Aerodynamic Characteristic And Structure Optimization Design Of Bionic Flapping-wing Air Vehicle

Bionics flapping wing air vehicle is a new kind of air vehicles that mimic theflying modes of insects and birds. It has the advantages of light weights, small sizes,good stealth abilities, high maneuverability and low costs. It is widely used in the fieldsof military and civil application. The studies of aerodynamics and bionics indicate thatfor the air vehicle which the characteristic dimension almost equate to insect or bird, theflapping flight mode is precede to be more efficient.Firstly, this paper analyzed and summarized the actual flapping-wing movement ofbirds. On the base of uniform speed and non-tilting flapping-wing model, new model isdeveloped by considering the pitching motion of wing and the change of flappingvelocity, so it can simulate the flap motion of bird wing better. According to theaerodynamic and scaling rules of biological flight, the motion parameters anddimensions of the flapping wing air vehicle can be chosen. With a numerical simulationmethod, the aerodynamic of different flapping-wing models are measured andsimulated.Through analyzing the drive of existing flapping-wing air vehicles, symmetricaldouble crank rocker mechanism and four-bar linkage are chosen to be the drive of theflapping-wing air vehicle. According to identified motion parameters, the length ofevery connecting rods of the wing can be calculated. Then the motion of the model issimulated. After that, rear link mechanism is designed to achieve the pitching motion.According to the formula of aerodynamics, the required torque of motor can becalculated. According to the results, we can select motor that meet the requirements.The structure of flap-wing air vehicle is designed by three-dimensional modelingsoftware. According to the identified data of shape dimensions and rod length, thestructure of the wing, tail and fuselage are designed. After interference checking, themotion of the model is simulated. In the moving parts, the force of gear is the largest, socheck the strength of gear. Through the center of gravity analysis, make the focus of themodel locate in the symmetry plane.Finally, Acrylic and ABS are chosen to be the materials of flapping-wing airvehicle parts. The materials are processed by laser cutting. Through processing andassembly, flapping-wing air vehicle are produced. Then the actual stress conditions are tested.