A new aerodynamic wake model has been developed for horizontal axis wind turbines. The aim is to develop an engineering tool for investigation and design of furling turbines. The prescribed vortex wake code HAWTDAWG , developed at the University of Glasgow, has been extended for dynamic flow conditions. This dynamic prescribed wake model is built into the aerodynamic code AERODYN and linked to the structural dynamics code FAST . The new model has been compared to unsteady aerodynamic experiment Phase VI wind tunnel data. Comparisons are also made to blade element momentum and generalized dynamic wake models built into AERODYN . Results are encouraging and justify further investigation.