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Aviation History
1953
1953 - 1179.PDF
FLIGHT, 4 September 1953 335 PROPRIETARY EQUIPMENT its associated tank. Since the rotational speed of each vane assembly is the same as that of its neighbours, it follows that each metering unit will deliver fuel at the correct rate to ensure that proper balance and tank-state relationship is maintained in all conditions of flight. Teddington Controls, Ltd., Cefn Coed Merthyr Tydfil, South Wales (Stand 63), are responsible for a very wide range of air and electric devices for controlling all types of aircraft auxiliary systems. In the field of engine accessaries, the company will show, at Farnborough, de-icing valves and controls, starting-cycle time switches and the latest patterns of fuel-tank pres- surization. In the latter connection, the air/gas valve illustrated on this page is of interest. Styled Type FLA, it is designed to pass large flows at low pressure-drops; it is suitable for air inlet pressures up to 180 lb/sq in, and nitrogen pressures of 1,800 lb/sq in. Waymouth Gauges and Instruments, Ltd., Station Road, Godalming, Surrey (Stand 1), will exhibit for the first time, indicators, tank units, and power unit of the Smiths-Liquidometer fuel gauge. This system utilizes a special, self-balancing capacitance bridge circuit, which includes a reference capacitor; the latter is immersed in the fuel to cancel out differences in dielectric constant when varying types of fuel are to be measured. The system can be arranged to give in dividual or summated contents indication in terms of either fuel volume or weight. Waymouth will also show a gas-turbine temperature-control amplifier. Fed with signals from thermocouples mounted just downstream of the turbine, the amplifier controls an electro-magnetic valve which, in turn, actuates an hydraulic servo con nected to the engine fuel control unit. Landing Gear British Messier, Ltd., Gloucester (Stand 56), are producing new main and nose undercarriage units, and a variety of brakes to be shown publicly for the first time next week. A typical example of Messier work is the big bogie under carriage of the Britannia; a more recent design is that shown on page 337. Although no details of the latter are forth coming, it can be seen that it is for a swept-wing aircraft. The tyre is Dunlop size 33 x 6.75-20—which, from the cata logue of that company, is found to be one of the most advanced units yet developed, with the extraordinary performance of: maximum dynamic load, 39,220 lb, at 280 lb/sq in inflation pressure. It will b? interesting to see what aircraft this landing gear is fitted to. In the realm of brake development, Messier continue their work with various types of disc and plate units, and their associated pumps. Another line of development concerns brakes for helicop ter rotors; the type on view will be that produced for the Sycamore, which is an hydraulically actuated unit weighing less than corresponding mechanical brakes. Dowtv Equipment, Ltd., Arle Court, Cheltenham, Glos. (Stand 205), are the patentees of the Liquid Spring method of shock absorbing. They have developed numerous undercarriages utilizing this principle, and the latest example to go into quantity production is that for the Hawker Hunter. No performance details may yet be given, but it can be said that the main- leg shock-absorber efficiency is over 90 %. A feature of this landing gear is the manner in which the operating cylinders of the Dunlop plate brake have been attached directly to the leg, instead of be ing fixed to the usual brake back-plate. Not only has this procedure effected a signifi cant saving in weight, but the capacity of the brake has also been increased. In a very much bigger scale, the under carriage developed for the Avro Vulcan is an impresive example of Dowty engineer ing. Here, the main leg slides in a large light-alloy casting which contains no shock-absorber at all. In fact, only one shock strut i used, and this is mounted between the mid-point of the bogie beam and the rear of the main casting. The bogie beam carries four double-tyred wheels and is pivoted about the axle of the front pair; numerous advantages accrue from this geometry, including reduced wear on the front wheels and the unit's ability to fold neady into the Vulcan wing. Dunlop Rubber Co., Ltd., Aviation Division, Holbrook Lane, Foleshill, Coventry (Stand 154), now mould a new dimpled tyre, which has gone into ser vice with the B.O.A.C. Comet Fleet during the past year. The original Comet tyre was ribbed, and the circumferential serrations could pick up stones, and other matter, and cause damage both to the tyres them selves and to the airframe. The new pattern has a smooth tread and is also strengthened to allow greater sideways loads. As a result, wear resistance to all kinds of arduous treatment is markedly improved. The tread is also flatter—to give an increased contact area—and has a pattern of shallow dimples which give an indication of wear. Electro-Hydraulics, Ltd., Liverpool Road, Warrington, Lanes. (Stand 76), are the producers of the Victor undercarriage fit will be shown in the outdoor exhibi tion at Farnborough). This superb piece of engineering fills a most difficult require ment, for the great weight of the Victor bomber is supported on a main under carriage which retracts into a thin wing. Each mam leg has four double-tyred wheels, and very careful design has kept weight to a minimum; in fact it is the company's proud boast that the complete undercarriage installation for the Victor weighs no more than three per cent of the aircraft all-up weight. The outdoor exhibit will feature a main bogie mounted on a dummy section of Victor wing, into which it will retract under control from a demonstration con trol box. The "three per cent" includes the nose unit, with twin steering jacks and hydraulic steering panel mounted on the main casting. The Goodyear Tyre and Rubber Co. (Great Britain), Ltd., Wolverhampton (Stand 58), now have their new Aviation Teddington nitrogen/air valve. Division factory at Wallasey producing to augment the flow of tyres, wheels and brakes from die parent factory. Two wheel and brake assemblies are of particular interest. The first, illustrated on page 337, is an automatic unit for use in heavy and faster aircraft, in which brake requirements are exceptionally severe. The dual-disc brake is actuated by four cylinders, and is unique in that it is contained entirely within the wheel. This total enclosure confers numerous advantages; the discs are cooled and venti lated by airflow through the wheel. The weight of this wheel, tyre and brake unit is 446 lb: it is used on the Martin B-57A. The other automatic brake assembly is more conventional in pattern, but it will be shown at Farnborough in conjunction with a wheel of the new Goodyear "wave" type. This was originally a development by the American branch of the company, in response to a requirement for a wheel which could be forged in magnesium alloy. In place of radial spokes the wheel has a disc which is corrugated—each corruga tion running radially—into a wave pat tern. The example shown will, in fact, be cast but, whether cast or forged, the design shows great promise in carrying increased loads for a reduced weight (332 lb, in the case of the type shown). A Farnborough exhibit will be a demon stration of Goodyear automatic braking control. Based upon the maintenance of full braking so long as a set deceleration is not exceeded, the "A.B.C." system centres about a generator and control box, the latter being shown sectioned so that its operation can be studied. The Lockheed Hydraulic Brake Co., Ltd., Leamington Spa (Stand 35), con tinue to design oleo-pneumatic shock- absorber struts for the undercarriages of all types of aircraft. All these units employ air springing, and the fluid is kept remote from the compressed air, so preventing aeration. Weight is kept down by using light alloys whenever possible. The biggest recent production of these legs has probably been for the various
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