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Aviation History
1953
1953 - 1257.PDF
FLIGHT, 18 September 1953 RADIO AT FARNBOROUGH A Commentary on New Equipment and Requirements: Notes from the Stands AIR transport—with which, in this case, we may include L private flying—cannot function on an economic basis without communications services; and it is encouraging to see that British radio manufacturers are now exhibiting equipment which will meet the foreseeable needs of the industry. Aircraft flying on international services must be fitted with radio sets that meet the needs of all routes, because the changing of equipment en route is disastrous and very costly. Further, it has been clear for some years that radio telephony is to be the pre ferred means for all air-to-ground communications, long-range and short-range; so there is already a demand for long-range K/T. sets (and short-range) which can be set up at the home base for working on any, or all of the world's trunk routes, and which need no attention in flight apart from switching from one fre quency to another. Until now, the demand for such a long-range equipment could not be satisfied in England, but at the S.B.A.C Show there was one set—the STR.18C—with 100 frequencies and 100 watts power on H.F. R/T. It was shown as a prototype, and no doubt will undergo modification and development; but it shows promise of success—sufficient to justify ordering it for the Britannia fleet of B.O.A.C. Meanwhile, for the lack of a set in this category to suit the immediate demands, foreign buyers of Comets and Viscounts are supplying their own radio. They refuse to use the aircraft of to morrow with the radio of yesterday. There are, of course, reasons for this state of affairs, associated with the limited resources available and the need to satisfy imme diate military demands; but none the less, it is an unfortunate situation. The available Marconi H.F. longe-range and high-power R/T. set is developed from an older equipment, and has not enough frequencies for world-wide operations; but it does satisfy the frequency needs for single-route operation, for which it was made. There are two lower-powered H. F. R/T. sets—to satisfy the needs of short-haul carriers in the less dense traffic areas— making their first appearance: the Marconi A.W.A. HAC-1 (8 fre quency 50 watt) and the S.T. and C. STR.19, 4 frequency 50 watt. There is a need for equipment like this in many places. The S.T. and C. set is just approaching production; and is entirely British in design and build, whilst the design of the A.W.A. set is strongly American, as are many of its components. In some cases this will be an advantage. Marconi-A.W.A. (the initials stand for Amalgamated Wireless Australasia) also have an aircraft H.F. receiver with provision for 120 frequencies, especially for trunk-route R/T. working. The receiver uses up to 60 crystals, and up to 120 sets of tuning coils, and is built in Australia. For short-range R/T. working, for approach and aerodrome control, and for aircraft flying, V.H.F. is the accepted medium of communications and the airlines with widespread services have long since realized the need for multi-frequency V.H.F. sets. In this field, both Marconi and Standards are producing sets with 10-15 watts power and 140 frequencies, and these sets will satisfy every likely demand during their life; they are already holding their place with overseas buyers. Standards also make a 10- frequency set, which is adequate for most "local-service" needs outside the areas of high traffic-density; it is the STR.9X, 5 watts power and 26 lb weight. Light-aircraft V.H.F. There are also several other aircraft V.H.F. sets, lower in power, and lighter in weight, and with smaller capacity for frequencies. These find their application in lighter aircraft, for private owners, and on very short-haul operations, e.g., m helicopters or gliders. The prospective buyer has a choice of six, all of about one watt power. The Burndept, one frequency, weighs 9 lb, and it is essentially an "emergency use" set. The Ekco, 11 or ^frequen cies, weigh 16 lb; A.W.A. AirMite (three frequencies), 12 lb, Murphy 5, 23, or 36 frequencies, 17 lb; and Plessey (six frequen cies), 17 lb; all are suitable for regular use, with a range of about 50 miles at 5,000 ft. In the very light class the Pye watele phone" has one frequency, and weighs 8 lb including its battery Each of these has its own application, with its advantages as well ^There^fonly one A.D.F. shown, and that was the Marconi AD 7092C, with its recessed aerial, as fined in Comets; and, it is only fair to add, it is being retained by all buyers of Comets be muse it does it job. The recessed (or suppressed) loop aend has been proved to be at least as effecuve as the jtreamluied loops fitted on slower aircraft; and it may be added that it is usual THIS commentary was prepared after an examination of appropriate