The two rear skids, of which one is shown in Fig. 5, consist each of two 5-inch strips of bamboo S, likewise bent at either end in opposite directions to form arms S₂ and S₃, The arms S₂ are fastened to the strips A by strong thread and glue. To stiffen the skids a strut C₁ is provided for each skid. Each strut consists of a 3-inch strip of bamboo bent over so as to form arms C₂. Strong thread and glue are employed to fasten each strut in position on the strip and the skid. In the crotch of the triangular space B₁, a tie bar J, Figs. 4 and 5, is secured by means of thread and glue. This tie bar connects the two skids, as shown in Figs. 1 and 4, and serves to stiffen them. The triangular space B₁ is covered with paper, preferably bamboo paper. If bamboo paper is not available, parchment or stiff light paper of some kind may be used. It does not need to be waterproof. Thus triangular fins are formed which act as stabilizing surfaces.
Fig. 5. Enlarged Details of One Rear Skid, Aeroplane Model
Main Planes. The main planes are two in number, but are different in size. Contrary to the practice followed in large man-carrying monoplanes, the front supporting surface is comparatively small in area and the rear supporting surface comparatively large. These supporting surfaces L and P are shown in detail in Figs. 6 and 7. It has been found that a surface of considerable area is required at the rear of the machine to support it, hence, the discrepancy in size. Although the two supporting surfaces differ in size, they are made in exactly the same manner, each consisting of a thin longitudinal piece of spruce R, to which cross pieces of bamboo Q are attached. In the smaller plane, Fig. 7, all the cross pieces are of the same size. In the larger plane, Fig. 6, the outer strips S are somewhat shorter than the others. Their length is 2 1/2 inches, whereas the length of the strips Q is 3 1/2 inches. In order to allow for the more gradual tapering of the plane, around the outer ends of the longitudinal strips R and the ribs Q a strip of bamboo is tied. The frame, composed of the longitudinal strip and cross strips, is then covered with bamboo paper, parchment paper, or any other style light paper, which is glued in place.
Fig. 6. Details of Main Plane of Aeroplane Model
Fig. 7. Details of Smaller Plane of Aeroplane Model
The forward or smaller plane has a spread of 8 1/2 inches and a depth of 3 1/4 inches. The main plane has a spread of 20 inches and a depth of 3 1/2 inches at the widest portion. The author has made experiments which lead him to believe that the tapering form given to the outer edge of the plane improves both the stability and endurance of the machine.
The planes are slightly arched, although it will be found that flat planes will also give good results. The rear edge of the main plane should be placed 4 1/4 inches distant from the forward edge of the propeller block E₁.