Optimization of CFRP skeletal structure of morphing wings and manufacturing by electrodeposition resin molding method

To enhance flight efficiencies, unmanned aerial vehicles (UAVs) for long-distance flight adopt the main wing with high aspect ratio. However, because the wing is elongated, the gap between main wing and aileron is relatively wider than that of a normal wing, thus, the air resistance becomes larger. Therefore, instead of ailerons, the development of the morphing wing that enables the torsional deformation of the entire wing like a bird is expected. In this study, a twist morphing wing for the wingtip of the UAV was developed. Firstly, the design of the skeletal structure of the morphing wing by CFRP was optimized. Using the finite element analysis, the torsional rigidity was minimized for the twist morphing, while maximizing the bending rigidity to support the lift. Secondly, the optimized skeletal structure was manufactured by the electrodeposition resin molding method, which was developed by the authors. In this method, CFRP skeletal structure can be easily manufactured without using prepreg or resin injection by vacuum pressure. That is, immersing the carbon fiber in the electrodeposition solution containing the epoxy polymer, resin was impregnated by the electrophoresis. Thirdly, the optimized skeletal structure was covered with a stretchable rubber film, and installed to the UAV. Conducting the wind tunnel tests, the lift could be controlled by morphing, without considerable increase of the drag.