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Study of a static torque measurement device for composite variable pitch propeller blades

The propeller engine uses the rotation of the propeller to push the air behind the aircraft, which would produce the reaction force to propel the aircraft forward. The propeller is generally made up of multiple propeller blades and a propeller hub. The overall balance of the assembly needs to be measured to ensure that the unbalanced synthetic torque generated by the individual blades is within a reasonable range when the propeller engine is rotating. Therefore, it is essential to measure the static torque of each propeller blade after production and before assembly. Due to the unique irregular shape of the propeller, the radial torque varies at different rotation angles. Moreover, the variable pitch propellers with adjustable blade angles have been widely used, so the measurement of the radial static torque of the propeller at different working angles also needs to be addressed. The existing propeller blade static torque measurement devices are mainly based on the principle of torque balance, which has the advantages of low measurement error, high stability, and repeatability, and the results can be traced using weights. In this paper, a propeller static torque measurement device is developed for the new composite variable pitch propeller, which can achieve the measurement of both propeller axial static torque and radial multi-angle static torque measurement. Besides, a specified gauge is developed for the device and the performance parameters of the device are tested by the gauge and the actual blades to verify the feasibility of the device.