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Aviation History
1944
1944 - 0501.PDF
MARCH OTH, 1044 FLIGHT 257 SORTING OUT THE SNAGS port engine might be fifty or so down. Usually it will mean that the instrument is faulty or the generator is dirty, but the c.s. stop might have slipped and the revolutions of that engine may really be down. The test pilot would match the engine synchronisation by ear and note the readings of the two dials; if, throughout the range, the port indications are lower, then it is reasonable to suppose that the instru ment is slightly out. Even so, what portion of the layout, from the instrument itself to the drive from the generator on the engine is faulty? At present, one thing is tried at a time. As I say, one can go on giving examples almost for ever, and I have produced by no means the best or most interest ing ones. There is far too much hit-and-miss about snag- hunting in aircraft, and the introduction of some really fault-proof series of universally applied rigs for different items would save a great deal of unnecessary thought and work. The naturally mechanical pilot may hit on the cause of the trouble immediately and will at least give a coherent and intelligent account of it. The naturally intelligent fitter or rigger will jump to the possible causes when he is given the slightest items of evidence. But we have to T^deal with the non-mechanical pilot and with the grounds man who either fails to listen, or who, from habit, puts everything down to "cockpit trouble." Like the annoy ing chap who, after one has struggled in for miles on one motor, comes forward with the bright suggestion that the trouble is really only an unserviceable boost gauge. There are plenty of bright and ingenious people, but the proportion is numerically low, and thenf is no reason at all why the bright people shouldn't beAssisted as far as possible by mechanical means if these are available. The other week I heard a story of true natural ingenuity in an individual. He was flying a single-engined aircraft somewhere near the coast of Iceland, when he realised that he wasn't at all certain in which direction land lay. 1 can't remember whether his compass had gone queer or whether he wasn't sure which side of the enormous island he was near. At any rate, he found a flock of sea-birds sitting around on a fishing expedition, and conceived the idea of frightening them into continued flight and noting the direction in which they wenty It seemed likely that they would .head towards their lyesting place and he hoped this wasn't in the Hebrides, Courland or the Faroes. Sure enough, after one or two attempts, they lost patience and set off for home. He got back. The story is not to be confused with that apocryphal one about the pilot who examined the cows in the field, saw they were all facing one way and deduced that they would be standing with their backs to the wind. Unfortunately, they were a breed of cow which always stood head to wind when it is cold and wet. When I look at cowsriiey're all facing in different directions or sheltering und«f trees. "INDICATOR." Radio in the R.A.F. E TLE has been published, during the present war, about the part played by wireless and radio equip ment in the R.A.F., and while it is obvious that security considerations forbid anything in the nature of a detailed description of either the various kinds of equip ment used or the precise nature of its employment, it is now permitted to publish a few broad generalities -on this highly specialised subject. In the first place, the equipment itself has to fulfil cer tain vital requirements from the purely operational view point. It must operate in aircraft flying at high altitudes under decreased atmospheric pressure, and it must be just as efficient at the Equator as in the Arctic. It may have to be used on the ground in steaming jungles, on dusty plains, or amid desert sands. Thus every radio set for the R.A.F. is first put through an operational test in tem peratures ranging from —30 deg. to +60 deg. Centigrade, after which it is tested in special low-pressure chambers. Robust build and fool-proof efficiency are likewise essen tial, and much research and development have gone into fthe production of materials and components capable of standing up to these exacting conditions, for the success of an operation may depend upon the successful working of radio. Records show that in a recent month the wire less transmission failures throughout the whole of Bomber Command were less than one per cent. W/T and R/T Sets Ground radio equipment, of course, is subjected to the same searching tests as the transmitting and receiving sets designed for use in our fighters and bombers. A standard general-purpose wireless telegraphy (W/T) set is used for all high-frequency W/T purposes in all bomber, general reconnaissance, training and transport air craft at home and overseas. This equipment is required in tremendous quantities. Radio telephony (R/T) facili ties are provided by two main R/T sets. Fighters, heavy and medium bombers, and close-support aircraft are equipped with a very high-frequency R/T set. The bdmbers communicate with their bases on their long-range W/T set, and use their R/T for communications between aircraft (including escort fighters) and for receiving landing instructions from the airfield control towers. All aircraft radio equipment has to be as light and small as possible, consistent with strength and durability. The entire fighter installation, for instance, including the power supply, weighs only about 90 lb. In the larger types of aircraft, more wireless equipment is essential. It includes (a) a general-purpose W/T set manipulated by the wireless operator; (b) a pilot-operated high-frequency R/T set; (c) a Beam Approach receiver, operated by the pilot, which enables him to make a safe approach to an airfield in conditions of bad visibility ; (d) a Direction-Finding (D/F) loop—the responsibility of the wireless operator—which makes it possible for the air craft to '' home " on to any medium frequency transmis sion ; and (e) an intercommunication amplifier, linking up all members of the air crew. Second Front Requirements An interesting comparison is the gigantic radio apparatus at a main airfield—almost a wireless '' station '' in itself— and the mobile radio equipment. The latter is probably the most remarkable development in the whole vast system of R.A.F. communications. For the Second Front operations, mobility is extremely important, and every type of communication can now be provided by mobile stations mounted on vehicles, ranging in size from light vans to five-ton trucks. A unit, known as a "Heavy Mobile Wireless Station," employing diver sity receivers and a transmitter with an aerial power of 5 kw., provides high-speed W/T communication. These units can be put into operation within a few hours of land ing, and can handle a vast quantity of '' traffic'' between the operational command concerned and the home bases. Mobile equipment covers requirements for high frequency communication between ground and aircraft; and/or very high frequency D/F stations. Even transmitters with an aerial power of 10 kw. have been successfully made mobile. By this wide adoption of W/T communications, the R.A.F. is able to operate without the use of landlines, which are seldom available in the early stages of a cam paign, and cannot be supplied in sufficient quantities for some time after the occupation of new territories. Another type of set which no doubt will play its part in forthcoming operations is the pack set.
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