Gust Response Sensitivity Characteristics of Very Flexible Aircraft

This paper studies the effect of varying structural stiffness parameters on the gust response of a very flexible aircraft (VFA). Twelve different aircraft models, as well as the baseline model, are subjected to a temporally and spatially distributed gust of varying durations. The open loop response of the models is examined as a function of different natural frequencies and frequency ratios. Linear models are extracted from the nonlinear data using system identification. These linear models are then examined to determine their stability and controllability properties. A Linear Quadratic Gaussian (LQG) controller is used to determine the closed loop response of the models to a pitch step command in the presence of gust. Finally, the models are given a 0° pitch command in order to examine the ability of the LQG controller to maintain level flight while encountering gust.