Experimental investigation on aerodynamics of nonplanar rotor pairs in a multi-rotor UAV

This paper presents a new configuration of multi-rotor unmanned aerial vehicle (UAV) with non-planar rotor pairs and investigates the aerodynamics by experimental measurements with a test rig and wind tunnel. Two types of adjacent non-planar rotor pairs, face to face (F-F) and back to back (B-B), are investigated at different disk plane tilt angles ranging from 0° to 50° and different transverse rotor spacing ranging from 1.0 to 1.8 times rotor diameter. In addition, the effect of wind on two types of non-planar rotor pairs is also investigated in wind tunnel with various wind speeds ranging from 0 to 4m/s. Experimental results show that two adjacent non-planar rotors have strong aerodynamic interference which affects their overall aerodynamic performance significantly, but the aerodynamic performance can be improved with an optimal combination of tilt angle and rotor spacing. It's observed that smaller rotor spacing reduces the aerodynamic performance significantly, while higher tilt angle and large rotor spacing usually contribute to the total thrust of the rotor pairs. Wind also has strong influence on the aerodynamic performance of non-planar rotor pairs, making the thrust and efficiency reduced significantly. B-B rotor pair is more sensitive to the wind disturbance than F-F rotor pair, the aerodynamic performance of B-B rotor pair reduced more significantly with wind speed.