Preliminary Sizing Method for Hybrid-Electric Distributed-Propulsion Aircraft

Abstract

The use of hybrid-electric propulsion (HEP) entails several potential benefits such as the distribution of power along the airframe, which enables synergistic configurations with improved aerodynamic and propulsive efficiency. This paper presents a comprehensive preliminary sizing method suitable for the conceptual design process of hybridelectric aircraft, taking into account the powertrain architecture and associated propulsion–airframe integration effects. To this end, the flight-performance equations are modified to account for aeropropulsive interaction. A series of component-oriented constraint diagrams are used to provide a visual representation of the design space. A HEPcompatible mission analysis and weight estimation are then carried out to compute the wing area, powerplant size, and takeoff weight. The resulting method is applicable to a wide range of electric and hybrid-electric aircraft configurations and can be used to estimate the optimal power-control profiles. For demonstration purposes, the method is applied to a regional HEP aircraft featuring leading-edge distributed propulsion (DP). Three powertrain architectures are compared, showing how the aeropropulsive effects are included in the model. Results indicate that DP significantly increases wing loading and improves the cruise lift-to-drag ratio by 6%, although the growth in aircraft weight leads to an energy consumption increase of 3% for the considered mission.