Sail Kite

Fig.17  larger view

This kite shows the influence of the box kite in its structure. It is in two parts; one being in the form of a triangle; the other in the form of a sail. It is designed to achieve steady flight in different weather conditions, and should be capable of attaining to a good height quickly. It is robust in construction to with­stand the normal wear and tear of flying and handling.

The first stage is to make the crossbars, A and B. They are formed from 1/4 in. square stripwood. A is 2 ft. 6 in. in length, and B is 1 ft. 8 in. The ends are grooved, as shown at C (Fig. 17). Next, make the two longerons, D and E. These are each 2 ft. 6 in. in length, and are cut from stripwood, 3/8 in. square. Groove them at the ends, as at C.

Assemble the four pieces to form a framework. Lay the lon­gerons on top of the crossbars, and join together with glue and | in. fretwork nails. Bend the ends of these over and hammer flat. Before nailing, part drill through the wood to prevent it splitting. Inject a little light machine oil into the holes as a further safeguard. See Fig. 17 for the measurements relating to the assembly of the framework. Now bind round the joints with fine string. This frame must be really firm, so that it will keep its correct shape in flight.

Proceed by making the triangular framework. A third longeron, F, which is 2 ft. 6 in. in length is cut from 1/4 in. square stripwood. Two upright struts, G and H, are also needed. Cut them from 1/4 in. square stripwood, and make them 97/8 in. in length. Cut a V-shaped groove at one end of each, to a depth of 1/8 in. to act as a cradle for the top longeron. Bind round the struts with strong thread just below the V-shapes. This will prevent them splitting during flight. Now smooth every part with fine sandpaper, and apply a coat of clear varnish, after which the frame pieces may be enamelled, if desired.

Next, brace the sail frame. Bind round and tie a length of fine string to the right-hand end of the top crossbar, leaving a 5 in. tail where it is knotted. Take the string round the edges of the frame to form an outline for the sail. Complete the bracing by tying to the tail at the first knot. The bracing must be taut in order to provide a firm support for the sail.