Aero-optic aberrations for an optical system carried by a helicopter are expected to originate primarily from rotor-blade tip vortices that propagate down into the line of sight of the optical system. Landgrebe's prescribed wake model in conjunction with a revised Biot-Savart law is used to calculate the velocity field beneath a medium-sized helicopter in hover. A thermodynamic numerical routine calculates the corresponding density and index-of-refraction fields associated with the velocity field. The approach is used to determine spatially- and temporally-resolved predictions of the aero-optic aberrations on an optical system mounted on a hovering helicopter. Metrics for the farfield optical performance and potential adaptive-optic correction approaches are discussed.
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