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112-461: Unlike many other four wheel steering systems, HICAS and Super HICAS are fitted to improve handling rather than just as a parking aid. Disabling or removing HICAS has become a popular aftermarket modification, with proponents citing more predictable steering behavior as an advantage. However, after disabling HICAS, it has been noted that slow maneuvers including parking and quick response steering seemed more difficult. The versions are distinguished by

224-482: A Royal Navy officer, C.H. Latimer-Needham , who sold his idea to Westland (by then the parent of Saunders-Roe's helicopter and hovercraft interests), and who worked with Cockerell to develop the idea further. The first passenger-carrying hovercraft to enter service was the Vickers VA-3 , which, in the summer of 1962, carried passengers regularly along the north Wales coast from Moreton, Merseyside, to Rhyl . It

336-493: A capacity of 418 passengers and 60 cars. These were later joined by the French-built SEDAM N500 Naviplane with a capacity of 385 passengers and 45 cars; only one entered service and was used intermittently for a few years on the cross-channel service until returned to SNCF in 1983. The service ceased on 1 October 2000 after 32 years, due to competition with traditional ferries, catamarans ,

448-414: A centering cam which pushed the steering rack and wheel back to the straight-ahead position. The centering force increased with speed, requiring more effort to turn the wheel at greater speeds. Modern speed-sensitive power steering systems reduce the mechanical or electrical assistance as the vehicle speed increases, giving a more direct feel. This feature is gradually becoming more common. For example, it

560-666: A characteristic rounded-rectangle shape. The first practical design for hovercraft was derived from a British invention in the 1950s. They are now used throughout the world as specialised transports in disaster relief, coastguard, military and survey applications, as well as for sport or passenger service. Very large versions have been used to transport hundreds of people and vehicles across the English Channel , whilst others have military applications used to transport tanks, soldiers and large equipment in hostile environments and terrain. Decline in public demand meant that as of 2023 ,

672-466: A design that relied only on the momentum of the air to provide lift, like a helicopter . In terms of power, a hovercraft would only need between one quarter to one half of the power required by a helicopter. Cockerell built and tested several models of his hovercraft design in Somerleyton, Suffolk, during the early 1950s. The design featured an engine mounted to blow from the front of the craft into

784-407: A driver a greater mechanical advantage, resulting in its use on larger, heavier vehicles, while the rack and pinion would originally be limited to smaller and lighter ones; due to the almost universal adoption of power steering , however, this is no longer considered an important advantage, leading to the increasing use of rack and pinion mechanisms on newer cars. The recirculating ball design also has

896-419: A driver to control the direction of the vehicle by turning the direction of the front wheels using a hand–operated steering wheel positioned in front of the driver. The steering wheel is attached to a steering column , which is linked to rods, pivots and gears that allow the driver to change the direction of the front wheels. The mechanism may include a rack and pinion mechanism that converts several turns of

1008-775: A fast torpedo boat , the Versuchsgleitboot had a top speed of over 32 knots (59 km/h). It was thoroughly tested and even armed with torpedoes and machine guns for operation in the Adriatic . It never saw actual combat, however, and as the war progressed it was eventually scrapped due to a lack of interest and perceived need, and its engines returned to the air force. The theoretical grounds for motion over an air layer were constructed by Konstantin Eduardovich Tsiolkovskii in 1926 and 1927. In 1929, Andrew Kucher of Ford began experimenting with

1120-477: A large wheelbase, while at higher speeds both front and rear wheels turn alike (electronically controlled), so that the vehicle may change position with less yaw and improved build-up of the lateral acceleration, enhancing straight-line stability. The "snaking effect" experienced during motorway drives while towing a travel trailer is thus largely nullified. Four-wheel steering found its most widespread use in monster trucks , where maneuverability in small arenas

1232-404: A low cost press forging process to manufacture the racks, eliminating the need to machine the gear teeth. Other arrangements are sometimes found on different types of vehicles; for example, a tiller or rear-wheel steering. Tracked vehicles such as bulldozers and tanks usually employ differential steering , where the tracks are made to move at different speeds or in opposite directions, using

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1344-408: A means to directly cause the turn. On the ground, aircraft are generally steered at low speeds by turning the nosewheel or tailwheel (using a tiller or the rudder pedals) or through differential braking, and by the rudder at high speeds. Missiles, airships and large hovercraft are usually steered by a rudder, thrust vectoring , or both. Small sport hovercraft have similar rudders, but steer mostly by

1456-526: A new form of high-speed land transportation, probably in the field of rail surface travel, for fast trips of distances of up to about 1,600 kilometres (1,000 mi)". In 1959, Ford displayed a hovercraft concept car , the Ford Levacar Mach I . In August 1961, Popular Science reported on the Aeromobile 35B, an air-cushion vehicle (ACV) that was invented by William R. Bertelsen and

1568-471: A number of niche roles where its combination of features were advantageous. Today, they are found primarily in military use for amphibious operations, search-and-rescue vehicles in shallow water, and sporting vehicles. Hovercraft can be powered by one or more engines. Smaller craft, such as the SR.N6 , usually have one engine with the drive split through a gearbox. On vehicles with several engines, one usually drives

