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Aviation History
1963
1963 - 1145.PDF
Air-Cushion Vehicles WESTLAND RIDE HIGH . . . the Westland SR.N3, which is now being built for the Ministry of Aviation for the Joint Services Trials Unit at Lee-on- Solent to carry out operational experi ments. The SR.N3 will be fitted with long skirts. "Looking to the future, a strong Westland team of project and design engineers is actively engaged on investi gations of new and improved ACVs. A 170 ton craft to meet the transport requirements across the English Channel has reached an advanced stage in the engineering study." The last-mentioned craft is the SR.N4, some particulars of which are given later. The principle of the Westland flexible skirt One of the biggest surprises which Westland had been saving up for the occasion was the SR.N5 mentioned in the foregoing statement—a small high- performance craft with a wide range of applications. The cabin is 13ft long and 7ft 6in wide, and is entered through a loading door in the bow. Up to 20 passengers can be seated. All accom modation and machinery is contained in a central structure only 8ft 4in wide—a feature claimed to enable the SR.N5 to be air-lifted, or transported by road, with the minimum of dismantling. The basic vehicle is readily adaptable to a number of roles, including passenger ferry; rough-country transport with up to two tons of freight; logistic support, with seating for 15 fully equipped troops; search-and-rescue craft, with davit hoist and cabin equipped for stretcher cases; and fire-fighting plat form for high-speed operation in rivers and harbours. Leading particulars of the SR.N5 are: gross weight, 7 tons; length, 38ft; beam, 22ft; power unit, Bristol Siddeley Gnome; cruising speed, 70kt; maximum endurance, 3hr; rough-country obstacle clearance, 4ft over solid obstacles and 6-8ft over waves. Much new and significant information was forthcoming from Westland senior executives, both in prepared statements and in subsequent questioning. 74 Sir Eric Mensforth said that Westland had put in a thousand man-years of engineering development on hovercraft. In some respects SR.N2 had exceeded estimated performance and the company were now completing definite design for the Mk 2 version of this craft. They were prepared to supply six variants of the Mk 2. Sir Eric alluded to his company's close co-operation with Hovercraft Develop ment Ltd and with the inventor, Mr Christopher Cockerell. Hovercraft, he said, could do work that aeroplanes or helicopters could not do, and with a fraction of the power. Mr Boddington alluded to the Cana dian visit of SR.N2 and to the SR.N3, which he described as an immediate development with an extra 10ft of length in the centre section. Construc tion work on SR.N3 for the Ministry of Aviation is well advanced, and the craft should be in operation early next year. Mr Boddington made particular refer ence to the Westland patented skirt, describing it as one of the most significant glimpses of the company's future inten tions. It is made of rubberized fabric, two sheets of which comprise an inner and an outer skirt, between which the peripheral jet is ejected. Obstacle clearances of up to ten times the distance attainable without skirts are possible. Looking to the future, Mr Wheeldon said that his company would offer, on a basis of experience with the SR.N2 prototype, basic hovercraft in civil and military versions, with varying skirt lengths to suit differing operational requirements. He spoke of his com pany's confidence in the future. Q and A Round-up Questions and answers elicited the following random items:— Twenty or more ACVs could now be built at Cowes each year. Commercial studies showed that the first main applications would be ferry ing in Scandinavia, the Mediterranean and Japan, and rough-country work in Canada and America. The SR.N5 would be most suitable for the Canadian North, and Mr Gordon, who had recently returned from Canada, reported tremendous interest. The same, in fact, has been reported from all over the world. The following direct operating costs per seat-mile were quoted: SR.N2,4d to 5d; SR.N2 Mk 2, 3d to 4d; SR.N5, 4d to5d. The company's investment to date was "heading up to £2m," and this figure did not include tooling-up for production. The staff at Cowes have learned to design for production and to use simple jigging and tooling. They have found, FLIGHT International supplement, 23 May 1963 moreover, that compared with aviation practice many corners can be cut. Maximum range over Which it would be sensible to use an ACV would be similar to that for a helicopter—say 150 n.m. Many operations would be over much shorter stages—down to 20 miles, or even less. Ten SR.N4s in cross-Channel service would carry all the passengers, cars and light freight visualized as using a Channel tunnel by 1970. Typical loads would be 600 passengers, 350 passengers plus 26 cars, or 65 tons of freight. Waves 4-5ft high could be negotiated at a speed of 90kt, and 50kt could be maintained over 8ft waves. The N4 could be avail able three years from now. Charging only £1 return, an operator could still SR.N5: general arrangement make a good profit. Turn-round times could be about 20min on the shorter runs, and the craft could cruise at 90kt. The company would be "extremely likely" to build an SR.N4, even without orders. Hovercraft Development Ltd paid for the building of SR.N1 but Westland have now bought it for themselves. Hovercraft production at Cowes would be unlikely to increase employ ment but might maintain jobs at their present level. The company's ACVs leave no wake,
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