Month: May 2013
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Pros & Cons
Advantages Pump jets have some advantages over bare propellers for certain applications, usually related to requirements for high-speed or shallow-draft operations. These include: Higher speed before the onset of cavitation, because of the raised internal dynamic pressure High power density (with respect to volume) of both the propulsor and the prime mover (because a smaller, […]
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Workings
Workings A pump-jet works by having an intake (usually at the bottom of the hull) that allows water to pass underneath the vessel into the engines. Water enters the pump through this inlet. The pump can be of a centrifugal design for high speeds, an inducer for low speeds, or an axial flow pump for […]
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Pump-jets
A pump-jet, hydrojet, or water jet is a marine system that creates a jet of water for propulsion. The mechanical arrangement may be a ducted propeller with nozzle, or a centrifugal pump and nozzle. The Italian inventor Secondo Campini showed the first functioning man-made pump-jet engine in Venice in 1931. However, he never applied for […]
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Recent developments
Recent developments The British Ice Challenger exploration team used a screw drive in their Snowbird 6 vehicle (a modified Bombardier tracked craft) to traverse the ice floes in the Bering Strait. The rotating cylinders allowed Snowbird 6 to move over ice and to propel itself through water, but the screw system was not considered suitable […]
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Amphibians
Amphibians The threaded cylinders are necessarily large to ensure a substantial area of contact and buoyancy. Being lightweight, the cylinders may conveniently serve as floats and the arrangement may be used in the design of an amphibious vehicle. During the Vietnam War, the American Waterways Experiment Station (WES) tested the Marsh Screw Amphibian, designed by […]
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Second World War period
The Second World War period With the occupation of Norway by Nazi Germany in World War II, the quixotic Geoffrey Pyke considered the problem of transporting soldiers rapidly over snow. He proposed the development of a screw-propelled vehicle based on the Armstead snow motor. Pyke envisaged that the vehicles would be used by a small […]
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Armstead Snow Motor
Armstead Snow Motor In the 1920s the Armstead Snow Motor was developed. When this was used to convert a Fordson tractor into a screw-propelled vehicle with a single pair of cylinders. A machine used in the Truckee,CA area was referred to by locals as the “Snow Devil” and that name has been erroneously attached to […]
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Early developments
Early developments One of the earliest examples of a screw-propelled vehicle was designed by Jacob Morath, a native of Switzerland who settled in St. Louis, Missouri in the United States in 1868. Morath’s machine was designed for agricultural work such as hauling a plough. The augers were designed with cutting edges so that they would […]
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screw-propelled vehicle
A screw-propelled vehicle is a land or amphibious vehicle designed to cope with difficult snow and ice or mud and swamp. Such vehicles are distinguished by being moved by the rotation of one or more auger-like cylinders fitted with a helical flange that engages with the medium through or over which the vehicle is moving. […]
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Type 63A
The Type 63A (also known as the ZTS63A) is an Amphibious light tank upgraded from the Type 63, designed for river-crossing operations at inland rivers and lakes. Its industrial designation is WZ213. Development Before the mid-1990s, Chinese ground forces relied on the Type 63 amphibious light tank developed in the early 1960s. The low swimming […]