Hovercrafts

Air-Cushion Vehicles (ACVs); Ground effect vehicle or (GEVs); sometimes refered to as Wing In Ground effect or WIG

Hovercrafts

A Hovercraft, or Air-Cushion Vehicle (ACV), is an amphibious vehicle or craft, designed to travel over any sufficiently smooth surface - land or water - supported by a cushion of slowly moving, low-pressure airiness, ejected downwards against the surface close below it. Recreational hovercrafting, while popular in England and elsewhere in Europe, enjoys relative obscurity in the United States. But the time for riding on air may be at hand considering this country's ravenous appetite for new and cool things to do.

There are a large number of sports that involve water. Usually a boat (a watercraft designed to float or plane on water, and provide transport over it) is used. Hovercrafts, however, provides unbelievable freedom compared to most other land and water craft because you will be able to drive from land to water and back again. The age of the Hov Pod is NOW! A hovercraft such as the Hov Pod, can glide over any smooth surface, moving directly from land to water, mud, sand, ice, and snow.

A well-designed hovercraft is far more superior to a boat because it has less drag and requires less horsepower to operate. Hovercrafts are usually 100% more fuel-efficient than boats with similar capacity or size. And, rising fuel prices and shortages will make the hovercraft a more desirable form of transportation in the near future.

Hovercraft have one or more separate engines (some craft, such as the SR-N6, have one engine with a drive split through a gearbox). One engine drives the fan on the bottom of the hovercraft,(the impeller) which is responsible for lifting the vehicle by forcing high preassure air under the craft. The air therefore must exit throughout the "skirt", lifting the craft above the area on which the craft resides. One or more additional engines are used to provide thrust in order to propel the craft in the desired direction (these engines help push the hovercraft). Some hovercraft utilise ducting to allow one engine to perform both tasks by directing some of the air to the skirt, the rest of the air passing out of the back to push the craft forward.

The Principals of a hovercraft are very similar to that of an airplane or helicopter. Helicopters have the ability to hover in-ground-effect (IGE) and the capability to hover out-of-ground-effect (OGE). There is a roll, yaw and pitch associated with a hovercraft. However, it does not fly high enough to be significant in a roll, yaw, or pitch scenario. It can be precarious due to the lack of experience of the pilot and can result in severe damage to the craft and other objects.

Licensing a hovercraft is no different than licensing a boat. Except for certain unofficial rules that are set forth by representatives of individual districts, regulations are vague to non-applicable. Hovercraft are listed under the Coast Guard regulations in all 50 states. You can get a courtesy sticker from the Coast Guard to show that you are a caring and confident pilot in your Hovercraft. You will earn a lot more respect from this action, especially from your passengers.

Hovercraft --- Fly on a cushion of air; gliding across the sea, lakes, rivers, grassland, marsh, sand, snow and ice!

 

One interesting variation on the hovercraft is the "wing in ground effect," or WIG, craft. Not available for general sale, WIGs currently are in the domain of the homebuilder and experimenter.

 

Ground effect vehicle or (GEVs):

Ground effect is a phenomenon of aerodynamics where the flow of air around part of an aircraft is interrupted by the ground.

Aircrafts obtain increased lift when flying very close to the ground. Therefore, Ground effect affects most aircraft only at takeoff and landing. Ground effect occurs over water as well as over land. On a fixed-wing monoplane this lift occurs about half the distance from a wingtip to the fuselage. Ground effect vehicle or (GEVs), sometimes refered to as Wing In Ground effect or WIG are designed to only fly in ground effect.

A ground effect vehicle (GEV) cannot sustain flight more than a few feet above the ground. Thus, GEVs are aircrafts that always operates in the ground effect. Hovercraft are often erroneously called ground effect vehicles. Most GEVs are intended to operate over water since suitable operational areas over land are rare.

Most pilots, especially of small aircraft, will experience ground effects on landing. In fact the art of landing largely comes down to understanding when these effects need to be taken into account. The aircraft is not affected by ground effect as it descends towards the runway. Ground effect only cause a pronounced increase in lift as the aircraft flares and descends the last few feet. If not anticipated by the pilot this can cause the aircraft to rise suddenly and significantly, an effect known as a "balloon". Ballooning can lead to a dangerous situation if left uncorrected. Landing speeds are generally just a very small margin above the stall speed. The ballooning aircraft is rising yet decelerating, a condition which can rapidly lead to an untimely stall. A stall even from a few tens of feet above the ground can cause a major, possibly fatal, crash. Ballooning may be corrected provided there is sufficient runway remaining. However, for novice pilots a better option is a "go around", increase spead and go around the traffic patern again for another landing. A good landing allows for ground effect. The pilot flares the aircraft and hold off in ground effect until it gently descends to the right height, then the pilot stall the aircraft onto the runway.

 

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