Hovering Performance of a Rotor in a Dynamic Ground Effect

Modern day helicopters are frequently required to operate close to non-uniform ground surfaces. During operations above a moving ship deck, it can be foreseen that the hovering performance of the rotor has very different behavior compared with the cases of hovering above stationary flat ground plane. In this report, the hovering performance of the rotor above the moving ground in full ground effect is experimentally studied in order to provide qualified database for the validation of analytical study on dynamic ground effect. The moving ground is simulated by means of harmonic rolling and heaving motions of ground effect plate with variable amplitude and frequency. The thrust, torque and blade flap angle of the rotor were measured at rotor height from 0.4 to 1.5. It is shown that motion types of the ground and the amplitude and frequency of the moving ground have important effects on the variable loads in and out of the rotor disk in dynamic ground effect.