Investigation of universally electric propulsion systems for transport aircraft

Hybrid electric as well as universally electric aircraft are promising approaches fulfilling the targeted emission improvements stipulated by the NASA N+3 goals and the European Strategic Research Innovation Agenda. For high power applications required in transport category aircraft high-temperature superconducting (HTS) motors seem to be a key technology for which accurate mass and efficiency models are required. This paper introduces a comprehensive mass and efficiency estimation approach for full HTS motors including also the estimation of the required inverter and cooling system devices. Finally, the applicability of the HTS motor sizing and performance model to a ducted fan propulsion system featuring 22.2MW take-off power is demonstrated. An optimal motor design for this power range was identified at 11000 rpm with a specific power of 15.8 kW/kg at 99.2% efficiency and controller design with 23 kW/kg and over 99.5% efficiency. The demonstrated approach serves as baseline for further investigations of optimized electric motor design driving a ducted fan for different thrust and power ranges. Furthermore, analysis has shown that the electric motor geometrical model for rotor and stator has to be refined for different pole pairs.