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Glossary.
In this section I'll attempt to explain the various terms used on the rest of this site.
If you find any terms misleading or poorly explained, please drop me a line.
- Bag skirt.
- A simple skirt consisting of a bag extending around the edge of the
hull.
- Bowden cable.
-
Typically used
for throttle or brake cables, bowden cables have a flexible steel stranded
cable, surrounded by an outer flexible sleeve. the outer sleeve is fixed at
each end, allowing the inner to be pulled. A bowden cable can only be used to
pull and so some kind of spring return must be used. See Morse cable. - Chip bag.
A chip bag is another variation on the standard open segment. This time the modification is to
improve the segments performance at the rear of the craft. An extra flap of
fabric is sewn into the segment to prevent water rushing in when the craft is
not on full cushion over water. - Kill switch.
- The kill switch is part of the ignition circuit. It has two contacts held
apart by a small clip attached to the lanyard. In order
for the engine to run, the Lanyard must be in place. If
it is removed, the kill switch will close,
killing the spark and stopping the engine.
- Lanyard.
- A lanyard on a hovercraft is a piece of rope or similar, worn
around the wrist of the driver and connected to the kill switch. If the driver is
thrown from the craft, the lanyard will pull free from the kill
switch, stopping the engine.
- Morse cable.
- A Morse cable is similar in construction to a bowden cable but can also be used to push. It achieves
this by using a sleeve at the end of the cable to contain the flexible inner
and a steel rod transmits the movement.
- Open segment.
An open segment is the
most basic of the skirt segments. Usually made from a
single piece of fabric, the bottom edge is completely open. Compare this to a
chip bag or pressure
segment, both of which have additional pieces of fabric to control the air
flow.- Plough-in.
- A craft is said to "plough-in" when the skirt segments (usually at the
front of the craft) collaps on water. This is more likely to happen when
travelling down wind. As the front of the craft is pushed down by the
following wind, the skirt segments are pushed down into the water and drag
increases. This in turn pulls on the segments slowing them down and forcing
the air out of them. Friction increases and the craft can slow down
dramatically, often resulting in the driver being thrown out. Integrated
craft are more likely to suffer than those with a lift fan.
- Pressure Segment.
A pressure segment is similar in design to a
basic open segment but with an extra piece of fabric inside. The idea is that
when the segment starts to collapse, either due to a plough-in or because of some obstacle, the front of the
segment closes in on the flap inside and keeps the air in, preventing the
segment from deflating completely.- Segmented skirt.
- Skirts of this type are made up of series of
individual cushion segments. Usually between 54 and 60 will be used. These are
fixed to the hull at the top and bottom. Three main types of segment are used;
open, pressure and chip
bags.
- Skirt.
- The skirt is fixed around and
below the hovercraft. It provides a flexible interface between the
craft and the ground, conforming to the surface whilst keeping the
air cushion inside. There are two main types of skirt used in racing
hovercraft, the segmented skirt and
the bag skirt.
(c)2003 Andy Collins. If you find any errors please email.