The paper presents a method for obtaining the flight dynamics, stability and control characteristics of flexible airplanes. Computational fluid dynamics techniques are used for the aerodynamics, while finite element techniques are used to evaluate structure deformations. The coupling between aerodynamics and structure is done by using multi-field Fluid Structure Interaction. Results are generated for an example airplane that has high aspect-ratio wing and fin fuselage. The results indicate that aerodynamic derivatives, static and dynamic stability are changed with dynamic pressure. Results also indicate that the controller design (gain scheduling) for an example automatic flight control system, pitch-attitude hold, has some changes. Furthermore, flight simulation based on fourth-order Runge-Kutta numerical integration indicates small changes on airplane's trajectory during a pull-up maneuver.