Fig. 479
Another Glider. Cut out a piece of paper 8 inches by 4 inches, A B C D in Fig. 478. Mark B E and D F each 1 inch; make cuts along the dark lines at E and F to the depth of 1 inch. Draw the broken lines along the paper, dividing it into four equal strips. Bend sides A E and C F downward along dotted lines. Bend E B and F D upward along middle dotted lines, and press side C F toward side A E, part way along this line, but leaving the part near the ends A C flat; to this end plane K will be gummed (Fig. 479). K is 6 inches by 1 inch. Cut tail, G, and gum on as in diagrams. It can be weighted at H by gumming several strips of cardboard across or by affixing sealing-wax. Although this is not a very graceful-looking glider it works most successfully, and will describe quite a graceful curve toward the ground.
The child will find it interesting to make a number of these gliders and then go one day to a window or high place and let them glide to the ground and thus find out the bird that has the longest flight. Or a number of children can have glider races and see who can make a glider that alights on the ground farthest from them. Other forms of gliders can be made, but they are all on the same principle, a somewhat long body, wings and weight adjusted to keep them from falling.
Fig. 480 shows a glider made from a dowel rod, with slits in it at each end through which two cardboard planes are passed and fastened. The cardboard must be of light weight and yet stiff enough not to flap. The size of the planes must be found by experiment, for their size will depend naturally upon the weight of the material used. The bigger plane should be in length about twice the smaller one. It is best to fasten the large plane on first and then adjust the smaller one to give a long, graceful flight.
If a split pole can be found it is an easy matter to fasten the planes in. Canes (bamboo) split readily and can be used as centre pole.
This glider can fairly easily be made into an aeroplane and worked with a propeller. It may be mentioned here that model aeroplanes are generally worked with the propeller in front and not in the rear.
To make Propellers. These can be made of tin or wood. A tin propeller can be cut from any old tin with a pair of shears or strong scissors kept for the purpose. Cut two blades to the shape shown in Fig. 481.
Next cut an oblong block of wood (Fig. 482); notice that width a b in Fig. 482 must equal a b in Fig. 481, therefore width of a b must be a little less than a b in Fig. 481. Slit each end diagonally as in Fig. 482 for about ½ inch to hold the blades. Drill a hole through centre of block for the wire axle d c. Insert the blades in the slots, bend the ends over slightly and nail them in the wood to keep them firm. Fix the wire shaft firmly in the block as in Fig. 482. The propeller is now ready to be attached to the glider.
Before this is done, however, we shall consider the making of a wooden propeller. This is rather more difficult to make. Cut a piece of wood to the shape shown in Fig. 483 with a sharp pen-knife. The propeller must then be given the correct twist by means of the steaming kettle. Take hold of the extreme ends of the propeller and hold it over the jet of steam so that steam plays upon the blades at each side of the thick central portion.