An air cushion
is a space containing air under pressure, generally placed under a
vehicle or an object to be moved. This air must be constantly renewed,
either by a fan or by the movement of the vehicle as it
"bleeds" from the relevant peripheries about the vehicle.
The flow of air leaving the hovercraft air cushion is directly
proportional to the craft peripheral length and hovercraft height. In
order to reduce the flow and the power required to maintain it, flexible
skirts were developed, allowing the hovercraft to maintain a reasonable
hover height with a few centimetres air escape gap and minimal
Below are some
of the common style "skirts" employed by various hover craft
over the years.