Patent GB-691002-A (GB)
Title: Improvements in or relating to craft guidance apparatus
IPC: G01C19/38
Filed: 1950-06-30
Abstract: 691,002. Electric indicating systems. SPERRY CORPORATION. June 30, 1950 [July 29, 1949], No. 16385/50. Class 40 (i) [Also in Group XL(c)] Relates to a visual flying aid for a manually piloted aircraft of the type described in Specification 690,985, [Group XL(c)], comprising an indicating member movable relative to a reference index under the control of the algebraic sum of two signals corresponding respectively to the angular deviation of the aircraft from a predetermined altitude about the pitch or yaw axis and to the rate of change of said deviation whereby when the aircraft is displaced from the predetermined altitude the pilot may restore it to said altitude smoothly by continuously adjusting the ' altitude controls to maintain the indicating member and reference index coincident. According to the present invention the deviation signal is produced by integrating the rate signal. For azimuth control, the integral of the deviation may be added to the control signal. In order to maintain the aircraft at a predetermined altitude or on a radio-defined flight path, a signal proportional to deviation from said altitude or path is added to the control signals. As shown the sliders 11, 111 of potentiometers 12, 121 connected across a D.C. supply 15 are controlled by an azimuth rate of turn gyro 10 so that the magnitude and polarity of the voltages at the sliders are proportional to the magnitude and sense of the azimuthal rate of turn and slider 11 is connected to a summing circuit 7 controlling the horizontal deflection of the vertical pointer 2 of a cross-pointer indicator 1. Slider 111 is connected to the control winding 16 of an integrating motor 17 whose field 18 is energized by D.C. supply 15 and the output shaft is coupled via a viscous coupling 27 and magnetic clutch 25 to the spring-centered slider 21 of a potentiometer 23 also connected across D.C. supply 15 so that the voltage output from slide 21 is proportional to the integral of the rate of turn and hence to the angular deviation and this voltage is also applied to the summing circuit 7. In order to improve the control, a voltage proportional to the angular deviation (i.e. heading error) as determined by a magnetic compass may also be applied to the integrating motor so that the resultant control is proportional to rate of turn, angular deviation and integral of angular deviation. When the pilot changes the heading deliberately, the pointer 2 may be zeroed by opening switch 26 thereby deenergizing magnetic clutch 25 and allowing the potentiometer slider 21 to centre itself. The horizontal pointer 3 is controlled in a similar manner by the pitch rate of turn gyro 30 but the rate signal may be disconnected from the summing circuit 8 by opening switch 70. If it is desired to fly at a predetermined altitude, a D.C. error signal proportional in magnitude and polarity to any deviation from said altitude is produced by potentiometer 54 controlled by altimeter 50 and applied to summing circuit 8 and similarly if it is desired to follow a radio range track or a landing path defined by a localizer and glide-path beacon, D.C. error signals from the appropriate receivers 61, 62, 63 are applied to the appropriate summing circuits 7 and 8 by selector switch 60. The cross pointer indicator may be replaced by a cathode-ray tube and the rate responsive devices may be of the type shown in Specifications 592,645, [Group XX], and 601,051.