Aerodynamic performance of a non-planar multi-rotor air-craft in hover

Experimental tests and numerical simulations were typically presented with a rotor spacing of 1.2 times the diameter to investigate the effect of disc angle (DA) on the hover performance of non-planar multi-rotor unmanned aerial vehicles (UAVs). Torque, thrust coefficient, power coefficient, and power loading measurements were performed to evaluate the performance of the vehicles with different rotor rational speeds and DAs. The hovering performance exhibits a maximum improvement of 10.3 % when DA = 50 degrees compared with the traditional planar muti-rotor system. The flow fields were also simulated by unsteady Reynolds-averaged Navier-Stokes solver. The downwash shifts, flow contractions, pressure difference enlargements, and wake inclinations were discovered and contributed to the interference reduction with the increasing DA. Based on these observations, the tilt-rotor configuration has a noticeable enhancement on the hovering performance of UAVs with proper DA. The insights gained can be applied as guidance for further UAV design.