Wheel Controls.
Fig. 101.—Arrangement of wheel control.
While the “joy-stick” type of control is greatly in favour, there are various forms of wheel control in use. American machines are almost entirely fitted with wheel controls, and all things considered, it appears that modern practice is evenly divided between the two types. The sequence of movements of the wheel type may be varied in a number of ways, the general arrangement shown by [Fig. 101] being typical of an average system. In this case the hand-wheel is mounted on a central column, which in turn is rigidly fixed by some form of Tee joint to a transverse rocking shaft. A sprocket attached to the wheel centre engages with a short length of chain, which connects to the aileron control, while the elevator wires are connected to short tillers, arranged to work on the outer side of the fuselage. With this system the hand-wheel is rotated for the aileron movements, a fore-and-aft rocking motion for the elevation, and the rudder is actuated by an outward movement, with either foot on the rudder bar. A development designated “three in one” embodies all these movements in the wheel column, which in this case is pivoted at its base: a to-and-fro motion in the column for the elevators, sideways for the ailerons, while the rudder control is effected by the rotation of the wheel. This system is fitted to a number of American machines, but it is a moot point whether the rotation of the wheel for warping or steering is quite such an instinctive action, as the sideways movement of the lever combined with the movements of the foot on the rudder-bar; in any case, there is just a suspicion of complication in its working which is undesirable, that is, for machines intended for popular use.