Shape design of a morphing elevator to enhance aircraft low speed efficiency of a regional aircraft

Control surface aerodynamics plays a crucial role in aircraft performance, both in cruise and low speed conditions, where fuel consumption and stability are most critical. This study presents an aerodynamic shape design based on numerical optimization applied to a future green aircraft elevator, to reduce its drag, maintaining required stability and control authority during the low-speed phases. A numerical aerodynamic optimization based on the application of Covariance Matrix Adaptation Evolution Strategy (CMA-ES) to Computational Fluid Dynamics (CFD) has been performed to identify aerodynamic improvements of the baseline configuration. The methodology integrated parametric shape modifications, by means of Radial Basis Functions (RBFs), assuring a smooth elevator’s deflection maximizing aerofoil’s lift capabilities, improving or keeping baseline’s efficiency. The optimization process was executed under representative low speed conditions (Mach number equal to 0.23, sea level altitude, International Standard Atmosphere (ISA) with temperature difference deviation null – K –), so results are directly applicable to operational flight regimes. Results demonstrate that the optimized elevator can improve aerofoil lift (up to above 9%), reducing drag (up to above 7%), contributing to improve fuel efficiency (up to 10% aerodynamic efficiency improvement), reducing environmental impact. The study highlights the importance of tailoring control surface geometry also for low-speed efficiency, an aspect often overlooked in conventional design practices. This work underscores the potential of aircraft design advanced optimization techniques, offering a pathway toward more sustainable and cost-effective operations. The methodology presented can be extended to other control surfaces and flight regimes, reinforcing the role of aerodynamic optimization in modern aircraft development. The activities here reported have been carried out within the EU-funded research project HERFUSE (Hybrid-Electric Regional FUSelage & Empennages), aimed to develop advanced designs for the fuselage and empennages of Hybrid-Electric Regional (HER) aircraft.