Aerospace Engineering Department
BS in Aerospace Engineering
This report details the design and construction of a testing apparatus for characterization of small electric aircraft power systems designed for use in the California Polytechnic State University San Luis Obispo Aerospace Engineering department’s subsonic wind tunnel. This apparatus was constructed and implemented with the goal of determining system and component efficiencies of an entire power system using RC Aircraft components as an analog for systems currently in use in the current generation of small electric UAV’s in service with the US Armed Forces. The goal of these experiments was to determine where improvements in the system architecture can be made with a specific goal of extending flight time beyond the current maximum of approximately two hours. It was found that for the test system, the biggest hindrance to optimal performance is the inverse relationship between motor and propeller efficiency. As motor efficiency is increasing, propeller efficiency decreases and the net effect is poor efficiency at all operating points. Additionally, it was found that input voltage has a large effect on overall motor and controller efficiency with a measured change in efficiency of 11% for a constant 10,000 RPM output at voltages ranging from 16.8 to 12 Volts. It was also found that further development is needed to make this apparatus an acceptable solution for precise characterization of actual UAV power systems. The current standard deviation in the power measurement of 28% or is much too large to provide any kind of accurate picture of the actual operating conditions.