EADS E-Thrust Hybrid Jet A Future Vision of Distributed Electrical Aerospace Propulsion Airbus and EADS Innovation Works – the European Aeronautic Defence and Space Company's network of research centers, along with companies like Rolls-Royce and Siemens, are exploring solutions to the challenges facing the aerospace industry in the future. One possible solution is the E-Thrust - a hybrid/electric propulsion system that is an intermediate step toward fully electric airliners. For the E-Thrust concept, DEAP - Distributed Electrical Aerospace Propulsion - means that multiple electrically-powered ducted fans are distributed in clusters along the wing span, with one advanced gas power turbine unit providing the electrical power for the fans and for the recharging of the onboard energy storage device – essentially a serial hybrid propulsion system, similar to the Chevrolet Volt. The separation of turbine and fans allows for the optimization of both units. Current airliners have large high bypass fans directly connected to jet turbines but this type of propulsion unit has limited versatility. The large fan diameter and weight of conventional turbofans limit where they can be located on an airframe – usually under the wing. This location does not enable advanced aerodynamic efficiency techniques to be used, whereas having a number of electrically driven fans that are integrated into the airframe allows for a generally more aerodynamic design.
Overall, the concept of the E-Thrust is centered around energy management – using the optimal propulsion/energy configuration for each phase of flight. During take-off and climb full power is taken from the gas turbine and the onboard energy storage system (battery). However during the cruise phase the turbine alone will provide power to the fans while charging the battery. When it is time to descend the turbine can be shut off and the E-Thrust will be a glider. Power for the onboard electronics will come from the battery and the now inactive fans will be windmilling, producing energy to top-up the energy reserves in the battery. For landing the turbine is switched back on to provide power to the fans as a safety measure to cover the hypothetical emergency situation of the loss of power from the onboard energy storage system.
In addition to improved efficiency, distributed propulsion offers a greater flexibility for the overall aircraft design that could result in reduced structural weight and aerodynamic drag. By eliminating the constraints on where engines can be mounted an aircraft can have smaller tail surfaces, better weight distribution of the power and propulsion units, and the engines can be used for re-energizing the momentum losses in the boundary layers that grow over the wing and fuselage causing wake turbulence. An additional efficiency gain appears possible if this boundary layer is ingested and accelerated by the fans, because it can reduce the aircraft’s wake and hence its drag. For more information: http://www.eads.com/ ***
