Design, Development, and Closed-loop Flight-Testing of a Single Power Plant Variable Pitch Quadrotor Unmanned Air Vehicle

This paper describes the design, development and flight testing of a single power plant variable pitch quadrotor unmanned air vehicle (UAV). The use of variable pitch rotor enables replacement of four motors of the conventional quadrotor design with a single power plant, opening up the possibility of use of fuel engine. The work is carried out in two phases. In the first phase, a proof-of-concept prototype of variable pitch quadrotor powered by a single brushless DC motor is fabricated to demonstrate the variable pitch concept and to develop the control strategy required for attitude stabilization and trajectory tracking. A PID based closed loop controller is developed and implemented on PixHawk autopilot board and its performance is demonstrated through flight test of the electric quadrotor prototype. In the second phase, two stroke internal combustion engine powered prototypes are developed based on the understanding generated from the first phase. The gasoline powered quadrotor with all up weight of 10 kg is estimated to offer hovering endurance of 2.4 hours with 2 liters of fuel. This design revisits the possibility of developing helicopters without cyclic pitch control which was first explored nearly a century ago.