PRESENTATION ON

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PRESENTATION ON HOVERCRAFT
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CONTENTS

• INTRODUCTION
• HISTORY
• DESIGN AND OPERATION
• OTHER APPLICATIONS
• ADVANCEMENT IN TRANSPORTATION METHOD
• FUTURE OF HOVERCRAFT
• SOME AVAILABLE HOVERCRAFT

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INTRODUCTION

• Known as Air Cushion Vehicle (ACV).
• It flies like as an aeroplane , float like a boat
  ,can drive on land like a car.
• Its engine provides the power to drive large fans
  that blows air under the craft, this air is
  retained by a rubber skirt that helps to move the
  hovercraft.

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A hovercraft
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Tchnical definition

• Any of the machines characterized by movement in
  which a significant portion of the weight is
  supported by forces arising from air pressure
  developed around the craft, because of which they
  hover in close proximity to the Earths surface
  can be put under the category of HOVERCRAFT or
  GROUND EFFECT MACHINE.

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HISTORY

• First man to introduced the concept of ACV was
  Sir John Thornycroft in 1870.
• First practical use was made in 1929 by German
  Dornier DO X flying boat.
• Work went on its peak during World War -2.
• In 1960s,American aerodynamicist developed an
  experimental craft.Experiment went on many more
  experimental craft. But they remain experimental.
• Finally invented by Christopher Cockerell of UK.
• He patented it on Dec. 12, 1955.

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Theory of sir Cockerell

• If air were pumped under the vessel through a
  narrow slot running entirely around the
  circumference, the air would flow toward the
  centre of the vessel, forming an external curtain
  that would effectively contain th ecushion.this
  system is known as the Peripheral Jet. Once air
  has built up below the craft to a pressure
  equaling the craft weight, incoming air has
  nowhere to go but outwards and experiences a
  sharp change of velocity on striking the surface.
  The momentum of the peripheral jet air keeps the
  cushion pressure.

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DESIGN AND OPERATION

• Basic elements
• Skirt arrangement
• Power plant
• Thrust propeller
• ACV operation

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BASIC ELEMENTS

• A HULL
• A SKIRT SYSTM
• A PROPULSION SYSTEM
• A LIFT SYSTEM

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Skirt system is beneath the hull .On the skirt
system accomodation for passenger, crew and
fright is built. Lift system feeds air into the
plenum chamber below the craft in order to
provide a cushion. The propulsion and lift system
can be driven by the same power plant or by
separate unit. The power to weight ratio is very
critical and it detrmines not only the payload
and performance of the craft but also the ground
clearance between the surface and the skirt. Hull
structure are of marine aluminium skin,welded or
riveted onto aluminium webs or frames. The cavity
or chamber in which the air is kept is called a
plenum chamber.
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SKIRT ARRANGEMENT

• The skirt is a shaped, flexible strip fitted
  below the bottom edges of the plenum chamber
  slot. As the hovercraft lifts, the skirt extends
  below it to retain a much deeper cushion of air.
  The development of the skirt enables a hovercraft
  to maintain its normal operating speed through
  large waves and also allows it to pass over
  rocks, ridges and gullies. It is of semicircular
  shaped .

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POWER PLANT

• Early crafts used piston type engine.
• After that gas turbine engines were evolved.
• The engine has a main shaft having a compressor
  and a turbine .A starter motor is connected to
  one end of the shaft and the other end is to lift
  fan and propeller gearbox.
• These engine creates a lot of noise.
• Newer engines are made to make engine noise low
  and greater fuel efficiency.

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Centrifugal lift fan
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THRUST PROPELLER

• Usually an aircraft type with variable pitch
  blades.
• The propeller can vary from four-bladed versions
  and about 9 feet in diameter to the 4 propeller
  and 19 feet in diameter.

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ACV OPERATIONS

• Confined to commercial passenger-carrying ferry
  service(5 to 40 KM), military operations.
• Also used for seismic survey parties,either over
  shallow-water areas or in deserts, search and
  rescue operations.
• US used these in Vietnam operations. Later used
  as mine-countermeasure works,antisubmarine
  works,aircraft carrying and missile launching.

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OTHER APPLICATIONS

• Experiments are going on for hover car and hover
  train.
• This principle is used for moving large or heavy
  objects.

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Advancement in the transportation method

• Air cushion concept was used for passenger
  carrying trains.In 1970s 235 mile/hr. speed was
  achieved.
• French French got 300 mile/hr.
• Many experiments are going on this project but
  now emphasis has diverted to magnetic trains

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Future of hovercraft

• ACV vehicles have not yet fulfilled their
  origianal promise. These hovercrafts are not
  economical although they are idle in military
  application.
• So research is mainly going on for military
  purposes.

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Some available hovercraft

• Surveyor Mk3  
• Type           Enclosed Cabin, high-class
  passenger style hovercraft.
• Length         10.0metres
• Width          4.1 metres
• Capacity      18 passengers or 2,000kg
• Engine         Deutz BF6M-1013ECP
• Application   Passenger transport, Coast
  Guard/Military Patrol, Search Rescue, Medivac,
  Freight

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Pioneer Mk2  Type            Enclosed Cabin,
high-class passenger style hovercraft.
Length         11.6 metres Width          4.8
metres Capacity      30 passengers or 3,000kg
Engine         Deutz BF6M-1015C (330 kW _at_
1900rpm) Application   Passenger transport, Coast
Guard/Military Patrol, Search Rescue, Medivac,
Freight.
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Special Purpose Hovercrafts AIRLIFT
950A          (Ambulance) Type            Enclosed
Cabin. Installed ambulance equipment.
Length         9.5 metres Width          4.2
metres Capacity      1 crew 14 seats, centre 6
seats can be converted to 2 stretcher spaces or
operating table. Engine         2 x Cummins 6BTA
5.9 diesel, 2 x 134kW _at_ 2600rpm
Application   Ambulance, health services.
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AIRLIFT 1060FT     (Fire Tender)
Type            Fire-Fighting and Rescue
hovercraft. Length         10.6 metres
Width          4.6 metres Capacity      2 to 6
crew plus equipment Engines       2 x Cummins
6BTA 5.9 diesel, 2 x 134kW _at_ 2600rpm
Application   Fire fighting, Pollution control,
Dive tender, Rescue.
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