Amphibious vehicle Totally Explained

Everything about Amphibious Vehicle totally explained

An amphibious vehicle (or simply amphibian), is a vehicle or craft, that's a means of transport, viable on land as well as on water - just like an amphibian. This definition applies equally to any land and water transport, small or large, powered or unpowered, ranging from amphibious bicycles, ATVs, cars, buses, trucks, RVs, and military vehicles, all the way to the very largest hovercrafts. Classic landing craft are generally not considered amphibious vehicles, although they are part of amphibious assault. Nor are Ground effect vehicles, such as Ekranoplans. The former don't offer any real land transportation at all - the latter (aside from completely disconnecting from the surface, like an airplane), will likely crash on any but the flattest of landmasses.

General technical notes

Apart from the distinction in sizes mentioned above, two main categories of amphibious vehicle are immediately apparent: those that travel on an air-cushion (Hovercraft) and those that don't. Amongst the latter, many designs were prompted by the desire to expand the off-road capabilities of land-vehicles to an "all-terrain" ability, in some cases not only focused on creating a transport that will work on land and water, but also on intermediates like ice, snow, mud, marsh, swamp etc.. This explains why many designs use tracks in addition to or instead of wheels, and in some cases even resort to articulated body configurations.
Most land vehicles - even lightly armored ones - can be made amphibious simply by providing them with a waterproof hull and perhaps a propellor. This is possible thanks to the vehicle's volume usually being bigger than its displacement, meaning it'll float. Heavily armored vehicles however sometimes have a density greater than water (their weight in kilograms exceeds their volume in liters), and will need additional buoyancy measures. These can take the form of inflatable floatation devices, much like the sides of a rubber dinghy, or a waterproof fabric skirt raised from the top perimeter of the vehicle.
In the case of the Land Rover pictured to the side, floats in the shape of oil-drums have been used to create a vehicle that will swim much like an improvised raft.
For propulsion in or on the water some vehicles simply make do by spinning their wheels or tracks, while others can power their way forward more effectively using (additional) screw propellor(s) or water jet(s). Most amphibians will work only as a displacement hull when in the water - only a small number of designs have the capability to raise out of the water when speed is gained, to achieve high velocity hydroplaning, skimming over the water surface like speedboats.

History

Some of the earliest known amphibious vehicles were amphibious carriages, the invention of which is credited to the notorious Neapolitan Prince Raimondo di Sangro of Sansevero (ca. 1750

) or (1781).
The first known self-propelled amphibious vehicle, a steam-powered wheeled dredging barge, named the Orukter Amphibolos, was conceived and built by United States inventor Oliver Evans in 1805, although it's disputed to have successfully travelled over land or water under its own steam(External Link

).
Although it's unclear who (and where and when) built the first combustion-engined amphibian, in all likelihood the development of powered amphibious vehicles didn't start until 1899. Until the late 1920s the efforts to unify a boat and an automobile mostly came down to simply putting wheels and axles on a boat hull, or getting a rolling chassis to float by blending a boat-like hull with the car's frame (Pohl, 1998). One of the first reasonably well documented cases was the 1905 amphibious petrol-powered carriage of T. Richmond (Jessup, Iowa, USA). Just like the world's first petrol-powered automobile (1885, Carl Benz) it was a three-wheeler. The single front wheel provided direction, both on land and in the water. A three-cylinder petrol combustion-engine powered the oversized rear wheels. In order to get the wheels to provide propulsion in the water, fins or buckets would be attached to the rear wheel spokes. Remarkably the boat-like hull was one of the first integral bodies ever used on a car (Pohl, 1998). Since the 1920s development of amphibious vehicles greatly diversified. Numerous designs have been created for a broad range of applications, including recreation, expeditions, search & rescue, and military, leading to a myriad of concepts and variants. In some of them the amphibious capabilities are central to their purpose, whereas in others they're only an expansion to what has remained primarily a watercraft or a land vehicle.

Small wheeled amphibians

Amongst the smallest non air-cushioned amphibious vehicles are amphibious bicycles

, (see also

) and ATVs. Although the former are still an absolute rarity, the latter saw significant popularity in North America during the nineteen sixties and early seventies. Typically an Amphibious ATV or AATV is a small, lightweight, off-highway vehicle, constructed from an integral hard plastic or fibreglass bodytub, fitted with six (sometimes eight) driven wheels, with low pressure, balloon tires. With no suspension (other than what the tires offer) and no steering wheels, directional control is accomplished through skid-steering - just as on a tracked vehicle - either by braking the wheels on the side where you want to turn, or by applying more throttle to the wheels on the opposite side. Most contemporary designs use garden tractor type engines, that will provide roughly 25 mph top speed on land.
Constructed this way, an AATV will float with ample freeboard and is capable of traversing swamps, ponds and streams as well as dry land. On land these units have high grip and great off-road ability, that can be further enhanced with an optional set of tracks that can be mounted directly onto the wheels. Although the spinning action of the tires is enough to propel the vehicle through the water - albeit slowly - outboard motors can be added for extended water use. Current AATV manufacturers are Argo

, Land Tamer

, MAX ATVs

and Triton

.
Articulated-body designs in this category were the Coot

and the very similar TAG Croco

.
Recently some efforts are made towards amphibious ATV's of the straddled variety. For instance in the form of an add-on inflatable pontoon kit

, that can be installed on any quad-bike ATV with front and rear metal frame racks and at least 14" water fording ability. A new development was shown in 2006 by Gibbs

Technologies. Their Quadski is a prototype for a cross between a Jetski and a Quad-bike.

