Fig. 13.
A. Elevating Plane; B.B. Outriggers; C.C. Operating Wires;
D.D. Position for ascending; E.E. Position for descending.
The inventor employed the suggestion made by Wenham, and fitted his lifting planes one above the other; while he used a horizontal plane in front of the machine to act as an elevator. This plane could be tilted up and down; and the idea was that, when it was tilted upward as the machine ran forward upon its rails, it would exercise such a lifting influence that the front of the craft itself would be raised, and so cause the main-planes to assume a steeper angle to the air; and the result of the planes being inclined thus more steeply would be to give them a greater lift, and so induce the whole machine to raise itself from the ground. This system is explained in [Fig. 13], and is important because such lifting planes, for rising or descending, have now come into general use.
Sir Hiram Maxim employed another controlling surface which has become a feature of present-day aircraft, and this was an upright plane, which could be swung from side to side, and by which his craft was to be steered. Such a rudder-plane is illustrated in [Fig. 14]. By this means, as will be shown later, practically all aeroplanes are steered to-day. The action of the aerial rudder, when it is moved from side to side, is like that of swinging the rudder of a ship; but for the same reason that propellers have to be made large—owing to the small density of the air—so an aeroplane rudder needs to be a comparatively large plane, in proportion to the size of the craft, before it will exercise an adequate turning influence.
Fig. 14.
A. Vertical steering rudder; B.B. Outriggers; C.C. Operating wires;
D.D., E.E. Positions assumed in turning.