The variant aircraft can flexibly change its shape to achieve the best sports performance under different flight environments and flight missions. Changing the shape of the wings is a major form of variant aircraft. In this paper, the kingfisher was selected as the bionic object to design a morphing wing. A three-stage lateral folding morphing wing based on Sarrus linkages was presented and applied to the construction of an underwater–aerial transmedia aircraft. The multi-body dynamics method

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... s used to analyze the kinematic characteristics of the morphing wing and to optimize the design of the folding mechanism for the torque values of the hinges between the bottom links. The results showed that the optimized hinge torque value was reduced to 1.2085 N·m, and the lengths of the bottom two links were calculated to be 140 mm and 142 mm, respectively, based on the optimized results. Finally, a series of wing folding and unfolding motion experiments were conducted to prove that the mechanism enabled the span change smoothly, which verified the rationality of the design of this paper.