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Aviation History
1962
1962 - 0296.PDF
298 FLIGHT International, 22 February 1%2 FLIGHT SYSTEMS the American company. Eclipse-Pioneer division are designing a micro-wave guidance system called Microvision, which would give the pilot some directly derived visual representation in the cockpit of the runway ahead of him. It has been described in Britain as "like BLEU's Televiewer, but it works." Bendix are not prepared at the moment to release any information. Pacific Division designed two pulse radar altimeters, the APN-141 and APN-146, for use at low level in connection with the Army Navy Instrumentation Programme (ANIP) and these are now being modified to fit the requirements of the BLEU system. Eclipse-Pioneer have a programme to improve and extend the capabilities of the PB-20 autopilot now used in Boeing 707s and 720s with a view to lowering approach minima and, eventually, to providing landing automation. Already available are a newly wired amplifier computer chassis into which existing modules can be plugged, and certain improved modules to provide better performance in such areas as VOR station passage and rapid cross- wind computation. Yet further improvements are to be introduced next year to make the PB-20 more reliable. At a rather later date, Bendix will introduce additional com ponents in the PB-20 to facilitate glide-path extension, control- wheel steering, automatic speed control and such factors as auto matic flare-out computer and divided control systems for combined manual and autopilot control duiing autoflare landings. Bendix have been working with Boeing, who are themselves introducing control improvements in the aircraft. Boeing, Eclipse- Pioneer and the USAF are flight testing divided control; and Bendix have been flying their B-25 for the FAA, testing Regal and Flarescan. THE BOEING COMPANY FOR some years Boeing have been considering the implications of automatic landing and low approach in relation to their existing aircraft and projects such as the 727. With the hard-worked "dash 80" prototype and simulators they have done a considerable amount of practical research, but have been working in the rather simpler stages of low approach on the assumption that an advanced degree of automation will be uneconomical because of the expense of installation and maintenance. Instrument panel of the TF-I02A with Autonetics APN-114 In parallel with Bendix autopilot improvements, Boeing are introducing a number of improvements to the control systems of the 707 series, particularly in the tailplane trimming, rudder and aileron controls. The stick-top trim switch is being modified and an instinctive override system introduced to overcome the effects of possible tailplane runaway close to the ground. Trim range is being slightly reduced to cover only the useful travel. Asymmetric spoiler extension is being prevented and nosewheel steering over a restricted range is being coupled to the rudder pedals. Lift sensing devices, thrust controls, better non-skid brakes and windscreen rain-clearance should all contribute to better approach and landing performance. The "dash 80" prototype is now fitted with Smiths PVD, a modified flight system and the Lear flare-out director instrument. The company are also planning a flare-out computer, use of radar altimeter, angle of attack sensors for speed control and a thrust command computer, both the last two being applied to the appro priate elements in the flight director instruments. The autopilot for the new 727 is to be the Sperry Phoenix SP-50, and Boeing will certainly apply their experience with the 707 series, to offer the best possible low-approach capability in the new type. AUTONETICS THE APN-114 automatic landing system, now tested in a TF-102A. bears some resemblance to BLEU Autoland. It involves manual setting of the aircraft at over 200kt and 1,500ft at a point where the autopilot captures the ILS localizer on barometric height-lock. At glide-path intercept, speed is automatically reduced to 170kt and held by air-brake adjustment with a datum engine power manually set. At 100ft, sensed by radio altimeter, a flare computer takes over, datum speed is reduced to 140kt and the flare is aimed at a touch down point. Any disturbance leads to immediate computation of a new flare-path to the original touchdown point, giving terminal control. Meanwhile bank limit is reduced from 33° to 15° and heading is held according to ILS localizer. At 7ft, a light tells the pilot to de- crab manually, if necessary, but localizer guidance continues on the runway as long as rudder remains effective. At any time during the flare-out, the pilot can modify the flight path by control-stick steering, overriding the automatics. Alternatively, the whole approach can be made manually, but with automatic speed control, using the flight director instruments normally available for monitoring. The flare computer and inertial rate of descent indicator (IRODS) are separate from the autopilot. A test button may be pushed at any point down to flare initiation to insert calibrated voltages at the sensor inputs and check command voltages. A fault actuates a failure light. The design attempts to ensure only "soft" faults leading to a levelling-off tendency in case of autopilot or computer failure, but the system is single-channel. APN-114 was first tested in autumn 1960, completed a 45-day test in November 1961, was delivered for initial USAF evaluation in January and is to be tested by FAA next month. Autonetics flew tests at Palmdale and six other airfields. A "second generation" landing computer, containing APN-114 and IRODS in half the former volume, has been loaned to Boeing for evaluation this month in the 707 prototype. COLLINS RADIO COMPANY AUTOPILOTS and flight directors produced by Collins have long been in use by a considerable number of airline and military trans port aircraft. Improvements to the present equipment include an experimental application of micro-circuits in the flight director, which entirely eliminates the present separate computer unit and incorporates it in the instrument cases themselves. Another pro gramme has produced a new set of warning flags of larger size and positioned to obscure the indicator element which has failed. In an effort to lower the weather minima for the autopilot/flight director combination, Collins are working on glide-slope extension methods, using both radio altimeters and aerodynamic sensors to derive a rate of descent signal to take over from glide-slope guidance at low levels. Head-up displays of various kinds are being tested in simulators, and new methods of manoeuvring during autopilot approaches are being tried. In one case, manual manipulation of
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