Proposal and Numerical Validation of Passive Morphing Wing Mechanism for Small Unmanned Aerial Vehicle

A passive morphing wing was designed to achieve flap-like aerodynamic functionality without using actuators. The structure includes springs and stretchable materials between the leading and trailing edge ribs, allowing the trailing edge to deform in response to flight speed. This passive deformation enables appropriate aerodynamic performance across various flight conditions. To evaluate the aerodynamic characteristics, fluid–structure interaction (FSI) simulations were conducted at 2.8 m/s, 8.3 m/s, and 13.8 m/s, and the results were compared with those of a conventional wing without a flap mechanism. At 2.8 m/s, corresponding to the takeoff phase, the passive morphing wing achieved a higher lift coefficient than the conventional wing. At 8.3 m/s, during the climb phase, both lift and drag coefficients were slightly higher, with a similar lift-to-drag ratio. At 13.8 m/s, which corresponds to cruise, the drag coefficient decreased while the lift-to-drag ratio increased. Additionally, the passive morphing wing showed smaller fluctuations in lift coefficient over time, indicating enhanced flight stability. These results confirm that the passive morphing wing offers flap-equivalent aerodynamic performance while contributing to weight reduction by eliminating the need for actuators.