To drive on land, you need some wheels. To drive on the water, wheels won’t do any good but a propeller will get you going. To travel on ice, you’ll need skis, snow tires, or chains to keep from slipping and sliding out of control. Right?
Well, kind of right. Right in most cases, anyway. But if you’re driving a hovercraft, all you need is one vehicle and you can travel across the land, over the ice, and straight into the water without ever slowing down.
A hovercraft doesn’t have wheels at all, or skis, but it does have at least one propeller. And a skirt. The propeller sits high above the back of the craft and it powers the engine, just like it does with a boat, but it does something totally different, too.
The hovercraft’s propeller also powers a specially designed fan, called an impeller, which forces the air above and around the hovercraft to go down below the vehicle, where a layer of high-pressure air forms a cushion above the ground. It’s this cushion of pressurized air that makes the hovercraft go. The hovercraft’s skirt helps keep the pressurized air underneath the craft and it helps the propellers push air out the back end, which causes the hovercraft to go forward.
The air cushion underneath the hovercraft acts as the machine’s wheels, skis, snow tires, and propeller. The entire vehicle rests, or hovers, above the ground surface without touching the ground itself. Since it never touches the ground, the hovercraft can go just about anywhere, even when the ground surface changes from land to water to ice.
It may seem like a machine that floats along on a cloud of air would be pretty delicate but even armies use hovercrafts and they use them for some very important operations. The US Navy uses hovercrafts to transport soldiers from their ships to the land. During the Vietnam War, US soldiers used a hovercraft to travel across the marshy, treacherous Mekong Delta.
The biggest military hovercrafts belong to Russia. Their biggest can carry three army tanks, 140 soldiers and all their equipment, plus 260,000 tons of cargo – all at one time!
Military use isn’t the only thing a hovercraft is good for. The US Postal Service uses a hovercraft to carry mail from the city of Bethel, Alaska, to eight near-by villages along the river. There are no roads going from the villages to the city so the hovercraft just travels right along the top of the river, even when it’s iced over during the long, cold, Alaskan winters.
In Great Britain, they use a hovercraft like a ferry, transporting people and cars from the mainland to islands or from island to island. From 1965 to 2004, more than 20 million people traveled this way. The biggest hovercraft ferry can hold 418 people and 60 cars, all on a cushion of air above the water.
One hovercraft, named the Princess Anne, traveled across the English Channel in just 22 minutes in 1995. The English Channel is an arm of the Atlantic Ocean that divides England from France and is 21 miles wide at its skinniest point.
The speed record for the fastest hovercraft is 85 miles an hour, fast enough to get a speeding ticket if it traveled that fast on a public road or highway instead of a test field.
Cars are great to have around and boats can be a lot of fun. When it’s icy outside, skis or cars with snow tires are a good way to travel. But having a hovercraft means you can go almost anywhere you want to, any time you want to, without worrying about the weather. And it doesn’t matter at all if travel is over solid ground, water, or slippery ice.