’s Flightpath 2050 objectives: cutting emissions by 75%, reducing carbon footprint by 90%, and lowering noise pollution by 65%. Electrification is critical to fulfilling these ambitions.
During the 2018 Farnborough Airshow, UK Business Secretary Greg Clark announced that part of the Department for Business, Energy and Industrial Strategy’s £255 million funding would support environmentally friendly aviation technologies. At the June 2019 Paris Air Show, Rolls-Royce declared its acquisition of Siemens’ electric propulsion division, which employs around 180 personnel across Germany and Hungary.
On 19 August 2019, a compact generator underwent successful testing in Trondheim, Norway. It was combined with an AE2100 turboprop engine sourced from a Saab 2000 to supply power to the battery pack and drive a Siemens SP260D electric motor (with a power-to-weight ratio of 10 kW/kg) replacing one Honeywell LF507 engine paired with a Rolls-Royce AE3007 fan through a 3,000 volts AC/DC power distribution system.
By November 2019, the modified airframe (registration G-WEFX) arrived at Cranfield University; the initial flight was targeted for 2021.
In April 2020, the project was terminated due to impacts from the COVID-19 pandemic.
Design
The flying test platform based on a BAe 146 replaces one of its quartet of turbofan engines with an electric motor, with intentions to substitute a second unit later. Airbus is responsible for system integration and control architecture; Rolls-Royce adapts the Siemens motor and fan to fit within the existing nacelle, supplies the turboshaft, generator, and power electronics; while Siemens provides the electric motor, inverter, DC/DC converter, and power distribution components.
High-power propulsion systems encounter challenges such as thermal management, thrust control, altitude-induced corona discharge effects, and electromagnetic compatibility issues.
An inboard Lycoming ALF502 engine is swapped out for an AE3007 nacelle (originating from Citation X/ERJ-145), where its core is replaced by an electric motor combined with an inverter. The AE2100 turboshaft from the C-130J is installed in the rear fuselage; both units utilize the V-22 Osprey Liberty T406 core.
Rolls-Royce introduces pioneering aviation technology through a generator supplying a 3,000 V DC distribution system via an AC/DC converter. Airbus contributes a , capacity battery housed within the cargo compartment—approximately thirty times larger than that used on the E-Fan. The Siemens motor’s power-to-weight ratio exceeds that of the Siemens SP260D installed on the Extra 330 demonstrator showcased at the 2017 Paris Air Show.
Neither the motor nor generator employs cryogenic cooling or superconducting materials; losses surpass 15%, prioritizing practicality over maximum efficiency. The Rolls-Royce generator uses oil cooling with supercritical carbon dioxide as an intermediary coolant fluid, leveraging expertise developed by Rolls-Royce LibertyWorks for their Aurora XV-24A LightningStrike VTOL platform powered by AE2100-core turboshafts driving multiple Honeywell generators.
The external shape of the nacelle remains unchanged to preserve BAe 146 airworthiness certification.
Siemens’ DC/AC converter powers an SP2000 liquid-cooled motor—delivering eight times more power than the Extra 330E’s Siemens SP260D (260 kW at 50 kg). These electric machines target increasing power-to-weight ratios tenfold. Measures including pressurization, insulation, and physical separation are implemented to counteract corona discharge caused by high-voltage arcing at altitude.
Hybrid-electric propulsion offers commercial advantages by utilizing current battery technology to supplement power during takeoff and climb phases while enabling purely electric descent operations. This strategy can achieve double-digit reductions in fuel consumption per flight sector along with decreased noise levels and lower local emissions.