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Aviation History
1968
1968 - 2547.PDF
fUGHT International, 7 November 1968 tte) Hawker Siddeley Dynamics Ltd, ManorRoad, Hatfield, Herts (Hatfield 62300) Hawker Siddeley Dynamics is currently producing anti-icing equipment for all versions of the Trident, the complete system for which was developedin the company's extensive air conditioning test facilities at Hatfield. A similar system,using slightly modified Trident somponents, is now being supplied for the HS.801 Nimrod.The Trident's hot air anti-icing installation consists of two main systems. First, eachengine and its intake has an individual sub- system that is selected and controlled indepen-dently of the second main system—that of the airframe—although each draws high-pressurebleed air from the final compressor stages of the three engines. Engine low-pressure bleedair, also, is fed into the airframe system, each of the three supply circuits of which comprisespneumatically operated high- and low-pressure bleed air control valves—both HSD com-ponents—manual shut-off valves, and a mixing chamber incorporating temperature sensorsand cut-out switches. Mixing chamber output passes, at the correct flow and temperature,through non-return valves into the main dis- tribution gallery leading to the wings and tailunit. (25) Imperial Chemical Industries Ltd, Mill-bank, London SW1 (01-834 4444) IC1 silicone rubber, produced in Scotland by the NobelDivision Silicones Group, is used for flexible connectors—such as those supplied by Bell'sAsbestos & Engineering—in hot air ducting. Silicone rubber can be fabricated to any shape,remains flexible from — 40°C to 23O°C, and is unaffected by hydraulic fluid or condensation.. Isopropanol, another ICI product (from the ' Heavy Organic Chemicals Division) is usedalone, or as a component, in aircraft de-icing fluids. 26) Isopad Ltd, Barnet By-pass, BorehamWood, Herts (01-953 2817) Isopad electric surface heaters, described in detail in Flightas long ago as March 1, 1957, are still widely used on Dowty Rotol propeller blades andspinners in Dart-powered aircraft. The spinner elements comprise practically alkali-free glassyarn, interwoven with special resistance wire. Isotapes, manufactured to suit any type ofvoltage, are applied with thermal insulation for frost protection of waste water lines in the B ACOne-Eleven, among other aircraft. Isotapes use a high-temperature p.v.c. extrusion over theheating elements, and are suitable for tempera- tures up to 60°C. Isopad products are also used for frost pro-tection on valves, cameras and missile com- ponents. (27) Kigass Ltd, Kigass House, Chapel Street,Leamington Spa, Warwicks (Leamington Spa 22241) Kigass produce a range of hand-operated pumps—with capacities of 5, 10, 20 and 40 c.c. per stroke, and spray nozzle jetunits—which are suitable for windscreen fluid de-icing systems in helicopters and light air-craft. : <28) Kilfrost Ltd, 162-164, Uxbridge Road,, Hanwell, London W7 (01-567 7274) Pioneers of chemical de-icing and de-frosting underwartime conditions. Kilfrost have been supplying defrosting fluids to the Servicesand to airlines for some 25 years. More recently this company has developed, in con-junction with BEA, the hot defrosting tech- nique for removing frozen deposits fromparked aircraft. The original hot defrosting concentrateUC2, and the later DC2A, have now been superseded in Service and airline use by astill more advanced product—the Kilfrost Anti-icing Barrier Compound (ABC). Thiscan either be applied to aircraft during turn- round as a hot defrosting fluid or, byapplication as a cold concentrate, can give Protection to parked aircraft for up to•fws, Kilfrost ABC is now used by three air forces, 13 airlines and two airportauthorities. Other Kilfrost compounds include de-icingnuids for T.K.S. airborne airframe de-icing systems, hoar-frost remover and Arcticae-icing fluid for parked aircraft, and a wing oe-icing paste designed for manual pre-fiightapplication. Latest product for de-icing and cleaningPilots windshields is Windscreen Washing fluid Mod. 2. (29) Lucas Gas Turbine Equipment Ltd,Shaftmoor Lane, Birmingham 28 (Spring- field 3232) Lucas combustion heatersrepresent the alternative to compressor bleed, or exhaust gas heat exchangers, asthe heat source for built-in hot air anti- icing systems. Temperature controlled, theair combustion heaters take their fuel from the aircraft main supply. The full systemcomprises, in addition to the heater, fuel and electrical control units, ram air pressureswitch, and control panel. On the ground the output from Lucasmobile air heaters, employing similar com- bustion heaters to the airborne units, canbe used for external defrosting of parked aircraft. (30) Miraflores, The Friary, Old Windsor,Berks (Windsor 63742) Kleerscreen rain repellent, supplied by Miraflores in kit formfor external, pre-flight application by hand in a matter of seconds, is in world-wide useby airlines and light aircraft operators. One kit is sufficient to treat 50 airliner wind-screens, and each application should, properly applied, last about 200 flyinghours. Kleerscreen is not a de-icing com- pound, but its properties can deter the onsetof icing. (31) Mobil Oil Co Ltd, Caxton House, Tot-hill Street, London SW1 (01-839 6645) Mobil aero de-icing fluid No. 1 is a special isopropylalcohol, supplied for