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Aviation History
1962
1962 - 0298.PDF
300 FLIGHT International, 22 February l%2 FLIGHT SYSTEMS even when glide-slope angles vary between 0.5° and 10° and the flare paths take various geometric forms. Altogether, testing so far completed has been successful, but little quantitative data have yet been gathered. Nevertheless, very considerable knowledge of a variety of systems will result from the Regal tests, even if, as seems possible, Regal itself is not actually adopted in the end. Sufficient improvement may yet be obtained from advanced ILS and the various 1LS glide-slope extension systems proposed for autopilots, to make a final choice of a totally new system premature. AIRBORNE INSTRUMENTS LABORATORY FLARESCAN-ILS, developed by Airborne Instruments Laboratory of Cutler-Hammer Inc, has been initially tested at an airfield on Long Island and is now to be evaluated at Atlantic City by the FAA. It is intended for use in conjunction with the new narrow angle ILS localizer and wave-guide glide-slope and projects a 16,000Mc/s angle-coded microwave fan pattern from a position 2,500ft along the runway beyond the ILS glide-slope aerials. The glide-slope beam and Flarescan angles can be used by an airborne receiver to initiate flare-out at a certain cross-over point between the two beams and to bring the aircraft down onto a minimum Flarescan angle for touch-down. Flarescan extends to 20 miles from touch down and can therefore be used for confidence checking and ILS monitoring throughout the approach. It is also free from site effects. Angular sensing accuracy is between 0.5° and 0.1°. As the beam sweeps through its vertical arc of about 20°, it is coded by a con tinuous series of single pulses whose time interval represents the instantaneous angle. The spaces decrease towards the lower angles, giving the finer accuracy in the most critical region. The beam is generated by a mechanically nodded aerial whose angle is sensed by a photoelectric device at the pivot. Scan rate is eight to ten times per second. The airborne receiver averages the spacings of between 16 and 100 pulses received at each sweep, according to the angle being measured. The transistorized airborne receiver will weigh about 201b and various forms of path computer can be used to suit a variety of autopilots. Alternatively an ILS cross-pointer can be provided for manual approaches, with a third needle to show the approach to the particular cross-over point chosen to mark the beginning of the flare-out. Idle time in the receiver can be utilized for self- checking routines. The ground aerial is 8ft high and the equipment fits into three standard 6ft racks. Initial flight test with a B-25 and optical checking during 50 touch-downs and 50 low passes have shown Flarescan-ILS accuracy within 4ft throughout the approach and 2ft at touch-down. In straight Flarescan passes, accuracy has been within 10ft inside three miles, 3ft inside one mile and 2ft during the last half mile. Some of the points claimed for Flarescan—and for Regal—are Airborne Instruments Laboratory's Flarescan glide-slope aerial that it is independent of terrain characteristics short of the runway, that it provides guidance throughout the approach, and that it facilitates either manual or automatic landings. The first two considerations are put forward in opposition to the radio altimeter technique, used by the BLEU system, among others. Flarescan airborne equipment would cost about $8,000—more or less as much as DMET. Each ground installation would cost about $100,000. BELL AEROSYSTEMS THE Bell GSN-5 (ST) landing radar, made for the USAF and using simulated ILS commands is now under test by FAA. The GSN-5A uses radar beam coding for commands and an S-Band beacon for tracking. It provides flare guidance and a signal telling the pilot when to decrab. Final tests were completed with the Bell Aero Commander and several Army aircraft at Niagara Falls airport last August and witnessed by agencies and airlines. Bell are now making 12 sets of the SPN-10 carrier-borne auto matic landing system under a $10m contract from the US Navy. The system will bring an aircraft down onto the carrier deck in zero visibility. If the aircraft is not properly positioned at the final point, an automatic "wave-off" is given. Carrier deck movement is taken into account. More than 3,000 automatic landings, on land and at sea, have been made so far. Deliveries will be between late this year and 1964. fie// Aerosystems Aero Commander lands under GSN-SA guidance ILS FOR some years to come, ILS will continue as the main ground- based guidance element for landing and approach automation, although the quality of the course and glide-slope signals will be, and is already being, considerably improved. Additional safety will also be required in the form of faster change-over from main to stand-by in case of failure, and closer monitoring. The ICAO Com Division meeting in Montreal has recommended three cate gories of accuracy-tolerance for standard ILS; and these will have to be implemented in due course. Investigations so far made seem to indicate that a good ILS, such as the Pye system, is adequate for the auto-flare type of landing to be introduced with the Trident. Standard Telephones and Cables STAN.7, 8 and 9 ILS, giving high accuracy is being installed in Britain and abroad. The FAA is experimenting with waveguide aerials for both localizer and glide-slope, and these systems apparently offer a very high degree of accuracy.
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