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How a Hovercraft Works

Extracts from the book 'Discover the Hovercraft'

By Kevin Jackson  ISBN 0-9753414-0-5

 

 

'Discover the Hovercraft'

Tells you how it all started -

 

A Hovercraft is also sometime called an Air Cushion Vehicle or ACV. This is a vehicle that flies like a plane but can float like a boat, can drive on land like a car but will traverse ditches and small gullies like it is flat terrain. The Hovercraft is a unique method of transportation.

 

Modern Hovercraft are used for many applications where people or equipment need to travel at speed over water but be able to load and unload on land. The hovercraft engine provides the power to drive large fans that blow air under the craft. The air is retained by a rubber ‘skirt’ that enables the craft to travel over a wide range of terrain. The skirt simply gives way when an obstacle is encountered.

 

The engine also supplies power to a thrust propeller of some kind that pushes the craft forward on its ‘bubble' of air. Rudders, like on a airplane, steer the direction of the craft.

 

So how did this craft come to be designed, who worked on the design and who invented the Hovercraft? Well,  it all started with two tin cans and a vacuum cleaner……… 'Discover the Hovercraft' tells you how and when it all happened.

 

All Text Copyright © 2004 Flexitech LLC 

 

'How a Hovercraft works' is a preview extracted from: 

 

Discover the Hovercraft 

by Kevin Jackson 

Available Now

ISBN 0-9753414-0-5

Click on the book cover below 

for more details

 

Just $11.99

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Sample Text from Chapters of 'Discover the Hovercraft'

 

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Small Boats and Air Bubbles

 

The idea of supporting a vehicle on a cushion of air developed from an idea to increase the speed of boats by feeding air beneath them. The air beneath the hull would lubricate the surface and reduce the water drag on the boat so increasing its speed through the water.

 

The idea first came to Christopher Cockerell  who was later knighted Sir Christopher for his work on the Hovercraft. He was an engineer at heart and was always looking for solutions to difficult problems.

   

 

 

 

Developing the Air Cushion

 

In a basic Hovercraft design large ducted fans, like enclosed propellers, are used to provide lift by keeping a low-pressure air cavity under the craft full of air. As the air pressure is increased the air lifts the craft by filling the cavity.

 

To maintain the lift the engine and propeller or fan have to be sufficiently powerful enough to provide a high airflow rate into the chamber. The flow has to be greater than the amount of air that escapes from around the edges of the plenum chamber. The rate of the air loss is not constant and there is no way of ensuring that any air escapes evenly all around the craft. A solution to this problem had to be found.....

Background - The book gives an account of Sir Christopher's life and traces his Hovercraft development work in detail


 

Want to know more? - Some of the detailed information available in 'Discover the Hovercraft'

 

 

Packed with hovercraft facts and figures - 

 

                - Explore Hovercraft Design

      

               - Understand the Hovercraft Principle

 

               - Trace the History of its invention 

 

               - Build and experiment 

 

This Books covers:

  • Hovercraft theory

  • Hovercraft history

  • Basic design principles

  • Hovercraft applications

  • Hovercraft skirt operation

  • Momentum curtain effect

  • Early Hovercraft designs

  • Hovercraft models

  • Lift and thrust

  • Hovering power

  • Modern craft designs

  • Other hover applications

  • The future

      To buy a copy now Click HERE


Fig 1. The original two cans experiment

Two Tin Cans and a Bit of Air

 

His first experiments were conducted with the aid of two cans and a vacuum cleaner . 

 

Figure 1:  shows the original configuration of the two cans and vacuum.

 

The resulting experiments demonstrated a feasible design for a Hovercraft the key to improving the crafts stability. 

 

Experiments - The book shows you how to build and demonstrate the above experiment yourself using standard household items

 

 

Hovering Power

 

If the craft is to hover, the pressure of air forming the cushion must meet certain criteria. From existing designs of  Hovercraft that have been developed, it is possible to make some simple estimate of the power needed to lift a Hovercraft. 

 

Math - The book shows you step-by-step how to calculate the exact pressure required to lift a craft of a given size

   

 

 

SR.N6 Hovercraft

The Thrust Propeller

 

The propeller used to drive the hovercraft along is usually an aircraft type with variable pitch blades. 

The amount of propulsion which the propellers provide is obtained by varying the propeller pitch.

 

 

All Text Copyright © 2004 Flexitech LLC 

 

'How a Hovercraft works' is a preview extracted from: 

 

Discover the Hovercraft 

by Kevin Jackson 

 

Buy your copy now by 

clicking HERE

 

ISBN 0-9753414-0-5

 

 

Hovercraft Skirts

 

Simple obstacles such as small waves, or tide-formed ridges of shingle on a beach, could prove to be too much for the simple hovercraft designs. These problems led to the development of the 'skirt'.

 

The skirt of a hovercraft is one of its most design sensitive parts. The design must be just right, or an uncomfortable ride for passengers or damage to the craft and the skirts results. The skirt material has to be light flexible and durable all at the same time.

 

The Lifting Fan

 

The fan needs to force air into the chamber below the craft so creating a specific pressure under the craft. The lifting fan on most Hovercraft uses what is known as a centrifugal fan (See fig 2). This is a fan in which two discs and fitted together and looks rather like a doughnut with angled slats at their edges. 

 

This type of fan has some specific characteristics that make it very suitable for this type of application.

The Engine

 

The engines used in Hovercraft have evolved like the skirt design. The SR.N1 and other early craft used piston type engines. As models like the SR.N4 and SR.N6 were brought into service they tended to favor the use of gas turbines. 

However the use of these engines results in a very high level of engine noise outside the craft. With the newer generation of craft close attention was  paid  to engine noise and fuel efficiency. 

 

Hovercraft Applications - The book discusses past and current Hovercraft applications, where and how they are used.

 

 

 

- Use of this text is not authorized 

for any commercial purposes -

 

 

 

 

 

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 November 05, 2004