Design and Experimental Analysis of Propeller Variable-Pitch Mechanism for Near-Space Aircraft

Most of the existing propulsion systems that can rotate around the rotation axis and change the pitch angle of the propeller are applied to helicopters and ships. Their structure or weight cannot meet the requirements of lightweight and high bearing performance for near-space aircraft. To improve the adaptation range of near-space aircraft, this paper proposes a new variable-pitch vector mechanism for propellers based on a sine mechanism. The mechanism can adjust the blade angle of the propeller to produce unbalanced thrust. Firstly, the structural design and optimization of the variable-pitch mechanism are carried out, and the transmission system is designed according to its kinematics and statics. Secondly, the parts with high stress in the mechanism are analyzed using ANSYS. Finally, the principle prototype design and experiment are carried out. The experimental results show that the pitch-change mechanism designed in this paper can be matched with a pair of propellers of 6 m in diameter. When the propeller is running on the ground at 200 rpm, the pitch variation error is less than 0.5°, and the weight of the mechanism is only 18.78 kg.