Experimental study on efficient propulsion system for multicopter UAV design applications

The usage of multicopter unmanned aerial vehicles (UAVs) has increased for various military and civilian purposes. The choice of propulsion system of such a vehicle is crucial to fulfill the intended mission requirements. The present study focuses on evaluating the efficiency of propulsion system by experimenting with different motor, propeller and battery combinations. The connection between the electronic speed controller (ESC) signal, current, power, thrust and torque in relation to propeller size is determined. It is observed that regardless of battery capacity or motor type, the thrust and torque produced for a given motor speed (RPM) for a specified propeller are similar. The higher capacity battery with 6000 mAh, denoted as B2 battery, consumes less current and can attain higher motor speed to produce the required thrust force than a lower capacity battery with 3300 mAh, denoted as B1 battery. The most efficient propeller, 12 inches in diameter (P4 propeller), is observed to achieve efficiency levels of 12.9 % for the B1 battery and 11.4 % for the B2 battery. Similarly, the most efficient motor, 700 KV motor (M1), is determined to exhibit efficiency of 64.29 % when coupled with the B1 battery and 62.01 % when coupled with the B2 battery. It is identified that using the B2 battery results in an increased payload capacity of 5.82 N, compared to 2.02 N with the B1 battery. Furthermore, when considering both scenarios with and without payload, greater endurance is observed when B2 battery is used as opposed to the B1 battery.