Patent GB-877788-A (GB)
Title: Aircraft control system
IPC: G05D1/06
Filed: 1957-11-13
Abstract: 877,788. Automatic control systems for aircraft. SPERRY RAND CORPORATION. Nov. 13 1957 [Nov. 13, 1956], No. 35329/57. Class 38 (4). An aircraft control system comprises an airspeed meter 10 coupled to transmitter 15 interconnected with receiver 18, a control signal developed in rotor 17 being used to control servomotor 46 for positioning throttle valve 56 and adjusting the forward speed of the aircraft. The control signal passes through amplifier 50 which is also supplied from rate network 48, an A.C. generator 51 also supplying displacement and rate feed-back signals to the amplifier. The rotor 17 may be positioned by an air-speed setter 21 coupled to transmitter 22 connected to receiver 27 whose rotor 31 is mounted on shaft 32 and provides a signal which passes through amplifier 35 to induction motor 34. This motor controls the movement of shaft 32 and drives generator 40 providing speed feedback for damping. A monitor switch 37 may be adjusted to disconnect the air-speed setter 21 and connect a monitoring system in its place, a potentiometer 66 being controlled by a percentage stall-speed setter 62. Potentiometer 67 is adjusted by an air stream direction detector 71 consisting of an angle-of-attack vane positioned in accordance with the angle between the airstream direction and the fore-andaft axis of the aircraft. Any unbalance in bridge network 66, 67, 72 causes a signal to be applied to summing amplifier 98 the output of which is fed to amplifier 35 to drive the motor 34 which re-positions the rotor 17. The change in speed of the aircraft is in the sense to change the angle-of-attack to eliminate unbalance of the bridge 66, 67, 72, the airspeed then having the value which provides the percentage of stall speed indicated on setter 62. A signal voltage dependent on the angle-of-attack is provided by potentiometer 85, the average value of the signal being stored in capacitor 89 whilst the remainder is fed through diode 91 so charging capacitor 92 to a voltage proportional to the peak deviation of the angle-of-attack from its average value. A signal proportional to this voltage is fed, after modulation by diode modulator 94, through capacitor 97 and switch 96 to summing amplifier 98. This gust-compensating signal increases the average air speed reference set by rotor 17 by an amount proportional to the difference between the average and peak values of the gusts. A transmitter 103 operating in conjunction with vertical reference 102 supplies signals through mixer 141 and amplifier 106 to servomotor 105 controlling elevator 104. Feed-back signals corresponding to the elevator adjustment are supplied to the amplifier 106 by transmitter 113. Control signals may also be selectively supplied from glide path receiver 115 or altitude control 120. When compensation switch 122 is closed, transmitter 101 injects signals into mixer 141, the transmitter being coupled to the motor 46. Thus, when the throttle valve 56 changes the thrust of the engines, the pitch angle of the aircraft is altered to maintain the lift more nearly constant when the aircraft is making a landing approach with its flaps down. Specifications 655,172 and 877,789 are referred to.