1680-604: A number of smaller cylindrical skirts instead of one large one in order to avoid the problems noted above. During the early 1960s he developed a series of prototype designs, which he called "terraplanes" if they were aimed for land use, and "naviplanes" for water. The best known of these designs was the N500 Naviplane , built for Seaspeed by the Société d'Etude et de Développement des Aéroglisseurs Marins (SEDAM). The N500 could carry 400 passengers, 55 cars and five buses. It set

1792-582: A perceptible lash, or "dead spot" on center, where a minute turn of the steering wheel in either direction does not move the steering apparatus; this is easily adjustable via a screw on the end of the steering box to account for wear, but it cannot be eliminated because it will produce excessive internal forces at other positions and the mechanism will wear very rapidly. This design is still in use in trucks and other large vehicles, where rapidity of steering and direct feel are less important than robustness, maintainability, and mechanical advantage. The worm and sector

1904-660: A plane; and the Army were 'plain not interested'." This lack of military interest meant that there was no reason to keep the concept secret, and it was declassified. Cockerell was finally able to convince the National Research Development Corporation to fund development of a full-scale model. In 1958, the NRDC placed a contract with Saunders-Roe for the development of what would become the SR.N1 , short for "Saunders-Roe, Nautical 1". The SR.N1

2016-488: A section of a large aerofoil (this creates a low-pressure area above the wing much like an aircraft), the craft was propelled by four aero engines driving two submerged marine propellers, with a fifth engine that blew air under the front of the craft to increase the air pressure under it. Only when in motion could the craft trap air under the front, increasing lift. The vessel also required a depth of water to operate and could not transition to land or other surfaces. Designed as

2128-613: A service to Calais from Dover, which was soon superseded by that of Seaspeed . As well as Saunders-Roe and Vickers (which combined in 1966 to form the British Hovercraft Corporation (BHC)), other commercial craft were developed during the 1960s in the UK by Cushioncraft (part of the Britten-Norman Group) and Hovermarine based at Woolston (the latter being sidewall hovercraft , where the sides of

2240-458: A space below it, combining both lift and propulsion. He demonstrated the model flying over many Whitehall carpets in front of various government experts and ministers, and the design was subsequently put on the secret list. In spite of tireless efforts to arrange funding, no branch of the military was interested, as he later joked, "The Navy said it was a plane not a boat; the RAF said it was a boat not

2352-412: A special type of active four-wheel steering. It operates by steering all wheels in the same direction and at the same angle. Crab steering is used when the vehicle needs to proceed in a straight line but at an angle: when changing lanes on a highway at speed, when moving loads with a reach truck, or during filming with a camera dolly. Rear wheel steering can also be used when the rear wheels may not follow

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2464-470: A speed record between Boulogne and Dover of 74 kn (137 km/h). It was rejected by its operators, who claimed that it was unreliable. Another discovery was that the total amount of air needed to lift the craft was a function of the roughness of the surface over which it travelled. On flat surfaces, like pavement, the required air pressure was so low that hovercraft were able to compete in energy terms with conventional systems like steel wheels. However,

2576-413: A steering mechanism called a rack and pinion . The steering wheel turns a pinion gear, which moves a rack back and forth to steer the wheels. This mechanism converts the circular motion of the steering wheel to linear motion , which is applied to the wheels of the car via tie rods and a steering knuckle . Rack and pinion steering has several advantages, such as a direct steering "feel". This means that

2688-409: A suggestion made by his business partner Arthur Ord-Hume. In 1958, he suggested the use of two rings of rubber to produce a double-walled extension of the vents in the lower fuselage. When air was blown into the space between the sheets it exited the bottom of the skirt in the same way it formerly exited the bottom of the fuselage, re-creating the same momentum curtain, but this time at some distance from

2800-649: A version of this electronic four-wheel steering system on the Mazda 626 and MX6 in 1988. The first rally vehicle to use the technology was the Peugeot 405 Turbo 16 , which debuted at the 1988 Pikes Peak International Hill Climb. Previously, Honda had mechanical four-wheel steering as an option in their 1987–2001 Prelude and Honda Ascot models (1989–1996) later upgrading to electronically controlled. General Motors offered Delphi's Quadrasteer in their Silverado/Sierra and Suburban/Yukon. Due to low demand, GM discontinued

2912-428: A vessel can steer the ship only when water is passing over it. Hence, when a ship is not moving relative to the water it is in or cannot move its rudder, it does not respond to the helm and is said to have lost steerage . The motion of a ship through the water is known as making way . Boats on rivers must always be under propulsion, even when traveling downstream, in order to steer, requiring sufficient water to pass over

3024-698: A walled air cushion vehicle, the Glidemobile . Because the project was classified by the U.S. government, Fletcher could not file a patent. In April 1958, Ford engineers demonstrated the Glide-air, a one-metre (three-foot) model of a wheel-less vehicle that speeds on a thin film of air only 76.2 μm ( 3 ⁄ 1000 of an inch) above its tabletop roadbed. An article in Modern Mechanix quoted Andrew A. Kucher, Ford's vice president in charge of Engineering and Research noting "We look upon Glide-air as

3136-430: Is achieved through various arrangements, among them ailerons for airplanes, rudders for boats, cylic tilting of rotors for helicopters, and many more. Aircraft flight control systems are normally steered when airborne by the use of ailerons , spoileron , or both to bank the aircraft into a turn; although the rudder can also be used to turn the aircraft, it is usually used to minimize adverse yaw , rather than as

