ABSTRACT
There are many practical applications were airfoils are required to operate under stalled conditions; in cluding aircraft operating at high angles o f attack, and helicopter blades in the retreating part o f the rotation cycle. Although aeroelastic analyses often assume that both the aerodynamic and structural forces are linear, it has become apparent in recent years that nonlinearities can affect not only the post instability behaviour o f an aircraft, but also its re sponse at velocities below the flutter boundary (Lee et al. 1999). To conduct an aeroelastic analysis o f an airfoil undergoing stall it is necessary to account for the dynamic nature o f stall, which produces a sig nificantly different unsteady aerodynamic loading than that obtained under static conditions.
