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Aviation History
1962
1962 - 0838.PDF
836 FLIGHT International, 24 May 1962 FLIGHT-TEST INSTRUMENTATION that the ultimate goal in relieving the analyst of this flood of data would be to carry a special-purpose computer in the aircraft. He predicted that, if it could be suitably programmed, this compu ter would output the aerodynamic derivatives, give yes/no answers to engineering questions—such as "is the engine-bay temperature below X°F?"—progress the flight trial through the autopilot and finally deliver a report ready for distribution on landing! The difference between the meanings of data and information has become increasingly important, now that the capacity of these flight-recording systems has increased to the stage where a long time is taken to search the data in order to retrieve the useful in formation. This adds to the flight development time of an aircraft, and Avro's C. F. Bethwaite, in his paper "Digital data acquisition systems—breakthrough on breakdown," suggested that this deve lopment time should not be wasted for the sake of obtaining high accuracy and large data capacity in the instrumentation system. Where space permits, much may be done actually in the aircraft, as described in an extremely lucid manner by H. Y. Hitch of Vickers-Armstrongs (Aircraft). In discussing flight flutter-excita tion methods he detailed the arrangements made for testing the VC10. Complete vector plots in the form of Kennedy-Pancu dia grams are provided by Polaroid-Land cameras photographing twenty cathode-ray tubes in the aircraft. The data reduction is thus effected in the air, and Mr Hitch felt that this would consider ably shorten the time for flight flutter clearance, compared with traditional methods involving ground analysis of continuous- trace recordings. Current instrumentation techniques at the Centre D'Essais En Vol at Bretigny were presented in a paper by M Petit, who is the Chef Adjoint du Service des Methodes. Amongst the variety of instruments and systems available to the French aircraft industry an adaptation of the well-known Beaudouin A13 recorder to com bine both analogue and digital recording was worthy of note. The system gives a "quick look" record in analogue form, but at the same time this record can be processed by a relatively cheap reading machine to produce punch cards from the digital tracks which are placed alongside the normal analogue record. By standardizing their instrumentation, the French have succeeded in producing a chain of measuring equipment consisting of compatible instru ments and devices—even though these components may be pro duced by different manufacturers. This may mean a slight reduction in flexibility in the measuring system, but we would do well to study their methods in this country The French are also willing to adopt American standards where necessary, on the grounds that it enables certain special items to be purchased direct from the USA in instances where the quantity required does not justify development in France. In the United Kingdom there are few standards laid down for flight-test instrumentation. Those which have been recommended by the SBAC—for example, in magnetic-tape recording—are "British" standards" in the sense that they do not conform to anyone else's standards. British manufacturers of this highly specialized equipment, for which there is only a small market in this country, are handicapped by these standards if they are to compete with their equipment abroad. Last month's symposium showed the need for close co-operation on a European, and preferably on an international, basis as regards standardization of flight-test equip ment, specifications and terminology. With the advent of the Common Market, it is in our case particularly important to have an international, rather than an insular, outlook. Perhaps the greatest revolution in airborne instrumentation systems has been the application of transistors to flight equipment. As A. H. Smith of RAE Farnborough pointed out in his paper, semiconductors have many advantages over thermionic valves, and have made possible the construction of compact airborne digital data-handling systems. Mr Smith gave examples of various signal conditioning units using transistors which have been developed at the RAE for flight-test purposes. Electrical transducers were conspicuous by their absence from the papers presented. One paper, by J. R. C. Fearon of Rolls- Royce, and another, by D. R. B. Webb of RAE Farnborough, on outside temperature and pressure fluctuation measurements respectively, discussed the application and deficiencies of two particular types of transducer. Most other speakers made only passing reference—usually derogatory—to transducers, describing them as being the limiting factor in the improvement of measuring systems at the present time. It seemed that more fundamental research was required into possible transducing methods, coupled with an improvement in the manufacturing technology of existing devices. During the symposium 22 manufacturers exhibited a variety of flight-test instruments, many of which were from overseas and were shown by their UK agents. The symposium ended with a dinner at which the guest speaker was S. F. Follett, CMG, Deputy Director (E) at the RAE. The Proceedings will be available from Pergamon Press, and the College expects to hold its next such symposium in 1964. BEAVER No 1,500 On May 15, at a ceremony at the Downsview, Ont, plant ofde Havilland Aircraft of Canada Ltd, the I,500th Beaver to be built was handed over to the Manitoba Government Air Service. Since the first Beaver appeared, 15 years ago, the type has gone into civil andjor military service in 63 countries. MGAS already operates seven Beavers and two Otters on forestry and numerous other duties
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