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Aviation History
1963
1963 - 1129.PDF
Air-Cushion Vehicles FLIGHT International supplement, 25 April 1963 Cushion-assisted Land Vehicles VICKERS-ARMSTRONGS' LAND-ROVER CONVERSION DEMONSTRATED THE WORD "Hovertruck" (writes Brian Phillips) became current some three years or so ago, when Folland Aircraft Ltd began to take an interest in the hovercraft field. Most of the work at Folland in 1960/61 was directed at solving overland problems by air- cushion means. A fairly extensive investigation into the soil conditions affecting the go-ability of off-the-road transport was carried out there, and the concept of a cushion-assisted conven tional vehicle which would rely on its wheel system for propulsion, steering and stability was propounded. It is unfortunate that this work was dis continued, for subsequent tests have shown the basic concept to be sound. Vicker-Armstrongs (Engineers) Ltd are to be congratulated on seeing the possibilities of this system, and on taking the work several stages further. They, too, have adopted the name Hovertruck. Following trials and demonstrations last year, representatives of the Press were invited on March 26 to see a demonstration of three converted Land- Rovers on fenland near Ely. Two of the vehicles have recently been bought by Soil Fertility Ltd, who have, in fact, been carrying out spraying operations with a prototype vehicle for the past nine months. As many readers of this journal will know, any given soil condition can be shown to have an optimum wheel loading which gives maximum tractive effort. In many cases this wheel loading is considerably less than that which would obtain from the fully loaded vehicle condition. A vehicle, the wheel load of which may be reduced by the application of an air cushion to its Tractor bogged down; air-cushion Land-Rover cruising happily over similar going underside, has the fortunate capability of being able to vary its wheel loading at the will of the driver. Vickers- Armstrongs have taken a standard 109in wheel-base Land-Rover, extended the bodywork all round, fitted it with a rectangular skirt system capable of being rai5ed and lowered, and with two double-entry 25in centrifugal fans feed ing air to a plenum space bounded by the skirt and the vehicle underside. The fans themselves were originally driven by a 2J litre Rover engine; this has recently been changed to the 3 litre, to give increased load-carrying capacity. The fans are mounted with horizontal concentric shafts coupled by constant- velocity universal joints and belt-driven from a layshaft direct-coupled to the engine. In conjunction with Soil Fertility Ltd the vehicles have been fitted with a tank for liquid fertilizer, a pump (remarkably enough, capable of emptying the tank in just over a minute) and spray equipment for dispensing a liquid fertilizer behind the vehicle. Of the maximum loaded weight of over 8,0001b, well over 6,0001b may be supported on the air cushion, leaving the wheels in a lightly loaded condition if required for soft-ground operation. The range of wheel loadings with typical net tractive effort curves is shown in an accompanying graph. The air- cushion pressure is varied by raising and lowering the skirt, a greater gap under the skirt causing a corresponding fall in pressure. The maximum working loading of 501b/sq ft is achieved at a nominal ground clearance of Jin. A hydraulic jacking system permits the skirt to be raised and lowered from the driving cab, and the front and rear portions can be raised and lowered independently. Two ACV Land-Rovers spraying liquid fertilizer on a winter corn crop near Ely 60
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