Hovercraft – Wikipedia

And hovercraft O aeroscoper ^[first] (or also spray As it is sometimes translated into Italian) is a vehicle supported by an “air cushion” and moved by one or more propellers. It is able to move on different surfaces and to reach speeds above 150 km/h. Made in industrial form or hobby in measures ranging from 2 meters in length to 57 meters of the Russian landing hovercrafts of the Zubr class. It is used for amateur use, rescue and military for its speed of launch, its speed and above all for its versatility in crossing surfaces of different composition. The Hovercraft was classified as a penultimate invention in the transport sector, before the Space Shuttle.

According to some authors, technically a hovercraft can be classified as belonging to the aircraft class ^[2] and in this area it can therefore be defined as a hero to Support for direct reaction (the “air cushion”) and also to the boats class, although it does not have propellers immersed in water. In fact, in many states, including Canada, in the case of large means for driving, both the aeronautical license and the nautical license is required.

Hydrodynamically is considered to be a boat with a hull of air: sustenance is not a libration like the helicopter hovering, but it is a floating with or without the swollen pillow. The amphibian performance are allowed by the perimeter escape of the air constantly produced, air that constitutes a lubricating “veil”. In the first vehicles the edge was rigid and to create a sufficient veil, great powers were needed, the invention of the perimeter skirt and the single skirts later, which adapt to the roughness of the soil as a soft garnish, made it possible to significantly decrease the thickness of the veil of air and therefore the power necessary for sustenance.

Beyond the different opinions, in any case by international convention Hovercrafts are considered boats in all respects, or “dynamically raised ships” and described by the IMO (International Maritime Organization) Hig Speed ​​Craft: Code 1.4.2 “Air-Cushion Vehicle (ACV) ”is a craft such That the Who or a significant part of its weight can be supported, whereher at rest or in motion, by continuously generated cushion of air dependent for its effectiveness on the proximity of the surface over which the Craft Operes. “(trad: air cushion vehicles (ACV)” is a hull that the totality or a significant part of its weight can be supported, either at rest or moving, by an air cushion generated continuously employee for its effectiveness to the proximity of the surface during which the boat operates). With the new European legislation also acquired in Italy for the guidance of Hovercraft with a power higher than 30,4 kW , even if classified as boats, the nautical license is required. Specifically for the hovercrafts, the “EC” marking is not possible 2003/44/EC and the engines are also exempt from adapting to anti -pollution regulations.

In Italy, and with laws quite similar throughout Europe, the reference regulations for construction, management, and use are different for any boat and hovercraft, following the general or more simplified rule, required for pleasure.

The foreseen use determines the legislation to be followed, indicated by law 472 of 1999, art 25 which expressly provides for:

“Minor ships and floating, referred to in article 146 of the navigation code, having a length outside of everything not exceeding 24 meters, can be registered in the registers and intended for special services for private use or for use in account for its own for the navigation in maritime waters within 12 miles from the coast. “.

later it is specified:

A) for private use, the use of unit as a means of proper locomotion and third parties as friendly; … For the purposes of the safety of navigation to the units intended for private use, the safety regulation for navigation from pleasure, approved by decree of the Minister of Transport and navigation January 21, 1994, n. 232.

The prepaid category is intended for recreational activities and does not allow any type of work or professional activity, if not the one framed in the aforementioned law 472 or of the rental (but for pleasure). See also (pleasure code, tit.1, Capo, Art.1, General Provisions) The pleasure legislation accepts a simplification of the general safety standards, allows the use of more volatile fuels (petrol) but potentially explosive, the exemption from enlargement for lengths up to 10 m.

B) for use in its own account, the use of the unit for the satisfaction of needs strictly connected to the institutional activity of public or private entities or the entrepreneurial activity of commercial entities including the activity of aquaculture in marine waters with cages floating or submerged ….. to the units intended for the special services for use in their own account the regulation for the safety of navigation and human life at sea is applied, approved by decree of the President of the Republic 8 November 1991, n. 435.

The Presidential Decree 435/91, and in general the “safety regulation of navigation and human life at sea” which reflects the EU provisions, clearly defines in the first instance (book 1, Title 1, Chapter 1, Art.1, paragraph 1, par. 1) What should be understood by aeroscoper (hovercraft): a ship having means to generate an air pillow under it capable of lifting it on the surface of the sea.

With the exception of pleasure pleasure homologations, for all boats within the hovercraft, including expressively required (articles 81 and 193) the use of fuel with a flammability point greater than 38 ° C, i.e. diesel or kerosene, limited to hydrofoil or aeroscophy/hovercraft.

