THE LAST 100 FEET

for out of marker inbound for auto Landing Roger Fox trop Papa you are clear to land surface wind is 230° 10 knots [Music] [Music] is you have just seen a fully automatic Landing by a research aircraft operated by the flying unit of Smith's Aviation division this aircraft is equipped with Smith's sep5 flight control system and the evolution of this Multiplex system is the latest stage in a development program started in 1948 when Smiths began collaboration with the blind Landing experimental unit of the royal aircraft establishment the single Channel Autoland system that resulted from this partnership started practical trials several years ago and aircraft using this system have already made many more automatic Landings than all other known systems combined a single Channel military system similar to Smith's sep4 autopilot has been adopted by Britain's RAF and is being fitted to aircraft of the V bomber squadrons in the course of its development single Channel or Multiplex automatic Landing equipment has been installed or is being specified for many different types of new generation civil and military aircraft both propeller driven and jet [Applause] [Music] [Applause] [Music] these aircraft also include the canbera the arasy the comet the dc7 the transal the varsity the caravel the Belfast and the Trident the complex mechanisms and instruments required for these installations are made by Smiths at their cheltonham Factory the first to put such equipment into full production for for operational use careful precautions must be taken in manufacturing this kind of equipment to exclude dust and dirt for example the miniature and subminiature rate gyos that have been developed for the latest generation of autopilots are assembled and tested in a completely sealed assembly shop under strictly controlled and Ultra Clean conditions even individual ball bearings are microscopically examined and before the hermetically sealed Gyros are allowed to leave the assembly shop they're subjected to searching tests for each of these very small instruments is required to do its work for up to 4,000 hours without an overhaul while the single Channel or Simplex Autoland system provides a standard of reliability and touchdown accuracy appropriate to military aircraft a higher level of safety is required for civil operations in fact the possibility of an accident must be no greater than one in 10 million Landings this requirement could not be met with the Simplex system which has no built-in monitor a single fault can cause an unwanted maneuver and at low level the pilot might not have enough time to restore the aircraft to the correct flight path it is for this reason that Smiths have since 1957 been working on the development of the SE 5 flight control system which utilizes the multiplex principle one example of this is the duplex system which consists of two independent subchannels in each axis of control working together and continuously checking on each other any failure in either will result in the disengagement of both and thus cause no appreciable disturbance to the flight path the pilot can then Take Over Control of the aircraft and either land or go round again for regular automatic Landing under blind conditions however even this level of safety may still be inadequate and three or more independent subchannels are required to meet this stringent operational requirement the failure of any one of them will now result merely in the disengagement of that subchannel alone leaving the others to complete the landing the sep5 multiplex installation in the deavalon Trident will be used initially as a duplex system and subsequently at Triplex or three Channel level although the Trident will not initially make fully blind Landings its duplex system is designed to be capable of Auto flare or Auto Landing in comparatively good weather as a necessary preliminary stage for autof flare lateral control in the Final Phase of Landing is taken over by the pilot while pitch control of the aircraft remains automatic throughout the duplex pitch Channel system brings the aircraft down the correct Glide path to a height of about 150 ft when the Glide path coupling is disconnected and the aircraft is locked at a precomputed pitch attitude ude this attitude phase is maintained to about 50 ft when the radio altimeters take control through the autopilot and complete the flare phase automatically azimeth control of the aircraft is automatic down to about 150 ft which is the point at which the pilot takes over he controls the aircraft laterally during the automatic flare maneuver and kicks off drift this autoflare concept is based on the established fact that a pilot emerging from cloud has better visual guidance in azimeth than in Pitch when sufficient experience has been gained with autoflare the Trident system can be used for full automatic landing at duplex level or extended to Triplex level to provide regular blind Landing in the Trident cockpit every effort has been made to achieve a clean and uncomplicated layout of controls and instruments and the same principles have been applied to the housing of equipment in the forward equipment Bay here all the drive amplifiers and computers are carried compactly on Smith's ATR racking with space provided for the addition of further units when the system is operated at Triplex level a third in dependent power supply is also available in Readiness for this development modular design and the use of Smith's ATR boxes ensures that all units can be checked serviced or if necessary changed very easily and quickly the junction box is located at the back of these racks while the radio junction box is at the side this incorporates three Smith's radio switching units which enable port and starboard V and ILS information and Doppler information to be fed to the autopilot and flight system the vertical reference units and azimeth Gyros are also conveniently arranged and easily accessible it is the triplex version of the sep5 system that has been installed by smiths in this specially converted research aircraft which has been allocated to them by the ministry of Aviation as part of the development program and is the first aircraft in the world to be fitted with automatic Landing system at Triplex level one of its important functions is to enable Pilots to gain experience in the system by using it in genuine fog operations as distinct from simulated conditions in addition to automatic Landing the sep5 system provides many new flight director and autopilot control facilities and these will now be shown in the course of a typical flight just before takeoff the