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Aviation History
1961
1961 - 0532.PDF
540 FLIGHT, 20 April 19 i SURVEY Automatic Landing in France Sup AVIATION are investigating automatic landing techniques witha view to fitting Caravelles with suitable equipment. A system proposed by Lear, considerably more simple than those nowunder development in Britain, is to be installed for trials in the second prototype Caravelle at Toulouse. All types of ground-based guidance equipment are under investigation, including improved ILS of both. French and foreign manufacture, theFrench ASV.23 microwave system, Elliott Leader Beacon, Murphy Leader Cable and the Bell radar system, though the last-named isnot considered suitable for civil applications. Sud appear to feel that the high degree of protection againstfailure which characterizes the two British systems, and their resultant complexity, may not be necessary in achieving adequateautomation. Any prospect of simplification must be based on the assumption that the pilot can remain in the control loop even duringthe final critical phase of the landing; and Sud apparently consider that this is possible and that the performance of the human pilotcan be effectively predicted—partly in view of the fact that the landing manoeuvre is less critical in aircraft of the size and approachspeed of the Caravelle than it might be in the larger airliners. They feel that the pilot will be most unwilling to be excluded from thecontrol loop, and will in any case become fully accustomed to the equipment before actually attempting blind landings. It is thoughtpossible to ensure that a failure during the critical time would affect only one axis of a single-channel system rather than the wholesystem, and that the pilot would have no difficulty in taking over control of this channel. Though a simplified solution is obviously highly attractive, itremains to be seen whether a sufficient guarantee of safety can be achieved. British investigations, carried out independently bySmiths and Elliotts, have tended to suggest that it could not. VHF Homing for Light Aircraft THROUGH their distributors, Radiostal (at Aerodrome St Martin,Bernay, Eure, France) the French company Cotelec is marketing a simple attachment for airborne VHF radios to allow homing to aground station which is continuously transmitting. The equipment consists simply of an electronic unit built into an instrument caseand bearing a small left/right needle on the instrument face. This unit is connected to the existing VHF radio and to two vertical whipaerials mounted one on each side of the aircraft centre-line, about 16in apart. When the selector switch on the instrument is set to"Homing," a small vibrator causes the receiver to use the aerials alternately at 770 microsec intervals, thedifference in received energy being translated into deflection of the left/right needle.When the aircraft is close to the transmitter the sensitivity of the needle can be reducedsimply by adjusting receiver volume. The course to the transmitter is shown by theaircraft heading when the needle is centred, the inbound or outbound sense being notedby observation of the direction of deflection of the needle when turning off course. Weight of the instrument unit is 1.31band versions for 12V or 27V are available. Frequency range is from 108Mc/s to 132Mc/sand VOR transmissions can presumably be used for homing. On communications frequencies the pilot as ;s the ground station to transmit continuously for a period. Eitr >r telephony or morse can be received and the range of the horn: ig device is stated to be the same as that of the VHF radio to which r is attached. Smiths Prepare for FAA Trials THE Douglas DC-7 which is to be used by the Federal Aviati >nAgency for trials of the Smiths automatic landing system is at pre- sent fitted with a Sperry autopilot; and special analysis and analoguecomputer-studies were necessary before the Smiths equipment could be matched with it. This work having been completed,Smiths automatic throttle controls are being dispatched to Sperry,' New York, where they will be fitted to the aircraft. The aircraftwill then be flown to Britain and fitted under Smiths direction with special couplers designed to match the Sperry autopilot with theBritish system. Also to be fitted are the Standard Telephones and Cables radio altimeter and Murphy Leader Cable receiver; and thework will be begun next October. Flight trials will be carried out at the Blind Landing ExperimentalUnit at RAE Bedford and the aircraft should return to Atlantic City for the FAA evaluation "some time in March 1962." Reportsfrom the USA state that the programme is considerably behind schedule. An engineering representative from Smiths at Cheltenhamwill remain with the aircraft during the trials in America. ADF Improvements MARCONI announce two new components designed to improve theefficiency, reliability and life of the well-known AD.7092 series of radio compasses, 3,500 of which are still in use. One is a tran-sistorized switching unit to replace the vibrator and the other is a static a.c. power unit to replace the existing rotary transformer.Either component can be fitted separately and only minor modi- fications are required. The switching unit replaces the mechanicalunit serving the balanced modulator in the loop aerial circuit and loop drive motor. It will be available in June and will cost £55.The power unit, also available in June, will cost £65 and save 0.51b in weight over the old unit. Frequency Measurements for the RAF FREQUENCIES of both ground and airborne RAF transmitters arechecked to accuracies of between 0.003 per cent and 0.02 per cent, according to internationally agreed tolerances, by the RAF Fre-quency Measuring and Monitoring Station at Stoke Hammond. Bucks. All RAF transmitters, including those at Nairobi, Gibraltar,Cyprus, Ottawa, Gan, Aden and Malta, are constantly checked and their accuracy recorded, as is interference with or from other trans-mitters. For these purposes two Racal RA.17 receivers are used at thestation in conjunction with two Racal RA.37LF converters and an RA.63 SSB adaptor. An SA.21B digital frequency meter is usedwith radio equipment for direct reading of measured frequencies, and accuracies of one part in 106 can be obtained. The RAF stationis manned by civilians. A MIG from Ketay THE Norden division of United Aircraft Corporation have recentlyintroduced a new miniature integrating gyro, type RI-203, and this is now available in the UK through Ketay Ltd, Eddes House,Eastern Avenue West, Romford, Essex. Applications include inertial navigation and guidance for missiles and aircraft. The gyrois used, in conjunction with Norden single-axis accelerometers, in the new miniature all-attitude inertial platform recently shown inthe UK. The gyro is 3.1 in long by 2in in diameter and weighs lib includingheater and shields. Features include a random drift of less than 0.02 /hr and day-to-day stability of 0.r/hr without trimming. Lifeof the gyro is 3,000hr, to which the low spin rate of 12.CC0 r.p.m has contributed. Left, components of the Cotelec homing attachment for airborne VHF radios in light aircraft. The left/right meter and two aerials are coupled to an existing VHF radio (see news- item in column one above) Right, static power unit which replaces the existing rotary transformer in Marconi AD.7092 series ADFs (see "ADF Improvements"). It will be available in June
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