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Thursday, March 3, 2011

HOVERCRAFT



                                            Christopher Cockerell built the first hovercraft in 1959 .
                                             

                                                          






hovercraft (air-cushion vehicleACV) is a craft capable of traveling over surfaces while supported by a cushion of slow moving, high-pressure air which is ejected against the surface below and contained within a "skirt." Although supported by air, a hovercraft is not considered an aircraft.


Hovercraft are used throughout the world as specialized transports. They can also be used after a natural disaster for emergency purposes. Because they are supported by a cushion of air, hovercraft are unique among all other forms of ground transportation in their ability to travel equally well over land, ice, and water. Small hovercraft are used for sport or passenger service, while giant hovercraft have civilian and military applications, and are used to transport cars, tanks, and large equipment in hostile environments and terrain.
                                                                            
                  




for the full wikipedia of hovercraft click on below link


How does it work?


             Hovercraft runs on two main important functions, lifting and propelling. The craft is lifted above the surface with the help of a giant fan that creates a massive air draft in the downward direction which pushes the craft up wards. The lift can be of a few centimeters or even inches. The fan is moved with the help of an engine which is located at the rear of the craft.
To quarantine the air underneath the craft a flexible rubber skirt is used. This skirt prevents the escape of air from beneath the craft and flexible rubber allows it to move over any obstacle in the way. The skirt has small holes to allow the air to escape, which also helps the craft to move. The edges of the skirt are made of extra thick rubber to create a seal between the skirt and the surface, which prevents the escape of air and also to reduce wear and tear due to the constant contact with the surface.
For the propulsion of the craft, small propeller fans are fitted on the top of the craft. These fans are run by separate diesel engines. These fans pushes the craft forward by creating a backward force. The fans are not like normal fans which pushes the air in a spiral way but are fitted with stationary blades which resist the spiral flow of air and thus provide a greater thrust.
For steering the craft, rudders are installed behind the fans. The rudder swivels the air from side to side to provide the required steering.

                                                          

                                                                Reference link -
                                     http://www.brighthub.com/engineering/marine/articles/31617.aspx