Elastic hooks, formed from No. 16 gauge wire, are fixed at the rear end of the fuselage, and serve the double purpose of providing an anchorage for the bottom spar, which is whipped and glued with the hooks to the top spar. [Fig. 114] shows clearly what is meant. Bamboo, of ³/₁₆-in. by ₧-in. cross-section, is used for the tail skid, which is secured to the fuselage by thread binding. Piano wire is used for the landing chassis, and of the same gauge as hitherto used on the spindles.
The triangular side struts of the chassis should first be framed up from one continuous length of wire, lugs being bent at the point where they meet the fuselage, to be bound with fine tinned iron wire and soldered to the spar. Figs. [113], [117] and [118] clearly show its construction. Make the axle of such a length that a 12-in. wheel-base may be left after the wheels are placed on. The writer found that 2-in. rubber-tyred disc wheels left nothing to be desired for rising off short grass. Care should be taken that the measurement from the periphery of the wheel to the top spar, measured, of course, in a vertical direction, shall be 9 in. ([see Fig. 113]).
Fig. 117.—Plan
Fig. 121.—Kingpost
Fig. 122.—Wing Bracing Attachment
As twin gears of equal size are used, the torques of the oppositely revolving skeins of rubber will be balanced. Hence no bracing will be found necessary on the motor spar. The gearing, by the way, is bound to the top and bottom members of the fuselage with tinned iron wire, and soldered as shown in [Fig. 115].
The main plane is of rather a large span, and it is essential that birch be used, ½ in. by ³/₃₂ in. in section. The wing spars are bent at their centres, to impart a tapering wing plan analogous to the Martinsyde monoplane. Seven ribs connect the spars, and these are cambered to ¾ in. The wing tapers from 10 in. at the centre to 7 in. at the tips, the centre rib projecting for ½ in. fore and after of the wing. The tin clips shown in detail in [Fig. 119] slip over these, and so provide a means of adjustment to the centre of pressure of the complete machine.