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Aviation History
1964
1964 - 2070.PDF
-L/GHT international, 16 July 1964 91 elation to the damage caused by the strike and in relation to the oroblems of designing adequate structures, it is of benefit that eading edges are of such a shape that generally impact is only serious if the bird strikes a very limited area of the leading edge, otherwise the bird is usually deflected. A further beneficial feature is that modern aircraft fail-safe structures go a long way towards providing against catastrophic failure in the event of a bird strike. Apart from this work related to specific aeroplane types, research work of a more fundamental nature is starting in some states. This work is aimed at investigation of the ability of various structural design methods to withstand impact. The results of these various programmes will become available during the next three years. The committee concluded its work on the bird strike problem by recommending states to submit summaries of the data collected by them on bird strike incidents. It was requested that "near-misses" as well as "strikes" should be reported. Prevention of Crash Fires Papers on current research in the USA were supplemented by films of recent tests. These included the full-scale test in which a DC-7 was crashed into various obstruc- tions. Crash-fire research work in the USA is being concentrated into three principal areas: (1) Containment of the fuel; (2) Develop- ment of fuels which did not burn, or were less readily ignitable and slower burning, under ambient conditions; (3) The elimination of ignition sources. The work includes efforts to improve the crashworthiness of both integral and bladder type fuel cells. The possible use of plastic liners for integral tanks is receiving consideration, and substantial improvements in the crashworthiness of integral tanks have been achieved by careful attention to detail design, with only slight increases in weight. The use of additives to "gel" fuel under crash conditions is also a promising line of research which was of great interest to the committee. In the USA and the United Kingdom work has proceeded on water inerting systems for turbine engines. The UK has demon- strated the practicability of such systems but believes that their adoption would probably need to await international agreement. The weight penalty per large jet engine is 1001b of water, plus an approximately equal weight penalty involved in installing the system. It is believed that another potential source of ignition will be the sparkability of some of the aircraft materials proposed for use in future aircraft types including the SST. These and other prob- lems will require further study before recommendations can be made. Contingency Powers—Turbine Engines The use of contingency powers for turbine engines was originally considered for helicopter powerplants, but once agreement in the principle was reached it was perhaps inevitable that the procedure would be considered for aeroplanes. Some experience in the use of these ratings for helicopter powerplants has already been gained in operations in Pakistan, the USA and the UK. Two ratings are normally used. Maximum contingency power is a power used, for example, if one engine fails during take-off or during low hover, and this power is greater than take-off power. Because of the higher operating temperatures and possible blade creep which ensure the use of this power would be of short duration only such as 2Jmin. The intermediate contingency power is normally the same as take-off power, but would be used for longer periods, ranging from 30min to unlimited. In the event of the operational use of either of the two powers, it will probably be a requirement that the duration of use be recorded and special subsequent maintenance inspections carried out. The UK is introducing the concept of contingency powers for aeroplanes into its national regulations. The economic benefits for operators of two and three engined aircraft are particularly obvious. For those aircraft payload limited by one-engine-inoperative-take- off performance, or one-engine-inoperative en-route performance, immediate gains are available. The problems involved in the adoption of such powers include the need to revise engine type tests and to establish that there is no undue reduction in the flying qualities of the aircraft. Any resultant reduction in engine life or reliability, and the costs of any additional flying training that might be required must also be taken into account. It was the feeling of the committee that it would be pre- mature to finalize agreement on contingency ratings, but work to this end is to continue. Altimeter Testing This item had been allocated to the committee by the Air Navigation Commission of ICAO. There was a sub- stantial measure of agreement within the committee on require- ments, and final agreement on the PAMC is expected in early 1965. The associated problems of static pressure system errors is to receive attention in the futue work programme of the committee. Other Business The committee agreed that its next full meeting should be held early in the second quarter of 1966, but that work would continue in the interim by means of correspondence and an informal meeting to be held in 1965. The French Government was host to the meeting and arranged a most interesting programme for the committee. On the first weekend of the meeting, members were flown to Biarritz and Toulouse in a Nord 262 to see the products, and meet some of the leaders, of the French aircraft manufacturing industry, including Breguet, Potez, and Sud. The many and varied products of the French light aircraft industry were available for inspection and flight demonstrations at Toussus, and at least one airline pilot present at the meeting rediscovered the joys of flying for fun. The Breguet company showed a remarkable film of the STOL capabilities of the 941, and the many novel features of this aircraft seemed, when taken together with other discussions which took place at the meeting, to give added point to the old dictum—"What we need is aircraft which land slowly and don't burn up." It would not be accurate to define the tasks facing the airworthiness committee in this simple way, but there is no doubt that the work it undertakes should be recognized as being an important factor in the aircraft industry's progress toward improved safety together with economic well-being. AIR TRANSPORT DEVELOPMENT Part 2 of Mr B. S. Shenstone's Mitchell Memorial Lecture Last week (pages 45-46) we reported the first part of the Mitchell Memorial Lecture given by Mr B. S. Shenstone, chief engineer of BEA. Here is the second and concluding instalment. As a result of this choice of the Trident rather than the other product, the other firms which were not chosen were not only disappointed but furious, and it was suggested that we made quite the wrong choice, because the de Havilland organiz- ation was not big enough to do the job. Maybe it was not big enough, but we shall never know, because long before the aircraft flew, de Havilland became part of the large Hawker-Siddeley Group. The point is that BEA stuck to its technical decision and so far has not regretted it. It is worth pointing out that there was not a great deal to choose between the various paper designs. This is in no way surprising because the designers had projected the aircraft precisely to the BEA requirement. If this had not been the case, the choice would have been easier, but the aircraft being so comparable, it was necessary to look not only at the design but at the background and experience of the firms involved. I mentioned earlier the matter of the airlines interfering in design. It may be thought from what I have just indicated that BEA had
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