The first project that came to us who was called Hovercraft is from 1716 on a design by the Swedish Emanuel Swedenborg who was a designer, philosopher and theologian. His air cushion platform powered by human force resembled an inverted boat with a seat in the center and rows in the shape of a ladle that would have had to push the air under the vehicle to each run down. No vehicle was never built with this principle, without a doubt no one could have made it operated because of the low available power.

In the mid -1870s the British engineer Sir John ThornyCroft built a series of experiments based on the use of air between the hull of the boat and the water to reduce the resistance to advancement. Although he obtained various patents on air -lubricated hulls (1877), practical applications were never found.

Over the years, many other people attempted other methods to reduce the resistance to the advancement of ships, but until 1952 there was no practical application.

In that year, the British inventor Christopher Cockerll proposed his solution and for this invention in 1969 he was granted the title of Sir or Baron.

With simple experiments using a vacuum cleaner engine and two cylindrical cans he proved that it was possible to make a vehicle that moved on an air cushion capable of moving on different types of surfaces. The greatest novelty introduced by him was a jet system capable of confining the air cushion under the vehicle. The air cushion allowed to move to muddy soils, water, swamps as if it were on compact soils.

The British aircraft manufacturer Saunders Roe developed the first hovercraft capable of transporting a man, it Sr-n1 with which many tests were carried out between 1959 and 1961 including a crossing of the sleeve. His first demonstration in public is from 1959. It was thus discovered that it was possible to increase the “sustenance” capacity with the addition of a “tube with skirt drain” of flexible rubber -tire canvas between the surface and the hull, having the purpose to “contain the air” under the hull giving a “floating” effect, even if minimal, in the air.

The first industrial production hovercraft was appointed Sr-n1 And it was equipped with piston engine that operated a series of intubated propellers that create a direct “sustenance” flow on the surface and which provide the push through air channels. With this vehicle on July 25, 1959, the sleeve channel is crossed in just 2 hours of navigation. Driving the Capt. Peter Lamba assisted by the engineer John B. Chaplin and as “counterweight in the bow” his inventor engineer Christopher Cockenll who will subsequently be appointed Sir.

The project was not very successful “commercial” because it was able to transport just over its own weight and two crew men.

The engineer Christopher Cockerll developed his project tenacious and far -sighted with the addition of “inflatable pipes”, “aeronautical propellers on mobile axis” and a “cylindrical fans” incorporated in the hull for “sustenance” and applied them to his Second “Srn2” project; He too had a modest commercial development, because it has no economic resources and in any case soon overcome and set aside by the “barons” of the British Air Force.

However the first real means of transporting passengers was the Vickers VA-3 That in the summer of 1961 the regular service began along the northern coasts of Wales between Wallasey and Rhyl: this hovercraft was moved by two turboelic engines, driven by propellers and governed by cyclopean bar rings. This model was also “incorporated” by the Saunders Roe and The British Hovercraft Corporation.

During the years “60 the Saunders-Roe Ltd, or Saro, always close to the aeronautical constructions (1910) with planes, seaplanes and helicopters, developed several models that were able to transport passengers. Among these the Sr-n2 which operated on the Solent since 1962 and later the Sr-n6 who served regular service on the Solent between Southsea in Ryde on the island of Wight for many years. The service began on 24 July 1965 with the Sr-n6 which transported 38 passengers. Nowadays two modern hovercraft AP1-88 With 98 seats follow the same route and over 20 million passengers (in 2004) they chose it to reach the island.

As Saunders Roe and Vickers did who join the British Hovercraft Corporation in 1966, other builders during the years “60 built their hovercraft: the cushioncraft, part of the Britten-Norman group, Hovermarine who introduced side bands” A drown “in the water with the task of trapping the air on the sides, the Lockheed Corporation (Textron Marine and Land Systems Lockheed), the ABS-Hovercraft with its modern M10 made exclusively in composite material (Kevlar/carbon).

In 1970 the largest English hovercraft in commercial service was the Sr-n4 , class Mountbatten , which made a regular service through the sleeve between having to England and Calais in France transporting passengers and cars; The Naviplane N500, the largest and most fast Hovercraft built, also operated on the same route. The service was interrupted in 2002 for a competition of apparent causes: the opening of the tunnel of the sleeve, the high operating cost due to the price of fuels and the advent of a system of fast land -effect catamarans (SES) light and a low cost of management, as well as the lack of state sponsorships now intended for Europe to large fleets.