3248-405: Is also possible. A Hydraulic Power Steering (HPS) uses hydraulic pressure supplied by an engine-driven pump to assist the motion of turning the steering wheel. Electric Power Steering (EPS) is more efficient than hydraulic power-steering, since the electric power-steering motor only needs to provide assistance when the steering wheel is turned, whereas the hydraulic pump must run constantly. In EPS,

3360-424: Is critical, and it is also popular in large farm vehicles and trucks. Some of the modern European Intercity buses also utilize four-wheel steering to assist maneuverability in bus terminals, and also to improve road stability. Mazda were pioneers in applying four-wheel steering to automobiles, showing it on their 1984 Mazda MX-02 concept car, where the rear wheels counter-steered at low speeds. Mazda proceeded to offer

3472-431: Is normally achieved by changing the rates of the rubber bushings in the suspension. Some suspensions typically have compliance oversteer due to geometry, such as Hotchkiss live axles , semi-trailing arm IRS, and rear twist beams, but may be mitigated by revisions to the pivot points of the leaf spring or trailing arm, or additional suspension links, or complex internal geometry of the bushings. Passive rear-wheel steering

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3584-415: Is not a new concept, as it has been in use for many years, although not always recognized as such. Articulated steering is a system by which a vehicle is split into front and rear halves which are connected by a vertical hinge. The front and rear halves are connected with one or more hydraulic cylinders that change the angle between the halves, including the front and rear axles and wheels, thus steering

3696-417: Is not suitable for turns. The angle the wheels make in the vertical plane, known as camber angle , also influences steering dynamics as do the tires. Steering wheel turning is often measured in terms of number of full 360-degree turns to go lock-to-lock . This is when the steering input mechanism is restrained at its mechanical limit from the full right-turn stop to the left-turn stop. Many modern cars have

3808-413: Is programmed to provide opposite-phase rear wheel steering before turning the rear wheels in-phase, effectively performing a Scandinavian flick . Later versions of Super HICAS moved to an electric actuator for the rear steering rack, making the system much lighter. Four wheel steering Steering is the control of the direction of motion or the components that enable its control. Steering

3920-565: Is used as a high-speed ferry for up to 47 passengers and 47,500 pounds (21,500 kg) of freight serving the remote Alaskan villages of King Cove and Cold Bay . An experimental service was operated in Scotland across the Firth of Forth (between Kirkcaldy and Portobello, Edinburgh ), from 16 to 28 July 2007. Marketed as Forthfast , the service used a craft chartered from Hovertravel and achieved an 85% passenger load factor . As of 2009 ,

4032-674: The 2007 UK floods . Since 2006, hovercraft have been used in aid in Madagascar by HoverAid, an international NGO who use the hovercraft to reach the most remote places on the island. The Scandinavian airline SAS used to charter an AP1-88 hovercraft for regular passengers between Copenhagen Airport , Denmark, and the SAS Hovercraft Terminal in Malmö , Sweden. In 1998, the US Postal Service began using

4144-465: The Aérotrain . These designs competed with maglev systems in the high-speed arena, where their primary advantage was the very "low tech" tracks they needed. On the downside, the air blowing dirt and trash out from under the trains presented a unique problem in stations, and interest in them waned in the 1970s. By the early 1970s, the basic concept had been well developed, and the hovercraft had found

4256-461: The Levapad concept, metal disks with pressurized air blown through a hole in the centre. Levapads do not offer stability on their own. Several must be used together to support a load above them. Lacking a skirt, the pads had to remain very close to the running surface. He initially imagined these being used in place of casters and wheels in factories and warehouses, where the concrete floors offered

4368-490: The MID4 concept vehicle (1985), was a passive system which steered the rear wheels up to 0.5° in phase with the front wheels at speeds greater than 30 km/h (19 mph). Because the passive system essentially compresses the rubber suspension bushings, the resulting angle of rear-wheel steering is relatively small. The power steering pump supplies pressure through two regulating valves to two spring-loaded hydraulic actuators on

4480-548: The ThrustSSC . In cars, rear-wheel steering tends to be unstable because, in turns, the steering geometry changes, hence decreasing the turn radius (oversteer), rather than increasing it (understeer). Rear-wheel steering is meant for slower vehicles that need high-maneuverability in tight spaces, e.g. fork lifts. For heavy haulage or for increased maneuverability, some semi-trailers are fitted with rear-wheel steering, controlled electro-hydraulically. The wheels on all or some of

4592-457: The bushings to correct this tendency and steer the wheels slightly to the inside of the corner. This improves the stability of the car through the turn. This effect is called compliance understeer ; it, or its opposite, is present on all suspensions. Typical methods of achieving compliance understeer are to use a Watt's link on a live rear axle, or the use of toe control bushings on a twist beam suspension . On an independent rear suspension it

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4704-418: The clutch and brakes, to achieve a change of direction. Common steering system components include: The basic aim of steering is to ensure that the wheels are pointing in the desired direction to move the vehicle as required. This is typically achieved by a series of linkages, rods, pivots, and gears. One of the fundamental concepts is that of caster angle . Each wheel is steered with a pivot point ahead of

4816-409: The hull , or air cushion, that is slightly above atmospheric pressure . The pressure difference between the higher-pressure air below the hull and lower pressure ambient air above it produces lift, which causes the hull to float above the running surface. For stability reasons, the air is typically blown through slots or holes around the outside of a disk- or oval-shaped platform, giving most hovercraft

