Monoplane Trussing.
From the standpoint of simplicity, the monoplane equals the biplane. As each wing of the former may be considered as a cantilever, it is the difficulty of adequately staying the wings above a certain span which forms the deterrent feature, for it is obvious that, as the span increases, in order to obtain a reasonable angle for the wires, the king post, or cabane, must be increased in height. This would necessitate an ungainly undercarriage, less able to withstand rough landings, with a consequent increase in both weight and head resistance. However, it seems that the monoplane will have a future for sporting purposes, where the span will not exceed 30 ft., and will probably be nearer 20 ft.
Fig. 57.—Monoplane wing bracing.
Various attempts have been made to obviate this inherent defect of the monoplane system of trussing, the first and most popular being the king-post system ([Fig. 57]), in which short masts are incorporated in the wing structure and wire-braced to the spars. From the points formed by the crossing of the mast and spar the main bracing-wires are taken. That this system is of real use is demonstrated by the fact that, amongst others, the Antoinette, Flanders, and Martinsyde monoplanes incorporated this system. It is worthy of note that this system also characterized the huge Martinsyde trans-Atlantic ’bus, the wing-spread being in the neighbourhood of 70 ft. Another original attempt at improvement, the wing-bracing of the Deperdussin hydro-monoplane, is of interest ([Fig. 58]). As regards the bracing, the machine was virtually a biplane, the wings being stayed by a steel tube running parallel with the wings, and connected to it at intervals by steel tubular struts, with cross-bracing between, as in a biplane. The abolition of the top wires rendered the machine of greater value for war purposes than other tractor machines of that period. The logical conclusion of this system is exemplified by the Nieuport scouting biplane, the lower plane of which corresponds to the streamlined steel boom of the Dep.
Fig. 58.—Deperdussin monoplane bracing.