Overhung Mounting.
Fig. 118.—Overhung rotary engine mounting.
The overhung type of engine mounting which is used for both propeller and tractor aeroplanes, is shown by [Fig. 118]. In this case the back plate of the motor is bolted to the capping plate, while an extension of the hollow crank shaft is supported by a smaller rear plate. This system has been very widely used, chiefly by reason of its extreme lightness, and the great facility afforded for the operation of dismounting the engine; indeed, it would be difficult to find an arrangement in which the demands of accessibility are so well satisfied. Another form of overhung mounting, which has been used for a radial Anzani motor, is shown by [Fig. 119]. In this case the four longerons of the fuselage are capped by a single flanged steel plate, to which the engine is attached by long bolts through the crank case. Additional support is provided by light steel tube stays, which are taken from various points on the front of the crank case to the centre section of the upper plane, or other parts of the machine.
Fig. 119.—Anzani type engine mounting.
FRONT ELEVATION SIDE ELEVATION
Fig. 120.—An overhung mounting built up of steel tubes.
A distinctly original type of overhung mounting is shown by [Fig. 120] in front and side elevation, this being used on a machine incorporating an all-steel fuselage. The ring to which the back plate of the engine is bolted, is supported from the four corners of the fuselage by steel tubing, while the bearing for the crank-shaft extension is formed by a pyramid of tubes welded to a pressing of sheet steel, to which in turn is bolted a ball-race housing. At each corner the three converging tubes are welded together, and bolted to small angle plates, which are also welded to the framework of the fuselage. It will be seen that the strength of this mounting is entirely dependent upon the welding; but such reliance, in view of the generally uncertain nature of this latter process, is not to be recommended.