edges of the planes may be tilted up, and by trial we can decide what we think the best angle, which should not be great. Possibly 14″ might be used under the front edge. It will pay to spend much time in experimentation on these gliders, and it should be carried on until long graceful glides are accomplished.
It will be discovered long before this, that in a very large percentage of cases the arrangement of planes is reversed in model aeroplanes and the large machines. The small planes are placed forward and are used largely as elevating surfaces. A few models have the large plane forward. It will also be noticed in looking over plans of model aeroplanes that a large majority are monoplanes, while in the large machines there are more biplanes.
Warping. No warping of the planes is necessary in the glider that has been discussed, but it is well in the lighter models to have some warping called camber, in the larger planes especially. Another warping is from end to end of the plane, that is, the ends tip upward, never downward. Sometimes models are made with the large plane warped from front to back, and with the small plane bent upward on each side, and again the large plane is sometimes bent in both directions as it is made. The last is more easily done when wire frameworks are used in the self-propelling models. In Fig. 217 the model is made lighter, the spine being a heavy piece of reed with a hook bent on the end and the planes 18″ or 116″ veneer wood.
The sling shot device for throwing the glider is made of heavy spring wire, and will require a strong metal vice to bend it in. A forked stick can be used, or one can be cut out with a turning saw. Fig. 218 is quite similar to Fig. 217 in weight, but a square spine 14″×38″×18″ with planes 18″ or 116″×2″×6″, 2″ in widest part and the other 18″ or 116″×4″×12″, 4″ in widest part. The force used to drive this glider is given thru a springy stick of some tough wood, as oak or hickory. The stick should be quite stiff so as to resist more pressure before its relaese. A little block on the under side of the spine might have a little hole in the back to receive a small nail in the end of the bow stick used to throw the glider, this will prevent the bow stick from slipping off in the throwing process.
