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Aviation History
1924
1924 - 0764.PDF
is spreading, it may be mentioned that the following constructors incorporate this feature in some of their machines: Breguet, Farman, Fokker, Latecoere, Delage (Nieuport-Astra), and Potez. Even the Armstrong-Whitworth " Siskin " can almost be said to belong to this type, its lower wing being of much smaller dimensions than the upper, although in other respects, such as form of wing bracing, etc., it is a normal biplane. Metal construction is making headway, although perhaps less rapidly than in previous years. On the other hand, such progress as is to be found is, gener ally speaking, of a more sound character than has sometimes been the case in the past, and methods are in process of being evolved which certainly seem to British eyes far in advance of some of those in vogue a few years ago. Duralumin is still the favourite metal with French designers, and we have not seen a single French machine in which steel was employed to any considerable extent. The two Dutch designers, on the other hand, employ it exten sively in their fuselages, Fokker in the form of welded steel tubing, and Koolhoven the same, except that he avoids any use of welding and employs a special form of tubular rivetting instead. The French designers prefer aluminium alloy, usually Duralumin, but occasionally other forms, possibly because the material is obtainable in France, while high-grade steel in thin sheets has to be imported, mainly from England, and thus is probably nearly as expensive as Duralu min. Unanimous as the French designers are in their choice of material for metal aeroplanes, they have very differing ideas on the subject of how to use it, and scarcely any two of them employ the same form of construction. It is noticeable that although for small wing spars, for instance, such as the rear spars of biplanes, the plain box-section Duralumin tube is still popular, the front spars are usually built-up, and the manner of building them varies greatly. Corru gated flanges, such as we employ in steel spars, are becoming more used, and the plain built-up box section is gradually being replaced by other forms capable of approaching closer to the ideal of making full use of the strength of the material. While on the subject of metal construction, it may be mentioned that the metal propeller is also coming into vogue, although the old laminated wood propeller is still in a large majority. The metal propellers are usually of the Curtiss-Reid type, the French rights for which have been obtained by Pierre Levasseur, but the Nieuport-Astra firm have recently produced a quite novel propeller, made of steel tubing, which may possibly be developed into a variable pitch airscrew (at present it only has adjustable pitch, i.e. the pitch cannot be altered during flight), and may ultimately be found to offer a solution of the problem. At the show one such propeller is fitted on a Nieuport-Delage machine, and a second specimen, resting on a table, was lifted and not found unduly heavy, in spite of the fact that its sections are, of course, solid steel. It is claimed that the balancing of an airscrew made on this principle is facilitated by the peculiar shape, and also that actual tests have shown the aerodynamic DECEMBER 11, 1924 * efficiency to be good at high speeds. There is no doubt that unless reduction gears are fitted in the future on high-speed engines the propeller problem will become a serious one, and already great difficulty has been found in getting the old type of laminated wood propeller to stand up at the high speeds now met with, and there is every indication that matters are likely to get worse in this respect. From the point of view of commercial aircraft the Paris Show is disappointing. It is true that the contraptions seen at some of the previous shows, in the form of most luxuriously appointed saloons built into very primitive aircraft, are happily absent from the present one, but there is still no sign of the really commercial aeroplane being in sight, or even any indication that we shall ever get it. The power expenditure per passenger carried is still far too high, and of attempts to reduce it without sacrificing too much in the way of performance there is little evidence. Yet there is no doubt that it can be done and will be done sooner or later, but constructors are not yet worrying over much about it so long as orders are to be obtained for military machines, for which a high price can be charged. Seaplane work seems to be very much where it was two years ago, and much the same types of machines are being shown. The C.A.M.S" twin- engined flying boat is a very nice piece of work, but it is scarcely new and has already been described and illustrated in FLIGHT. One machine which does strike a new note, although strictly speaking it is not a seaplane at all, is the Pierre Levasseur biplane, which has, M. Charles Frechet informs us, been designed to give the Navy a two-seater with a per formance approximately equal to that of the usual land machine, but capable of remaining afloat should engine failure or any other cause bring it down in the water. This machine has a watertight fuselage, with the bottom of V shape as in some flying boats. The undercarriage struts fit into forks on the fuselage, pointing downwards, and the single-bay lateral bracing can be released by a cable running to a lever in the pilot's cockpit. As soon as the bracing wires are slack the struts slip out of their forks, and the whole undercarriage falls into the sea. The machine then alights very much as would an ordinary flying boat, the lower plane being placed halfway up the side of the body so as to be clear of the water. An ingenious device enables the pilot to stop the engine in such a manner as to bring the propeller into a horizontal position. The idea is excellent, and might with advantage be developed on our side of the Channel also. It had been expected that probably the light aeroplane would be well represented, but actually there are but two specimens in the show. One of these is a Dutch monoplane of very pleasing lines and fitted with an Anzani three-cylinder " Y" type engine, and the other is a Dewoitine, with six-cylinder- in-line water-cooled Vaslin. The Dewoitine is similar to the familiar types, but the engine seems to have points of interest and should run particularly smoothlv. "FLIGHT" AT THE PARIS AERO SHOW Arrangements have been made for FLIGHT to be on sale in the Grand Palais during the French Aero Exhibition. Our stand is in the gallery, at the Champs -Elysees end of the building, and visitors wishing to leave messages relating to Editorial or Advertising matters should hand them to the Attendant. 764
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