Pseudospectral continuation for aeroelastic stability analysis

Abstract: This technical note is concerned with aeroelastic flutter problems: the analysis of aeroelastic systems undergoing airspeed-dependent dynamic instability. Existing continuation methods for parametric stability analysis are based on marching along an airspeed parameter until the flutter point is found - an approach which may waste computational effort on low-airspeed system behavior, before a flutter point is located and characterized. Here, we describe a pseudospectral continuation approach which instead marches outwards from the system's flutter points, from points of instability to points of increasing damping, allowing efficient characterization of the subcritical and supercritical behavior of the system. This approach ties together aeroelastic stability analysis and abstract linear algebra, and provides efficient methods for computing practical aeroelastic stability properties - for instance, flight envelopes based on maximum modal damping, and the location of borderline-stable zones.