SEMINAR ON HOVERCRAFT

Introduction A Hovercraft is a vehicle that

Flies like a plane but

Float like a boat

Drive like a car

It can hover over or move across land or water surfaces while

being held off from the surfaces by a cushion of air.

SOME PICS OF HOVERCRAFT

A Hovercraft can travel over all types of

surfaces including grass, mud, muskeg, sand,

quicksand, water and ice .Hovercraft prefer

gentle terrain although they are capable of

climbing slopes up to 20%, depending upon

surface characteristics.

SUMMARY

HISTORY - CONSTRUCTION OF HOVERCRAFT - VARIOUS PARTS AND ITS FEATURES - WORKING PRINCIPLE - VISUAL ANIMATION OF WORKING - ADVANTATES - FUTURE OF HOVERCRAFT - CONCLUTION

History The first design by Swedish designer Emmanuel

Swedenborg in 1716.

The project was short-lived because it was never built, for soon Swedenborg soon realized that to operate such a machine required a source of energy far greater than that could be supplied by single human equipment.

Until the early 20th century Hovercraft was not practically possible, because only the internal combustion engine had the very high power to weight ratio suitable for Hover flight.

THE FIRST HOVERCRAFT

Christopher Cockerel thought of using a load of stuff you might find about the house to make a hovercraft.

Cockerel took a set of scales and a long rod and arranged them so the rod was vertical.

He then affixed a vacuum cleaner to the rod so it pointed down.

THE FIRST HOVERCRAFT

Next he made a hole in a can and affixed a can that was smaller than the first in such a way it allowed air in-between the two cans. Cockerel made the vacuum cleaner blow instead of suck, blowing air through the gap in the two cans, and it worked.

The scale went down as far as it could!.

BASIC STRUCTURE OF HOVERCRAFT

Parts Of Hovercraft

Lower hull:-

It is the basic structure on which the Hovercraft floats when the engine is stopped while moving over water.

It supports the whole weight of the craft.

the lower hull of the craft include the craft floor, side panels, forward and aft panels, the top skirt attachment line.

materials used include balsa wood, PVC , SAN (styrene acrylonitrile) and plastic.

Requirements of Lower Hull:

needs to have adequate size for the total weight of craft and payload.

Must be strong enough to support craft  off cushion ( on landing pads). 

Have enough freeboard to support craft in displacement mode on water.

Must be watertight and as smooth as possible 

o Propeller :- It pushes the hovercraft ahead by

pushing air behind.

powered by a powerful gas turbine or diesel engine.

o Lift Fan :- Primary purpose is to inflate the cushion

contained within the skirt beneath the craft as well as to provide thrust with which to propel the craft forward.

Rudders :-They are similar to that used in an

aircraft

Rudders are moved by hydraulic systems

By moving the rudders we can change the direction of the craft

Skirt :-They are air bags inflated by air are

fitted around the perimeter of the craft hold air under the craft and thus upon a cushion of air.

It enables to obtain greater Hover height.

The material used is rib stop nylon or Polyethylene terephthalate.

Part that allows the hovercraft to clear obstacles. Generally speaking, the higher the skirt, the larger the obstacle that the craft will clear.

THREE TYPES OF SKIRTS

Bag skirtThe inflated loop consists of a tube of material (similar in a way to a car inner tube) which is inflated at a slightly higher pressure than the air cushion beneath the craft

Finger skirtThe finger skirt

is comprised of a large number of separate segments which are able to slide and bellow individually to conform with the shape of the water surface or terrain over which the craft is traversing.

Bag and finger skirtThe integrated bag and finger skirt compromises between the flexibility of the finger skirt and the economy of the bag skirt

PRINCIPLE OF WORKING To lift the craft by a

cushion of air to propel it using propellers.

The air sucked in through a port by large lifting

fans which are fitted to the primary structure

of the craft.

They are powered by gas turbine or diesel

engine.

Fan is used to inflate the skirt and rest is ducted down under the craft to fill area enclosed by the skirt.

At the point when the pressure equals the weight of the craft, the craft lifts up and air is escaped around the edges of the skirt. So a constant feed of air is needed to lift the craft and compensate for the losses.

ADVANTAGES OF HOVERCRAFT Travel over any surface.

Shortcutting routes.

Travel rivers up as fast as down, irrespective of the current.

Travel in dry water-beds.

No collision with debris, logs etc.

Access to 75% of coastal area instead of only 5% with conventional vessels.

Hovercraft are very fuel efficient (CO² friendly) as Hovercraft do not have to plough through

the water but "fly" above the surface At maximum speed fuel consumption of a

Hovercraft is approx. 70% less than of a fast patrol boat with similar payload capacity.

No turbulence or impact in water as no propeller

churns up the water so sea life remains untouched

It can travel with great speed of up to 60 knots

Hovercraft are unaffected by small waves and offer a comfortable smooth ride

It is safe around swimmers as there are no propellers in water

Many Hovercraft have sufficient hover height, ranging from 8 in to 18 in to pass right over a person in water

FUTURE OF HOVERCRAFT The future of

hovercraft seems uncertain, but there is a good chance there will be huge hover ports all over the world, like the one in the picture. Thinner hovercraft might be built so civilians can drive safely on roads. It also seems likely that the larger hover vehicles will become larger than ever! Hovercraft are likely to be capable of high flight.

CONCLUSION Hovercrafts are generally simple

mechanisms in theory. Yet the process from theory to manifestation is not as easy as it may seem. A plethora of problems exist and must be faced in order to attain a well functioning hovercraft. The plans and designs must be flawless. One must take under consideration the weight and the shape of each component in order to avoid problems such as instability and dysfunction. One thing is certain; when building a hovercraft, be well aware of the demands of construction. Be prepared and willing to embrace failure for it is the only way to success. Only after failed attempts will you be able to finally design an effective hovercraft.

REFERENCES

http://4wings.com.phtemp.com/tip/lh.html http://www.hovercraft.com/content/ http://en.wikipedia.org/wiki/Hovercraft http://www.hovercraft-museum.org/ http://www.deloreanhovercraft.com/

THANKS