The commercial success of the “civil hovercrafts” suffered from the rapid growth of the cost of fuel in the late years “60 and in the years” 70 following the conflict in the Middle East. The Hovercraft instead continued to enjoy a certain success in the military, in particular in the Americans with the LCAC, while only after the fall of the Berlin Wall did it be discovered in the West that the Soviet Union in the years of the “frost” had made real “hovegiant”. Defined by NATO as a classes Zumro and Katalyna, these huge hovercraft were able to transport military arsenal integers in any meteorological condition and on any battleground.

In recent years with the advent of Kevlar/Carbon, other means of transport have been developed that use “La Via del Mare” with innovative construction techniques and reduced consumption (weight/power) and with comparable performance if used in water: the hydrofoils , the catamarans, the trimarans, the seaplanes as large as a jumbo jet that travel by exploiting the soil effect and in strong development the ses, a middle ground between the catamarans and the hovercrafts, which have excellent speed skills, low consumption, and directionality .

In the mid -1960s, the company Department Store Alcer in Naples, in competition with the airline “Elivie”, started a maritime line service in the Gulf of Naples with the use of two hovercrafts. This passenger service connected the nautical station, specially built, of Piazza Vittoria, with the Golfo islands and Sorrento. The Neapolitan Hovercraft line service ended with the failure of the Alcer department store company.

Currently Hovercraft populate our globe at all latitude for both civil and military use. Indictionally for length or conformation are used as ferries, work means of lakes, rivers, swamps, delta and rescue vehicles both at sea and in internal waters, with considerable success have been tested as “taxi” to travel frozen rivers or as a breakdown and also as a landing means for military troops.

Very high speeds, easy maneuverability, great load capacity, multiplicity of use, indifference and insensitivity to the roughness of the surfaces traveled, invisibility to radar or sonar in the military versions, combined with the now low maintenance cost, make the Hovercraft a unique vehicle and irreplaceable.

Currently and in the whole world the hovercrafts are officially used in all measures by coastal guards, firefighters, forest guards, geology institutes, rescue teams, disinfestation teams, emergency room teams for reclamation from hydrocarbons spinning and finally as means of rescue or support in case of floods.

At the moment there is an increasing number of companies specialized in the construction of hovercraft built with the same techniques as the large hovercrafts that guarantee functionality and reliability of use. Even in Europe the interest in agonistic competitions with real formula championships is spreading. These races have not yet recalled many sponsors, but has recalled the “do -it -yourself” enthusiasts with demonstration of real racing machines that “slip or fly on the water” at speeds above 100 km/hour.

Typically, small hovercrafts have two separate engines for one for the “sustenance” and one for the “push”, both with one or more aeronautical propellers. The latest trend is to have an engine with a propeller or a pair of plywood propellers in venturi tube that transfer part of the air produced through a leap lecturer. Another trend is to use “skirts” and not a “unique skirt or tube” to control the stability of the vehicle and facilitate the spare part in case of tears.

The “concept” operation is very simple: the air produced by the propeller and conveyed to the skirts creates a constant flow of output to the surface, creating the “on cushion” effect (on the pillow). This “floating” effect allows the Hovercraft to lighten its weight called “Rabbit Footprint” in English as the weight that leaves the imprint “at that moment” is not higher than that of a rabbit. The skirts, as well as offering stability and “floating effect”, also serve to cross roughness without suffering how a boat walled would do. The part of the uncoated air is used as a “push” or to make the hovercraft move forward. The directionality is guaranteed by the rudders placed at the end of the Venturi tube. Small hovercrafts turn 360 ° on themselves without any problem, both by and at full speed. The large hovercraft of the last generation are equipped with variable step propellers that serve as a help for a rapid turn on themselves or as a brake in case of slowdown.

Some even small hovercrafts have a new concept push reversal system, a US patent for Eng. Christopher Fitzgerald, which allows a more effective maneuverability even in restricted environments, in addition to the rotations on the axis, braking and reverse. This system proves to be very useful on ice and for rescue operations in fast waters, allowing the Hovercraft to remain still on the spot in the middle of the current. The new and last Flapton system used on the MacP in addition to these performances, allows the control of the complete lateral and longitudinal structure, automatically maintaining the correct set -up parallel to the surface even in the narrower and maximum power.

The Hovercraft remains with the Ekranoplano and before the Space Shuttle the last invention of the twentieth century in the transport system and does not replace the boat, the seaplane or the helicopter but is placed as a multifunctional means to be used for the passage On surfaces of different nature, without leaving “furrows” and above all respecting the ecosystem.

International Maritime Organization

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