An electro-magnetic controllable dry friction damper has been designed and numerically simulated. The gust response of a three degree-of-freedom typical airfoil section with a control surface using this nonlinear damper has been studied theoretically. The effects of different gust excitations and parameter variations of the nonlinear damper on the nonlinear aeroelastic response are discussed. The numerical results show the present electro-magnetic dry friction damper can be used to alleviate the dynamic response to both a periodic and a linear frequency sweep gust excitation, especially for the plunge and pitch responses. The theoretical results are also verified by an experimental investigation in the Duke wind tunnel test. The fair to good quantitative agreement between theory and experiment verifies that the present electromagnetic dry friction damper can be used to alleviate the gust response, especially for the plunge and pitch responses. It also shows the present theoretical method can be successfully applied to determine the nonlinear gust response when an electro-magnetic dry friction damper is added to a linear aeroelastic system. © 2003 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.