Hovercraft Questions and Answers

Hovercraft Questions and Answers

What is a hovercraft? 

A hovercraft is a vehicle that floats on a cushion of air, and is propelled by air generated by a fan.

How does a hovercraft work? 

Some hovercraft have separate engines for lift and thrust, but as smaller hovercraft are weight sensitive, they tend to have one engine that generates air that is split 75/25% with 25% directed under the skirts for lift, and 75% of the air directed via rudders for thrust and left to right steering.

How is a hovercraft different from a boat? 

Boats have propellers than can get snagged on rocks and coral, and cannot operate when tide is out, in shallow waters and fast running water. Hovercraft can travel over any flat surface, so water, land, sand, mud, ice, snow, up beach and slipway.

What are hovercraft used for?

Hovercraft are used for many different applications as well as for leisure fun.

Commercial applications for hovercraft include border patrol, flood, mud and ice rescues, surveying, for detection of UXO, for mosquito control, to scare birds from airports, bridge construction and maintenance, shell fish farming, providing access to areas that boats and other vehicles cannot reach. Commercial hovercraft need to be reliable, strong, durable, easy to use, and easy to maintain.

Do hovercraft hurt the environment?

Hovercraft are very environmentally friendly – unlike a boat or Jet Ski, a hovercraft does not use sea water for cooling or propulsion, they have no propeller to damage sea mammals such as manatees or sea turtles. They do not pump exhaust fumes into the sea. Hovercraft do not create a wave to damage river banks. While hovering, a hovercraft will weigh the same as a seagull standing on one leg, so they make very little impact on ground they fly over. A hovercraft can fly over bird’s eggs without breaking any as illustrated by this video https://www.youtube.com/watch?v=OY0pe-d-QQ8

How safe is a hovercraft?

Hovercraft have a very safe safety record – accidents usually only occur if fan guards are left unguarded, or where glass fibre hulls have been damaged when travelling over ice.

Are Hov Pod hovercraft less noisy than other hovercraft?

Yes, the Hov Pod hull is unique, manufactured from HDPE (High Density Polyethylene) which tends to deaden sound, unlike glass fibre that resonates sound like a string instrument. The Hov Pod has a wider more efficient duct than many hovercraft, and we fit more powerful engines to allow fan blade angles to push more air through the duct at lower fan rotation speeds. Most noise generates from the tips of the fan blades, the “air rush sound” so slower fan blades at higher pitch angle work best.

Will a hovercraft float? 

Most hovercraft float, but may sink heavy into the water due to the air holes that allow air to escape from the skirts – getting started from an on-water start can be difficult for some hovercraft – all hovercraft create a pressure wave known as “The Hump” when starting on water, so always check the on-water payload specification of a hovercraft before purchase – hovercraft generally pick up 50% more weight when starting on land since no pressure wave exists. Some suppliers fudge payload ratings, preferring to quote only land payload – if you get this wrong, it could result in a long swim home. The Hov Pod Hovercraft is made from very buoyant HDPE which sits higher in the water to air starting.

Are hovercraft easy to operate?

Some hovercraft have two engines with two sets of controls for lifting and thrust – the single engine design splits air reducing the need for two engines, to save weight and simplify operation. Some hovercraft are overly complicated with trim levers, elevators and reverse mechanisms, the Hov Pod is designed to be very easy to operate.

How does a hovercraft steer?

Left and right direction is managed by a steering handlebar or joystick to control rudders in to the rear of the fan duct assembly. Some hovercraft have a high centre of gravity and can be difficult to steer around corners; like a car, a lower centre of gravity aids cornering.

How does a hovercraft stop?

It is best to stop in a straight line to allow the flattish bottom of the hull to make contact with the water to slow progress. Stopping on land, most hovercraft have runners like a sleigh to protect the underside. The second way to stop is the manoeuvre the hovercraft into a 180 turn, which acts to loose velocity.

Can a hovercraft be driven on the road?

Physically yes, although any gap in the road like a drainage grill will allow air to escape. Whether the police will allow a hovercraft to be driven on the road is another matter – hovercraft generally do not have brakes or indicators (not many car drivers use indicators) Keith Moon, drummer with pop group The Who purchased a hovercraft to get to his local pub after a drink driving ban – the police stopped him and pointed out that he was banned from driving on the road – he pointed out to the police officers that hovercraft do not drive on the road, they hover 9 inches over it! The police officers were last seen consulting their rule book.

