Sizing Considerations of an Electric Ducted Fan for Hybrid Energy Aircraft

Hybrid and universally-electric aircraft are promising configurations to potentially handle the ambitious emission reduction targets set for example by the Advisory Council of Aviation Research in Europe with the Strategic Research and Innovation Agenda. Those concepts are confronted usually with high mass impacts caused by the electric system architecture design. In this paper a closer look is taken on the sizing of the electric power train components and sizing options of the electric motor powering a ducted fan for a discrete parallel hybrid-electric aircraft concept. In such a configuration, the electric system is used as an assistance system to enable a downsizing of the gas turbine and to increase the overall power train efficiency. The studies include considerations concerning geared versus direct drive systems and its implications on overall aircraft level. Furthermore, using the electric system as assistance system different motorization options are discussed to identify the sizing point offering the best utilization of the electric system during the entire mission. As baseline an A320 class aircraft is used for an entry into service year of 2035+ and a 1300nm design range. Finally, for this aircraft concept trade-factors will be provided to cover the impact of a changed electric system mass and efficiency on the overall aircraft mass.