MEASUREMENT OF STATIC AND DYNAMIC PERFORMANCE CHARACTERISTICS OF SMALL ELECTRIC PROPULSION SYSTEMS By

Unmanned aerial vehicles are being utilized by numerous groups around the world for various missions. Most of the smaller vehicles that have been developed use commercially-offthe-shelf parts, and little information about the performance characteristics of the propulsion systems is available in the archival literature. In light of this, the aim of the present research was to determine the performance of various small-scale propellers in the 4.0 to 6.0 inch diameter range driven by an electric motor. An experimental test stand was designed and constructed in which the propeller/electric motor was mounted in a wind tunnel for both static and dynamic testing, and the results were compared to those from previous studies. For static testing, the coefficient of thrust, the coefficient of propeller power, and the total propulsive efficiency, defined as the ratio of the propeller output power to the electrical input power, were plotted versus the propeller rotational speed. For dynamic testing, the rotational speed of the propeller was held constant at regular intervals while the airspeed was increased from zero to the windmill state. The coefficient of thrust, the coefficient of propeller power and the propeller efficiency were plotted versus the advance ratio for various rotational speeds. The thrust and torque were found to increase with rotational speed, propeller pitch and diameter, and decrease with airspeed. Using the present results and data from archival and non-archival sources, it was found that the coefficient of thrust could not be correlated with propeller diameter for square propellers where D = P. For a family of propellers (same manufacturer and application), correlations for the coefficient of thrust, the coefficient of propeller power and the propeller efficiency could be improved by modifying either the coefficients or the advance ratio with D/P. This dimensionless ratio allows for the propeller pitch to be accounted for in the performance coefficients.