How fast will a hovercraft go?

Race hovercraft can travel at up to 75 mph. According to Wikipedia, Bob Windt (USA) achieved the world record of 85.87 mph. Most leisure hovercraft travel at up to 40 mph.

What is the gas mileage of a hovercraft?

This will vary according to type, size of engine, whether 1 or 2 engines are used, for lift and thrust, the payload – weight of passengers and fuel, whether you stop and start frequently since this takes more effort especially on water, and conditions such as strong headwind or tail wind.

What is the hovercraft payload?

Payload is the lifting capability of the hovercraft. There are two types of payload, the on-land weight lift capability, and the on-water weight lift capability. Hovercraft generally lift 50% more weight when starting on land, some suppliers fudge their on-water capability, so never ask – how many seats doe the hovercraft have, check the on-water lift capability if you plan to go over and stop or want to start on water. When hovercraft start on water, the hovercraft creates a pressure wave known as the Hump – sometimes hard to get over and become airborne. You can illustrate the hump by pushing a piece of paper on a desk, whilst pinning it down with another finder – the paper arches up like a wave. Getting over hump is more difficult to do in shallow water. Don’t get the hump, get a Hov Pod!

Can a hovercraft operate on ice?

Yes, if it is flattish. Ice is quite hard, so glass fibre hovercraft hulls can suffer damage, the Hov Pod hull is manufactured from HDPE so is far stronger than GRP. Also consider skirt materials – the Hov Pod is supplied with very strong anti-rip polyurethane coated nylon 375 gsm – some hovercraft have easy to rip Hypalon or UV degrading neoprene coated nylon.

Can a hovercraft be used on swift water and rough waves?

Larger un-breaking waves are like small hills, so fun to play on, but short sharp waves can slow progress. Care should be taken in the marine environment. Some hovercraft are top heavy, so likely to topple, so a low gravity design will work best. Another feature to consider is freeboard – the distance between the water line and the freeboard deck of the hovercraft – if this is low, water can ingress into the hull. Some hovercraft designs have a very low freeboard, especially those copied from a race hovercraft design (race hovercraft rarely travel very far over water). If waves are high, there is a danger that waves could ingress into the hull and make it heavy – water being heavy stuff could then create problems, especially if no bilge pump is fitted. The Hov Pod SPX TCC HDPE hull is very buoyant and is calculated to take over a ton in weight (the weight of a 5 year old elephant) before water could ingress into the hull.

Who invented the hovercraft?

Sir Christopher Cockerell first patented the word hovercraft, although the concept had been considered in various forms by other engineers.

How large of a “step” can a hovercraft handle?

This will depend on the size of the hovercraft – a small hovercraft could step off a surface 1 or 2 feet high, but much depends on the design and speed, and construction method. The larger the hovercraft, the higher the step. Moving down a flight of steps would not be such a good idea though, since the lift air would escape, and lift would be lost.

What slope can a hovercraft climb?

Much would depend on the approach speed, conditions, passenger weight, type and size of hovercraft, so with all these variables in consideration, perhaps the best answer would be to suggest you take a look at hovercraft in operation in the following videos, see http://hovpod-in-use.blogspot.co.uk/p/slopes.html

Can you buy a hovercraft kit and build it yourself?

You can but home built hovercraft projects can take a long time, so be sure you start with a good design. Look for features such as safety, in recent years home builders have lost fingers from unguarded fans, so be sure the design has front and rear fan guards. We think the fun in hovercraft ownership is in operation, so purchase a ready-made hovercraft with great design credentials and safety features.

How is a hovercraft transported?

Some people make complicated trailers to transport their hovercraft, so attempt to fly the hovercraft onto a flatbed trailer, we think this can be a little dangerous, if speed and steering is not exact. Take a look at our trailer design video at http://www.hovercraft-options.com/p/standard.html

What safety features should be considered when choosing a hovercraft?

Make sure the fans are properly guarded, front and rear. Make sure the skirts are strong and unlikely to fail. Segmented skirts are easy and cheaper to repair than one piece bag skirts. Make sure the exhaust system is guarded and covered to prevent burns. Check whether the hovercraft has a tendency to plow in on water (The Hov Pod has anti-plow skirt design). Check the on-water payload suits your intended purpose and weight expectancy.

Where can I buy a hovercraft?

Visit http://www.hov-pod-hovercraft.com