On the use of pressure distributions to model the hydrodynamics of air-cushion vehicles and surface-effect ships

This paper surveys the research conducted on the hydrodynamics of traveling pressure distributions in the period since the first air-cushion-supported marine vehicles appeared. Most of this work has been based on the approximations of potential-flow theory with linearized free-surface conditions, because the level of pressures in these craft is sufficiently low to make these assumptions valid. The specific topics considered include the influence of the planform shape as well as the nature of the pressure fall-off at the edges of the distribution. The effects of canal sides and bottom (as in a towing tank) can also be included. Additionally, arbitrary motion of the pressure (representing a maneuvering vehicle) and fluctuating pressure (modeling the motions in waves) can be studied by the methods detailed here. A number of experiments have also been conducted. These show that there are many instances where the theory can be used to predict the resistance and other important quantities with useful accuracy. I would like to express my appreciation to Mr. Allen Ford of the David Taylor Research Center, Bethesda, for suggesting the preparation of this paper and for his careful review of the manuscript. Mr. Ford has done much to encourage my SES research, including the arrangement of an extended stay at the center during 1977. Much of my research reported in this publication was supported by the Office of Naval Research, the Naval Sea Systems Command (Surface Effect Ships Program Office), and the Australian Research Grants Committee.