Steel Tube Fuselage Construction.
WELDED WIRES 18 BWC
Fig. 84.—Welded joint in steel tube fuselage.
In certain isolated instances, the fuselage is built up of steel tubing, and on one machine of recent design the joints throughout are effected by welding: a detail of the attachment of the vertical and cross struts to the longerons is shown by [Fig. 84]. It will be noticed that a small quadrant-shaped piece of tube or rod is welded to the struts, and from this are taken the bracing wires. As the welded joints impart a certain rigidity to the structure, the fact that the wires are exerting a side pull on the struts may be of little consequence, although this method could hardly be used in conjunction with the fuselage construction of average English machines. A rather unusual feature may be noticed in the attachment of the bracing wires, which are not finished off with the orthodox wire ferrule, but are arranged as a loop, the turnbuckle forming the anchorage for the two ends. The trend of design in this country seems to incline towards the clip stamped out from sheet steel and bent up. This class of fitting can be produced accurately and quickly, and, in the writer’s opinion, is by far the best manufacturing proposition. Aluminium castings are quite obsolete, and the built-up fitting, involving welding or brazing, does not seem greatly in vogue.
CHAPTER X.
UNDERCARRIAGE TYPES.
The present chapter deals with the general arrangement of the different types of undercarriages, as distinct from the details of construction. The principles of design embodied in the undercarriage are necessarily a compromise, this position being due to the fact that its construction has to be considered from two distinctly opposed view-points, and undue attention to the requirements of either does not produce the best results. Thus, on the one hand, we have the desirability of great strength to withstand landings on very rough ground, ploughed fields, and the like; and on the other hand, we have the considerations of aerodynamical efficiency in flight, which, taken to one extreme, would be best satisfied if the undercarriage did not exist, and at most calls for a system in which the head resistance is brought to an irreducible minimum. By the ordinary process of evolution the agglomeration of ideas existing in the early days of flying with regard to the most suitable form of landing gear, have given place to something which, for machines of modern attainments, approaches finality. This has resulted from improvements along the line of (1) simplification of general design, (2) the reduction of head resistance and weight without a consequent diminution in its powers as an alighting gear. A better impression of the distinguishing points of the various types will be gathered if we consider the desiderata of an ideal undercarriage.