- The purpose of this paper is to examine the leading-edge flow structure during dynamics stall under realistic helicopter flight conditions (M = 0.2 and Rec = 2 106). The test article was a rectangular wing with a NACA 0012 airfoil section. The wing was dynamically pitched about the 1/4 -chord at a reduced frequency of 0.1. The leading-edge flow structure was quantified experimentally using high-fidelity PIV (measurement resolution of 0.25 mm 0.25 mm). Numerical simulations were performed using a variety of turbulence models. The experimental and numerical data were analyzed to provide better understanding of the leading-edge flow dynamics. Improved understanding of the leading-edge flow dynamics has the potential to provide the scientific background necessary to identify new flow control opportunities. Copyright 2009 by the American Institute of Aeronautics and Astronautics, Inc.