Design of Bionic Flapping-wing Vehicle for wing folding based on lever mechanism

Flapping-wing vehicles have attracted extensive attention due to their high maneuverability and high efficiency under low Reynolds number flow conditions. Among them, the foldable flapping-wing vehicle effectively improves flight performance by imitating the deformation of wings during the flight of living organisms. Therefore, Inspired by the active contraction and deformation of wings in birds and bats during flapping, this study designed and tested two types of active folding wing mechanisms based on the lever principle (lever type and lever-scissors combination type). The key flight parameters (flapping-wing frequency, amplitude, and elevation Angle) were optimized through fluid-structure coupling simulation. Force measurement experiments and flight tests show that when the flapping frequency is 5 Hz, the flapping amplitude is 120°, and the takeoff elevation Angle is 16°, both mechanisms can achieve rapid folding (<0.3 s), with wing folding rates of 1.92 and 2.06 respectively. And it significantly increases the dive acceleration in the folded state, indicating the effectiveness of independently controlling the folding wing motion in enhancing the maneuverability of flapping-wing vehicles.