Amphibious cars

Amphibious automobiles have been conceived from ca. 1900, however the Second World War significantly stimulated their development. Two of the most significant amphibious cars to date were developed during World War II. The most proliferous was the German Schwimmwagen, a small jeep-like 4x4 vehicle designed by the Porsche engineering firm in 1942 and widely used in World War II. The amphibious bodywork was designed by Erwin Komenda, the firm's body construction designer, using the engine and drive train of the Kübelwagen. An amphibious version of the Willys MB jeep, the Ford GPA or 'Seep' (short for Sea jeep) was developed during World War II as well. A specially modified GPA, called Half-Safe, was driven and sailed around the world by Australian Ben Carlin in the 1950s.
One of the most capable post-war amphibious off-roaders was the German Amphi-Ranger, that featured a hull made of sea-water resistant AlMg2 aluminium alloy. Extensively engineered, this costly vehicle was proven sea-worthy at a Gale force 10 storm off the North Sea coast (Pohl, 1998). Only about 100 were built - those who own one have found it capable of crossing the English Channel almost effortlessly.
Purely recreational amphibian cars include the 1960s Amphicar and the contemporary Gibbs Aquada. With almost 4.000 pieces built, the Amphicar is still the most successfully produced civilian amphibious car to date. The Gibbs Aquada stands out due to its capability of high speed planing on water.
Other amphibious cars currently in production include the Dutton Commander

'AmphiJeep' (GB), the US Hydra Spyder

and WaterCar, as well as several Chinese designs like the JMC BY5020TSL

(see also

) and BJ5032(XZHE)

, and the even longer JMC JX5021TLYDS

. American distributor Rodedawg

is now seeking to bring an adapted version

of the Chinese amphibs to America.

Articulated and multi-unit tracked amphibians

The unique capability that distinguishes multi-unit vehicles from single unit ones, is the ability to help each other. According to a 1999 article

in Military Parade magazine, multi-unit, all-terrain transport vehicles were first proposed by the British in 1913, and by the 1950s, over 40 types of articulated tracked vehicles (ATVs) were in production. The articulated tracked concept is chosen primarily for its combination of high maneuverability, cross-country abilities, and remarkable load-carrying capacity. In some cases the design is made amphibious, giving them all-terrain capability in the truest sense. Usually the front unit houses at least the engine, gearboxes, fuel tank(s) and the driver's compartment, and perhaps there's some space left for cargo or passengers, whereas the rear unit is the primary load carrier.
Examples of this concept are the Russian Vityaz

DT-(10/20/30)P

models, the Swedish Volvo Bv202 and Hagglunds Bv206 designs, and Singapore Bronco ATTC

(All-Terrain Tracked Carrier)

.
A highly specialised development is the Arktos expedition and evacuation

craft, that uses a linkage with two joints to connect the two units, as well as fitting each unit with its own engine, to give each unit enhanced independence of movement.

Hovercraft

For certain applications wheeled and tracked amphibious vehicles are slowly being supplanted by Air-cushioned landing craft in many modern militaries. An Air-Cushion vehicle (ACV) or hovercraft is designed for traveling over land or water supported by a cushion of slow moving, low-pressure air ejected downwards against the surface below it. In principle a hovercraft can travel over any sufficiently smooth surface, solid, liquid, mixed, or anything in between. Considering that hovercraft can be quite large, some riding on an air-cushion contained by skirts several meters tall, these can deal with a reasonable level of unevenness in the terrain, unfazed by obstacles 1 to 2 meters in height. On the other hand the smallest personal hovercraft - ACVs no bigger than a compact hatchback - are nimble enough to follow some rolling of the terrain just as easily.
One of the benefits of this type of amphibious craft is the possibility of making them large - the British-built SR-N4 Mk-3 Channel-crossing ferries were 56,4m (185 ft) in length and 23,8m (78 ft) wide. Other benefits of ACVs include their very high water speed (an SR-N4 Mk-1 could do 83 knots - 95 mph or 154 km/h !) and the fact that they can make the transition from land to water (or vice versa) at speed - contrary to most wheeled or tracked amphibians. Drawbacks are high fuel consumption and noise levels.
For military purposes, the hovercraft's ability to distribute its laden weight evenly across the surface below it makes it perfectly suited to the role of amphibious landing craft. The US Navy LCAC can take troops and materials (if necessary an M1 Abrams tank) from ship to shore and can access more than 70% of the world's coastline, as opposed to conventional landing craft, that have only about 17% of that coastline available to them for landing.

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