Practical Applications for Hovercrafts

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Juniper Carpenter
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1 Morgan Macdonald 5/18/04 Practical Applications for Hovercrafts Before you know what a hovercraft can be used for you have to know how it works. A hovercraft rides on a cushion of air that is continuously supplied by a lift motor and pushed into the space under the craft. A skirt is attached to the outer perimeter of the craft to contain the air beneath the craft. A hovercraft is normally pushed forward with a propeller and can be driven directly by the engine, or driven by a belt drive. Hovercrafts have no brakes; to stop a hovercraft you have too reduce power to the engines or by turning 180 degrees and hitting full throttle. You can steer the craft with moveable rudders or by changing the direction of the propellers. To steer a hovercraft, a person requires many different skills and techniques. Since it does not make contact with surfaces, it has a greater turning radius and requires a greater stopping distance. There is a time delay between the moving of a control and the vehicle s reaction. All forward motion is provided by thrust. Hovercraft s can be stopped by applying reverse thrust, reducing power, or making a 180 degree turn and applying thrust, or any combination of these. A hovercraft can travel faster over land, ice, or snow than over water. Over water, the air cushion that lifts the craft presses the surface of the water down. Hovercrafts create wave s in front and must have sufficient propulsion to push

2 itself over the wave. After accelerating to a constant speed the hovercraft will require very little power to keep going. There are many kinds of drag that exist on a hovercraft. Aerodynamic drag, which is relative to the size, shape, and frontal area of the craft. Momentum drag is caused by the lift systems (usually located in the front of the craft) and depends on the amount of air you are supplying to lift the craft. Over water other forms of drag exist, impact drag, water spray drag, and drag by the skirt occasionally contacting the water. A hovercraft would go faster with a tail wind rather than a head wind, or smooth water as opposed to rough water. The history of hovercrafts: hovercrafts were invented in 1956 by a man named Christopher Cockerell. He based his work on experiments done on a cat food can and continued his work for 5 years. In 1959 he built a hovercraft capable crossing the English Channel, he used a skirt made of elastic to counteract the heavy waves on the English channel. The cross channel journey earned him a knighthood, but his experiment was costly and a British based manufacturing company called Sanders Roe was capable of making a hovercraft that was more powerful and cost efficient. They named the hovercraft SR-N1, capable of carrying two full grown men and traveling at speeds of up to 25 MPH. they manufactured a new series of new hovercrafts in 1961 capable of transporting up to 30 people along the coast of Wales. In 1966 they completed work on the SR-N4 which could carry 254 people and 30 cars, it weighed 190 tons and was 40 meters long. In 1974 they redesigned the craft, it weighed 75 tons more but was capable of carrying twice as many cars

3 and 150 more people. This new hovercraft could travel 83 knots against winds of up to 50 knots. Ice Breaking: The Hovercrafts air cushion platform's icebreaking technique is very simple, because of its air cushion pressure capacity. As the platform moves over the ice, the air cushion pressure from the platform creates a thin gap between the bottom of the ice and the water. The water is forced away, leaving the ice suspended above the water. As it becomes heavier the ice snaps off and sinks below the hover platform. Hovercrafts are more efficient and economical than a traditional ice breaker, the platform doesn t need any special refinements and could be used at other times of the year as a transporter. Wear and tear on a hovercraft is also reduced because the low temperature of the ice does not effect the skirt as it does on the metal of a conventional ice breaker. Ice Rescue/Patrol: Because of the hovercrafts ability to hover, it makes an excellent ice-rescue and patrol craft. For example if someone were stranded on an ice flow, a hovercraft could easily traverse the rough terrain, transitioning from

water to blocks of ice. By propelling itself faster over the ice then a normal boat can travel through it, the hovercraft far surpasses the speed at which an ice based rescue can be conducted.

4 water to blocks of ice. By propelling itself faster over the ice then a normal boat can travel through it, the hovercraft far surpasses the speed at which an ice based rescue can be conducted. Conventional size hovercrafts are capable of speeds of up to 60 mph which would increase the speed of a ice rescue. Because of the hovercrafts ability to break ice it is also able to rescue people from boat trapped in ice and for making paths for possibly faster boats to get to the ship. Over half of all people the people who die in frozen water, die because rescue can not be conducted in it time. River Rescue/Flood Rescue: Because a hovercraft is not submerged in the water it easier for a hovercraft to simply glide over rough waters and currents then it would be for a conventional craft to try to fight the powerful flow of water. A hovercraft could easily travel through a flooded town and pick people up off their houses, without having to worry about current or debris in the water that a boat would need to avoid. A hovercraft could also travel up stream, making it possible for a faster rescue time. It is also capable of holing its position over rushing water

5 which makes it possible to wait at one point in a river to catch someone traveling down. Transport: Hovercrafts make very efficient transport vehicle because of the amount of poundage it can carry for its size. A 50 by 50 hovercraft can carry over 200 tons and still use the same amount of fuel. Hovercrafts are very space efficient and their ability to transition almost seamlessly from water to land eliminates the need for crowded docks and ports. This also makes it a very useful troop and personnel transport, because it is quieter then a normal landing craft and can continue to transport the people inside further onto the land. Hovercrafts are also more fuel efficient then cars because they have no friction with the ground, thus the same horsepower engine provides more thrust on a hovercraft then it would on a car. Although it would not be practical to replace cars with hovercrafts because they are hard to stop is crowded conditions such as city streets and busy freeways. They would be a more useful form of public transportation because they would be able to provide the same amount of transport capacity with less fuel and they would be able to transport across water. It would be a good change of pace to see all the gas guzzling SUV s replaced by smaller, more fuel efficient,

6 hovercrafts that are actually capable of being a sport utility vehicle and not just a suburban man s mini van. Military applications: The unique operating profile of hovercraft allows numerous military advantages over standard displacement vessels. Not restricted to operating over water, hovercraft can park on land to become part of the land mass on enemy radar, and can then intercept even the lowest draft high speed boats which must remain in navigable waters. The craft also has the ability to deliver troops, supplies or even vehicles directly onto land. It is capable of transporting 50 troops and two tanks or foul light armored troop transports. Because it is very stable over rough terrain and choppy waters and can be very useful as gunboats. With the ability to support many machine guns and even a few heavy guns, the hovercraft is a formidable foe for many boats. It is capable of

7 outrunning and out maneuvering most light military boats. The hovercrafts air cushion provides any weapons with a stable firing platform. It is also almost impervious to torpedoes and can duck below radar and evade detection. unfortunately hovercrafts cant be used for everything and they are not invincible. Their skirt can be vulnerable and is not un popable, although not completely necessary to generate lift the skirt plays and important role in maintaining pressure under the craft and the hovercraft will slowly loose its ability to hover, requiring it to land. It cant be used in city applications because it is hard to turn the craft sharply around corners and is hard to stop sharply. It is also very loud and is not suitable for crowded cities and quiet towns.

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WARNING: CHOCKING HAZARD

Hover Racer WARNING: CHOCKING HAZARD - Small parts. Not for Children under 3 years. To Parents: Please read all instructions before giving guidance to your children. A. SAFETY MESSAGES 1. This kit is intended