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Aviation History
1962
1962 - 0705.PDF
-03 \GHT .national, fry 1962 HI- ^* H^fe aBfc/fl /^\ Dr A. E. RUSSELL Technical Director Dr W. J. STRANG Chief Engineer (Aircraft) D. I. VICKERY Assistant Chief Engineer (Aircraft) F. J. CHARD Manufacturing Development Manager G. L. AUTY Chief Test Pilot Technical direction of the programme has devolved largely upon these Bristol Aircraft executives room, where it will be processed and de-multiplexed. Some 'pilot information' quantities are presented in the form of visual displays on a duplicate set of aircraft-instrument dials at the control console. These dial presentations include indicated airspeed, Mach number, altitude, engine r.p.m., fuel consumption and jetpipe temperature. A ground pilot will monitor these displays, and will be able, over a VHF radio link, to give an advisory service to his colleague in the air; he will in fact take over the responsibilities normally allocated to a second pilot or observer. "A wider range of engineering quantities will be presented as time histories on multi-channel pen recorders, giving an immediate 'quick look' reference with an accuracy of ± 5 per cent. More accurate presen tation of selected portions of the record is obtainable from separate strip chart recorders, the portions being located with the help of the pilot's recorded commentary. "Flutter testing will inevitably loom large in high-supersonic re search, and the ground control room at Filton has special provision for recording and monitoring flutter quantities. Telemetered data will be automatically plotted, and presented as Nyquist diagrams. Trained observers monitoring these plots will immediately be able to warn the pilot of the onset of a dangerous trend. (Compare this with the former routine where the aircraft was flown, step by step, through the amplitude and speed range nearer to limitations, returning to base after each step for analysis of AOP records. It is obvious that telemetry, coupled with automatic data processing, gives far closer control of flutter programmes and will save invaluable flying time.) "The tape recordings, which give somewhat higher accuracy than the telemetered records, are used for quasi-static quantities such as systems pressure and temperatures. Quantities are sampled at a rate of 2c/s. The tapes are played back and presented on the quick-look pen re corders. One track produces 48 pen traces simultaneously on the three multi-channel recorders. "Twelve photographic trace recorders, using 35mm film, are carried under the pilot's direct control. These recorders give a frequency response of up to 50c/s, and a much higher rate is available if required. This system is therefore well suited to pressure plotting, structural investiga tions, and for recording performance and handling data. The 35mm records are analysed in trace reading equipment which presents the information either as time-histories, as punched cards for further computing, as typed columns of figures, or as x-y plots. "In the range, accuracy and volume of flight data recorded, and in the speed of collection and readout, the instrumentation matches the require ments of future high-supersonic research programmes. Every minute of flight time will be made to yield research information; there will be no dead time. But the speed and volume of data-production present their own problem, in that the human computers at the receiving end are in some danger of being swamped in automatically produced paper. Future developments will aim at direct computer action from magnetic tapes, providing automatic comparison of the record with prediction and printing-out only those sections where the record differs from prediction by more than an acceptable tolerance." The Present Programme The first airframe constructed was the static-test specimen, which was taken by road to the RAE Farnborough two years ago. After completing a loading programme in the unheated condition, it will be subjected to further tests in combination with infra-red heating equipment. Of the two complete aircraft, the first (XF923) is now flying and the second is almost complete. The latter is scheduled for delivery to the RAE Bedford, where it will be used in extensive research programmes presumably associated with Government projects. The first machine is at present based at the A&AEE at Boscombe Down, where the runway is adequate for unsticking at 1.4Vsi. Although it will ultimately be delivered to the MoA, this first machine will remain in the manufacturer's hands during its initial test-flying and calibration programmes, and will return to Filton for the major part of this work. Godfrey Auty, the c.t.p., will be assisted by his colleagues Ken Ashley and Ian Williamson. Most flights will be over the Bristol Channel and Irish Sea, Sopley radar being the prime source of navigation instructions and a Hunter T.7 being employed as chase aircraft whenever its relatively limited performance renders it of value. It is impossible to predict what the 188 will accomplish, nor how the knowledge gained with it will find practical application. In the author's opinion, the programme has suffered from the charac teristic British disease of trying to get by with rruriimum rate of expenditure; it is difficult to find any other reasonable explanation for the fact that the more radically advanced X-15 aircraft were started two years later and flew almost three years sooner. But it is also his opinion that the 188 will prove to be a research tool of greater value than its critics appreciate.
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