The increase in popularity of unmanned aerial vehicles (UAVs) has been driven by their use in civilian, education, government, and military applications. However, limited on-board energy storage significantly limits flight time and ultimately usability. The propulsion system plays a critical part in the overall energy consumption of the UAV; therefore, it is necessary to determine the most optimal combination of possible propulsion system components for a given mission profile, i.e. propellers, motors, and electronic speed controllers (ESC). Hundreds of options are available for the different components with little performance specifications available for most of them. In order to determine the performance specifications, a propulsion system testing apparatus has been developed and validated. This testing apparatus was designed to measure the performance and efficiency parameters of electric propulsion system components (propellers, motors, and ESC) while maintaining similar air flow characteristics in either a wind tunnel or on a moving automotive platform. Validation tests of four propellers are presented. All four propellers were tested under static conditions, and two were tested under advancing flow conditions where the testing apparatus was used on an automotive platform. The results show that this propulsion testing system provides for holistic testing of all possible compatible electric propulsion system components in a flight-like environment. Data from this system will be used in a mission-based propulsion system optimizer, currently in development, to select the best combination of components for a long-endurance solar-powered unmanned aircraft.