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Aviation History
1923
1923 - 0062.PDF
FEBRUARY 1, 1923 (280 sq. ft.), and the speed range. 180 km. (112 m.p.h.) to 60 km. (37 m.p.h.). The third machine exhibited, a touring and school type side-by-side two-seater, was shown in skeleton, and consequently was by far the most interesting, as the details of the metal construction could be thoroughly examined. Consequently this type, the XXII, will be dealt with at greater length, keeping in mind that many of the constructional features are common to all three machines. The fuselage of the S.E.C.M. XXII is constructed entirely of Duralumin tubes, joined together by very elaborate sheet Duralumin fittings wrapped around the longerons and struts. The details are shown in the accompanying sketches. Riveting is everywhere employed for joining two pieces of metal, or the edges of a folded piece, but it would appear at any rate possible that a certain amount of unscientific design is found in the manner in which the sockets terminate on struts and longerons. We believe we are correct in stating that several British constructors have found that where* a tube end is housed in a socket there is likelihood of the tube cracking just at the edge of the socket, unless this is thinned down to a feather-edge. This precaution does not appear to have been taken in the S.E.C.M. machine, and it is possible that trouble will arise out of this omission. The workmanship of the fitting, as indeed of the whole of the construction, is excellent, and it is claimed that the makers have discovered a method of rendering the metal immune from corrosion. The wing construction is, if anything, neater than that of the fuselage, and is considerably " cleaner " than on the majority of the all-metal machines. To a certain extent this is due to the fadt that the spars are merely rectangular, section Duralumin tubes, so that no latticework, riveting, etc., is required. Whether such a tube is very economical is another matter, but its use certainly makes for simplicity. The. ribs are of U-section, but the edges are pinched together so that the actual rib flanges almost become tubes, open on one side and having projecting flanges. The vertical web struts and diagonal ties are stamped from the flat sheet, THE S.E.Q.M. type XXII View showing simple engine mounting. and are given three corrugations, as indicated in one of the accompanying sketches. In between the main ribs are short nose ribs, also stamped from sheet, and having the, edges turned over to form channel sections. As the rear spars are placed relatively far forward in the wing section, in order, no doubt, to retain a spar of reasonable depth, the ailerons are hinged to a false rear spar of channel section. The details of this spar are shown in the top left- hand sketch. The ailerons themselves are of a construction similar to that of the main ribs, with a tubular leading edge, a wire trailing edge, and a channel section stringer running parallel to the spars approximately midway in the aileron chord. The strutting and bracing of the wings are of usual type.: - The Hispano engine is mounted on a very simple framework SOME S.E.C.M. CONSTRUCTIONAL DETAILS : 1 shows aileron hinge and outer end of trailing portion of fixed plane. In 2 is illustrated the general wing construction. The spars are square-section Duralumin tubes, while the rib webs are stamped from the sheet and the flanges are rolled to a bottle-neck U-section. A typical fuselage joint is illustrated in 3, while 4 shows the sheet-Duralumin fitting with the struts removed. The work- manship is excellent, but the fittings appear somewhat complicated. 62
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