Hovercraft :: Nauka ~ Tehnika ~ Military

A Hovercraft, or Air-Cushion Vehicle (ACV), is an amphibious vehicle or craft, designed to travel over any sufficiently smooth surface - land or water - supported by a cushion of slowly moving, low-pressure air, ejected downwards against the surface close below it.

History

*Early air cushion developments*

In the mid-1870s, the British engineer Sir John Isaac Thornycroft built a number of ground effect machine test models based on his idea of using air between the hull of a boat and the water to reduce drag. Although he filed a number of patents involving air-lubricated hulls in 1877, no practical applications were found. Over the years, various other people had tried various methods of using air to reduce the drag on ships.
Finnish engineer Toivo J. Kaario, head inspector of Valtion Lentokonetehdas (VL) airplane engine workshop, began to design an air cushion craft in 1931. He constructed and tested his craft, dubbed pintaliitäjä (Surface Glider), and received its Finnish patents 18630 and 26122. Kaario is considered to have designed and built the first functional ground effect vehicle, but his invention did not receive sufficient funds for further development.
The first to give scientific description of the ground effect and to provide theoretical methods of calculation of air cushion vehicles was Konstantin Tsiolkovsky in his 1927 paper "Air Resistance and the Express Train".[1][2] Since then Soviet engineer Vladimir Levkov began to develop air cushion vehicles. In the mid 1930s, Soviet engineer Vladimir Levkov assembled about 20 experimental air-cushion boats (fast attack craft and high-speed torpedo boats). The first prototype, designated L-1, had a very simple design which consisted of two small wooden catamarans that were powered by three engines. Two M-11 radial aero-engines were installed horizontally in the funnel-shaped wells on the platform which connected the catamaran hulls together. The third engine, also an air-cooled M-11, was placed in the aft part of the craft on a removable four-strut pylon. An air cushion was produced by the horizontally-placed engines. During successful tests, one of Levkov's air-cushion craft, called fast attack L-5 boat, achieved a speed of 70 knots (130 km/h).

*Air cushion on hovercraft principle*

The first hovercraft was invented and patented by the English inventor Christopher Cockerell in 1956.[3]

In the US during the Second World War, Charles J. Fletcher designed his "Glidemobile" while a United States Navy Reservist. The design worked on the principle of trapping a constant airflow against a uniform surface (either the ground or water), providing anywhere from 10 inches (25 cm) to 2 feet (61 cm) of lift to free it from the surface, and control of the craft would be achieved by the measured release of air. Shortly after being tested on Beezer's Pond in Fletcher's home town of Sparta Township, New Jersey, the design was immediately appropriated by the United States Department of War and classified, denying Fletcher the opportunity to patent his creation. As such Fletcher's work was largely unknown until a case was brought (British Hovercraft Ltd v. The United States of America) in which the British corporation maintained that its rights, coming from to Sir Christopher Cockerell's patent, had been infringed. British Hovercraft's claim, seeking US$104,000,000 in damages, was unsuccessful. However, Colonel Melville W. Beardsley (1913-1998), an American inventor and aeronautical engineer, received $80,000 from Cockerell for his rights to American patents. Beardsley worked on a number of unique ideas in the 1950s and '60s which he patented. His company built craft based on his designs at his Maryland base for the US Government and commercial applications. Beardsley later worked for the US Navy on developing the Hovercraft further for military use. Dr. W. Bertelsen also worked on developing early ACVs in the USA. Dr. Bertelsen built an early prototype of a hovercraft vehicle in 1959 (called Aeromobile 35-B), and was photographed for Popular Science magazine riding the vehicle over land and water in April on 1959. The article on his invention was the front page story for the July, 1959 edition of Popular Science.

In 1952 the British inventor Christopher Cockerell worked with air lubrication with test craft on the Norfolk Broads. From this he moved on to the idea of a deeper air cushion. Cockerell used simple experiments involving a vacuum cleaner motor and two cylindrical cans to create his unique peripheral jet system, the key to his hovercraft invention, patented as the 'hovercraft principle'. He proved the workable principle of a vehicle suspended on a cushion of air blown out under pressure, making the vehicle easily mobile over most surfaces. The supporting air cushion would enable it to operate over soft mud, water, and marshes and swamps as well as on firm ground. He designed a working model vehicle based on his patent. Showing his model to the authorities led to it being put on the secret list as being of possible military use and therefore restricted. However, to keep Britain in the lead in developments, in 1958 the National Research and Development Corporation took on his design (paying £1000 for the rights) and paid for an experimental vehicle, the SRN-1 to be built by Saunders-Roe to Cockerell's design. It was launched on 11 June 1959.[4] Shortly afterwards it made a crossing from France to the UK on the 50th anniversary of Bleriot's cross Channel flight. Cockerell was knighted for his services to engineering in 1969. Sir Christopher coined the word 'Hovercraft' to describe his invention.

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