pilot switches on the flight director master and sets initial climb reference the aircraft leaves the ground with all power supplies turned on jaros and flight instruments working but with no controls engaged while gaining height the pilot flies the aircraft manually using the full range of flight instruments at a few hundred ft he selects the autopilot by using the engagement levers this brings in automatic control to hold the aircraft at constant attitude he now engages the air speed lock and selects the required climbing speed then sets his heading on the port flight compass and moves the radio coupling switch to the across position when the azimeth master is switched on commands from the steering index are made available to the autopilot and the flight director the aircraft now turns to The Heading shown on the steering index we're now cleared to cruising altitude and the pilot uses the twoos setting knob on the flight controller first to set the prevailing pressure on the millibar counter and then to operate the select height counter he switches the height lock selector to acquire and pulls on the engage switch for radio navigation the system includes two radio selectors which enable the pilot to select the radio information to be displayed on each flight Compass before coupling to V he switches the port radio selector to nav 1 and the co-pilot switches the starboard selector to nav 2 he then then Tunes number two radio to the VR station and sets the starboard flight Compass to the desired radial this causes the V2 information to be shown by the flight Compass roller blind display he then moves the radio coupling switch to the up position thereby coupling the flight control system to the VR information the port starboard switch enables the appropriate Azimuth commands to be fed into the autopilot the aircraft subsides onto the V radial and the doctor drift maintains the precise track we are now approaching our cleared altitude and the height selector switch drops back to the lock position as the aircraft intercepts and holds flight level 90 although we're not flying fast enough to see it working the system also provides a Mac lock facility for use in Faster aircraft the V station is now almost below us and when the aircraft enters the cone of confusion the radio signal is suppressed by an automatic sensor in the azimeth computer and reconnected on leaving when the flight Compass roller blind display changes to VR from presentation we're nearing our destination now and the pilot selects the required rate of descent on the flight controller pulls on the engage switch sets the prevailing ground pressure and the selected height switches the height lock selectors to acquire and pulls on the engage switch at this point we revert to steering index control the pilot sets the radio coupling switch to a cross and takes azimeth control by moving the port starit switch to port numbers 1 2 and three navigation receivers are tuned to the Airfield localizer and this causes the flight compasses to display ILS information the runway qdm is now set on both the starboard and Port flight compasses the pilot slows down the aircraft sets the Speed Lock selector on the flight controller to throttle pulls the engage switch and uses the setting wheel to select the required initial speed the acquire height switch on the flight controller now drops back to the lock position and a moment or two later the aircraft intercepts the selected height at this stage we're flying a heading under radar control but now the radio coupling switch is moved to the up position thereby coupling the flight control system to the ILS beam this fact is shown by the beam indicator on the flight controller as the aircraft intercepts the localizer the blue and yellow areas on the flight Compass display begin to move we're now flying inbound on localizer for the sake of brevity we've made a radar assisted interception of the beam but the system has flexibility for covering all intermediate procedures and holding patterns Under full automatic control in the autol landing sequence which follows the Pilot's hands will be off the controls in order to demonstrate autopilot performance in actual operations he would normally monitor the controls and the cutout button in addition to the full range of flight instruments and warnings he now sets the prime switch to Glide and when the Glide path deviation pointer on the flight Compass becomes Central the nose of the aircraft automatically goes down as we couple to the Glide path at the outer marker the pilot checks the height and sets the initial speed for the approach meanwhile the flight systems panel has been checked to see that the autopilot is clear for a landing and the radio altimeter confidence switch is used to check the three Landing indicators for readout the pilot now sets the prime switch to land the altimeters are now indicating actual height above the ground an automatic overshoot can be initiated at any time on the approach down to flare by pushing the throttles fully forward this will lock the autopilot to approach speed reference for climbout the autopilot can if necessary be disengaged by its cutout button or by force disconnect at about 100 ft the radio altimeter signals disconnect Glide path coupling and the the aircraft continues at constant attitude at 50 ft the aircraft starts to flare under the control of the radio altimeters and the last phase before touchdown is the land phase in which the effects of any significant crosswind are cancelled out by Rudder action comprehensive safety Provisions are embodied in the sep5 system which is standard equipment in all Bea Trident warning flags are provided in the altimeter attitude director and other principal flight instruments which signal any malfunction the centralized warning system alerts the pilot to any failure of a key service in the aircraft other safety Provisions include the flight systems panel which as we've seen indicates the state of Engagement of the automatic controls in the Trident with its present duplex installation the automatic system will disconnect after a failure opening the shutters of the PVD displays which give instrumental guidance for reversionary control as the PVD displays are controlled independently of the autopilot channels the safety of the system is of a very high order the Trident enters Service as the world's foremost civil aircraft in the sophistication versatility and safety of its flight control facilities and as Forerunner of the not far distant day when all weather operation and automatic Landing will be an everyday part of Airline service the [Music] [Applause] the