4928-473: The pitman arm , which is connected to the steering linkage and thus steers the wheels. The recirculating ball version of this apparatus reduces the considerable friction by placing large ball bearings between the screw and the nut. At either end of the apparatus, the balls exit from between the two pieces into a channel internal to the box, which connects them with the other end of the apparatus. Thus, they are "recirculated". The recirculating ball mechanism gives

5040-435: The propeller pod only (i.e., Volvo Penta IPS drive). Steering wheels may be used to control the rudder or propeller. Modern ships with diesel-electric drive use azimuth thrusters . Boats powered by oars or paddles are steered by generating a higher propulsion force on the side of the boat opposite of the direction of turn. Jet skis are steered by weight-shift induced roll and water jet thrust vectoring . The rudder of

5152-471: The 1959 Mercedes-Benz W111 Fintail, along with crumple zones. This safety feature first appeared on cars built by General Motors after an extensive and very public lobbying campaign enacted by Ralph Nader . Ford started to install collapsible steering columns in 1968. Audi used a retractable steering wheel and seat belt tensioning system called procon-ten , but it has since been discontinued in favor of airbags and pyrotechnic seat belt pre-tensioners. See

5264-589: The British built Hoverwork AP1-88 to haul mail, freight, and passengers from Bethel, Alaska , to and from eight small villages along the Kuskokwim River . Bethel is far removed from the Alaska road system, thus making the hovercraft an attractive alternative to the air based delivery methods used prior to introduction of the hovercraft service. Hovercraft service is suspended for several weeks each year while

5376-554: The English Channel. Hoverlloyd operated from Ramsgate , where a special hoverport had been built at Pegwell Bay, to Calais. Seaspeed operated from Dover, England, to Calais and Boulogne in France. The first SR.N4 had a capacity of 254 passengers and 30 cars, and a top speed of 83 kn (154 km/h). The channel crossing took around 30 minutes and was run like an airline with flight numbers. The later SR.N4 Mk.III had

5488-655: The SR.N1 Mk II. A further upgrade with the Armstrong Siddeley Viper produced the Mk III. Further modifications, especially the addition of pointed nose and stern areas, produced the Mk IV. Although the SR.N1 was successful as a testbed, the design hovered too close to the surface to be practical; at 9 inches (23 cm) even small waves would hit the bow. The solution was offered by Cecil Latimer-Needham , following

5600-563: The US/Canadian Great Lakes operate hovercraft for water and ice rescues, often of ice fisherman stranded when ice breaks off from shore. The Canadian Coast Guard uses hovercraft to break light ice. In October 2008, The Red Cross commenced a flood-rescue service hovercraft based in Inverness , Scotland. Gloucestershire Fire and Rescue Service received two flood-rescue hovercraft donated by Severn Trent Water following

5712-547: The aegis of P & A Campbell, the paddle steamer operators. Operations by Hovertravel commenced on 24 July 1965, using the SR.N6, which carried 38 passengers. Two 98 seat AP1-88 hovercraft were introduced on this route in 1983, and in 2007, these were joined by the first 130-seat BHT130 craft. The AP1-88 and the BHT130 were notable as they were largely built by Hoverwork using shipbuilding techniques and materials (i.e. welded aluminium structure and diesel engines) rather than

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5824-506: The aircraft techniques used to build the earlier craft built by Saunders-Roe-British Hovercraft Corporation. Over 20 million passengers had used the service as of 2004 – the service is still operating (as of 2020 ) and is by far the longest, continuously-operated hovercraft service. In 1966, two cross-channel passenger hovercraft services were inaugurated using SR.N6 hovercraft. Hoverlloyd ran services from Ramsgate Harbour, England, to Calais , France, and Townsend Ferries also started

5936-409: The amount of assistance is easily tunable to the vehicle type, road speed, and driver preference. An added benefit is the elimination of the environmental hazard posed by leakage and disposal of hydraulic power-steering fluid. In addition, electrical assistance is not lost when the engine fails or stalls, whereas hydraulic assistance stops working if the engine stops, making the steering doubly heavy as

6048-481: The back to push the craft forward. The British aircraft and marine engineering company Saunders-Roe built the first practical human-carrying hovercraft for the National Research Development Corporation , the SR.N1, which carried out several test programmes in 1959 to 1961 (the first public demonstration was in 1959), including a cross-channel test run in July 1959, piloted by Peter "Sheepy" Lamb, an ex-naval test pilot and

6160-475: The bottom of the craft. Latimer-Needham and Cockerell devised a 4-foot (1.2 m) high skirt design, which was fitted to the SR.N1 to produce the Mk V, displaying hugely improved performance, with the ability to climb over obstacles almost as high as the skirt. In October 1961, Latimer-Needham sold his skirt patents to Westland , who had recently taken over Saunders Roe's interest in the hovercraft. Experiments with

6272-460: The capstan and bowstring mechanism) is also found on some home-built vehicles such as soapbox cars and recumbent tricycles . Power steering helps the driver of a vehicle to steer by directing some of its engine power to assist in swiveling the steered road wheels about their steering axes. As vehicles have become heavier and switched to front-wheel drive , particularly using negative offset geometry, along with increases in tire width and diameter,

