Hovercrafts

Presentation By-
Chirag Solanki

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

 Known as Air CushionVehicle (ACV).
 It flies like as an aero plane , 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.

 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
Earth’s surface can be put under the category
of HOVERCRAFT or GROUND EFFECT
MACHINE.

 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.

 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 the cushion .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.

 Basic elements
 How a hovercraft
works?
 Skirt arrangement
 Power plant
 Thrust propeller
 ACV operation

 A HULL
 A SKIRT SYSTEM
 A PROPULSION
SYSTEM
 A LIFT SYSTEM

A hover craft is a machine that rides on air
under pressure that is continuously supplied by
the lift system. A flexible curtain called a skirt
is attached to the base. The hovercraft is
propelled by a thrust propeller. The steering is
applied by using a rudder on the back of the
propeller. stopping is achieved with the
reduction of power engines or turning 180
degrees and applying full thrust.

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 .

Skirt system is beneath the hull .On the skirt system accommodation 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 determines 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 aluminum skin , welded or riveted onto aluminum
webs or frames.
The cavity or chamber in which the air is kept is called a ‘plenum’ chamber.

 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.

 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.

 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.

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

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

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

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

Pioneer Mk2
Type Enclosed Cabin, high-class passenger style
hovercraft.
Length 11.6 meters
Width 4.8 meters
Capacity 30 passengers or 3,000kg
Engine Duets BF6M-1015C (330 kW @ 1900rpm)
Application Passenger transport, Coast Guard/Military Patrol,
Search & Rescue, Medivac, Freight.

Special Purpose Hovercrafts:
AIRLIFT 950A (Ambulance)
Type Enclosed Cabin. Installed ambulance equipment.
Length 9.5 meters
Width 4.2 meters
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 @
2600rpm
Application Ambulance, health services.

AIRLIFT 1060FT (Fire Tender)
Type Fire-Fighting and Rescue hovercraft.
Length 10.6 meters
Width 4.6 meters
Capacity 2 to 6 crew plus equipment
Engines 2 x Cummins 6BTA 5.9 diesel, 2 x 134kW @
2600rpm
Application Fire fighting, Pollution control, Dive tender,
Rescue.

Hovercrafts

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Hovercrafts