Optimization-Driven Design of Composite Empennage Structures for Hybrid-Electric Aircraft

This paper presents the optimization-oriented structural design of aircraft empennages developed within the HERFUSE project, funded by the Clean Aviation Joint Undertaking. The study focuses on the horizontal and vertical tailplane of a hybrid-electric regional aircraft, considering the structural challenges introduced by distributed propulsion and novel integration requirements. The distributed propulsion layout influences the tail load envelope through powered-on maneuver/gust and asymmetric-thrust conditions, which contribute to the laminate redistribution in regions subjected to high bending–torsional demand. Starting from a conceptual structural configuration, the empennage is refined through a multi-objective optimization process. The structure is discretized into multiple regions, each characterized by independent laminate definitions selected from a predefined set of stacking sequences. The optimization aims to minimize the overall structural mass while ensuring adequate structural integrity under the project complete set of load cases. Structural performance is evaluated using a failure criterion suitable for composite materials, allowing the identification of critical regions and the redistribution of material accordingly. The results highlight the effectiveness of the adopted optimization strategy in improving structural efficiency, providing a refined configuration with a final mass of 433 kg, corresponding to an approximately 27.23% reduction with respect to the reference configuration coming from project specifications, while maintaining controlled failure index levels. The proposed approach demonstrates its suitability for supporting early-stage design decisions in next-generation hybrid-electric aircraft.