Efficient prediction of aerodynamics characteristics of flexible flapping wing
image: Development of the novel efficient aerodynamic prediction method of flexible flapping wing: from experimental observation to conical surface model formulation and finally achieving aerodynamic calculation via unsteady panel method
Credit: Chinese Journal of Aeronautics
Flapping-wing micro air vehicles (FWMAVs) are characterized by their compact size, lightweight design, and high maneuverability, making them highly practical for various applications. However, the intricate deformation mechanisms and pronounced unsteady aerodynamic effects associated with flapping wings result in prohibitively high computational and economic costs when high-fidelity fluid-structure interaction (FSI) methods are employed for aerodynamic force calculations. Consequently, these methods are unsuitable for rapid iteration during the preliminary design phase of such aircraft.
Current research primarily relies on simplified rigid-wing models, which fail to accurately predict aerodynamic performance or account for control effects caused by wing membrane deformation. Consequently, extensive physical prototyping and experimental optimization are required after preliminary design, significantly impeding rapid iteration and configuration determination in FWMAV aerodynamic and control design.
Professor Wu's team successfully addressed this challenge by developing an "efficient prediction method of flexible flapping-wing aerodynamic characteristics" published in the Chinese Journal of Aeronautics on June 20, 2025. This innovative method introduces a conical surface model to simulate wing deformation, combined with an unsteady panel method (UPM) for aerodynamic force calculation, enabling rapid and accurate prediction of aerodynamics and control moments for flexible flapping-wing. The study confirmed that the deformation patterns predicted by the conical surface model show excellent agreement with experimental observations. Furthermore, the instantaneous aerodynamic forces and moments predicted by the UPM align closely with CFD results (with average aerodynamic force errors below 3%), Notably, the computational time is reduced by at least one order of magnitude compared to CFD, thereby conclusively demonstrating the feasibility of this novel method.
One of the most exciting findings presented in this study is the elucidation of the influence of wing membrane tension on control moments. At an appropriate level of tension, roll, pitch, and yaw control moments all exhibit linear relationships with wing root deflection angles, with the roll control effectiveness being the highest, followed by pitch, and then yaw. As membrane tension increases, control effectiveness declines, and excessive tension may even lead to control reversal—highlighting the importance of avoiding overtight wing membrane from a control design perspective.
Furthermore, aerodynamic mechanisms behind additional control moments induced by coupled maneuvers were thoroughly investigated. Previous research by Keennon et al. (2012) demonstrated that employing a wing-root deflection-based control method can generate a substantial additional roll moment during simultaneous pitch and yaw control. The present study further reveals that pitch-yaw coupled control induces additional roll moments, reaching up to 30% of the maximum roll control moment. The roll moment is primarily generated by asymmetric lift distribution between the left and right wings during 0-0.25T and 0.5-0.75T intervals, preventing moment cancellation over a full flapping cycle. Notably, the coupled control-induced pitch and yaw moments were found to be negligible.
This research carries profound implications: the developed prediction method not only facilitates aerodynamic design but also enables the estimation of aerodynamic derivatives and real-time moment variations induced by disturbances. Future work will focus on integrating this aerodynamic prediction model with control models to create a real-time simulation platform for FWMAV control design, thereby accelerating the development of FWMAV control technologies.
Original Source
Zhang Yanlai, Guo Jiedong, Liu Ziming, et al. Efficient prediction of aerodynamic characteristics of flexible flapping wings based on unsteady panel method [J]. Chinese Journal of Aeronautics, 2025, https://doi.org/10.1016/j.cja.2025.103635.
About Chinese Journal of Aeronautics
Chinese Journal of Aeronautics (CJA) is an open access, peer-reviewed international journal covering all aspects of aerospace engineering, monthly published by Elsevier. The Journal reports the scientific and technological achievements and frontiers in aeronautic engineering and astronautic engineering, in both theory and practice. CJA is indexed in SCI (IF = 5.7, Q1), EI, IAA, AJ, CSA, Scopus.