Solder a tiny piece of 1/8-inch brass
tubing to the wire axle at A, close up to the rubber hook side of the
propeller, and file quite smooth. The only things now left to do are to
bend the wire into the form of a hook (as shown by the dotted line), and to
cover this hook, as already advised, with a piece of valve tubing to
prevent fraying the rubber skeins.
[Illustration: FIG. 136.--Axle and hook for propeller.]
Weight.--The weight of a model with a T-shaped central rod 1/16 inch
thick should be 4-1/2 oz. Probably it will be more than this--as a maximum
let us fix 6 oz.--although 4-1/2 oz. is quite possible, as the writer has
proved in actual practice. In any case the centre of gravity of the machine
without the rubber motor should be situated 1 inch behind the front or
entering edge of the main plane. When the rubber motor (14 strands of
1/16-inch rubber for each propeller, total weight 2 oz.) is in position,
the centre of gravity will be further forward, in front of the main plane.
The amount of rubber mentioned is for a total weight of 6-1/2 oz. If the
weight of the model alone be 6 oz.
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