Abstract: To enhance the attitude control capability of ducted fan UAVs in confined environments, an investigation into the aerodynamic interference mechanisms and optimal design of control surfaces was conducted based on CFD using a self-developed prototype. A multi-plate configuration, inspired by the high-deflection application of rocket grid fins, was introduced to improve control authority. However, simulation results indicated a reduction in control moment. Mechanism analysis revealed that the strong flow acceleration effect induced by small inter-plate spacing is the key factor causing reduced pressure difference of each control surface. Accordingly, collaborative optimization is conducted from three dimensions: pivot configuration, plate quantity and cross-sectional shape. A high-performance grid-type control surface with independent pivots for each plate and three rectangular plates with aligned leading edges is obtained, whose control moment is increased by 23.98% compared with the original control surface. Furthermore, leveraging regional moment contribution analysis, low-efficiency areas were trimmed, reducing mass by 13.3% while limiting the moment loss to less than 5%. This study realizes the synergistic optimization of lightweighting and high-moment output, providing theoretical insights and practical guidance for the design of efficient aerodynamic control surfaces on small ducted fan UAVs.

Key words: ducted UAV, control surface optimization, aerodynamic torque, attitude control, computational fluid dynamics