6384-472: The chief test pilot at Saunders Roe. Christopher Cockerell was on board, and the flight took place on the 50th anniversary of Louis Blériot 's first aerial crossing. The SR.N1 was driven by expelled air, powered by a single piston engine. Demonstrated at the Farnborough Airshow in 1960, it was shown that this simple craft can carry a load of up to 12 marines with their equipment as well as

6496-412: The corporate goal to become Japan's most advanced automobile manufacturer by the 1990s. "Project 901" resulted in several vehicles sharing a similar front- and rear- multi-link suspension design, including the 300ZX (Z32) , Infiniti Q45 (G50) , Primera / Infiniti G20 (P10) , Pulsar/Sunny (N14) , Silvia (S13) & S14) , Skyline (R32) , and Laurel (C33) . The earliest version of HICAS, as fitted to

6608-588: The current 5, 6, and 7 series, as an option. Renault introduced an optional all-wheel steering called '4control' in 2009, at first on the Laguna GT , which is currently available on the Talisman , Mégane and Espace vehicle lines. In 2013, Porsche introduced a system on the 911 Turbo as standard equipment. Since 2016, the Panamera has been offered with optional all-wheel steering. The 2014 Audi Q7

6720-403: The degree of rear steering and actuator for the rear steering rack, with the earliest version using a passive system to steer the rear wheels ("HICAS"), an intermediate version using a hydraulic actuator ("HICAS II"), and a later version using a hydraulic or electric actuator with additional programming ("Super HICAS"). Nissan initiated " Project 901 " in 1985, named for "90s-number-one" to embody

6832-667: The disappearance of duty-free shopping within the EU, the advancing age of the SR.N4 hovercraft, and the opening of the Channel Tunnel . The commercial success of hovercraft suffered from rapid rises in fuel prices during the late 1960s and 1970s, following conflict in the Middle East. Alternative over-water vehicles, such as wave-piercing catamarans (marketed as the SeaCat in the UK until 2005), use less fuel and can perform most of

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6944-487: The driver can feel the road better and have more precise control over the car's movement. BMW was one of the first manufacturers to adopt rack and pinion steering systems in the 1930s, with many other European manufacturers following suit. Auto manufacturers in the United States began to use rack and pinion steering with the 1974 Ford Pinto . Older designs use two main principles: the worm and sector design and

7056-495: The driver must now turn not only the very heavy steering—without any help—but also the power-assistance system itself. Speed-sensitive steering allows for highly assisted steering at low speeds for maneuverability, and lightly assisted steering at high speed for stability. The first vehicle with this feature was the Citroën SM with its DIRAVI system, first sold in France in 1970. The hydraulic steering system applied force on

7168-493: The effort needed to turn the wheels about their steering axis has increased, often to the point where major physical exertion would be needed were it not for power assistance. To alleviate this, auto makers have developed power steering systems, or more correctly power-assisted steering, since on road-going vehicles there has to be a mechanical linkage as a fail-safe . There are two types of power steering systems: hydraulic and electric/electronic. A hydraulic-electric hybrid system

7280-474: The extra thrust could be directed fore or aft, differentially for rotation. The SR.N1 made its first hover on 11 June 1959, and made its famed successful crossing of the English Channel on 25 July 1959. In December 1959, the Duke of Edinburgh visited Saunders-Roe at East Cowes and persuaded the chief test-pilot, Commander Peter Lamb, to allow him to take over the SR.N1's controls. He flew the SR.N1 so fast that he

7392-413: The fan (or impeller ), which is responsible for lifting the vehicle by forcing high pressure air under the craft. The air inflates the "skirt" under the vehicle, causing it to rise above the surface. Additional engines provide thrust in order to propel the craft. Some hovercraft use ducting to allow one engine to perform both tasks by directing some of the air to the skirt, the rest of the air passing out of

7504-601: The first Local Authority fire service in the UK to operate a hovercraft. It is used to rescue people from thick mud in the Weston-super-Mare area and during times of inland flooding. A Griffon rescue hovercraft has been in use for a number of years with the Airport Fire Service at Dundee Airport in Scotland. It is used in the event of an aircraft ditching in the Tay estuary. Numerous fire departments around

7616-468: The first to demonstrate a practical vehicle in continued use. A memorial to Cockerell's first design stands in the village of Somerleyton . Cockerell came across the key concept in his design when studying the ring of airflow when high-pressure air was blown into the annular area between two concentric tin cans (one coffee and the other from cat food) and a hairdryer. This produced a ring of airflow, as expected, but he noticed an unexpected benefit as well;

7728-444: The hovercraft became an effective transport system for high-speed service on water and land, leading to widespread developments for military vehicles, search and rescue, and commercial operations. By 1962, many UK aviation and shipbuilding firms were working on hovercraft designs, including Saunders Roe/ Westland , Vickers-Armstrong , William Denny , Britten-Norman and Folland . Small-scale ferry service started as early as 1962 with

7840-427: The hovercraft lift system acted as both a lift and a very effective suspension, and thus it naturally lent itself to high-speed use where conventional suspension systems were considered too complex. This led to a variety of " hovertrain " proposals during the 1960s, including England's Tracked Hovercraft and France's Aérotrain . In the U.S., Rohr Inc. and Garrett both took out licences to develop local versions of

