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Aviation History
1920
1920 - 0394.PDF
APRIL 8, 1920 THE JUNKER SINGLE-SEATER ALL-METAL MONOPLANE TYPE Dl (Continued from page 380.) Ailerons THE unbalanced ailerons pivot on axes which are not quite parallel to the leading edge of the wing. They are built up in the simplest possible way. A duralumin tube forms the aileron spar, and to this two separate corrugated sheets are riveted, one above and one below. At the rear the two sheets are riveted together, and a D-shaped duralumin sheet, without corrugations, is riveted on to form a leading edge, and so serves to bridge the gap between aileron and plane. There are no formers or ribs in the ailerons. The three hinges are of the usual construction, steel collars with welded-on lugs being pinned to the aileron spar. Corre- B Fig. 8.—(A. B. andC.) sponding lugs are riveted to the cnannel section strip mentionedin the wing description. FuselageThe body of the D.I. monoplane differs entirely in con- struction from that of the biplane. Ignoring for the momentthe front armoured portion of the biplane fuselage, the con- struction of the rear part goes only one step further thanthat of the usual German metal tube fuselage. The usual wire bracing (found in the metal-tube bodiesof the Fokker and A.E.G. machines) is replaced by rigid Fig. 9 tubular bracing. The designer of the monoplane, however,has evidently based the fuselage upon the familiar German construction, wherein a framework of wood longerons is coveredwith one or more skins of three-ply, and wherein wire bracing is entirely absent; and not being hampered by the necessityof arranging for armour-plating, he has been able to build a metal fuselage on sound " framework-and-covering-sans-bracing " lines. Generally speaking, the body consists of a framework of duralumin formers, covered by a single riveted-on skin of sheet duralumin corrugated lengthwise. Reference to the side-view in the scale drawings will show that the position of the built-up formers is revealed by double lines (dotted). .To the rear of the pilot's seat twosingle dotted lines are equally spaced between each pair of double lines. These represent strips of duralumin, havinga waved section, which are riveted to the covering. They are simply strips, and are not built up or braced in any way. The rivets are of aluminium, and are placed where thehollows of the strip wave touch the hollows of the covering wave. The body finishes abruptly, immediately in frontof the tail, and between this rear end and the bulkhead behind the pilot there is no construction other than thebuilt-up formers, the strip formers, and the covering. The covering thus constitutes an important factor in the fuselageconstruction, and takes a larger share in the strengthening of the body than does the three-ply of a wood fuselage, wheresubstantial longerons are generally employed. It is true that in the Junker a continuous channel section strip runs longi-tudinally along the top and bottom of the fuselage, thus serving to connect the various formers. This strip is so frail,however, that its obvious function is to assist in the assembly of the body by holding the formers in place while the coveringis riveted on. It takes no substantial place in the actual construction. The analogy between the" three-ply construction and thismetal body will now be evident—in both cases the covering is called upon to take an important share in the strengthof the structure, in contradistinction to being a mere covering or fairing. The lengthwise corrugations naturally stiffen the coveringagainst strains tending to bend the body of the machine, and enable the skin to be the only factor in the construction Fig. 10 which does perform this function. The strong cross bulk- heads provide stiffness in the direction of the covering's greatest weakness, i.e., against strains tending to deform the cross-section of the body. Thus, between the two a very rigid structure is obtained. A further analysis of the comparison and contrast between three-ply and metal con- struction leads one to realise that the corrugations take the place of the wood longerons found in the three-ply system. Fore Part of Fuselage.—The simple construction of the fuselage is modified forward of the pilot's cockpit.JJ.To allow the necessary elbow-room for the pilot, it has been jiecessary to eliminate one bulkhead, and the space between the former just behind the pilot, and the one immediately'behind the 394
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