Hybrid-Electric Aircraft with Over-the-Wing Distributed Propulsion

Abstract

Recent developments in the field of hybrid-electric propulsion (HEP) have opened the door to a wide range of novel aircraft configurations with improved energy efficiency. These electrically-driven powertrains enable “distributed propulsion” configurations, in which the aerodynamic interaction between the propulsive devices and the airframe is exploited to enhance the aero-propulsive efficiency of the aircraft. In this context, the present research focuses specifically on over-the-wing distributed propulsion (OTWDP) for regional propeller aircraft. Over-the-wing (OTW) propellers are particularly promising because they can significantly enhance the lift-to-drag ratio of the wing, as well as reduce flyover noise due to shielding by the wing.

The objective of this research is therefore to quantify the impact of OTWDP on the energy efficiency of hybrid-electric aircraft. For this, the research is divided into three main parts. First, a sizing method for hybrid-electric distributed-propulsion (HEDP) aircraft is developed, independently of where the propellers are positioned with respect to the airframe. Second, the aerodynamic interaction effects and performance characteristics of OTWDP systems are investigated, independently of the type of powertrain used to drive the propellers. And third, the sizing method and aerodynamic performance estimates of the previous two points are combined to assess the effect of hybrid-electric OTWDP on aircraft-level performance metrics. [...]