Aerodynamic interactions in quadcopter configurations with vertical rotor spacing

Abstract

The aerodynamic interactions in a quadcopter during forward flight reduce the efficiency of the back rotor(s) and increase generated noise levels. In order to alleviate interactions without compromising the vehicle’s compactness, a vertical offset between the front and back rotor(s) can be introduced as an alternative solution to increased hub spacing. The performance of a quadcopter in square and diamond configuration with a vertical spacing up to 0.38 rotor diameter is analysed experimentally and numerically using free-wake solvers. Forward flight conditions are considered, including high interaction cases with a nose-up tilt and close rotor hub spacing with overlapping blades. The results show that for the square configuration performance comparable to four isolated rotors is achieved by the elevation of both back rotors. In contrast, introducing a vertical separation to the already underperforming back rotor in the diamond configuration further reduces its efficiency.