Aerodynamic flutter is caused due to aeroelastic effects and lightweight and large aerodynamic loads. Flutter is an uncontained vibration. In an aircraft, this can occur on wings, horizontal tail, and in control surfaces. Flutter occurs due to the interactions between the aerodynamic, elastic and inertial forces. Flutter can be classified into two types hard flutter and soft flutter. In hard flutter, there is a sudden decrease in vibration to zero, whereas in soft flutter vibration decreases slowly and gradually.
Structures like wings and also bridges and chimneys which are exposed to aerodynamic forces are designed in such a way that it can avoid flutter. Changing the mass distribution of aircraft or stiffness of a component can induce flutter. This starts with less violent but it can be more violent and can be uncontrollable which can lead to damage or destruction of aircraft. In a propeller aircraft aerodynamic and inertial effects of the rotating propeller and stiffness of the supporting nacelle structure causes propeller whirl flutter.