A preliminary sizing method for hybrid-electric aircraft including aero-propulsive interaction effects

The potential benefits of hybrid-electric propulsion (HEP) have led to an increased interest in this topic over the past decade. One promising advantage of HEP is the distribution of power along the airframe, which enables synergistic configurations with improved aerodynamic and propulsive efficiency. The purpose of this paper is to present a generic sizing method suitable for the first stages of the design process of hybrid-electric aircraft, taking into account the powertrain architecture and associated propulsion–airframe integration effects. To this end, the performance equations are modified to account for aero-propulsive interaction. A power-loading constraint-diagram is used for each component in the powertrain to provide a visual representation of the design space. The results of the power-loading diagrams are used in a HEP-compatible mission analysis and weight estimation to compute the wing area, powerplant size, and take-off 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 a HEP concept featuring leading-edge distributed-propulsion (DP). Three powertrain architectures are compared, showing how the aero-propulsive effects are inlcuded in the model. The results confirm the method is sensitive to top-level HEP and DP design parameters, and indicate an increase in wing loading and power loading enabled by DP.