Patent GB-520175-A (GB)
Title: Improvements in gyroscopic apparatus for the automatic control of aircraft
IPC: G05D1/08
Filed: 1938-07-13
Abstract: 520,175. Gyroscopic apparatus. SMITH & SONS, (MOTOR ACCESSORIES), Ltd., S., and MEREDITH, F. W. July 13, 1938, No. 20797. [Class 97 (iii)] A control apparatus for aircraft comprising a gyroscopic device in which the rotor axis is normally inclined to the verticil, e.g., horizontal, for controlling the aircraft about an horizontal axis, precessing means for applying a torque to the gyroscopic device about said horizontal axis means automatically controlling the aircraft about a second horizontal axis and having a part rotatable through a distance corresponding to the angle of movement of the aircraft about said second horizontal axis and a coupling connecting said part to said precessing means to rotate the precessing means through the said angle so as to maintain the torque axis substantially horizontal. Means are also provided for displacing the datum of the second control device coupled to said precessing means for the purpose of maintaining the attitude of said precessing means about said second axis when said datum is altered. The gyroscopic device is adapted to control the rudder of the craft, and means are provided, sensitive to lateral acceleration, for controlling the precessing means applied to the gyroscope so as to adjust the rudder to reduce the side slip. In addition, means are provided which are controlled by rotation of said common member about one of said horizontal axes for bank control, for normally diverting the control provided by said means sensitive to lateral acceleration to means for precessing the gyroscope for bank control. The controlling gyroscopes 100, 200 have their rotor axis horizontal and mounted on a common platform 10 which may be rotated in the frame 12 about the X, Y axis by the pulleys 80, 81. The gyroscope 100 controls the elevators and rudder by means of valves 22, 25 linked to servomotors through follow up means of known construction. Its outer gimbal is unbalanced by a weight 23. Gyroscope 200 controls the ailerons through valve 34 &c. Both gyroscopes are precessed by means of motors, the motor 73 acting on the inner gimbal of gyroscope 100, and the motor 37, acting on the outer gimbal of gyroscope 200 and controlled by a valve 36 operated by the inner gimbal which is itself acted on by motor 70. The motors 70, 73 are worked whenever there is a pressure difference in the feeding air tubes 62, 72 and the sign and magnitude of this and therefore of the precessing means are controlled by the weighted blade 43, 44. When the blade is in its normal position, half covering the apertures, the air supply from 41 is so restricted that on leaving 42 and entering the valve 57 at 58 it is at the same pressure as the air entering valve 57 at 59 from a constant source. If the blade is moved relatively to the jets an air pressure difference is created between the two inlets to the valve which is continued in either the outlets 72 or 62 according to the position of the slidable member 56. This is actuated by a magnet 54 energized by a circuit which is closed or opened according to the position of the brush 48 relative to the contacts 50, 51, i.e., according to the movement of the platform about the X axis, since normally the blade 43 is not moved by the pulley 82. Thus, if the platform is not or only slightly inclined to the X axis the valve 57 permits working only of precessing means 37, through the motor 70 and valve 36; otherwise it permits working of only precessing means 73. The craft is pitched by rotating the platform about the Y axis causing relative movement of inner gimbal 19 and the platform and consequent operation of valve 22 and servomotor. By the pitching the platform reassumes horizontal attitude to the Y axis and the precessing torque applied to gyroscope 200 remains horizontal. The craft is banked by rotating the platform about the X axis causing relative movement of outer gimbal 32 and the platform and consequent operation of valve 34 and servomotor. By the rolling the platform reassumes horizontal attitude to the X axis and the precessing torque applied to gyroscope 100 remains horizontal. On banking side slip will occur if the rudder is incorrectly adjusted, causing movement of the weighted blade 43. Since the magnet circuit is energized an air pressure difference will be established in motor 73, causing precession of gyroscope 100 about the vertical and operation of valve 25 and servomotor until the rudder is adjusted sufficiently to avoid further side slip. To minimize the inevitable side slip associated with this correction the line of jets 41, 42 is displaced about the X axis : by this means the air pressure difference is created before the side slip occurs. A flat turn may be initiated by rotation of pulley 82 causing movement of blade 43 and the creation of an air pressure difference in motor 73, since the magnet circuit is energized. If the platform is slightly tilted about the X axis the magnet circuit is not energized and valve 57 permits a slight air pressure difference to be established in tubes 62 thereby operating the bank trimming motor 70 causing precession of the outer gimbal 32 of gyroscope 200 and operation of the ailerons through valve 34 and its servomotor. If the platform is only slightly tilted about the Y axis the weight 23 causes a torque to be applied to the outer gimbal 20 of gyroscope 100 and consequent precession of inner gimbal 19 thereby operating the elevators through valve 22 and its servomotor. Thus whether the platform is slightly tilted about the X or Y axis it is returned to the horizontal. Whatever the trim of the craft therefore the precessing means applied to each gyroscope are rotated so that the torque axis remains horizontal during a turn. Otherwise the gyroscopes 100. 200 operate as described in Specifications 365,186 and 422,813.