7952-784: The hovercraft's marine tasks. Although developed elsewhere in the world for both civil and military purposes, except for the Solent Ryde-to-Southsea crossing, hovercraft disappeared from the coastline of Britain until a range of Griffon Hoverwork were bought by the Royal National Lifeboat Institution . Hovercraft used to ply between the Gateway of India in Mumbai and CBD Belapur and Vashi in Navi Mumbai between 1994 and 1999, but

8064-785: The hull projected down into the water to trap the cushion of air with normal hovercraft skirts at the bow and stern ). One of these models, the HM-2, was used by Red Funnel between Southampton (near the Woolston Floating Bridge ) and Cowes . The world's first car-carrying hovercraft was made in 1968, the BHC Mountbatten class (SR.N4) models, each powered by four Bristol Proteus turboshaft engines. These were both used by rival operators Hoverlloyd and Seaspeed (which joined to form Hoverspeed in 1981) to operate regular car and passenger carrying services across

8176-480: The launch of the Vickers-Armstrong VA-3. With the introduction of the 254 passenger and 30 car carrying SR.N4 cross-channel ferry by Hoverlloyd and Seaspeed in 1968, hovercraft had developed into useful commercial craft. Another major pioneering effort of the early hovercraft era was carried out by Jean Bertin 's firm in France. Bertin was an advocate of the "multi-skirt" approach, which used

8288-442: The lean of the rider and the bicycle: Ships and boats are usually steered with a rudder . Depending on the size of the vessel, rudders can be manually actuated, or operated using a servomechanism , or a trim tab or servo tab system. Rowing may be used to steer rowboats by using specific paddle strokes . Boats using outboard motors steer by rotating the entire drive unit. Boats with inboard motors sometimes steer by rotating

8400-422: The loss of lift at that point, and this led to further pressure on the skirt. After considerable experimentation, Denys Bliss at Hovercraft Development Ltd. found the solution to this problem. Instead of using two separate rubber sheets to form the skirt, a single sheet of rubber was bent into a U shape to provide both sides, with slots cut into the bottom of the U forming the annular vent. When deforming pressure

8512-417: The mid to late 2020s. Traditionally, cars feature a collapsible steering column (energy absorbing steering column) which will collapse in the event of a heavy frontal impact to avoid excessive injuries to the driver. Airbags are also generally fitted as standard. Non-collapsible steering columns fitted to older vehicles very often impaled drivers in frontal crashes, particularly when the steering box or rack

8624-435: The mid-1950s, and some German carmakers did not give up recirculating ball technology until the early 1990s. Other systems for steering exist, but are uncommon on road vehicles. Children's toys and go-karts often use a very direct linkage in the form of a bellcrank (also commonly known as a pitman arm) attached directly between the steering column and the steering arms, and the use of cable-operated steering linkages (e.g.

8736-586: The modern features of a lift engine blowing air into a flexible envelope for lift. Kaario's efforts were followed closely in the Soviet Union by Vladimir Levkov, who returned to the solid-sided design of the Versuchsgleitboot . Levkov designed and built a number of similar craft during the 1930s, and his L-5 fast-attack boat reached 70 knots (130 km/h) in testing. However, the start of World War II put an end to his development work. During World War II, an American engineer, Charles Fletcher , invented

8848-570: The only year-round public hovercraft service in the world still in operation serves between the Isle of Wight and Southsea in the UK. Oita Hovercraft is planning to resume services in Oita, Japan in 2024. Although now a generic term for the type of craft, the name Hovercraft itself was a trademark owned by Saunders-Roe (later British Hovercraft Corporation (BHC), then Westland ), hence other manufacturers' use of alternative names to describe

8960-399: The path taken by the front wheel tracks (e.g. to reduce soil compaction when using rolling farm equipment). Many modern vehicles have passive rear-wheel steering. On many vehicles, when cornering, the rear wheels tend to steer slightly to the outside of a turn, which can reduce stability. The passive steering system uses the lateral forces generated in a turn (through suspension geometry) and

9072-420: The pilot and co-pilot with only a slight reduction in hover height proportional to the load carried. The SR.N1 did not have any skirt, using instead the peripheral air principle that Cockerell had patented. It was later found that the craft's hover height was improved by the addition of a skirt of flexible fabric or rubber around the hovering surface to contain the air. The skirt was an independent invention made by

9184-416: The pilot shifting their weight from side to side and unbalancing the more powerful lift forces beneath the skirt. Jet packs and flying platforms are steered by thrust vectoring only. Helicopter flight controls are steered by cyclic control, changing the thrust vector of the main rotor(s), and by anti-torque control, usually provided by a tail rotor. A conventional automotive steering arrangement allows

9296-666: The possibility of establishing a permanent service is still under consideration. Since the Channel routes abandoned hovercraft, and pending any reintroduction on the Scottish route, the United Kingdom's only public hovercraft service is that operated by Hovertravel between Southsea ( Portsmouth ) and Ryde on the Isle of Wight . From the 1960s, several commercial lines were operated in Japan, without much success. In Japan

9408-413: The rear axle; these valves are designed to selectively pass or stop pressure to one side of each actuator, according to vehicle speed and lateral acceleration, which then steers the rear suspension subframe and semi-trailing arms. The passive HICAS was fitted initially to regular production vehicles with the 1986 Skyline GTS (R31) coupes (GTS, GTS-R, and GTS-X). HICAS was almost used on the 1985 model but

