GB798486A - Roll control system for craft - Google Patents

Abstract

798,486. Fluid-pressure servomotor-control systems. BENDIX AVIATION CORPORA. TION. Oct. 27, 1955 [Nov. 5, 1954], No. 30798/55. Class 135. [Also in Group XXXV] In a system for controlling the operation of the roll control surfaces of a craft, such as an aircraft through a servomotor having a manual control and also an automatic compensatory control responsive to the yaw or side slip of the craft, the automatic compensatory control acts on the control surfaces through an auxiliary servomotor separate from the main servomotor and a positional follow-up coupling is provided between the output of the auxiliary servomotor and the automatic compensatory control. In Fig. 1 a control surface 20 is actuated by a servo-piston 21 under the control of a spool valve 24 operated by the pilot's control member 42 through a linkage 12 including a differential lever 30 pivoted to the piston-rod 33, a link 31 and a further differential lever 32, the pivot 45 of which is adjusted by an auxiliary servo-piston 44 which is normally at the right-hand end of its cylinder. The piston 44 is controlled by a spool valve 49 in turn controlled by an armature 53 co-operating differentially with leak-off nozzles 50, 51. The armature 53 is controlled by automatic compensating mechanism 15. The latter includes a vane 60 responsive to the difference between the heading of the craft and the relative wind and operative to energize a signal generator 62 the signal from which is effective through an amplifier 66 of the discriminator type and a low-pass filter 67 to energize a coil 68 surrounding the armature 53. The movement of the servo-piston 44 operates a further signal generator 71 which supplies a negative feed-back signal to the stator coil 63 of the signal generator 62. Following any manual control of the surface 20 the latter is re-positioned by the action of the auxiliary servo-piston 44 on the valve 24 if any yaw or side slip is detected by the vane 60. In the case of craft in which banking is controlled by spoiler surfaces which operate in one direction only from a neutral position, it is necessary to adjust this neutral position at landing or take-off and this is done by a spring- loaded piston 82 which is moved up against a shoulder 83 by fluid pressure admitted by a solenoid-operated valve 80 on closing a switch 78. Should the electric supply fail, a solenoid 95 is de-energized and a spool valve 93 is moved to the right by a spring 96 so that pipe 90 leading to the nozzles 50, 51 and the valve 49 is cut off from the fluid pressure supply P and the latter is connected through a pipe 56B direct to the left-hand side of the piston 44 so that the pivot 45 is moved to a safe position.