GB772426A - Improvements in or relating to aircraft navigation systems - Google Patents

Abstract

772,426. Automatic steering control systems. SPERRY GYROSCOPE CO., Ltd. Oct. 30, 1953 [Nov. 19, 1952; Jan. 29, 1953], Nos. 29223/52 and 2572/53. Class 38 (4). In a system for automatically controlling an aircraft, a signal dependent on pitch and a signal dependent on angle of attack combine to control a servomotor adjusting the pitch attitude of the aircraft. In Fig. 1 the angle of elevation of the flight path of an aircraft is maintained at a value determined by the setting of a manually operated potentiometer P1. A D.C. signal obtained from this potentiometer is combined with a D.C. signal obtained from a potentiometer P2 constituting the pitch pick-off of a gyro-vertical (not shown) and a D.C. signal obtained through potentiometers P6, P7 adjusted in accordance with airspeed and weight of the aircraft respectively. The resultant signal which is thus dependent on the pilot's setting of potentiometer P1, the pitch angle of the aircraft, the weight of the aircraft and the reciprocal of the square of the speed of the aircraft, and the density of the ambient air, is applied to a high gain drift-stabilized D.C. amplifier 1 which controls, through an electromagnetic clutch 20 operating a pilot valve 22, an hydraulic servomotor 23 adjusting the aircraft elevators 17. To prevent hunting, rate feedback is provided through condensers C2 and C4 from potentiometers P3 and P5 operated by the pilot valve 22 and servomotor 23 respectively. The input impedance of amplifier 1 is reduced by feedback through condenser C3. Potentiometer P7 may be either manually set in accordance with the weight of the aircraft or automatically set in accordance with the quantity of fuel in the aircraft fuel tanks. An arrangement for deriving a signal dependent on airspeed in which a differential bellows associated with static and dynamic air pressure heads controls, through a follow-up switch, a motor operating potentiometer P6, is described. If it is desired to fly the aircraft at constant altitude an altitude error signal may be substituted for manually-operated potentiometer P1. Specifications 666,882, [Group XL (c)], 690,982 and 718,171 are referred to and Specification 690,985, [Group XL (c)], is referred to in the second Provisional Specification.