Design of the optimal airfoil for a blade of a small-scale multi-rotor VTOL UAV

Abstract

Over the past decade, multicopter unmanned aircrafts have gained extreme popularity. Since their application spans from children toys to video surveillance, surface mapping, payload delivery, communication, etc, much work is being done worldwide on their promotion and advancement. With many electric components commercially available, it has become imperative to develop customized and optimized mechanical parts. This paper investigates the possibility of defining the optimal two-bladed propeller for an existing small electric motor of known characteristics. The propeller should be geometrically simple to reduce the cost of product ion but still provide the greatest thrust for given angular speed and available torque. While cubic chord and linear pitch distributions along the blade are predefined, the airfoil is parameterized by the Class-Shape Transformation (CST) technique (by 6 input parameters). Rotor performance is estimated by an improved blade element momentum theory (BEMT) while the two-criteria optimization is performed by genetic algorithm (GA).