Design, Testing and Optimization of a Constant Torque Propeller

This paper examines the viability of a passive variable pitch propeller for small aerial Remotely Piloted Vehicles (RPV’s) and Unmanned Aerial Systems (UAS’s) using a self adjusting mechanical pitch control mechanism. The work described in this paper includes the design and testing of a mechanical pitch change mechanism based on a constant torque spring for an off-the-shelf propeller. A propeller performance prediction code, based on the vortex lattice method, in combination with a genetic algorithm (GA) is used to optimize a propeller for given motor performance data. The optimization process includes results for both single point and multipoint design optimization efforts. Background Fixed pitch propellers have been used since the beginning of powered flight and are still used today because of their simplicity and weight advantage. One of the pitfalls of fixed pitch propellers is that they operate efficiently only at one propeller speed and one flight speed. Efforts on variable pitch propeller design started with the Frenchman named J. Croce-Spinelli in 1871. But it took the effort of several more inventors i