When it is not possible to place the fin both above and below the centre line it should be placed above rather than below.
Fins may be made out of thin wood, sheet aluminum or fabric stretched over a wire or rattan framework.
CHAPTER IV. THE FUSELLAGE OR FRAMEWORK.
By the term "fusellage" or frames, that part of the aeroplane which serves as the "backbone" and to which all the other members are attached is implied.
The fusellage above all must be strong. The second requisite is lightness. The simplest frame for a model aeroplane is a long straight stick. The cross section of the stick may vary and be either round or square. A careful workman, however, can build them of "I" section like a steel girder. Increased lightness and strength is the result.
FIG. 21. A simple "motor base" or fusellage.
A single skein of elastic when wound up tends very strongly to twist the framework of the machine out of true. Since the tail and elevator are usually attached to the ends, the adjustment is thrown out to a marked degree and the flight of the machine is liable to be erratic.
We have tried building the fusellage of a network of girders such as the Bleriot and Voisin aeroplanes employ. Nothing could have been prettier than these carefully designed and constructed frames with their little struts and guy wires, but we soon found that for plain ordinary everyday efficiency, the simple stick is the best, provided, of course, that it is of the proper size to resist the twist of the rubber.
In some cases it is desirable to retain the framework because of the realistic appearance of the model to the larger machines which it gives. The only practical method then is to employ a plain stick backbone to withstand the torque of the rubber and build a false framework around it. The framework need only be strong enough to support the fabric and resist the shocks of landing. This method of construction is best suited to models of the Bleriot and Antoinette types.