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Aviation History
1958
1958 - 0701.PDF
FLIGHT, 23 May 1958 Helicopter Icing Research 717 SEVEN YEARS' WORK IN CANADA WORK by the National Research Council of Canada in thefield of helicopter icing was described by Mr. J. R.Stallabrass, of the Council's low-temperature laboratory, in a lecture to the Helicopter Association of Great Britain onFriday, May 9. The title of the paper was Canadian Research in the Field of Helicopter Icing. After tracing the history of helicopter-icing work in Canada,which began at Edmonton in the winter of 1951-52 and was continued by means of two successive rigs at N.R.C., Ottawa,between 1954 and the present time, Mr. Stallabrass compared the present N.R.C. facility with similar ones at Mount Washingtonand Eglin A.F.B. in the United States. The Ottawa rig consists of a 75ft x 15ft frame, mounted on a 50ft mast and carrying 161spray nozzles. The simulated icing cloud, in which the helicopter under test hovers in free flight, is formed of steam-atomizedwater-droplets. Since the present Ottawa rig began operation in January 1955,the speaker revealed, tests had been carried out on Bell HTL-4, H-13H and 47G-2, Sikorsky H04S and Bristol Sycamorehelicopters, Mr. Stallabrass next dealt in turn with the effects of icing onhelicopter performance and handling, methods of icing protec- tion, requirements for a main rotor de-icing system, and controls.In conclusion, he said that Canada's flight-test work in this field had done much to indicate the nature of the icing problem and its The present hcu^-— •—"» *<-^ - -•» at the National Research Council's Ottawa laboratories, with a Bell 47 undergoing trials. The icing cloud is produced by steam-atomized water droplets from the 761 spray nozzles of the mast-mounted frame. serious aerodynamic and mechanical effects. It had shown thatpractical icing-protection systems for helicopters were possible and that the electro-thermal method held particular promise forsuccess. By the end of 1960 helicopters should be entering service fully protected from the effects of icing. FIREFIGHTERS FROM ALVIS IN evolving the Salamander, their Mk VI crash/fire tenderchassis, Alvis, Ltd., argued that if such a vehicle is to be effective at all it must be able to go directly to the scene ofan accident, regardless of any mud, rocks or tree stumps that may be in the way. The conventional light commercial vehicle chassisloaded with the general paraphanalia of fire-fighting and rescue is suitable only for roads and runways; and a tracked vehicle, whileexcellent over rough country, has casual regard for runway lights and tends to be rather slow. The suspension of the Salamander is virtually identical withthat of the Alvis Saracen armoured personnel carrier—six wheels all independently suspended on wishbone links and sprung onlong torsion bars. Each wheel unit is damped with a battery of shock absorbers and are all independently driven. The chassis is a pontoon-type of structure which protects thesuspension units over really rough going, and also provides some protection from temperature extremes; the inside can be heated, or cooled by air-ventilation. By interlinking the steering so thatall four front wheels are driven, it is possible for the Salamander to continue to operate if it loses any one wheel, or any two wheelsexcept the forward pair. The result is a chassis of considerable robustness and a weight,for the complete vehicle, of around twelve tons. Nevertheless, the Salamander achieves a potent performance—a standingquarter-mile in 32.6 sec and a maximum governed speed of 50 m.p.h. —from its eight-cylinder in-line 6.5 litre Rolls-Royce engine.Each of the six wheels is driven through a pre-selector gearbox, a transfer box, shafting to each wheel and an epicyclic reductiongear in each hub. During a recent visit to Coventry, Flight had the opportunityof sampling the Salamander's unusual form of suspension by driving an Armoured Command Post—with similar wheel anddriving arrangements—over the Alvis test field. Both the Sala- mander and the Command Post chassis, the Saracen, can crossa trench five feet wide, surmount a verticle obstacle 18in high, cross a ford up to 2ft 6in deep or climb a 24 per cent gradient.What these figures do not convey is the extraordinary smoothness with which these manoeuvres are performed. Firm but not harshriding on the road is transformed to a wonderful smooth rolling ride on the great 14.00 x 20in tyres over hillocks and slopes. The vehicle is not difficult to drive, and the steering is hydraulic-ally power assisted (with proportional feel) but has manual rever- sion. Relatively little care is needed to pick the easiest path whendriving over rough ground, but it is fairly important to select the right gear (there are five forward speeds) for the particularconditions. Alvis have supplied about 80 Salamander chassis for servicein various parts of the world, many of them for the Royal Air Force. The firm manufacture chassis only which go to Pyrene orTecalemit to be fitted with bodies and special-purpose equipment. Alvis emphasize that, irrespective of the type of equipment fitted,the Salamander can arrive at the scene of an accident much more quickly than conventional crash trucks and this facility alonejustifies the rather high cost of the complete vehicles (about £13,000). The finest fire-fighting equipment, Alvis suggest, justi-fies the best carrier that can be made. Capable of a vigorous cross country performance^ the AMs Salamander crash-tender chassis (the suspension is similar to that of the Saracen armoured fighting vehicle) is designed to provide rapid access to an accident. The fire-fighting equipment illustrated is supplied bv Pyrene.
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