Possible hybrid propulsion configuration for transport jet aircraft

Abstract

This research is aimed at studying the possible advantages of installing, for a hybrid propulsion aircraft, electric motors and related propellers into the dedicated supplementary nacelles. This innovative solution is different from the configuration, already studied for a regional turboprop (Chiesa et al.2013), in which the electric motors are in the same nacelles of the internal combustion engines. As it has been expected, it offers the advantages of avoiding mechanical links between the two units and, more importantly, can also be applied to jet aircraft. In fact, the main contribution of electric motors is expected during ground operations, take-off and descent phases (i.e. at low speed), in which it can be useful to integrate the propellers or even substitute the jet engines with them. At high speed, the propellers, of course, are configured in order to reduce drag. When considering the design of a new airliner concept, a preliminary design study is necessary to optimize the location of the supplementary nacelles. The nacelles, which only hold the electrical motor, can also be considered retractable, as is usual for a RAT (Ram Air Turbine). Please note that in the hybrid propulsion context, the RAT function can be clearly allocated to the electric motor, with the advantages of optimizing drag at high speed, taking into account installation problems.

Keyword : hybrid propulsion, electric taxi, nacelles location, RAT, propeller design, retractable nacelle, energy storage system