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Aviation History
1912
1912 - 0766.PDF
the observer might concentrate his attention on the detail of the picture thrown on the plate instead of peering over the side of the machine at the country generally. This would tend also to combine the observation powers of pilot and passenger by leaving the general direction in the hands of the pilot and the particular investigation to the passenger, who would report immediately to the pilot whe;her it was necessary to manoeuvre for a closer inspection of the spot. Whatever comes of the idea, however, there can be no doubt that it is worth someone's while to take it up seriously, and to proceed as quickly as may be with the construction of a suitable instrument. In a large measure, of course, this question of the necessity or otherwise for the observer and of the part he must play, vitally affects the design of the machine. Shall he, for example, sit side by side with the pilot or in tandem ? and if the former is desirable, as some have suggested, it would be interesting to have more opinion on the subject of whether the arrangement is inimical to steadiness in flight on moderate span machines. If the question of armament arises, as indeed it must, a new complication is introduced by reason of the necessity of giving the gun a wide range of firing angles, and in this connection especial interest attaches to the performances of those machines in the trials that are well known to be capable of lifting more than the specified load. There is no doubt that aeroplane construction has entered on a new phase with these trials. The machines, even when they do not go to the length of the Avro enclosed body, are altogether more like vehicles than anything that has been produced before, and it is clear that the lesson of the motor car, with its modern wind-screen and general protection for occupants, will find its parallel in the evolution of the flying machine. There is, too, a marked change in the constructive detail of most machines, which in many cases seems to me to be rather overdone. _ Formerly, a pilot was expected to risk his life on a single piano wire, now he is given a collection of great cables any one of which looks strong enough to hang the machine. Surely there is need for moderation in this direction, too. The change from solid drawn steel wire to stranded cable seems to me to be a sound departure for the reason that a solid drawn wire is liable to sudden and complete fracture, whereas a cable seldom parts at once. A reasonable factor of safety should, therefore, be considered sufficient, otherwise the design lacks balance and the machine is handicapped from the start. One thing that is, however, of the utmost importance in the use of cable is to inspect it regularly and with the greatest care. Cables used in mine haulage are inspected daily, and a very few broken strands is sufficient for the rope to be condemned. Although only the outside strands fray through, it is most unlikely that the same strand breaks twice, consequently an occasional loose end in several feet may easily mean a completely faulty cable if repeated throughout a very great length. Many of the wires used in aeroplane construction are quite short, but the warping wires are generally of some length and in this connection the above remark should be borne in mind. CLASS DESIGN IN THE MILITARY TRIALS. WHEN the aeroplane manufacturers and other interested people attended at the House of Commons some months ago to confer with Col. Seely, then Under-Secretary of State for War, about the Military Trials, much point was made of the necessity of knowing exactly what the authorities required in order that they might design accordingly. And, as there is now such an extraordinary difference between the machines entered, it may not be without interest to endeavour to investigate the results obtained by measurement against an arbitrary standard based as far as possible on the figures cited in the official conditions. Hitherto my philosophical commentary on the technology of the event has had for its purpose an endeavour to appreciate each machine on its own merits by trying to ascertain how far it was making good use of its engine power. Aeroplanes, in common with all other forms of machinery, must submit to the efficiency test as the ultimate criterion of design, and the data provided by the present trials affords an invaluable opportunity that it would be absurd to lose. Nevertheless, the performances of the machines vary widely among themselves, and if it were true that each had been especially designed for the purpose of doing well in this particular trial then the variation is certainly sufficiently curious to call for some explana tion and comment. In any case, alternative lines of thought, seriously pursued, frequently expand the understanding, and it is obviously worth while to try and get all we can out of the present occasion. Let us begin with the question of speed. Para. 6 of the revised regulations published in FLIGHT, May 25th, states as an essential: "Attain an airspeed of not less than 55 m.p.h. loaded." Then IlWTTTi lis • 1 ^•£2*?*''" !*•« !5"' *r~- ; _/, 4 *# P& '-'- 1 • • MARTIN- HANDA5YDE j*t tttt MV Mc nop! 2ni.c "Flight" Copyright. Three views of the 75-h.p. Ch:nu-motored Martin-Handasyde mono, in the Army Competitions. 766
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