Rotating shaft balance for measurement of total propeller force and moment

At NLR a six-component rotating shafl balance has been developed. The rotating shaft balance (RSB) is intended for use during propeller forces measurements, both installed and isolated testing. By using an RSB it is possible to determine the propeller wing interference effects on the propeller as well as on the wing. The development work included the design of the RSB, the creation of a suitable dynamic data acquisition system and a series of proving trials. An Fast Fourier Transform (FFT) system has been used to support the determination of the off-axis components of the forces and moments. During these trials the RSB was calibrated statically on all components and dynamically on thrust and torque. In addition propeller performance measurements have been wormed to acquire operational experience and to determine the influence of oblique inflow into the propeller plane. Both the proving trials and the performance measurements have been performed in the NLR closed circuit Low Speed wind Tunnel (UT). The RSB was mounted on an isolated propeller rig which has been used in previous wind tunnel tests. An extensively tested one fifth scale Fokker 50 model propeller has been used, thus a subslantid performance database and experience of the rig was already available. Trials showed that an accuracy of 0.2 96 on torque and 0.3 % full scale on thrust was rea l id . Results of the propeller performance test indicated an accuracy for the off-axis components of 1.5 % and 1.8 % for ESP. the off-axis moment and force. The tria Is and isolated propeller tests have given confidence in the RSB design, manufacturing and testing capabilities and a design and production approach is now defined. It is planned to use the existing RSB in conjunction with an extemal six-component balance in an installed propeller half model test. With the availability of the RSB it is now possible to close the accounting scheme in determination of propellerlwing interaction forces and moments . ' J =