A Method for the Conceptual Design of Hybrid Electric Aircraft

The growing interest into hybrid electric propulsion as a possible solution to reduce in-flight emissions has led to the investigations of many innovative propulsive system architectures that couple higher system efficiency with improved aerodynamic propulsion integration strategies. The paper presents amethodology to model and size generic hybrid electric propulsion system at the conceptual level allowing for a rapid exploration of the vast design space. The generalization of the propulsive system using a basic propulsive power unit object is discussed highlighting the control parameters needed to fully define the propulsive system architecture. Three case studies for a 2035 turbo-prop regional aircraft using parallel, series/parallel and distributed series configurations showthat improvements to the fuel and energy consumption are affected by the system morphology, its control strategy and the maturity level assumed for its components. Using conservative estimations for the battery and electric components performances indicate that the best configurations can only provide a fuel reduction of around 5% while weighting 25% more than the reference design. Using more optimistic assumptions leads to a larger feasible design space where the best performing configuration, the series/parallel one, realizes more substantial fuel and energy reductions of 28% and 14% with a 24% higher take-off mass