Suppression of Variation in Cushion Pressure for SES Using Vertically Moving Nozzles

In this paper, variation in cushion pressure is investigated theoretically to achieve SES ride comfort. A simple and practical control method is proposed to control cushion pressure changes caused by pumping that appears in SES cruising over waves. Cushion pressure is controlled by varying the discharge height of the vertical nozzle. In this method, the nozzle height (hover height) is kept constant according to craft motion. As the result of investigations, cushion pressures are controlled successfully by the proposed method. In addition, we show that the pressure variation depends both on hover heights and on the rates of change in cushion volume. Therefore, it is necessary to consider phase differences between craft motion and vertical nozzle displacements.