whether W.I.G.
vehicles were aircraft or
boats. Some could fly, some could not. Some were built by ship builders, some by aircraft
builders. By the early nineties authorities in Russia recognized the need for an
international approach to this uncertainty and convinced the IMO to start working on rules
for W.I.G. craft.
The International Maritime Organization (IMO) is the United
Nations' specialized agency responsible for improving maritime safety and preventing
pollution from ships. The new rules were based on the International Code of Safety for
High-Speed Craft (HSC code) which was developed for fast ships such as hydrofoils,
hovercraft, cats and the like. Currently the International Code of WIG Craft Safety
(WIG code) is nearing completion.
The WIG code
covers a lot of aspects of WIG craft design and operation, but one of its
most important issues is the definition of three different types of WIG craft, depending
on their ability to fly without ground effect. In that case not only IMO, but also ICAO is
concerned with the rules.
The International Civil Aviation Organization (ICAO), like the IMO, is
also a UN agency. It is responsible for safety and overall organization of civil aviation
world-wide. A very important aspect of this recognition of three different types of WIG
craft is the fact that not all WIG craft need to comply with the very strict aviation
rules (Type C only). So far this has never been clear. This saves money, since some redundant equipment
and special aviation rated parts are no longer required and cheaper marine equipment can
be used.
The three types are defined as follows:
-
Type A
A WIG craft that is not able to operate without ground effect at all.
-
Type B
A WIG craft that is capable of temporarily increasing its altitude beyond the extent of
ground effect in order to jump over an obstacle. Temporarily means that the craft cannot
maintain flight without the support of ground effect, it is only possible by converting
kinetic energy into potential energy (height). The maximum height during such a
maneuver
is less than the minimum safe altitude for an aircraft as prescribed by ICAO.
-
Type C
A WIG craft that is capable of maintaining flight without ground effect at altitudes
exceeding the minimum safe altitude for an aircraft as prescribed by ICAO. The only thing
that distinguishes these craft from floatplanes or flying boats is its design that is
adapted to safe flight in ground effect.
The areas of competency of the different agencies explained in the following
table:
| Operational mode |
Type A |
Type B |
Type C |
| Displacement |
IMO |
IMO |
IMO |
| Transitional |
IMO |
IMO |
IMO |
| Skimming |
IMO |
IMO |
IMO |
| Take off / Landing |
IMO |
IMO |
IMO |
| Surface effect |
IMO |
IMO |
IMO |
| Fly over |
n/a |
IMO/ICAO |
IMO/ICAO |
| Aircraft |
n/a |
n/a |
ICAO |
n/a = not applicable
The operational modes are:
| Displacement |
is the regime where the weight of the craft is predominantly supported by hydrostatic
forces, either at rest or in motion |
| Transitional |
is the regime between displacement and skimming. |
| Skimming |
mode is where the weight of the craft is supported mainly by non-hydrostatic forces
(aerostatic or hydrodynamic). |
| Take off / Landing |
is the mode between skimming and surface effect flight. |
| Surface effect |
(also denoted by Flaring mode) is the main operational mode where the weight of the
craft is supported by aerodynamic ground effect, there is no water contact. |
| Fly over |
means that the WIG craft is not supported by ground effect anymore, but is still below
the minimum safe altitude for an aircraft over sea (150 m). |
| Aircraft |
is true flight, over the minimum safe altitude. |
The speed, height and design of of the craft determine in which mode a craft is. The
operational modes are not dependent on the type, so for example a Type C craft can be in
surface effect mode or in fly over mode. Of course a Type A craft can never be in aircraft
mode.
The WISE series by Pacific Rim Design
Center will be designated
Class B vehicles:
-- capable of flight above ground effect -- but only for sustained flight at altitudes
below 150 meters. This altitude (487 feet) provides the pilot with ample
maneuvering
room to clear bridges, yachts, floating cranes, buoys, derricks, power lines, or many
similar obstacles. Our craft will fly
at a cruising altitude of 15 to 50 feet, depending on wingspan.
