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Aviation History
1954
1954 - 1588.PDF
FLIGHT, 28 May 1954 705 "Flight" photographs The G.F.A. chlorobromomethane equipment mounted on a Land Rover and (right) seen in action at the Rovingdon demonstration described below. 66 C.B." AGAINST FIRES AS we briefly recorded last week, a convincing demonstration of • the properties of "C.B." (chlorobromomethane) as a fire- extinguishing medium was given recently at Bovingdon Airport. It was staged by the General Fire Appliance Co., Ltd. (11 Waterloo Place, London, S.W.I), who have introduced and pioneered in Britain the use of this chemical as a means of com bating fires involving highly volatile oils and solvents, and who produce the necessary equipment for applying it in the most effective manner. The American Forces in Western Europe have ordered a number of sets of the equipment—these have already been delivered by B.E.A. to Holland, where they are being installed on U.S.A.F. fire-fighting vehicles; and, we learn, the Air Ministry are also recommending the use of C.B. by the R.A.F., following extensive trials. The equipment used in the Bovingdon demonstration was the G.F.A. C.B. 240 type, very similar to that adopted by the U.S.A.F. Mounted on a Land Rover—typical of the light, fast type of vehicle which can be employed—it consisted of two 12- gallon containers of C.B., delivery pressure being supplied by a small cylinder of nitrogen, at 100 lb/sq in, mounted above each container. Two hose-lines and reels completed the equipment, though mention should be made of the applicators; these, the design of which has involved considerable research, ensure that the C.B. is sprayed in a cone of precisely determined shape, with the chemical atomized into droplets of controlled size. At Bovingdon, a mock-up of a metal aircraft was built in a depression into which 150 gallons of oil and petrol were poured, further petrol being gravity-fed from a pipe while the fire was in progress. When the blaze had reached its maximum intensity the two hose-operators (wearing, so far as fireproof clothing was concerned, only light asbestos jackets and helmets with visors) went into action. It was noticeable that they were very quickly able to attack the fire at almost arm-length range and, after 15 seconds' application of C.B., the flames appeared to be sufficiently subdued for a rescue from the cockpit section to have been effected. A further 18 sec—making 33 sec in all—sufficed to extinguish the fire completely, and there was no flashback or re- ignition. Only about seven gallons of C.B. had been used for the complete operation. In a two-day series of demonstrations before M.T.C.A. and Air Ministry representatives at Cardiff Airport last January, comparative tests were made with C.B., CO 2 and foam. Records of the results suggest that the performance of the C.B. equipment, particularly in speed of extinction, was outstanding. REINFORCED-PLASTIC AERIAL MASTS ILLUSTRATED below is an aircraft aerial mast which formed part of the exhibit of Chelton Electrostatics, Ltd., of Marlow, Bucks, in the plastics section of the recent British Industries Fair. Typical of the range of masts produced by this company, it is A.R.B.-approved for use with M.F. and H.F. equipment in both pressurized and unpressurized aircraft. The aerofoil-section shell is a glass-fibre laminate bonded with polyester resin and protected from erosion by no fewer than ten coats of neoprene paint, to a thickness of approximately O.Olin. The black polythene head-cap is moulded directly on to the shell, and the lead-in assembly is embodied in the moulding, so that the lead-in is completely insu lated in polythene from the point of connection of the aerial to the transmitter terminal. The 17in mast—other typical lengths are 7in and 12in—is A Chelton aerial mast; on the left is the shell, moulded from resin-bonded glass-fibre laminate. designed to support an aerial having a working tension of up to 70 lb and equipped with a weak-link insulator at the after end. Applied at an angle of not more than 15 deg to the fore-and-aft axis, the breaking load of the mast itself is 500 lb. In electrical tests, the breakdown voltage was found to exceed 20 kV. Chelton Electrostatics also make a range of aerial insulators, and another of their aircraft specialities is the "Driwik" static- electricity discharger, illustrated in Flight of June 5th, 1953. FOR CARBON REMOVAL AN extremely powerful decarbonizing agent is now being marketed by Bennett (Hyde), Ltd., Boston Mills, Hyde, Cheshire. Known as Gunk Compound Hydro-Seal, it is claimed virtually to, "do the impossible" by dissolving—or, at any rate, digesting—the hardest carbon deposits from aluminium-alloy pistons, cylinder heads and other engine components. It can be used either cold or hot, the action in the latter case being approximately doubled in speed for each 10 deg F rise in temperature to a maximum of 100 deg F. An important feature of the compound is the sealing medium which it contains. This is a glycerine-like, water-based fluid which, floating on the active agent, prevents evaporation-loss; it is stated, also, to prevent the escape of vapours which might be inhaled, to reduce inflammability, and to prevent the chance of the active agent splashing into the operator's eyes or on to his skin. Hydro-Seal is sold in containers which incorporate a dipping- basket, and a one-gallon supply of "rejuvenating" liquid can be supplied as an extra item. For users with large-scale dipping facilities, Hydro-Seal is also available in 10- and 45-gallon drums.
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