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HISTORY OF TECHNOLOGY, TECHNOLOGY, OBJECTS AROUND US
Hovercraft. History of invention and production
Directory / The history of technology, technology, objects around us The idea to increase the speed of a ship or boat with the help of "air lubrication" was born at the end of the 1916th century. Its essence was as follows. If a powerful fan blows air under the flat bottom of the vessel, then the water resistance will decrease; hence the speed will increase. And so that the air does not "run away" to the sides, the ship's hull must be equipped with longitudinal keels - skegs. The Austrian engineer Dagobert Müller von Thomamühl was the first to realize this idea in 40. The torpedo boat he created was able to develop a speed of almost 74,08 knots - 480 kilometers per hour, the engine power was XNUMX horsepower. Then a new idea arose: the skegs were replaced with a rubber "skirt". Now the forced air came out from under the bottom even more slowly, and a real air cushion was obtained. Vessels of this type really hover above the water, can "crawl" ashore and even move on land.
The first idea of such a hovercraft was expressed by K.E. Tsiolkovsky in 1927, in his work "Air resistance and fast train". This is a wheelless express that rushes over a concrete road, relying on an air cushion - a layer of compressed air. This idea prompted the associate professor of the Novocherkassk Polytechnic Institute Vladimir Levkov to create his own design, however, not a train, but a boat. And here is what Stanislav Zigunenko writes in the World Pathfinder magazine: “He began, as usual, with calculations and building models. The first structure built by a young aerodynamic scientist looked like an inverted basin. an ordinary basin is supposed to be the bottom, there was an electric motor with a propeller.The screw, pumping air, under the "basin" created increased pressure. And the whole structure, as it were, floated above the floor, leaning on an air cushion. For about five years, Levkov tested this simplest model, trying to understand how it could be controlled, how high the pillow should be, so that excess power would not be wasted, and the future vessel would develop as high a speed as possible ... In 1932, Levkov, already a professor, began testing a new model. She had an elongated, teardrop shape, two engines: in the bow and stern. A small hovercraft glided effortlessly over the tiled floor of the aerodynamic laboratory. Soon the appearance of the model changed again. It became like a long upside down box with the sides cut at an angle. In the cutouts in an inclined position, electric motors with propellers were strengthened. The air thrown out by the propellers accumulated under the body of the model, lifting it up. According to this scheme, then Levkov created all the first large hovercraft. In the spring of 1934, Levkov moved to Moscow - he was invited to work at the Moscow Aviation Institute (MAI). He brought with him a large (more than two meters long) model of a hovercraft. Designed according to all the rules of structural mechanics, it made a good impression. The ease of construction and the beautiful exterior finish of the model were striking. Her weight was only about six kilograms. To test the model at the Moscow Aviation Institute, a special room was assigned. It has a shallow pool. Two wires were stretched over it to power the electric motors of a small boat. He flew well. In a couple of seconds, it was easily transferred from one side of the pool to another. Then the Experimental Design Bureau was organized, headed by Professor Levkov. It began to develop a three-seater boat L-1. Its trials began in the summer of 1935 near Moscow, on Lake Pleshcheyevo. The mass of the boat was 1,5 tons. Its wooden hull consisted of two narrow boats connected by a platform. Two aircraft engines with propellers pumped air into the space bounded by the platform and boats. The boat was controlled with the help of rotary shutters - blinds, reinforced under the motors. With the shutters in the vertical position, the air flow was directed downward, and the boat hung motionless. If the blinds deviated back, the reactive force moved the boat forward, deviated forward - reverse was given. In addition, there was a vertical and horizontal tail, which also participated in the control of the flying boat.
This boat became the prototype of other flying ships created under the leadership of Levkov, in particular the L-5 boat. Its mass reached 9 tons, since its body was already metal, duralumin. Behind the driver's cabin and the flight mechanic arranged a room for passengers. First, the boat was tested on land. We watched him fly. Then sea trials began. They tried to accompany the car with ordinary boats, but they soon fell behind hopelessly. And when the stopwatch was turned on at the measured mile, the testers could not believe their own eyes: it turned out that the speed of the boat was more than seventy knots, that is, about 140 kilometers per hour! Tests also showed that the boat could just as easily pass over a swamp, over a snow-covered field or ice.
