This thesis was conducted at KVE Composites Group (The Hague, The Netherlands). The aim of this thesis is to create an aeroelastic model that can be used during the design phase of these rotor blade projects. An aeroelastic was created consisting of a Ritz-Hamilton structural model, a lifting line quasi steady aerodynamic model with two inflow models. The aeroelastic model includes effects due to centripetal and gravity forces and conservation of angular momentum. A fourth order Runge-Kutta integration method is used to numerically integrate the aeroelastic model to obtain the response of the system. The aeroelastic model was validated by comparing results calculated using the aeroelastic model with theoretical results and results obtained by measurements. A uniform beam and several rotor blades were modelled for this validation. The calculated steady state deflections and natural frequencies of the uniform beam were compared with values obtained from literature. The calculated steady state deflections and natural frequencies of the rotor blades were compared with values obtained from measurements on the rotor blades. The calculated drag for the rotor blades was compared with values obtained in a series of whirl tower tests. The predicted steady state response and natural frequencies of a uniform beam are very close the values from literature. The error for the steady state response and natural frequencies of a rotor blade is larger than that for the uniform beam. This error reduces if more elements are used. The power required predicted is higher than the power required measured at low angels of incidence and within the bounds of power required measured for high angles of incidence. Using this model KVE is able to predict initial loads, deflections and the consequences of changes in the design of their rotor blade.