Human powered aircraft (HPA) have a number of special design features. They are of a high aspect ratio, have a very low weight and are consequently equipped with very flexible wings. The aeroelastic behaviour of such aircraft is of great interest. At the Institute of Aeroelasticity of the German Aerospace Center (DLR), a 1:3 scale section of a light-weight wing has been built and tested in an open wind tunnel with comparable Reynolds number of model and original HPA. Representative values for geometry and stiffness were derived from an original HPA design. During the experiment, vibration tests of
the structure were performed. During the wind tunnel test, static and transient investigations were performed. Finally, using a modified mass distribution, the flutter point was determined numerically and experimentally, and limit cycle oscillations (LCO) could be observed in the experiment. Measurements indicate that the LCO is due to massive flow separation at positive and negative high angles of attack.