29,117. Doutre, A. Dec. 30, 1910, [Convention date]. Steering and balancing; planes, arrangement of.-Vertical planes, normally parallel to the longitudinal axis of an aerial machine, are mounted above and below the main supporting- plane or planes and at equal distances above and below the centre of gravity. The vertical planes tend to increase the natural transverse stability of the machine and to prevent lateral deviations from the flight path and may be adjusted manually or automatically about vertical axes when the machine tilts or deviates beyond the limits within which the machine is normally stable. In one arrangement, the vertical planes 1, 2, Figs. 2 and 3, are arranged above and below the main planes of a biplane. When the machine tilts as shown in Fig. 3, due to a side current, the upper planes 1 are screened by the main plane while the lower planes being operative introduce a force R<2> tending to right the machine. The pivots 3 of the planes are arranged in a transverse vertical plane passing through the centre of gravity G and are connected to operating-mechanism so that the planes above and below the main planes can be turned oppositely for balancing the machine laterally and the planes at the right or left hand side of the machine can be turned independently of those on the opposite side for steering. The operating-mechanism comprises a lever 13, Fig. 12, secured to a plate 9 rocking on bearings 10, 12, Fig. 10, carried by a spindle 16 supported in fixed bearings 17, 18. Plates 6, 7 normally held in an horizontal position by spring hinges rest on the plate 9, and are connected by cords to the vertical planes. When the lever 13 is rocked to the right or left, one or other of the plates 6, 7 is raised, operating the planes at one side of the machine. If the lever is rocked about the axis 16, the upper and lower planes are turned in opposite directions. The lever 13 may be controlled manually or automatically. In the latter case, the lever is formed with curved slots 46, 49 through which pass blocks 50, 45 connected to servomo.tors controlled by a gyroscope and pendulum respectively. The pendulum 26<1>, Fig. 15, moves in a slot 28<1> in the piston-rod 31 attached to the valve gear of a compressed-air motor, and when the machine inclines transversely beyond the limits of natural stability air is admitted to one side of the stationary piston 39 so that the cylinder 38 is moved to operate the rod 13 through the link 44. The gyroscope controls the direction of the machine. When the main planes are arranged in tandem, as shown in Fig. 8, the vertical vanes 1 are arranged above and below the planes and at equal distances to the front and rear of the centre of gravity. For balancing laterally, the upper and lower vanes are moved oppositely, and for maintaining the direction of flight or steering the front and rear planes are moved oppositely. The vanes may be controlled by arms 26, 27, 28, 29, Fig. 14, secured at right-angles to one another to a lever 23 mounted on a ball joint 25, and controlled manually or automatically. The pendulum and gyroscope are arranged to be inoperative during disturbances of the equilibrium of the machine within the limits of its natural stability, and in place of the slotted connexion between the pendulum 26' and the valverod 31, two pendulums are employed mounted on the same axis of rotation and each resting against a stop which prevents it from assuming a vertical position. The pendulum is inoperative so long as it rests against the stop, but when the machine tilts so that the stop moves away from the pendulum, this relative movement operates the valve of the servomotor and actuates the planes.