Amphibious vehicle
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An amphibious vehicle (or simply amphibian), is a vehicle that is 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(see also), 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.
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[edit] History
Some of the earliest known amphibious vehicles were amphibious carriages, the invention of which is credited to the notorious Napolitan Prince Raimondo de Sangro of SanSevero (ca. 1750) or Sir Samuel Bentham (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 is disputed to have successfully travelled over land or water under its own steam[1].
Although it is unclear who (and where and when) built the first combustion-engined amphibian, in all likelihood the development of powered amphibious vehicles didn't get afloat 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 worlds 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, leading to a myriad of concepts and variants. Many of those were conceived for military applications. Soft-skinned and lightly armored vehicles need only a waterproof hull and a propellor. More heavily armored vehicles need additional measures.
[edit] Some 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.
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.
[edit] Amphibious cars
Several amphibious automobiles have been developed, including the Amphicar in the 1960s and the contemporary Gibbs Aquada. The most proliferous was the German Schwimmwagen, a small jeep-like 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' was developed during WW II as well. A specially modified GPA, called Half-Safe, was driven and sailed around the world by Australian Ben Carlin in the 1950s.
[edit] Amphibious trucks
The most famous such vehicle of World War II was the DUKW Amphibious Truck. It was deployed in the Pacific theatre to establish and supply beachheads. It was designed as a wartime project by Sparkman & Stephens, the famous yacht design firm who also designed the hull for the Ford GPA 'Seep' (short for Sea jeep).
During the Vietnam War, the US Army used the amphibious Gama Goat to move supplies through the canals and rice paddies of Southeast Asia and the huge LARC-LX or "BARC" to take vehicles and supplies onto the beaches.
The British used the wheeled Alvis Stalwart as their amphibious cargo carrier.
[edit] Tanks and armored Vehicles
Many modern tanks and armoured personnel carriers have an amphibious mode in which a fabric skirt adds buoyancy, and the tracks, sometimes with added propellor, to provide motive power. The Sherman DD tank used in the D-Day invasion had this setup. Some military vehicles are not truly amphibious but are capable of "wading" using waterproof screens to keep the upper hull dry. In WWII the tanks following the Sherman DDs were given waterproofed hulls and trunking was fixed to the engine intakes and exhausts to allow them to come ashore from landing craft in shallow water. The Germans gave their Tiger tank a long schnorkel, essentially a long tube on the commanders hatch that allowed it to wade through 4 metres of water.
A modern amphibious vehicle, the Véhicule de l'Avant Blindé or VAB ("Armoured Vanguard Vehicle" in French), can be used as a personnel carrier, anti-tank missile platform and even for riot control with a water cannon.
The United States Marine Corps currently uses the AAV7A-1 Amphibious Assault Vehicle, which was preceded by a long line of LVT (Landing Vehicle Tracked) designs, that started around 1940.
For certain applications amphibious vehicles are slowly being supplanted by air cushion vehicles, such as hovercraft, in many modern militaries.
[edit] See also
[edit] Further reading
- René Pohl: Mit dem Auto baden gehen. HEEL Verlag, Gut-Pottscheidt Konigswinter 1998, ISBN 3-89365-702-9
- Ben Carlin, Half-Safe, Andre Deutsch Ltd 1955
- Ben Carlin, The Other Half of Half-Safe, ISBN 0-9598731-1-2, Guildford Grammar School Foundation 1989
[edit] External links
