Problems Associated with the Use of Skirts on Hovercraft

Abstract

The lecture commences with a brief description of early hovercraft work and shows how the advent of flexible extensions to the peripheral jets—or ‘skirts’—constituted a breakthrough without which the hovercraft would never have become a practical proposition with the ability to operate over waves and rough ground. It is shown that the introduction of skirts, whilst providing a solution in one respect, also led to a series of problems and three of these are singled out for further discussion.

First it is shown that whilst a relatively high internal skirt pressure is desirable to maintain skirt shape under operational conditions, this pressure can also lead to a high rough water drag.

The second problem is that of ‘plough in’ and overturning, which is intimately associated with the use of skins. The hydrodynamic mechanisms of both these undesirable phenomena are for the first time explained in detail and are illustrated by means of data obtained from two- and three-dimensional model tests.

The third problem raised by the introduction of skirts is skirt oscillation and wear. The techniques necessary to investigate delamination are described and some of the factors which have been shown to be important in increasing delamination life are outlined.