The paper presents a methodology for calculating the flight dynamic characteristics and gust response of highly flexible aircraft. The aeroelastic model is based on a geometricallyexact, nonlinear beam model coupled with large angle aerodynamic model. The gust response is calculated based on various gust models. It is shown that the calculated gust response spectrum as well as the RMS values can be very different for different models. For a high-aspect-ratio flying wing example the spanwise non-uniform gust model predicts much higher response as compared to a uniform gust model.