The loading on an airfoil during dynamic stall is examined in terms of the augmented lift that occurs and the associated penalties in pitching moment and drag. It is shown that once stall occurs, and a leading-edge vortex is shed from the airfoil, there is a unique relationship between the augmented lift, the negative pitching moment, and the increase in drag. This relationship shows limited sensitivity to a number of parameters that govern dynamic stall, such as steady and alternating pitch angles and reduced frequency. Second-order polynomials are used to characterize this dynamic stall behavior. It is shown that the dynamic stall performance of most single-element airfoils is similar, and it appears that little can be done to significantly improve rotorcraft maneuverability except to provide good static C_(l_(max)) characteristics and the chord or blade number that is required to provide the necessary rotor thrust.
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