Societies demand for sustainability is one of the main drivers for innovation in the wind energy industry. The increasing size of wind turbines implies increasingly flexible turbine blades. The flexibility of the blades induces the occurrence of fluid-structure interaction (FSI) phenomena. The simulation codes that are used for the design of wind turbines need to be validated with observational data. In the current research a FSI experiment of a wing equipped with a trailing edge flap is performed to provide validation data. Little data is available in literature of free motion FSI experiments. Therefore, a FSI experiment is performed with a freely moving wing equipped with a trailing edge flap.