Aerodynamically Efficient Rotor Design for Hovering Agricultural Unmanned Helicopter

Unmanned aerial vehicles, especially agricultural unmanned helicopters (AUH), are nowadays extensively used in precision agriculture. AUHs have recently become responsible for spraying fertilizers and pesticides for crop yields. The strong downward rotating flow produced by the main rotor helps very uniform crop spraying which determines that how important is the aerodynamics of rotor blade in AUH. In this work, the aerodynamic performance of AUH rotor blades is evaluated and an efficient blade is obtained by numerically investigating the influence of design variables on the aerodynamics of rotor blades. The design variables consist of airfoil shape, pitch settings, and twist angle. The limited power available in hover and aerodynamic requirements (lift and drag) are the aerodynamic constraints. This analysis only considers the hovering flight condition at a constant rotational speed. The aerodynamically efficient rotor blade which is based on gradually varying and linearly twisted airfoil shapes, show a significant improvement in hover performance with relatively uniform blade loading. After testing, the optimum blade can be used as the main rotor in the AUH to perform precision farming