Hybrid-electric propulsion systems offer the potential to make aircraft more efficient by using electric energy to cover a share of the total energy demand. However, resolving questions related to aircraft hybridization, namely the potential fuel consumption benefits and the energy management throughout the mission, is vital. This highlights the importance of holistic evaluation methods. Hence, this paper introduces a method for the design and evaluation of hybrid-electric propulsion systems. The method enhances current sizing methods by modeling a hybrid-electric turbofan and estimating electrical losses for the electric power train to explore hybrid energy management strategies. The method is demonstrated using the short–medium-range concept aircraft D239. Initial simulations indicate a total increase in the block fuel mass of approximately 2.7% with constant hybridization throughout the 800 n mile reference mission. However, optimizing the energy management strategy reveals an improved result of a 1.6% increase in mission block fuel. Key factors contributing to this improvement include using hybrid-electric power exclusively during the climb phase, shorter mission ranges, and omitting battery charging during flight. However, an overall increase in the block fuel mass persists under realistic assumptions. This highlights the need for further exploration of hybrid-electric concepts and methodical refinement.
Beschorner et al. (Mon,) studied this question.