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The theory is really quite simple to explain, however building a hovercraft that will perform well is not so simple. This is a great illustration for helping us to understand what makes a hovercraft fly, yes fly. Since most light hovercraft hover approximately 8 inches off of the surface, you really are flying. Let's take a look at each component in the drawing to help us figure out what each element does to contribute to a hovercraft's performance and its ability to fly.
1. The Skirt - This is the apparatus that traps air underneath the craft. Hovertechnics, Inc. uses a premium material called Hypalon to form the air curtain around the hull. The skirt is made up of several individual pieces called segments. Each skirt segment is attached to the craft's hull by steel clips (on top) to a molding running around the entire perimeter of the hull and by plastic wire ties (on the bottom) to the hull's underside. They are attached in this way so that they create a tight seal to prevent air loss and so that they can mold and fit to the terrain the hovercraft is passing over. Using segmented skirts also allows for individual replacement should it be necessary. Skirts can take a lot of punishment. Should a skirt become snagged on something, it is designed to break the plastic wire ties holding it in place rather than tearing the skirt segment. If the wire ties break, the hovercraft's air cushion will still be maintained since the neighboring segments will billow out to fill the new gap. Most light hovercraft use between 66 and 100 segments to complete the air barrier. In an unusual situation where a hovercraft might lose many skirts, it will still be able to hover. It is always recommended to keep your skirt in the best condition possible to experience optimum performance.
2. Steering - Hovertechnics, Inc. hovercraft use a typical "motorcycle" type handle bar for steering. Turn right, the craft turns right. Turn left, the craft turns left. The handle bar is connected by cabling to the rudders on the rear of the craft.
3. Seat - Most light hovercraft use standard tandem seating. The seating is arranged on the craft's center-line. It is fashioned in this way to allow for proper craft trim. This prevents the craft from leaning to one side or the other while carrying its operator and passengers.
4. Engine - Most light hovercraft use two-stroke motors. This is largely because they weigh less than four-stroke engines and can produce more horsepower at a lower weight. Today's two-stroke engines are very reliable. Hovertechnics, Inc. uses Rotax engines. Rotax is a commonly used engine in sport aviation. To be used in aviation, these engines must be reliable or they wouldn't even be a consideration. Most Hovertechnics, Inc. hovercraft offer oil injection as a feature with the Rotax engine. This eliminates the need for pre-mixing the oil with the fuel. It also ensures that the engine always gets the right amount of fresh oil. When properly maintained, two-stroke engines can run for several hundred hours before needing a top end overhaul and well over one thousand hours before needing a rebuild of the low end.
5. Transmission - The power from the engine is transmitted to the fan by a belt and pulley system. A small pulley is mounted to the engine's crank shaft. A large pulley is connected to the fan shaft. A timing belt is routed from the pulley on the crankshaft to the fan pulley, thereby turning the fan.
6. Fan - The hovercraft's fan is typically made out of different types of plastic composites. This composition of plastics is very strong and durable. Most Hovertechnics' hovercraft use 12 fan blades. This design produces the most air movement possible for the best available performance. Hovertechnics' uses an integrated design, which means that one fan and one duct provide air for both thrust and lift. 2/3 of the air is used for thrust and 1/3 is used for lift. The air that is used for thrust passes over the rudders to provide directional control for the operator. The air that is used for lift passes under the splitter plate (the dividing point separating lift and thrust air) and through the craft's hollow inner hull. The air exits the inner hull through holes throughout the craft's perimeter, each aligned with a skirt segment. This escaping air billows the skirt segments and pressurizes the space between the ground and the craft's bottom hull. When the pressure amounts to approximately 11 psi, the craft will lift off of the surface.
7. Fan Duct - The fan duct serves several purposes, the greatest of which is to increase the flow of air through the fan. Imagine water pouring out of a faucet. Unchanneled, the water moves at the same rate from the nozzle to its destination. However, if the same water is poured into a funnel, the water escaping the funnel is exiting at a more rapid rate than the rate at which it's leaving the faucet. Since air is a fluid, it acts just like water. Once the air begins moving through the duct, its volume is being compressed, which creates more pressure. This translates into more thrust for a hovercraft and better overall performance. Secondarily, the fan duct provides protection from the rotating fan. This is a major safety benefit. In the unlikely event of the craft rolling over, the fan duct also acts similar to a roll bar.
8. Rudders - Rudders are devices used to channel the thrust air either left, right or straight. They are instrumental in the turning capabilities of a hovercraft. However, a hovercraft may still be turned without rudders. Hovercraft are very sensative to trim adjustments. The best illustration for this is to visualize the hovercraft operator leaning to either side of the cockpit. Leaning to the right results in the craft turning right, vice versa is true as well. Experienced hovercraft pilots use both the rudders and leaning to help the craft turn.
9. Splitter Plate (lift/thrust divider) - This plate divides or splits the air that has passed through the fan. Splitter plates are positioned behind the fan and are approximately set at one third of the duct's opening. One third of the fan's air is needed to provide the air cushion on which the hovercraft rides. The splitter plate is the device that directs the lift air into the craft's inner hull. Hovertechnics, Inc. offers an optional variable splitter plate on all of their craft. This option allows the operator to adjust the amount of air volume that is used for either lift or thrust. Sending more air to the cushion assures the highest hoverheight available, which can be a valuable attribute over rough or uneven terrain. If more thrust is needed, the splitter is lowered so that more air goes through the duct for thrust. This is valuable when getting over the hump on water or when trying to reach higher speeds. The variable splitter plate may be adjusted on the fly, which provides unsurpassed controllability in many different situations. | 
