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Mitsui Archimedean Screw Tractor
Japan · Screw tractor · built by Mitsui Engineering & Shipbuilding Co., Ltd.
| Also known as | Mitsui AST, AST-001, AST-002 |
|---|---|
| Manufacturer | Mitsui Engineering & Shipbuilding Co., Ltd. |
| Country | Japan |
| Built | 1978– |
| Type | Screw tractor |
| Status | Prototype |
| Use | Civilian |
| Propulsion | |
| In water | Archimedes screw |
| Hull | Aluminium |
| Engine | Deutz air-cooled V12 four-stroke diesel, 300 hp, Fuller hydrostatic transmission (AST-002) |
| Power | 300 hp |
| Dimensions & performance | |
| Length | 8.85 m |
| Width | 4.9 m |
| Weight | 10,800 kg |
| Speed on land | 11 km/h |
| Speed on water | 8 km/h |
| Seats | 5 |
Specifications need checking. Some figures here were taken from the archive and have not been confirmed against a source.
The Mitsui Archimedean Screw Tractor (AST) was an amphibious vehicle developed by Mitsui Engineering & Shipbuilding for transport, survey and support work in ice-covered seas and marshland, with Arctic oil and gas development in mind. Instead of wheels or tracks it rides on a pair of large cylindrical rotors fitted with helical blades under the hull, which provide both buoyancy and propulsion on water, ice, snow and mud.
Development
Work started in 1976. After tests of screw rotors and one-metre models in an ice basin, water and mud, Mitsui built the experimental AST-001 in 1978: 3.69 m long and weighing 1.6 tonnes, it was tested on Saroma Lagoon in Hokkaido in February 1979 and later in marshy areas. The larger AST-002, 8.85 m long and 10.8 tonnes, followed in 1979 and was tested in pack ice off Mombetsu on the Sea of Okhotsk and on Komuke Lagoon in February 1980. In spring 1981 it was taken to Prudhoe Bay, Alaska, where until the end of that year it ran in as many ice conditions as possible, towing loaded sleds and a hover-barge. Mitsui's engineers presented the results at the 1982 Offshore Technology Conference in Houston, and the AST was shown at the Nor-Fishing '82 exhibition in Norway.
Design and performance
The AST-002 has a corrosion-resistant aluminium hull about 8.85 m long and 4.9 m wide, a 300 hp air-cooled Deutz V12 diesel with hydrostatic drive, and room for a crew of five. It can make about 6 knots on ice and 4.3 knots in water, with a bollard pull of up to 10 tonnes on ice. It moves easily between open water and the ice surface, and can haul itself out of the sea onto an ice shelf. It is a powerful icebreaker for its size: a US Army Cold Regions Research and Engineering Laboratory review describes it breaking ice up to 45 cm thick by climbing onto the edge, and up to 80 cm by repeatedly ramming or rocking on the edge, clearing 3-4 hectares of level ice an hour. The design stayed stable even with only one screw turning.
Only two were built. A surviving AST-002 was later offered for sale on eBay, with the seller noting that it had cost close to $500,000 new.
3 Photographs
9 photographs in the archive folder. Click any image to view it full size.
4 Documents
- Manual US Army Corps of Engineers EM 1110-2-1612, chapter 3: Ice control for flood damage reduction and hydropower operation (2002) original
- Other US patent 1,431,440: Snow motor vehicle (scanned, no text layer) original
- Article MORICE Phase 1 report: mechanical oil recovery in ice-infested waters (incl. Archimedean screw vehicle concept) original
- Article CRREL Special Report 98-14: Nonstructural Ice Control (R.B. Haehnel, 1998) original
5 Related vehicles
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