Stability of an Unsymmetric Rotor on an Unsymmetric Support

The stability of unsymmetric rotors on unsymmetric supports has long been of interest to engineers of rotating machinery. This topic is particularly germane to the study of two-bladed helicopter rotors, which are unsymmetric by design. The equations of motion are derived for a two-bladed rotor on an unsymmetric elastic support. Four degrees-of-freedom are considered. Two of these represent support flexibility, and two represent rotor flexibility. Stability is determined by various methods, and the results obtained are compared with previous work. These comparisons verify some qualitative predictions of earlier research and also identify new mechanisms of instability that have not been previously understood.