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Aviation History
1926
1926 - 1011.PDF
December 30, 192:> Supplement to FLIGHT K ENGINEERINGV SECTION Edited by C. M. POULSEN December 30, 1926 CONTENTS PACEThe Paris Aero Show. By .1. D. North, F.R.Ae.Soc lo;i Tendencies of Design at the Paris Aero Show. By F. M. Green, M.Inst.,C.E., F.K.Ae.S ' ins OUR CONTRIBUTORS This issue of THE AIRCRAFT E.VGINEEK is mainly in the form of a series of reflections on the machines exhibited at the Paris Aero Show, which has just concluded. Mr. J. D. North has for once abandoned his series of articles; on " Aircraft Performance," and has instead devoted his attention to some impressions of the show. His opening remarks should, we think, be kept in mind in reading some of the criticisms which he has to offer. There is undoubtedly a tendency to look with distrust upon something with which one is unfamiliar, something in our nature that, in a slightly different form, caused the saying " who is e ''. A Foreigner ! 'Eave a brick at 'im." Not that we would suggest for one moment that Mr. North is " 'Eaving bricks." In point of fact, we think it will be agreed that he is treating his subject in a most sympathetic manner, and is obviously greatly concerned to be scrupulously fair, earnestly trying to get at the funda- mental reasons underlying much that may seem to us obscure or incomprehensible. It will be noted that Mr. North has seen something at the Paris Show which has pleased him a good deal, chiefly the skill in forging displayed by the Forges Foulain. an example of whose work is the Breguet spar box of forged duralumin. There is no doubt that this is a-very fine specimen of the forger's art, and it might be difficult to get it made in this Country, but the question that one naturally asks is whether it is reallynecessary. Another point in Mr. North's article which deserves attention is the reference to the channel-section duralumin construction on the S.I.M.B. (Bernard) single-seater fighter, type 12 C.I. This machine made a belated appearance at the show, and may have been missed bv carlv visitors. It is a develop- ment of a "freak" racer exhibited at a previous show, and has multispar wing construction. Personally we cannot quite share Mr. North's appreciation of this form of construc- tion, although we do agree that the production of tapered strip duralumin may open up a wide field for development. Major F. M. Green also deals with tendencies of design at the Paris show, and to some extent his views appear to tally with those expressed by Mr. North. He points out what seems to us a fundamentally important difference between British and French policy, ours being based upon the possibility of repair, while the French appears to be based upon that of replacement. This is a fact that may help a very great deal to throw light upon, and even to explain altogether, such differences in methods as will have been observed. THE PARIS AERO SHOW. Some Impressions. By .1. J). NORTH, F.R.Ae.S. The critical appreciation of foreign engineering products is a task of considerable difficulty. They are as much indige- nous as cooking or dress, and arouse easily enough the innate xenophobian instincts which to a greater or lesser degree per- vade the human race. To see something different arouses incredulity and even hostility. A writer on psychology has termed this innate hostility to novelties " alexic " (u.'/.i^nv), because it arises from a train of thought which conveys to the mind some danger of disturbance to its preconceived opinions and to the personality some risk to its reputation, established or otherwise. So was Wagner hissed and Picasso ridiculed; not as foreigners in a national sense, but men of strange ways in their profession. We ought to put severely" out of our minds the idea that our methods are necessarily generally applicable or even, (if it be possible to do so), that they are right. The statement that an engineering product is difficult to make, often on analysis is found to mean that the critic does not know how the product may be or is made, and his criticism is purely a subconscious alexie impulse. Although I have outlined the pitfalls that beset the critic I luive not much confidence in my ability to avoid them in giving a critical appreciation of the Salon de FAenmautique. Considering first the question of general arrangement one should find here indication of some definite logical purpose to attain, either special aerodynamic advantages, economic structure, manufacturing economy, or special facilities for military functions such as good views, free arcs of gun fire, etc. One very characteristic type of structure arrangement is shown in Fig. 1, types of which are seen in the Nieuport- Delage, 42 C. and 48 C,, and in the Breguet type 1!) and 26 T. A special feature of this arrangement is that in order to obtain a favourable angle for the lift wires or corresponding structure these wires are attached to the undercarriage. In the case of the Breguet, a very considerable relief of the compression in the top wing spars is obtained in this manner, while in the Nieuport 42 C. a small bottom plane exists to stabilise the long supporting strut to the principal parasol wing. The disadvantage of this type of structure, which offers certain undoubted economies from the point of view of weight, is the limitation placed upon undercarriage travel and the suscepti- bility of the whole wing structure to be damaged by bad ground conditions. As is well known, the shock-absorbing mechanism of the Breguet machines is accommodated within the wheels, 866a
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