9520-457: The rear axles may be turned through different angles to enable tighter cornering, or through the same angle (crab steering) to move the rear of the trailer laterally. The aim of steer-by-wire technology is to completely remove as many mechanical components (steering shaft, column, gear reduction mechanism, etc.) as possible. Completely replacing conventional steering system with steer-by-wire has several advantages, such as: Steer-by-wire without

9632-456: The rear wheels are steered by a computer and actuators. The rear wheels generally cannot turn as far as the front wheels. There can be controls to switch off the rear steering and options to steer only the rear wheels independently of the front wheels. At low speed (e.g. parking) the rear wheels turn opposite to the front wheels, reducing the turning radius, sometimes critical for large trucks, tractors, vehicles with trailers and passenger cars with

9744-505: The river is beginning to freeze to minimize damage to the river ice surface. The hovercraft is able to operate during the freeze-up period; however, this could potentially break the ice and create hazards for villagers using their snowmobiles along the river during the early winter. In 2006, Kvichak Marine Industries of Seattle , US built, under licence, a cargo/passenger version of the Hoverwork BHT130 . Designated 'Suna-X', it

9856-415: The screw and nut. Both types were enhanced by reducing the friction; for screw and nut it is the recirculating ball mechanism, which is still found on trucks and utility vehicles. The steering column turns a large screw, which meshes with the nut by recirculating balls. The nut moves a sector of a gear, causing it to rotate about its axis as the screw is turned; an arm attached to the axis of the sector moves

9968-417: The section § Bicycles . Differential steering is the primary means of steering tracked vehicles , such as tanks and bulldozers; it is also used in certain wheeled vehicles commonly known as skid-steers , and implemented in some automobiles, where it is called torque vectoring , to augment steering by changing wheel direction relative to the vehicle. The bicycle is steered by turning the handlebar and by

10080-567: The services were subsequently stopped due to the lack of sufficient water transport infrastructure . In Finland, small hovercraft are widely used in maritime rescue and during the rasputitsa ("mud season") as archipelago liaison vehicles. In England, hovercraft of the Burnham-on-Sea Area Rescue Boat (BARB) are used to rescue people from thick mud in Bridgwater Bay . Avon Fire and Rescue Service became

10192-425: The sheet of fast-moving air presented a sort of physical barrier to the air on either side of it. This effect, which he called the "momentum curtain", could be used to trap high-pressure air in the area inside the curtain, producing a high-pressure plenum that earlier examples had to build up with considerably more airflow. In theory, only a small amount of active airflow would be needed to create lift and much less than

10304-428: The skirt design demonstrated a problem; it was originally expected that pressure applied to the outside of the skirt would bend it inward, and the now-displaced airflow would cause it to pop back out. What actually happened is that the slight narrowing of the distance between the walls resulted in less airflow, which in turn led to more air loss under that section of the skirt. The fuselage above this area would drop due to

10416-511: The smoothness required for operation. By the 1950s, Ford showed a number of toy models of cars using the system, but mainly proposed its use as a replacement for wheels on trains, with the Levapads running close to the surface of existing rails. In 1931, Finnish aero engineer Toivo J. Kaario began designing a developed version of a vessel using an air cushion and built a prototype Pintaliitäjä ('Surface Glider'), in 1937. His design included

10528-429: The steering wheel into a large linear displacement. Alternatively, it may use a recirculating ball system. The mechanism may be power-assisted , usually by hydraulic or electrical means. The use of a variable rack (still using a normal pinion) was invented by Arthur Ernest Bishop in the 1970s, so as to improve vehicle response and aim to allow for more comfortable steering, especially at high speeds. He also created

10640-417: The surface of the rudder to effect changes in the direction of the boat in response to the helm. This is called having "steerage way". Hovercraft A hovercraft ( pl. : hovercraft ), also known as an air-cushion vehicle or ACV , is an amphibious craft capable of travelling over land, water, mud, ice, and various other surfaces. Hovercraft use blowers to produce a large volume of air below

10752-460: The technology at the end of the 2005 model year. Nissan/Infiniti offer several versions of their HICAS system as standard or as an option in much of their line-up. In the early 2000s, a new generation of four-wheel steering systems was introduced into the market. In 2001 BMW equipped the E65 7 series with an all-wheel steering system (optional, called 'Integral Active Steering'), which is available on

10864-824: The use of a steering column was first offered in a production car with the Nissan Infiniti Q50 in 2013. Steer-by-wire continued to be offered with the QX50 and QX55, and as of 2022 is being offered with the Infiniti Q60 coupe. Production battery electric vehicles in the 2020s that offer steer-by-wire with no steering column include the Canoo Lifestyle Vehicle , Lexus RZ 450e , REE Automotive P7-module -based vehicles, Toyota bZ4X , and Tesla Cybertruck . As of 2023 Lotus , Peugeot , and Mercedes-Benz plan to offer steer-by-wire cars in

10976-755: The vehicle. This system does not use steering arms, king pins, tie rods, etc. as does four-wheel steering. If the vertical hinge is placed equidistant between the two axles, it also eliminates the need for a central differential in four-wheel drive vehicles, as both front and rear axles will follow the same path, and thus rotate at the same speed. Articulated haulers have very good off-road performance. Vehicle-trailer-combinations such as semi-trailers, road trains , articulated buses , and internal transport trolley trains can be regarded as passively-articulated vehicles. A few types of vehicle use only rear-wheel steering, notably fork lift trucks , camera dollies , early pay loaders , Buckminster Fuller 's Dymaxion car , and

