TESTING AND CORRELATION ON AN ADVANCED TECHNOLOGY, BEARINGLESS ROTOR

This paper describes a wind tunnel test of a one-sixth Froude scale model of an optimized design, advanced technology, soft-inplane, bearingless rotor. The model was designed to match not only the first out-of-plane and first inplane frequencies of the full-scale optimized rotor, but also the rotor torsional and second order out-of-plane and inplane modes. The rotor support system was designed to simulate the flexibilities of the full-scale helicopter, including pylon mount flexibility, mast-bending flexibility, and control system stiffness. The model was tested for pylon stability in hover and for rotor lead-lag stability in forward flight. The effects of various aeromechanical couplings on aeroelastíc stability was investigated by testing four pitch-horn/pitch-link locations. The paper presents the results of these tests and correlation with the COPTER computer analysis.