Since the model is expected to rise unaided from the ground the question of the skids is very important. The design followed in the model is excellent. The front of the frame is supported by legs consisting of inverted triangles built of dowel sticks attached to the frame. The axle connecting the two runs on small wheels, such as may be borrowed from a toy automobile. The rear of the frame rests on a simple skid made of curved reed. These supports place the model at an angle which should enable it to rise easily without loss of power. There is a great deal of satisfaction in working on so large a model, the parts may be made stronger and there is less likelihood of its getting out of order.
Now turn from these broad planes to the rather slight model ([Plate 6]), and the faults of its proportion are at once obvious. The front plane is much too far back for stability. Such a model will glide fairly well, and, if the motor be powerful it will rise quickly, but a steady horizontal flight is out of the question. The size of the planes seems perilously small, and yet if they be well shaped and spaced they will prove large enough. This is just the sort of model a beginner is likely to make, and therefore serves a very useful purpose in pointing a lesson.
PLATE III.
An Ingenious French Model Made of Umbrella Wire.
It is not without its good points. The front plane has been carefully flexed and attached to the motor frame at a good angle. An interesting experiment has also been made in carrying the edges of the front plane a trifle behind the rear edge, thus making for stability. The vertical rudder above the rear stability-plane is well placed, although it appears rather small. The skids upon which the model rests and the proportion of the front to the rear elevation are excellent. It is a first rate plan in building such a model to attach the front plane temporarily to the motor-base, and move it back and forth in the trial flights until the best spacing has been found.
CHAPTER VII
ELABORATING THE MONOPLANE
IT is surprising to find how far the pure monoplane form has been developed by the builders of model aëroplanes. It is no exaggeration to say that they have carried some principles of construction even further than the builders of the large man-carrying monoplanes. Since a model is so easily built, and costs so little, it is of course possible to experiment with all sorts of new forms. A great many of these will doubtless prove to be all wrong, but some are certain to be valuable discoveries. In future years, when the aëroplane has been perfected and perhaps plays an important part in commerce, sport and warfare it will probably be possible to trace back many of its improvements to the model aëroplanes designed, built and flown by American boys of to-day.
A beautiful model of a pure monoplane form carefully elaborated is shown in [Plate 7]. In this case increased stability is obtained by throwing out additional planes both to the front and rear. It may appear at first glance that these stability-planes are very small compared with the broad soaring-plane, but they have not proved so in flight. It will be remembered that the elevating-plane of the Wright machine is very small compared with the spread of the main wings. There is besides a great advantage in placing the stability plane well forward since it makes it possible to build an unusually long motor-base and install longer and more powerful motors.