Abstract <p>On the basis of the original free-wake model the numerical study of the Mi-8 helicopter main rotor hovering above the edge of rectangular flat ground surface of limited dimensions was performed. The original free-wake model developed by authors is used. The study considers the range of distances from the main rotor plane to the surface in the range of 5–16 m. Four values of rotor/surface overlapping have been considered: 100, 75, 50, and 25% of rotor diameter. Hovering near an infinite ground surface was considered additionally. To simulate an infinite surface, the method of mirrored rotor’s wake is used. Limited surface is modeled by a layer of dipoles. Both approaches are validated by comparison with each other and with experimental data (for the case of an infinite surface). The main rotor wake shapes and flow structures have been obtained and analyzed. For constant rotor’s power, the curves of the thrust vs. hovering height have been constructed. Comparison with available experimental and calculated data has been performed. The authors made conclusions about the effect of a limited surface on the increase in rotor thrust with varying levels of rotor/surface overlapping area and hovering height values. In particular, the study showed that the maximum thrust gain (at the lowest possible hovering height) with the full (100%) rotor/surface overlapping is 22%. With a decrease in overlapping ratio to 75, 50, and 25% the thrust gain decreases to 15, 6, and 3%. The obtained results are the newest and can supply the computational and experimental data in this area.</p>