In practice, therefore, since it is difficult to supply sufficient power to a machine to keep it in motion horizontally, at all times, aeroplanes are provided with supporting surfaces, and this aid in holding it up grows less and less as its speed increases.
But, however strong the power, or great the speed, its control from side to side is not dependent on the power of the engine, or the speed at which it travels through the air.
Here the size of the vertical planes, and their angles, are the only factors to be considered, and these questions will be considered in their proper places.
CHAPTER III
THE FORM OR SHAPE OF FLYING MACHINES
EVERY investigator, experimenter, and scientist, who has given the subject of flight study, proceeds on the theory that in order to fly man must copy nature, and make the machine similar to the type so provided.
THE THEORY OF COPYING NATURE.—If such is the case then it is pertinent to inquire which bird is the proper example to use for mechanical flight. We have shown that they differ so radically in every essential, that what would be correct in one thing would be entirely wrong in another.
The bi-plane is certainly not a true copy. The only thing in the Wright machine which in any way resembles the bird's wing, is the rounded end of the planes, and judging from other machines, which have square ends, this slight similarity does not contribute to its stability or otherwise help the structure.
The monoplane, which is much nearer the bird type, has also sounded wing ends, made not so much for the purpose of imitating the wing of the bird, as for structural reasons.
HULLS OF VESSELS.—If some marine architect should come forward and assert that he intended to follow nature by making a boat with a hull of the shape or outline of a duck, or other swimming fowl, he would be laughed at, and justly so, because the lines of vessels which are most efficient are not made like those of a duck or other swimming creatures.