Gust Response Analysis of Flexible Aircraft

Aircraft flexibility causes problems and difficulties which this problems even might endanger health and safety of the aircraft. This phenomena changes dynamic response of aircraft to surface control and gust. Also it has diverse effect on flight quality and handling. then considering flexibility effects on dynamics response of aircraft is significant which requires that coupled dynamic and viberational equations of aircraft. In this paper, dynamics of a wide body aircraft has been developed on base of a six degree of freedom model witch includes two rigid and four flexible degree of freedom. Quasi steady aerodynamics has been used to describe interaction between solid and fluid. The characteristics of this model enhance perdition of dynamic response to gust and other external disturbances because of its development of elastic modes. the characteristics of this external disturbances causes more flexible modes to be exited and strain energy ratio in general dynamics of aircraft increases. In this simulation different parameters like stiffness ,gust length and its profile has been studied and a comparison between different length gust has been done .