Aircraft wings are becoming more flexible, making it important to take this flexibility into account from the start of the design process. With flexible wings, unsteady (time-varying) aerodynamics becomes important. For this reason, an unsteady aerodynamics model was constructed and coupled to an aeroelastic flight mechanics tool. This allows for investigating the response of the aircraft after gusts or control inputs. It was found that for wings of relatively high stiffness, unsteady aerodynamics is not important to take into account during gust response modelling. The difference between unsteady and steady aerodynamics was found to not be more that 5%. The short period motion is influenced significantly by the unsteady aerodynamics, with a change in period of 18%. Results have also indicated that unsteady aerodynamics is more important for more flexible wings. The current work allows for simulating these more flexible wings, in both longitudinal and lateral situations.