GB753371A - Improvements in or relating to control apparatus for aircraft - Google Patents

Abstract

753,371. Automatic steering control systems. NORTHROP AIRCRAFT, Inc. Feb. 26, 1954 [March 13, 1953], No. 5707/54. Class 38(4). Sideslip of an aircraft during a turn is detected by mounting a pair of accelerometers at a chosen point forwardly of the centre of gravity of the aircraft. Each accelerometer comprises a plastic case containing a conducting fluid, such as a solution of ethyl alcohol and sodium iodide, on the curved surface of which an air bubble 15, Fig. 5, moves to alter the relative resistance between contact 10 and contacts 11 and 12 respectively. The two acclerometers are mounted parallel to each other and connected as indicated at 45, Fig. 8, so that the effect of angular acceleration about a point between them is eliminated and an increased output signal dependent on sideslip angle is produced from an A.C. source 20 and applied to an electronic and mechanical amplifier-demodulator circuit 55, the D.C. output signal from which has a differential component added by a resistance-capacity circuit 49. This combined signal is added in a network 73a to a D.C. signal dependent on rudder position derived from a potentiometer 83 operated with the rudder 137, and a D.C. signal dependent on aileron position derived from a source 87, 88 by a potentiometer 75 operated with the ailerons. Delay corresponding to that between the operation of the ailerons and the commence. ment of roll is applied to the aileron position signal by a resistance-capacity circuit 42. A further small D.C. signal may be added by manual operation of a rudder trim potentiometer 50. The resultant signal is applied to an electronic and mechanical modulator-amplifier circuit 35 controlling a two-phase rudder servo. motor 107. Velocity feedback is provided by a tachometer generator 55. Compensation for airspeed variations is provided by attenuators 51, 74 and 63 adjusting the sideslip signal and the aileron position signal in accordance with airspeed. Rudder 137 may be pedal-operated through cables 122, 123, drum 117, cables 124, 125 and an hydraulic servomotor 135, the servomotor 107 controlling the relative lengths of cables 124, 125 through drum 113, cables 118, 119, and a bell-crank lever 114 so that the pedals are unaffected. A spring-loaded detent 133 tends to retain drum 117 in a neutral position. Use of a rate of roll signal instead of a delayed aileron position signal is referred to.