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Aviation History
1947
1947 - 1741.PDF
OCTOBER grn, 1947 FLIGHT 413 On the tight is shown the control and indicator units of the G.E.C. radio compass, with above it the torpedo housing for the loop. The dish type housing for future installation is shown above. There is, of course, a number of high or medium power ground tnfDsmitters, both H.F. and . v\H.F., which are highly essen- tial to the safe operation and control of aircraft. Of the navigational aids, the most interesting is probably the new G.E.C. radio compass which has been developed for the R.A.F. but will also be available for civil aviation. The most radical change from earlier equipment is the provision of an iron-C(5red loop. This enables a very much smaller " torpedo " housing to be installed on existing aircraft, but what is more important on future aircraft, it can be mounted in such a way that there is no projection outside the skin of the aircraft. This, of course, with the development of high-speed aircraft, is an extremely desirable feature. Other interesting details are the optically projected scale, which is very easy to read, and the Desynn tuning. The latter feels a little strange when compared to a normal direct tuning device, as the speed of operation is proportional to the amount of movement of the control knob, but the operator should soon become accustomed to it. Another detail is that the two motors driving the loop are ^running continuously, so that there is no error or lag due to Starting and stopping. •?' • ' Ground Equipment . Marconis have concentrated mainly on ground equipment, and have included on their stand the DFG26 HF/DF with cathode-ray presentation. This set incorporates a spinning goniometer and gives an instantaneous visual indication of bearing when the signal is received. They also show a model of a Consol transmitting station. This system, which has been fully described elsewhere, is now under test by the M.O.S. and M.C.A. to determine its usefulness as a navigational aid. The well-known Marconatpr may be seen, but apart from the single-channel V.H.F. transmitter/receiver, which is an airborne version of the police radio telephony set, the only other airborne set is the AD97, a low-power H.F./M.F. trans- mitter originally designed for the Dove. Metropolitan-Vickers have a M.F. Beacon with a power output of 10 watts for use on airports. The set is very simple In two units, the Murphy V.H.F. set is compact and light in weight. .:."' ,.;' The compact MF airport beacon manufac- .'•••-.- . r tured by Metrqpolitan-Vickers. A number :'. ••' . •""'''•. ore being supplied for use in Eire. and compact, in fact a toothed-wheel cut to the required code merely bears on a spring-loaded contact. The glide-path receiver section of the complete airborne Instrument Landing System is on show at the G.E.C. stand. The development of the localizer receiver has been completed but a model is not yet available. This set is designed to work as part of the blind approach system which has now been standardized by the I.C.A.O. The first localizer receiver will be for the amplitude comparison system ; the phase comparison system which is due to be introduced in a few years' time will" be catered for in a later model. The glide-path receiver has eleven channels available, each having its own crystal, these channels corresponding with the appropriate channels in the localizer. The channel selection for both receivers is carried out by a switch available to the pilot on a small control box. The Cossor Radar Co. are showing this year the new GEE Mk. Ill miniaturized airborne equipment, which is consider- ably smaller and lighter than the R.A.F. type which is at present in use by British European Airways and other air operators. From the navigator's point of view, the main improvement lies in the reading of the GEE co-ordinates which appear on a speedometer-type counter and can be read off immediately. Further developments are expected eventually to lead to the introduction of an automatic computer. The Ferranti Company are working on this computer, which will still further reduce the navigator's work. In the GEE Mk. Ill a 1 Jin diameter cathode-ray tube is used, the screen being viewed through a lens. As the required angle of view is small, the limitation imposed is no disadvantage, and the advantage of a larger screen is obtained without extra bulk. A Rebecca Mk. IV miniaturized airborne set is being demon- trated on the E.M.I, stand. This is the latest form of this type of equipment and has been developed for the R.A.F. It operates in the 200 Mc/s band but will eventually be super- seded by the 1,000 Mc/s band as the result of the last I.C.A.O. conference in Montreal and subsequent discussions between the U.K. and U.S.A. An example of the Eureka beacon with which the Rebecca, Mk. IV will operate is to be seen on the Murphy stand. Both the transmitter and receiver are crystal controlled and there is an automatic monitor which sends a signal back to any desired point if the performance drops by a predetermined amount. A coder for identification is incorporated in the transmitter and the maximum repetition rate of 10 kc/s should allow interrogation by a large number of aircraft without saturation. The coder unit is shown separately on the stand. The Decca Co. are not showing any apparatus in the exhibi- tion but they are giving a film show of the Decca Navigator. The exhibition gives a fair cross-section of the work which the radio industry is doing for aviation, although the numbei of items on show is rather limited. In spite of the growing complexity of all the airborne equipment every effort is being made to reduce the load on the operator, and miniaturization if helping to cut down the space and weight requirements. B T. O'K.
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