Jap silk is an excellent material for fabric covered planes, being at once light and strong. However, by far the most satisfactory plane of this kind is formed by silk bolting cloth which has been coated with collodion. The collodion is brushed on with a fine camel's hair brush after the fabric is in place and it is thereby rendered both waterproof and air-tight.
Fabrics should always be stretched over the planes from end to end and not front to back or vice versa. Make the lap joints or pockets around the end spars as long as possible so that they will not draw "dead air" and impede the forward motion of the machine.
Bamboo Paper is one of the best materials for covering the planes of a model aeroplane and is to be highly recommended. It is made in Japan from bamboo fibre and is very strong. It is usually stretched tightly over the framework and then given two coats of collodion or, what is much better, bamboo varnish.
The framework of the planes may be made of rattan, split bamboo, spruce, or steel piano wire. Piano wire is excellent for small machines since it is springy and light and able to withstand shocks. It is easily bent to any shape and offers considerably less head resistance than rattan because of its small diameter. Rattan can be bent into almost any shape by wetting.
Nothing is better for the cross pieces, ribs, etc., of the planes or framework than split bamboo. Bulk for bulk it is heavier but infinitely stronger than other woods. It is easily worked and can be bent into all kinds of shapes. Bamboo must always be bent while hot. The best source of heat is a spirit lamp or a bunsen burner. Always bend toward the hottest side. When bent apply a cold wet rag to cool quickly. If bent more than necessary, it may be straightened by applying heat again and allowing it to straighten itself.
In order to make long bends, such as the ends of planes, alighting skids, etc., first wind a strip of wet rag around, the bamboo and allow it to remain on for ten or fifteen minutes. Then remove the rag, heat the bamboo in a flame and bend slowly.
PLATE III.
With a little care, strips several feet long may be easily split from bamboo rods. The best method of accomplishing this is to use a fine saw, but a sharp knife will often be successful.
