Model Flying Machines

by Alfred Powell Morgan

It is therefore an easy matter to "create a breeze" and a kite can be kept in the air providing the person flying the kite and holding the string commences to run.

Although no wind is blowing, the pressure of the air through which the kite is moving will cause it to remain in the air. In other words, the kite would be sustained in the air by virtue of its own relative motion to the wind. In order that the kite may fly, it makes no difference whether the wind moves against the kite or the kite moves against the wind.

An aeroplane, in fact, is nothing but a kite which creates its own breeze. If an aeroplane were attached to a strong wire serving as the string in the case of the kite, it would fly in the same manner as the kite, providing of course that the wind were sufficiently powerful. If the wind were not blowing at all, or not blowing hard enough, the other end of the wire could be attached to an automobile and by driving the automobile fast enough the required relative motion of the air would be produced and the aeroplane would fly.

There could be no direct benefit derived, however, from an aeroplane which must remain attached to a machine running over the earth and travel in its wake. Some other means of producing the required relative motion is necessary so that the aeroplane may be free to fly in any direction and either with or against the wind. This is accomplished by a propeller driven by a motor revolving at high speed in the aeroplane itself.

The action of an aerial propeller is similar to that of its marine prototype employed for driving ships through the water. Each depends for its action upon the imparting of a sternward motion to a column of fluid, in the one case air and in the other water. A propeller screws itself forward into the surrounding media in identically the same manner that an ordinary screw forces itself into a block of wood. An aeroplane therefore essentially consists of the wings or supporting surfaces, also sometimes called planes, driven through the air in an oblique manner by the propeller and motor.

FIG. 2. Diagram representing a typical monoplane. The only remaining requisition is that the aeroplane may be guided at will, caused to rise or fall or be steered to the right and left. The devices used to accomplish this are two rudders called respectively the "elevator" and the "steering rudder." The "elevator" takes the form of a small surface carried either in front or behind the main supporting surfaces and enables the machine to take an upward, a horizontal or downward course accordingly as it is adjusted. It acts as a rudder to steer the aeroplane up or down or to hold it to its course in exactly the same manner that a ship's rudder steers it to the right or left. When it is desired to direct the aeroplane upwards, the front edge of the elevator is raised so as to set it at a greater angle with the horizontal. If the aeroplane's course is required to be downward, the front edge of the elevator is lowered.

Aeroplanes are usually of two general types, monoplanes and biplanes. A monoplane, as its name implies, is a machine having a single pair of wings or supporting surfaces. The Bleriot, Antoinette and Santos Dumont machines are the most prominent representatives of this type of aeroplane.

The "elevator" on a monoplane is usually in the rear of the main supporting surfaces. When in this position it also acts as a tail to furnish longitudinal stability to the machine in the same way that a feather on an arrow steadies its flight.