11088-407: The vehicles. There have been many attempts to understand the principles of high air pressure below hulls and wings. Hovercraft are unique in that they can lift themselves while still, differing from ground effect vehicles and hydrofoils that require forward motion to create lift. The first mention, in the historical record of the concepts behind surface-effect vehicles, to use the term hovering

11200-399: The wheel, which tends to make the steering self-centered in the direction of travel. The steering linkages connecting the steering box and the wheels usually conform to a variation of Ackermann steering geometry , to account for the fact that in a turn, the inner wheel travels in a path of smaller radius than the outer wheel, so that the degree of toe suitable for driving in a straight path

11312-549: Was an older design, used for example in Willys and Chrysler vehicles, and the Ford Falcon (1960s). To reduce friction, the sector is replaced by a roller or rotating pins on the rocker shaft arm. Generally, older vehicles use the recirculating ball mechanism, and only newer vehicles use rack-and-pinion steering. This division is not very strict, however, and rack-and-pinion steering systems can be found on British sports cars of

11424-436: Was applied to the outside of this design, air pressure in the rest of the skirt forced the inner wall to move in as well, keeping the channel open. Although there was some deformation of the curtain, the airflow within the skirt was maintained and the lift remained relatively steady. Over time, this design evolved into individual extensions over the bottom of the slots in the skirt, known as "fingers". Through these improvements,

11536-548: Was asked to slow down a little. On examination of the craft afterwards, it was found that she had been dished in the bow due to excessive speed, damage that was never allowed to be repaired, and was from then on affectionately referred to as the 'Royal Dent'. Testing quickly demonstrated that the idea of using a single engine to provide air for both the lift curtain and forward flight required too many trade-offs. A Blackburn Marboré turbojet for forward thrust and two large vertical rudders for directional control were added, producing

11648-478: Was by Swedish scientist Emanuel Swedenborg in 1716. The shipbuilder John Isaac Thornycroft patented an early design for an air cushion ship / hovercraft in the 1870s, but suitable, powerful, engines were not available until the 20th century. In 1915, the Austrian Dagobert Müller von Thomamühl (1880–1956) built the world's first "air cushion" boat ( Luftkissengleitboot ). Shaped like

11760-494: Was called HICAS II when it reached production with the Nissan 180SX . The hydraulic system again was powered by the power steering pump, using speed sensors to determine how much and in which direction to steer the rear wheels; for production vehicles, rear steering was limited to 1°. Compared to HICAS II, Super HICAS uses a dedicated computer instead of speed sensors to actuate rear steering by up to 1°; upon initial turn in, it

11872-422: Was envisioned to revolutionise the transportation system, with personal hovering self-driving cars that could speed up to 2,400 km/h (1,500 mph). The idea of the modern hovercraft is most often associated with Christopher Cockerell , a British mechanical engineer. Cockerell's group was the first to develop the use of a ring of air for maintaining the cushion, the first to develop a successful skirt, and

11984-714: Was launched with an optional system. Also the Japanese OEMs offer luxury segment vehicles equipped with all-wheel steering, such as Infiniti on its QX70 model ('Rear Active Steering') and Lexus on the GS. Italian manufacturers have launched the technology in the model years 2016–17 with the Ferrari F12tdf , the Ferrari GTC4Lusso as well as the Lamborghini Aventador S . Crab steering is

12096-412: Was mounted in front of the front axle line, at the front of the crumple zone . This was particularly a problem on vehicles that had a rigid separate chassis frame with no crumple zone. Many modern vehicle steering boxes or racks are mounted behind the front axle on the front bulkhead, at the rear of the front crumple zone. Collapsible steering columns were invented by Béla Barényi and were introduced in

12208-598: Was not ready in time for production. The system was later adapted to work on many models in the Nissan range, beginning with the Passage GT . A later version of HICAS, first shown on the CUE-X concept car (1985), added a hydraulic actuator and steering rack to the passive system, which allowed the car to steer the rear wheels up to 7° in opposition to the front wheels to aid maneuverability at lower speeds. This active system

12320-458: Was powered by a 450 hp Alvis Leonides engine powering a vertical fan in the middle of the craft. In addition to providing the lift air, a portion of the airflow was bled off into two channels on either side of the craft, which could be directed to provide thrust. In normal operation this extra airflow was directed rearward for forward thrust and blew over two large vertical rudders that provided directional control. For low-speed manoeuvrability,

12432-609: Was powered by two turboprop aero-engines and driven by propellers . During the 1960s, Saunders-Roe developed several larger designs that could carry passengers, including the SR.N2 , which operated across the Solent , in 1962, and later the SR.N6 , which operated across the Solent from Southsea to Ryde on the Isle of Wight for many years. In 1963 the SR.N2 was used in experimental service between Weston-super-Mare and Penarth under

12544-485: Was used on a production pickup truck, the Tesla Cybertruck, in 2023. Four-wheel steering is a system employed by some vehicles to improve steering response, increase vehicle stability while maneuvering at high speed, or to decrease turning radius at low speed. In an active four-wheel steering system, all four wheels turn at the same time when the driver steers. In most active four-wheel steering systems,

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