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Aviation History
1964
1964 - 1526.PDF
fLIGHT International, 21 May 1964 19 ELLIOTT HAVI: A SYSTEM... • •• to meet all the needs of the aircraft designer and operator for flight instruments and flight control. Elliott's team of twelve divisions have a unique capability and strength which springs from gathering in one company all the techniques needed for control of flight in all its aspects. Autostabiliser for the Bristol type 221 research aircraft The Autostabiliser supplied by Elliott Brothers (London) Ltd for the Bristol 221 comprises an integrated system designed to perform two main functions :- (a) To ease the task of the pilot in holding steady test con- ditions during the initial phase of the flight test programme. (b) To provide a flexible means of varying the handling charac- teristics and lateral stability of the aircraft during the principal and more important part of the flight test programme. The requirements of (a) have been met by providing auto- matic airspeed control and lateral autostabilisation. Control of airspeed will be obtained by automatic positioning of the aircraft throttle lever in response to departures in airspeed from a valve which is selected in flight by the pilot. The selected airspeed may be any valve chosen from a large range. This airspeed control system makes the aircraft 'speed stable' below minimum drag speed and improves speed stability over the range in-which it is operative. The lateral autostabiliser is of the conventional type and pro- vides additional damping in roll and yaw by deflecting the ailerons and rudder in response to roll rate and yaw rate signals obtained from standard Elliott Rate Gyros. An airborne computer is a main unit in the part of the system designed to meet the requirements of (b). The computer will receive signals proportional to airspeed, roll rate, yaw rate, lateral acceleration, sideslip, aileron position and rudder posit- ion. Extensive use has been made of standard removable cardmodules and the internal layout of the unit is such that all parts requiring frequent change or adjustment are easily accessible after opening a hinged top cover. The signals are passed to input or signal-shaping cards as required and are then routed, with the exception of the air- speed signal, to a programming card. By means of the programming card it is possible to select on the ground in minutes the signals or combination of signals which are to be used in the aircraft control equations. From the programming card it will be possible for the signals to pass through summing amplifiers to aileron and rudder channel servo amplifiers and thence to the control surfaces. Provision has been made for a substantial increase in the amount of information available from a given flight since any three of the above signals may be routed through the Pilot's Controller before being fed to the summing and servo amplifiers. The Pilot may then select any of five given levels of each signal or may switch out any of the three signals as required. Examination of the aircraft lateral stability and handling characteristic's in low speed flight as modified by the variety of possible autostabiliser and co-ordination control terms will be carried out after examination of the results of supporting simulation work carried out by Elliott Brothers (London) Ltd. military aircraft controls division mA Member of ths Elliott-Automation Group ELLIOTT BROTHERS (LONDON) LIMITED/AIRPORT WORKS / ROCHESTER /KENT / CHATHAM 44400
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