Patent GB-859792-A (GB)
Title: Aircraft control apparatus
Inventor: SUMMERLIN FREDERICK ARTHUR
IPC: B64C13/00
Filed: 1957-08-07
Abstract: 859,792. Fluid-pressure servomotor-control systems. SPERRY GYROSCOPE CO. Ltd. Aug. 1, 1958 [Aug. 7, 1957], No. 24855/57. Class 135. Aircraft control apparatus comprises an actuator control means 9, Fig. 1, for a control surface actuator 11, and a manual controller 2 coupled to the actuator via pivoted link 5, in which the actuator control means is controlled by automatic control means 3 and the manual controller follows the movements of control surface 1, or by differential displacement between the manual controller and the actuator for powered manual control, and wherein the link 5 is also connected to the actuator control means and acts as a differential lever during powered manual operation but has no effect thereon during automatic operation except when a predetermined lateral force is applied to the link to render the link effective to actuate the control means 9. To control the aircraft surface 1 from the pilot's control column 2 by means of a jack 11 the pivot of a lever 6 is locked at 26, 27 while the pivot of lever 5 is unlatched at 16 and 17. Movement of column 2 rocks the lever 5 about its top pivot so that its centre pivot actuates a control-valve 9 for the jack via a differential link 8 whereby the jack positions the surface 1 via lever 6 and the valve 9 is re-centred via the follow-up link 4, artificial feel being received from the device 7. For direct manual control of the surface 1, latches 18, 27 are disengaged, latch 18 also switching out at 34 the automatic pilot 3, and latch 19 is engaged in notch 17 in a slide 15 to fix the centre pivot of lever 5. Surface 1 is then positioned via link 4, lever 5, link 6a and column 2, the centre pivot of lever 6 moving with slide 25. If it is required to re-engage the surface 1 with jack 11 switches S1, S2 are closed so that feed-back via the automatic pilot 3 from potentiometers 31, 32 proportional to the difference between the movements of rods 6a and 13, operates the jack to keep notch 26 in slide 25 always under latch 27 whereby latch 27 can be re-engaged and latch 19, 17 disengaged to take up powered manual control of the surface 1. Feed-back may come from potentiometer 31<1>. To enable the automatic pilot to control surface 1, latches 18, 27 are engaged and latch 19 disengaged. The automatic pilot actuates the jack via actuator 14, differential link 8 and control valve 9, feed-back to the automatic pilot being taken from the potentiometer 32. Should there be a runaway in the automatic pilot, the feel device 7 will resist movement of the control column 2 so that latch 18 will be forced out of its notch to disable the automatic pilot via contacts 34 and allow powered manual control of the surface 1 from the column 2. Disengagement of the automatic pilot may also be effected by applying a force to the pilot's column to disengage latch 18. In the embodiment of Fig. 2 the surface 1 is moved under powered manual control from column 2 when switches S1, S2 are open to cut out electrical follow-up to the automatic pilot 3 and an actuator 22 disables the automatic pilot via switch 34 and frees the centre pivot 41 of lever 5 from notch 42. Column 2 moves floating lever 5 about its lower pivot to a follow-up connection 45, and through a lever 53 pivoted to the casing at 54, a link 55 and differential link 57 moves a control valve 37 to actuate a relay valve 35 controlling movement of the jack 11 operating the surface 1. Valves 35, 37 are re-centred via follow-up link 45. The floating lever is formed by lever 5 and a shorter lever 46 both pivoted to link 45, lever 46 being held in line with lever 5 by a pair of cantilever springs, whereby if the control valve of jack 11 becomes locked, the springs will give and column 2 and lever 5 can operate a control valve of a duplicate jack. Under automatic control the automatic pilot operates control valve 36 via an actuator 14, feed-back from the relay valve 35 taking place via floating lever 57 and valve seat 37, the lever 57 also moving control-column 2 via lever 5 which now pivots at 41. Follow-up between the column 2 and the jack is brought about via the potentiometers 31, 32 feeding into the automatic pilot. If the automatic pilot requires too great a movement of the jack, reaction from the feel device 7 forces pivots 41 out of the notch 42 and the system reverts to powered manual control. No direct manual actuation is shown in Fig. 2 but may be provided by means of a non-releasable lock on the central pivot of lever 5 together with means releasing the piston in the jack. Automatic stabilization by a rate gyroscope in the automatic pilot is superimposed via actuator 14 on the pilot's normal control movements to compensate extraneous aircraft movements.