Stability and coupling characteristics of flight vehicle consider with elastic freedom

In this paper, we establish the dynamic modeling of elastic vehicle acting with unsteady aerodynamic forces expressed by rational function matrices. When attitude dynamics is taken into account, the indicial lift functions are applied to describe unsteady aerodynamics for arbitrary motion. Stability of the coupling elastic vehicle system is studied through analysis of return difference matrix and multivariable Nyqiust locus, and a coupling measure is derived to indicate interactions between rigid-body motion variables, elastic variables, control variables and observation variables in frequency domain under open/closed-loop control . At the end, a practical example is given.