Fig. 78.—Fuselage fitting.
A similar clip is used by the German Aviatik firm, but it is certainly inferior owing to the very poor connection of the struts. Instead of the four lugs gripping the sides of the struts, they are punched up to form a square or tenon, over which the cross-struts are mortised. In any case it would not satisfy the standards maintained by our leading constructors, and certainly not the technical advisers to the Air Board. The clip indicated in [Fig. 78] does not encircle the longeron, but abuts against the two inner sides of the longeron only. The body of this clip is a stamping, bent to a right angle, to which the square sockets for the struts are welded. Attachment to the longeron is effected by an eyebolt, which passes diagonally through it, this also providing the anchorage for the cross-bracing wire. A form of this clip has been used on a certain make of machine for a considerable period, so that it has advantages that are not readily apparent. One outstanding defect is existent in that the pull of the wires would tend to lift the socket on the side opposite to the eye bolt, and this in turn would cause distortion of the struts. A connection favoured by an American firm is shown by [Fig. 79], and possesses the merit of extreme simplicity. The longerons are not drilled, the attachment being through the agency of an L bolt, which also provides the anchorage for the cross-bracing wire. To prevent movement the clip is additionally fixed to the longeron by wood screws.
Fig. 79.—Fuselage fitting.
Fig. 80.—Fuselage fitting.
The method shown by [Fig. 80] is that used on the Deperdussin monoplanes, being patented by that firm as far back as 1912, and consists of two cast aluminium sockets, bolted to the longeron. The struts, in this case oval in section, are fastened in place by steel bushes, which are driven through in the form of steel tube, and expanded and burred round the socket, at the same time forming the anchorage for the wires. This system has been used in the construction of a fast scout of comparatively recent origin, but it embodies the same defects as the Bleriot clip, i.e. four holes are needed in the longeron for every joint; but it has the advantage over the latter in that a better terminal is provided for the struts.
Fig. 81.—Fuselage fitting.