Patent GB-832798-A (GB)
Title: Improvements in or relating to indicating devices
Inventor: MAJENDIE ALASTAIR MICHAEL ADAI
IPC: G05D1/08
Filed: 1957-02-01
Abstract: 832,798. Electric indicating systems. SMITH & SONS (ENGLAND) Ltd., S. May 1, 1958 [Feb. 1, 1957], No. 3676/57. Class 40 (1). [Also in Group XXXV] The pitch of an aircraft is indicated on a scale 3 by a pointer 4 controlled by a meter 23 fed with a pitch altitude signal derived from a gyroscopic artificial horizon 20, the scale 3 itself being moved by error signals depending on deviation from a required type of flight, the altitude of the craft being manually controlled to bring pointer 4 to coincide with the datum position on scale 3. The required type of flight is selected by a multibank, 5-position switch 10. To fly at a predetermined altitude, switch 10 is set to position c, and the signal controlling the scale is derived from a preset potentiometer 14 which can be altered by operating a switch 26 energizing a motor 15 to drive potentiometers 14, 16 to a new position. These potentiometers may be set to the actual pitch value by simultaneously operating switches 21, 24 to feed the pitch altitude signal from 20 to motor 15. The pitch datum signal may also be derived from preset potentiometer 22 by setting switch 10 to position e. To fly at a predetermined Mach number switch 10 is set to position a, the scale controlling signal comprising a Mach deviation signal from 12 and a pitch error signal via potentiometer 14 adjusted by motor 15. The pitch of the craft is manually adjusted to maintain the pointer 4 on the datum position of scale 3, the pitch error signal being fed through a resistor 18 which causes motor 15 to operate at a speed proportional to this error. To fly at a predetermined height switch 10 is set to position b, and the system operates as above, except that the first component of the scale controlling signal is a height deviation signal derived from 13. To fly along a radio defined glide path switch 10 is set to a and the pitch adjusted to make pointer 4 coincide with a needle 2 actuated by a glide path signal from 24. Fig. 2 shows an automatic throttle control system for maintaining the air speed of an aircraft at a predetermined value, with automatic switching to manual control when the error signal is large. Switches 33, 43, 63 and 68 are shown positioned for manual control. At a predetermined air speed relay means change over these switches and energize clutches 47-50. An air-speed error signal at 31 is taken to differential 38 together with an integral thereof obtained via amplifier 39, motor 40 and potentiometer 41, and fed to four throttle servo systems operating in parallel to adjust the four throttles 51-54, and indicating potentiometers 55-58, to change the speed of the aircraft and eliminate the error signal. A second air-speed error signal is similarly derived at 66 and fed to differential 60 together with a signal from differential 59, determined by the deviation of the average throttle position signal, as obtained from potentiometers 55-58, from a datum determined by the setting of a potentiometer 65, this datum being made to follow the actual average throttle position by motor 64 operating slowly because of resistor 62. The output from differential 60 operates a throttle indicator 71. Specification 786,456 is referred to.