Patent GB-581891-A (GB)
Title: Improvements in or relating to gyroscopic systems
IPC: G01C21/18
Filed: 1942-05-16
Abstract: 581,891. Gyroscopic apparatus. BARNES, J. W. May 16, 1942, Nos. 6673 and 14043. [Class 97 (iii)] Relates to a gyroscopic system for controlling or stabilizing an indicating or other member forming part for example of an aircraft bombsight or automatic pilot installed in a craft subject to pitch and roll, and comprises an erecting system having a pendulous mass for defining a vertical datum associated with a second gyroscope to counteract the effect of centrifugal force upon the pendulous mass. As shown in Fig. 1, a gimbal-mounted platform 1 is stabilised in an horizontal position by pnelunatic servo motors (not shown) controlled by a free gyroscope whose air-driven rotor 3 is supported on a universally-mounted vertical spindle 5. A pendulum 7 responsive to pitching of the craft carries a vane 8 partially interrupting the air flow influencing a flexible diaphragm 12 which operates a rod 14 to apply a torque to the gyroscope and precess it so as to adjust the platform about its pitch axis. The. gyroscope 3 (and consequently the platform 1) is controlled during rolling of the craft by an airdriven pendulous gyroscope 18, 19 similarly controlling the air pressure on a second diaphragm which applies the necessary torques to the spindle 5. The torques applied to the two diaphragms a,re opposed by balancing torques exerted about both the pitch and roll axes by a third air-operated diaphragm 15. The gyroscope 18, 19 with its pendulous mass 17 is of the kind described in Specification 129,727, [Class 97 (iii)], wherein during curved flight the couples due to the pendulous mass and the gyroscopic action neutralize. each other to maintain the pendulum in a vertical position. To prevent error during steeply banked turns, the air supply to the diaphragms is automatically cut off by a valve 21 connected to the gimbal 2. In a modification, Fig. 3, the torques are applied to the vertical gyroscope spindle 5 by forks formed in bell-crank levers 22, 25 loaded with pendulous masses 7, 17. The bellcrank lever 25 is actuated from the turncorrecting gyroscope 18, 19 by a vertical arm 29 carried on the gimbal ring 18 and engaging a slot in the lever'25. The point of engagement of the arm 29 with the lever 25 may be manually adjusted to suit the various air speeds of the craft. The levers 22, 25 may be uncoupled from the gyroscope spindle 5 by cam mechanism during steeply banked turns. In the arrangement shown in Fig. 5, the roll pendulum 17 is connected to the gimbal 18 by a spring 37 and the gimbal 18 is connected to the platformsupporting gimbal 2 through a dashpot 36, 35 and toothed sectors 34, 33 with the object-of introducing a lagging effect so that the torque exerted by the second gyroscope is applied sluggishly to the pendulum 17 during change in the angle of side slip but promptly during correctly banked turns not involving change in the angle'of side slip. In a further modification, Figs. 6 and 7 (not shown), the two pendulous masses are replaced by a single rolling ball. According to the first Provisional Specification, the spindle of a gyroscope (or a parallel member of its casing) may be magnetized so as to cause the gyroscope to process about the north-south axis and thereby follow the earth.