GB835264A - Aircraft navigation apparatus - Google Patents

Abstract

835,264. Automatic steering control systems. SPERRY GYROSCOPE CO. Ltd. June 22, 1956, No. 19492/56. Class 38 (4). In an aircraft automatic pilot a gyro compass controls steering in azimuth and also operates a repeater compass the shaft of which rotates a course-setting pointer the position of which relative to the shaft is adjustable by manual means which also prepare the automatic pilot to steer the course selected. As shown in Fig. 1, to operate a repeater compass, signals from an inductive pick-off 4 associated with an azimuth gyro 2 are applied through an inductive device 5 to an amplifier 6, the output of which energizes a servomotor 7 which, in driving the rotor of inductive device 5 to a null position, sets card 9 of the repeater compass so that the course of an aircraft carrying the equipment is indicated by a lubber line 10. To maintain the repeater compass in correspondence with a magnetic flux gate compass 32, signals from the latter are applied to the stator of an inductive device 33, the rotor of which moves with the repeater compass so that an output is produced to control the gyro compass in the event of misalignment between the two compasses. This misalignment is indicated at 37. For automatic steering of the aircraft in azimuth signals from a second inductive pick-off 22 associated with gyro 2 are applied through inductive devices 21 and 22c to control the automatic pilot 1. The course to be maintained is selected by a knob 12 adjusting the rotor of inductive device 21 and since knob 12 can only be operated if gears 14, 17 are engaged, a pointer 11 on a transparent dial 13 is also rotated to indicate the chosen course against dial 9. The opening of a switch prevents operation of servomotor 7 during adjustment of knob 12 and a brake (not shown) may hold shaft 8 of dial 9 in a fixed position while gear 14 frictionally mounted on shaft 8 is rotated relative to shaft 8. For initially setting up the apparatus the stators of inductive devices 5 and 21 are adjustable by a knob 39. In a modification knob 12 controls an inductive device, corresponding to inductive device 21, indirectly through a follow-up servomotor system which is normally de-energized so that knob 12 may be operated in advance to select a new course which the aircraft takes up whenever a switch is operated to energize the follow-up servomotor system. In a modification of this arrangement operation of the autopilot is dependent on the position of the repeater compass and the means preventing operation of the repeater compass when resetting course is dispensed with, but a component introduced in dependence on misalignment between the gyro and its repeater normally eliminates repeater compass errors. The follow-up servomotor system of this arrangement is provided with heavy negative feed-back to reduce response to transient errors of the repeater compass but which is limited so that the larger signals occurring during a course change are properly effective. Specification 835,265 is referred to.