stands and equipment at Farnborough by one actively concerned with radio communications and navaids in the air-transport industry. It is followed by a stand-to-stand report on radio and associated equipment practice nowadays to fit two A.D.F. sets to new commercial aircraft. The M.F. beacon is still the most widely used aid to navigation, with world-wide applications of one kind or another. Beacon transmitters, high power or low power, are built by Redifon, S.T. and C, and Marconi's, but there is no novelty in them and they were not at the show. However, Marconi were showing a small- scale model of a V.O.R. station, the navigation aid which works on V.H.F., between 112 mc/s and 118 mc/s; it provides bearings up to a radius of about 100 miles, to aircraft with suitable receivers— and S.T. and C. make a receiver especially for the purpose, com bining the V.O.R. receiver with an I.L.S. receiver, and having the I.L.S. meter-indicator common to both systems. For good mea sure, the receiver will also pick up R/T. over either system, and has 100 receive-frequencies altogether. This may seem excessive, but for area cover, or V.O.R. cover over several adjacent airways, quite a lot of V.O.R. stations are needed. The V.O.R. system is not yet used very much outside U.S.A. Jet Operation and D.M.E. D.M.E. is usually associated, at least mentally, with V.O.R.; but it earns a place in its own right because of its importance to economic operation of jet aircraft. Jets should start their descent from their operating height at a point from which they can make a direct approach to destination, and the accurate determination of the appropriate point to begin descent can best be done by using D.M.E., with a responder beacon at the terminal airport. The responder beacon and D.M.E. equipments shown by Murphy are already in use and give ranges of up to 200 miles; and Marconi- A.W.A. were showing some similar—but not interchangeable— equipment, used on the Australian airways. Cossors now have the Gee Mark III receiver, which is a lighter and simpler version of the earlier Gee receiver and gives very accurate navigational information within the somewhat restricted service area of the Gee ground stations. The Decca navigator system, and its companion the Dectra system, were both explained on the Decca stand, and there was a working demonstration of a Decca receiver and Flight Log, worked from a simulator. The Dectra system, which provides accurate track-guidance and distance information over long dis tances, was portrayed in use for crossing the South Atlantic. The accuracy of the existing Decca system was emphasized, and one of the new receivers, which will function on nine Decca chains, was on show. There was also a lightweight Flight Log, which can be stowed in a map pocket and is suitable for light aircraft—and for helicopters, with their unusual navigational capabilities, e.g., to fly backwards immediately after take-off, so as to be able to land straight ahead in case of urgent need. The Decca system now provides coverage over nearly all Western Europe, and far out over the Atlantic ocean—a continuous area of coverage, extending from sea level to the highest flight levels. Automatic V.H.F. direction-finders for ground use are made by S.T. and C. and Marconi, the former with C.R.T. presentation, and the latter with large-scale meter presentation. The Marconi equipment, AD.200, was shown in association with air traffic control desks designed by International Aeradio, and they formed a combination which looked very useful and completely practical. The S.T. and C. set was not on show, but was fully described, with its application to an area triangulation D/F. service like that provided over France. The use of intercom equipment has not fallen off at all, although aeroplane cockpits are rather less noisy than they used to be. The reason, of course, is that intercom now provides a means of service control, and enables each crew member to select and use the radio sets which he needs, widrout interfering with other users' selections. Ultra Electric communications control equipments were again on show, in their two sizes, virtually unchanged since the original production five or six years ago, and exactly as fitted on most British-built airliners ever since. S.T. and C. and Mar coni are making equipments which provide similar facilities by slightly different methods; but Ultra continues to hold its place, even on "export" Comets, and against American competition. There may be little place for air-sea rescue radio sets in civil aviation, although dinghies and dinghy radios are mandatory for certain flights. Lightwight life-saving radio sets, weiehing only about 3 lb, were being shown by Burndept and by Ultra. The Burndept set works onl21.5 mc/s, the International V.HJF. distress channel, and provides two-way R/T. as well as a beacon signal, G
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