The objective of this study is to evaluate the aerodynamic effects of
leading-edge slats on rotor. blades under high-speed forward-flight co
nditions. A partial-span leading-edge slat is proposed for the inboard
portion of the existing UR-60A rotor. Some two-dimensional slat studi
es are done to optimize the slat orientation at low subsonic Mach numb
ers. A multizone unsteady three-dimensional compressible Navier-Stokes
solver is developed to compute such rotor/slat configurations. The ro
tor wake is captured from first principles. Some forward-night results
are presented for the UH-60A slatted rotor and compared with the base
line rotor case. The surface pressures and the force coefficients indi
cate that the slat is beneficial in reducing the retreating side dynam
ic stall. It was found that the slat reduces the torque and pitching m
oments on the retreating side compared to the baseline configuration.