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Aviation History
1964
1964 - 1930.PDF
FLIGHT International supplement, IS June 1964 Air-Cushion Vehicles Tests. Seminar B: Mr A. Burgess (University of Southampton), Applica- tion of Eulefs Momentum Theorem to the Hovercraft; Mr J. W. C. McDaid (Queens University of Belfast), Experi- mental Work on Two Dimensional Nozzles; Mr D. L. Hughes (University of Wales), An Outline of the Research Programme at the University of Swansea. Seminar C: Mr J. T. Everest (National Physical Laboratory, Feltham), Hydro- dynamic effects on Hovercraft; Messrs J. Bertin and M. Guienne (Bertin & Co, La Garenne, Colombes) (Subject to be circulated later). Seminar D: Mr A. G. Barnes (British Aircraft Corporation, Preston), Simulation of GEM Handling Characteristics; Mr I. L. Keeler (Royal Aircraft Establishment, Bedford), Con- trol Characteristics of the CC-2. Seminar E: Mr S. Ando (Proxy, Kawasaki Aircraft Co, Japan), Results of Wind Tunnel and Towing Tank Tests for the KAG-3; Dr J. A. Sandover (University of Wales), A Summary of Some Topics for Future Studies Revealed during the Symposium. The programme for the three days is: Tuesday, July 21: 6.15 p.m., opening address by Prof R. H. Macmillan; 6.30 p.m., dinner. Wednesday, July 22: 9.20 a.m.-10.45 a.m., Initial Lecture; 11 a.m.-12.45 p.m., Seminar A; 12.45 p.m.-2 p.m., lunch; 2 p.m.-3.45 p.m., Seminar B; 4 p.m.-5 p.m., demonstra- tion; 6.30 p.m., dinner. Thursday, July 23: 9.30 a.m.-10.45 a.m., outline of research at Swansea; 11 a.m.-12.45 p.m., Seminar C; 12.45 p.m.-2 p.m., lunch; 2 p.m.-3.45 p.m., Seminar D; 4 p.m.-5 p.m., Seminar E; 6.30 p.m., dinner. LOW-VELOCITY JET PROPULSION FOR THE CC-4 TWO PROTOTYPES OF a 5-6 seat light amphibious ACV vehicle, the CC-4, powered by a 250 h.p. Rolls-Royce LV-8 petrol engine and designed to sell for about £10,000, are under construc- tion at Bembridge, IoW, and timed to make their first hover this summer. Being built by Cushioncraft Ltd, of Bembridge Airport, in association with HDL, the CC-4 is backed by previous experience with the CC-1 and CC-2 (three of the latter were built) but does not resemble either. It embraces many novel features. The entire plenum and convoluted skirt are flexible structures, developed by HDL, and the "hard" central hull structure comprises a 20ft 9in X 7ft 3in flat box section carrying the machinery and superstructure. The flexible portions, spread on outriggers, can be deflated and brailed up on the sides of the centre hull, the outriggers folded, and the entire machine, reduced to a width of only a little over 7ft, can be towed on light sprung wheels. As an alternative refinement a gearbox and clutch could be fitted to drive these wheels. Aircraft-type propellers are now re- jected by Cushioncraft for the smaller type of craft they are licensed to build. On the larger craft, the company argues, propellers can be placed well away from the passengers; on small vehicles they constitute a real hazard and they involve costly transmission systems or separate, external power plants, adding drag and being vulnerable to salt-water spray and corrosion. Studies by Cushioncraft established that efficiencies comparable to those of the propeller could be obtained from fans, if these were designed with propul- sion in mind. With care in design it was also possible to use the same fans for lift. Accordingly, four relatively small centrifugal fans, 3Jft in diameter and built up of light alloy, are mounted toward the rear of the CC-4, vertically and in longitudinal banks of two. The fans exhaust aft through nozzles in which directional rudders are fitted to vary the direction of the low-velocity propulsive streams. Two-thirds of the flow from the two forward fans is supplied to the flexible plenum for lift. A test rig has been built of the lift- propulsion system and the values obtained have been used to calculate performance. The transmission system is cheap and simple. The Rolls-Royce LV-8 engine (a largely aluminium unit and the same as that which has given good service in the three experimental CC-2s) drives a Jaguar differential and rear axle mount- ing pulleys and notched belts, which in turn drive the fans. The speed reduction is made on the pulleys, thus eliminating both the cost and noise of gearboxes. Cabin structures for the two proto- types are already completed. Built of flat aluminium panels riveted and cold bonded, the cabin has a V-fronted plan- form. The driver will sit well up in the V, with large, flat windows, each with a wiper. This is considered to be better than the fenestration in the CC-2, which consists of a flat windscreen and curved corner windows, through which vision is definitely sub-standard. Spray over the glazing can be almost blinding in small overwater air-cushion vehicles; it will be avoided in the CC-4 to the greatest possible extent by having the driving position almost directly over the bow. In contrast to the complex CC-2, the CC-4 has been designed with simplicity, ease of production and cheapness as the guiding criteria and is the first Cushion- craft design for which serious production plans are being made. The two proto- types, one of which will go to the HDL and the other retained by Cushioncraft, are having wooden centre hulls with aluminium superstructure, but it is envisaged that widespread use of glass fibre, reinforced with a tubular structure, will be employed in the production run. The convoluted HDL skirt to be fitted beneath the flexible plenum will be very similar to that now worn by Cushioncraft's own CC-2, which is illustrated on page 77. This is a modular unit, in which many small panels, retained by bungees, comprise the whole. If a panel is ripped in passing over an obstruction it can be replaced with very little trouble. By having a flexible plenum as well as a flexible skirt, it is calculated that a total obstacle clearance of about 3ft will be obtained. Actual ground clearance beneath the skirt is estimated to be 3in at a speed of 45kt and a gross weight of 3,570lb. CC-4 Design Data:— R-R LV-8 powerplant, 8001b; radiator, oil and water, 1601b; exhaust system, 401b; hull structure, 5001b; fans, 2401b; transmission, 1201b; cab and controls, 2001b; ducting, 1001b: flexible plenum, 1501b; flexible skirt, 1501b; total unladen weight, 2,3601b; six passengers, 9601b; two hours' fuel, 2501b; gross weight, 3,5701b. 79
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