Airbus, Rolls-Royce, and Siemens are teaming up to move electric aircraft from the small and experimental to the large and practical. At the Royal Aeronautical Society in London, the three giant engineering concerns announced that they are pooling their resources to build the E-Fan X hybrid-electric technology demonstrator that is based on a BAE Systems 146 flying testbed and is slated to fly in 2020.

Hybrid electric aircraft are very attractive to both engineers and environmentalists. The EU is dedicated to reducing dependence on fossil fuels and the European Commission's Flightpath 2050 Vision for Aviation mandates reducing emissions of carbon dioxide by 75 percent, nitrogen oxides by 90 percent, and noise by 65 percent. According to Airbus, these goals are outside the reach of conventional aircraft designs, but not that of ones based on electric propulsion.

For the engineers, the use of a hybrid electric system means a lighter, less complex aircraft that's more suited to intelligent computer control and is cheaper and easier to repair and maintain. The trick is to find the best way to scale up the technology and adapt it for commercial use.

For the E-Fan X, the BAE 146 will look very much as it does now, except that one of its four jet nacelles will be very different inside. Instead of a jet turbofan powerplant, it will contain a fan run by a two-megawatt electric motor built by Siemens. Siemens will also provide the power electronic control unit, as well as the inverter, DC/DC converter, and power distribution system.

This electric fan will run on electricity provided by a two-megawatt generator powered by a turbo-shaft engine, both of which will be provided by Rolls-Royce. Meanwhile, Airbus will be responsible for overall integration, control architecture of the hybrid-electric propulsion system, the batteries, and integration of the modifications with the cockpit flight controls. Airbus and Rolls Royce will collaborate on modifying the drive fan.

If the first tests are successful, the partners intend to replace a second turbofan engine with an electric propulsion unit. The goal of the demonstrator is to study thermal effects, electric thrust management concerns, altitude and dynamic effects on electric systems, and electromagnetic compatibility issues. This will not only test the performance, safety, and reliability of hybrid electric systems, but will also help establisg requirements for future certification of electrically-powered aircraft and train designers and engineers for the next generation of hybrid-electric commercial aircraft.

"The E-Fan X is an important next step in our goal of making electric flight a reality in the foreseeable future," says Paul Eremenko, Airbus' Chief Technology Officer. "The lessons we learned from a long history of electric flight demonstrators, starting with the Cri-Cri, including the e-Genius, E-Star, and culminating most recently with the E-Fan 1.2, as well as the fruits of the E-Aircraft Systems House collaboration with Siemens, will pave the way to a hybrid single-aisle commercial aircraft that is safe, efficient, and cost-effective. We see hybrid-electric propulsion as a compelling technology for the future of aviation."

Source: Airbus

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