use in propeller, wind- screen, carburetter and other airborne fluidde-icing systems. (32) Negretti & Zambra Ltd, AviationDivision, Stocklake, Aylesbury, Bucks (Aylesbury 5931) Differential pressureswitches are supplied by Negretti & Zambra for engine mounting, to detect changes inpressure drop caused by ice accretion across the engine fuel filter when there is noprovision for fuel heating other than through the oil cooler. The type of switchfitted to the Rolls-Royce Spey is designed to signal when a differential of 51b/sq in existsin the system. This operates a panel light to give warning for reduction of the fuel flowrates, thus permitting increased heat pick- up through the oil cooler. Negretti & Zambra also manufacture arange of thermal units—temperature-sensing devices designed for servo control ofactuators or for electrical switching. (33) Page Engineering Co (Sunbury-on-Thames) Ltd, Page Works, Forge Lane, Green Street, Sunbury-on-Thames, Middx(01-768 4242) A two-minute delay device is incorporated in the Trident's anti-icingsystem to cater for intermittent icing con- ditions while under automatic control. Thisice detector delay unit, manufactured by Page Engineering, provides two controlledoutputs, one to the anti-icing control system operated by the ice detector contacts; itspurpose is to maintain the anti-icing system in operation after the detector contacts haveopened. (34) Palmer Aero Products Ltd, PenfoldStreet, Edgware Road, London NWS (01-723 8822) Palmer aerofoil de-icerequipment, Goodrich-licence manufactured at the Leyland works of BTR Industries,is produced in a range of systems to suit small piston-engined aircraft such as theIslander and Beagle B.206 series, and turbo- props such as the HS.748, Skyvan andJetstream. These externally mounted, lightweightrubber de-icers are attached with an air- 753 cure cement, and are manufactured totolerances approaching those of metal leading-edge skin profiles. In the HS.748installation, engine bleed air is used to inflate the mainly chordwise tubes, throughsolenoid-operated distributor valves; altern- ate tubes are cyclically pulsated under thecontrol of an electronic timer. Tubes are deflated under suction from ejectors, whichalso derive their forcing pressure from com- pressor bleed air. In the light aircraft system, the spanwisetubes are simultaneously inflated by air at 151b/sq in from the exhaust side of thestandard engine-driven vacuum pumps. A transistorised electronic timer operates thecontrol valve solenoids and, when the systems is de-energised, pump suction keepsthe deflated tubes flat against the skin. (35) Plessey Co Ltd, Dynamics Group,Ilford, Essex (Tel 01-478 3040) A miniature temperature controller for electrically heatedwindscreens or de-icer elements is now pro- duced by Plessey. The operation-point ofthis 28V d.c. controller is adjustable over a wide range of settings, and its constructionlends itself to stacking. It may be used as an ON/OFF control for any function whichcan be sensed as a change of resistance. Other Plessey products used in anti-icingsystems include hot-air stop-valve actuators and ducting components. (36) Porter Co (Great Britain) Ltd, H. K.,Cameron Street, Hillington, Glasgow SW2 (Moss Heights 8771) Porter V-bandclamps, incorporating fail-safe protection, provide a positively sealed, compact light-weight joint suitable for use in hot air ducting systems. Porter also supply heavyduty Thermoid ground air starter delivery hose. (37) RoIIason Engineering Ltd, CroydonAirport, Surrey (01-688 7238) Rollason's Thawspray trolleys are supplied to airlinesand other operators, for ground application of hot defrosting concentrates such as Kil-frost's anti-icing barrier compound. This mobile spraying plant is equipped with a50gal insulated tank, petrol-engine-driven pump, thermostatically controlled mainspowered immersion heaters, delivery hose and two 9ft spray lances. (38) Rosemount Engineering Co Ltd,Durban Road, Bognor Regis, Sussex (Bognor Regis 4101) Currently manufac-turing a new type of miniature ice detector suitable for both ground and airborne use.It is capable of sensing very low thresholds of ice accretion, is proof against dirt andinsects and has no moving parts. The detector head can be mounted on the for-ward fuselage or, alternatively, directly in the engine intake. The output of the detectorcan be processed further to give a measure of icing intensity. Rosemount manufacture two types ofminiature electrical heating cable capable of producing a high power output per unitlength, and these cables are being used for de-icing the intake leading-edges, variable-geometry ramps and the extreme wing leading-edges of the Concorde. The Trident 1C, IE and Nimrod carryRosemount temperature-control equipment which measures and controls the wing-skintemperatures. For the Trident 2E this equipment provides automatic control ofthe hot air de-icing valves and controls wing and tail skin temperatures automati-cally. Teddington's icing-rate system. The leading heater/sensor is exposed to the airstream and the rear heater/sensor is shielded by an inenial droplet separator. With both maintained at con- stant temperature, dif- ference in power re- quirement is a function of cooling effect FRONT HEATERl SENSOR (WET) OTECTIVE TUBE p-BOPY r REAR HEATER|SENSO«<DRY) \ / SHKXJD A i /
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