Page 12 - Theory and Design of Air Cushion Craft

Preface

It is 39 years since sea trials of the first hovercraft. Hovercraft are a new means of
transportation, and so machinery, equipment and structural materials have had to be
adapted for successful use in their special operating environment, which differs from
that in aviation and for other marine vessels.
A somewhat difficult technical and economic path has been negotiated by the devel-
opers of hovercraft technology to date. Currently about 2000 craft are in operation for
commercial water transportation, recreation, utility purposes and military applica-
tions around the world. They have taken a key role for a number of military missions,
and provide utility transportation in a number of applications which are quite unique.
Hovercraft in China have developed from prototype tests in the 1960s, to practical
use as ferries and military craft. More than 60 hovercraft types have been constructed
or imported for operation in China. This book has been written to summarize the
experience in air cushion technology in China and abroad to date, with the aim of
improving understanding of air cushion technology.
Due to the relatively quick development of the cushion technology relative to other
water transportation, the theories and design methods applied to hovercraft design
and operations are continuing to develop at present. For instance various quasi-static
theories of the air jet cushion were derived in the 1960s, but once the flexible skirt was
developed, the hydrodynamic and aerodynamic forces acting on hovercraft changed
so significantly that these earlier theories and formulae could not continue to serve in
practice.
The theory of air cushion performance has therefore changed significantly since the
1960s. On one hand a lot of technical references and some technical summaries and
handbooks with respect to air cushion technology are available to translate the phys-
ical phenomena but on the other, owing to different research methods, objects and
means, there are many different methods which suggest how to deal with such theo-
ries. So far no finalized rules and regulations for hovercraft construction can be stated.
In addition regulatory documents concerned with stability, seaworthiness and the cal-
culation methods determining the static and dynamic deformation have not reached
public literature.
The aim in writing this book has been to summarize the technical experience, both
in China and abroad, to systematically describe the theory and design of hovercraft,
and endeavour to connect the theories with practice in order to solve practical prob-
lems in hovercraft design.