The military became very interested in the test results, and Professor Levkov soon headed a special design bureau for hovercraft. Vessels weighing up to 15 tons were built. Even larger ones were designed - up to 30 tons with two engines. So more than sixty years ago, a small fleet of fifteen hovercraft was built in the USSR. Unfortunately, during the Great Patriotic War, experienced boats that were in the Baltic died. After the victory, the development of such ships was continued. But at the beginning of 1954, Professor Levkov died, and the business stalled. An important stage in the development of hovercraft was the invention in England in 1955 by Professor Christopher Cockerell of a nozzle scheme for forming an air cushion. He also owns the invention of flexible fences, which were immediately appreciated in our country. In 1959, a strange vessel appeared in the English Channel with a cylindrical tower in the middle. Starting from France, it crossed the strait. Having reached the coast, it, as if nothing had happened, continued on its way. The ship designed by Cockerell was twice as heavy as Levkovo's and three times as fast. Now hovercraft are not a novelty. They are being improved in many countries. They are recognized as a very promising mode of transport. They are used as landing craft in the navy, as civilian ferries transporting people and cars across the English Channel. One of the most successful foreign developments is the 1972-ton boat BH-33 Wellington, created in Great Britain in 7. It can carry 14 tons of cargo and at the same time fly over water at a speed of about 60 knots - 111,12 kilometers per hour. In the USSR, the specialists of the Navy were the first to appreciate the enormous capabilities of amphibious ships. After the break, the work begun by Levkov continued, but at a new level of funding. A base was created for the design and production of landing ships. The leading enterprise in Russia in the field of creating hovercraft is the Almaz Central Marine Design Bureau. The landing craft "Skat" was the first serially built. It could carry forty paratroopers at a speed of 49 knots. On their basis, three boats were created to rescue astronauts. It was followed by Kalmar, with a displacement of 114 tons. He could carry cargo weighing 37 tons, at speeds up to 55 knots. In total, ships were built serially at Almaz according to ten projects. Among them is the amphibious assault ship Zubr, which has a carrying capacity of 150 tons, a total displacement of 550 tons, a full speed of 60 knots and 40 knots in a sea of 2 meters high. Experts believe that a displacement of 1000 tons is not the limit for the displacement of such ships, and in practice speeds of up to 80 knots can be achieved. In 1987, the small missile ship "Bora" was created in the USSR - the largest hovercraft in the world. Even an eight-point storm does not bother him, and if the sea is calm, he moves at a speed of 53 knots - 98,16 kilometers per hour. "Almaz" has developed a number of civil hovercraft projects - river cargo ship "Bober", passenger hovercraft of project 12270, multi-purpose hovercraft "Chilim". Depending on the purpose of the vessels, such an important parameter as the installed capacity per ton of displacement changes. For military boats, where the economic indicators of operation do not have a predominant value, this figure is in the range of 65-120 kW per ton. Such a high power-to-weight ratio is not caused by the magnitude of the full speed in calm water or with little excitement. To achieve it, only 60-70 percent of the installed capacity is used. The reason is different - the need to achieve a given guaranteed speed in sea waves. In the practice of civil shipbuilding, where this indicator determines the efficiency of operation, despite possible refusals of flights due to weather conditions, it can be increased to 30-36 kW per ton while maintaining a speed of 40-50 knots in calm water. The first hovercraft, following aviation traditions, were created riveted, but the experience of their operation at sea showed the low reliability of this type of connection. Since 1974, the hulls have become welded. For them, high-strength corrosion-resistant marine aluminum-magnesium alloys were created and the production of pressed panels with stiffeners of various sections was mastered. A large amount of research has been carried out in the field of creating flexible fences. The dependences of the strength and wear resistance of flexible fence materials on the nature of the used filament fibers, torsion and type of weaving of filament yarns, impregnations and the composition of the coating rubber mixtures were established. The rubber-fabric materials used on the ships of the latest projects provide good seaworthiness of the ships and the possibility of long-term operation without repair. For hovercraft, it was necessary to develop a special profile of propeller blades, which made it possible to achieve a high efficiency at low, compared to aircraft, speeds. For all hovercraft with a displacement of more than 100 tons, a single propeller hub has been developed, which ensures high reliability of the propellers when their pitch changes. Of decisive importance for the seaworthiness, amphibiousness and wear resistance of a flexible barrier is the air flow through the air cushion. For air supply, our scientists have developed special schemes of axial and centrifugal superchargers, which have a high efficiency with small dimensions. To drive propellers, superchargers and other consumers, high-temperature gas turbine gear units were created. In terms of their weight, size and operational parameters, these units still occupy a leading position in the world. The safety of a high-speed craft is largely determined by the availability of reliable and proven traffic control systems. A feature of hovercraft is the lack of direct contact of steering devices with water, which makes it difficult to maneuver and makes the ship very dependent on the weather. In Russia, various ship control schemes have been developed and tested, including aerodynamic rudders, jet rudders (jet nozzles), and variable pitch propellers. Author: Musskiy S.A.
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