The thesis describes the process of designing and developing a measuring system that enables in-flight torque measurement on the aircraft propeller shaft. With known aircraft characteristics, torque measurement allows us to determine the thrust value in horizontal flight. Based on the aircraft, engine and propeller configuration, we performed a calculation and optimisation of a custom propeller shaft. The shaft’s geometry enabled the installation of a strain gage and the required measuring equipment. A static maximum-load test was performed on the propeller shaft, and the impact of cross-force and thrust force on torque measurement was also tested. With known measurement characteristics of the system, static thrust tests and flight tests for three different propeller pitch settings were performed. In flight torque measurement was successful, but with unsatisfactory repeatability for most measurements. Propeller efficiency was calculated based on the torque measurement, which means the results of the efficiency calculations are also not sufficiently repeatable. The method has proven to be acceptable, but it has its drawbacks since constant and repeatable atmospheric conditions cannot be ensured.
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