Patent GB-1234073-A (GB)
IPC: B64D45/00
Filed: 1968-04-17
Abstract: 1,234,073. Aircraft instrument display. KAISER AEROSPACE & ELECTRONICS CORP. 17 April, 1968 [24 April, 1967], No. 18209/68. Heading B7W. [Also in Divisions G3 and H3-H5] A mobile object has a visual display including an attitude symbol and a position command symbol and an automatic pilot system utilizing the difference between commanded and actual position of the object to change its attitude. In the embodiment an aircraft carries a cathoderay tube 48 which displays a sky portion, a horizon line, a ground texture and a flight path indication consisting of a wedge-shaped outline; a fixed, central, reticle 49. In addition to providing a pilot's display of the aircraft attitudes and control of those attitudes in normal, level flight, the system responds to commands fed into it to display the selected command and variations of attitude about one or more axes in response to the command. Ailerons 130 change roll attitude so as to direct the aircraft to a selected course or heading and elevators 156 change pitch attitude to bring or maintain the aircraft at the desired pitch or altitude or on a selected glide slope. Pitch to maintain level flight.-With switch 163 in the pitch/roll position, the A.C. pitch output of gyro 10 is fed to a demodulator 26 to afford D.C. signals on line 28 to a waveform generator 4 which incorporatesa delay circuit 38, a horizon generator 34, a ground-texture circuit 90 and a mixer 42 the output from which is connected to an intensity-modulation control electrode of display 48 ; these circuits are of the kind described in Specification 921,528. The output on line 28 is also fed to a mixing circuit 144 the output from which is applied to a servo system 9. If, for example, the aircraft pitches downwardly the horizon line and ground texture on display 48 move vertically by a related amount and the servo system brings the aircraft back to level flight. Command pitch change.-With switch 100 set to AH (altitude hold) and selector 21 set to a desired altitude, signals representing the difference between actual and desired altitudes are fed to a circuit 50 to effect vertical displacement of the path apex relative to the horizon and to a limiter 140 (to restrict the amount of pitch change in changing to the selected altitude) and thence to the elevator servo system. Immediately the aircraft pitches, e.g. upwardly, gyro 10 provides signals to cause the horizon line, ground texture and path apex to move downwardly by a related amount. Glide slope.-Signals via position GS on switch 100 represent the aircraft's position relative to the glide slope and (i) cause related vertical displacement of the path apex on display 48 as for altitude hold, and (ii) cause system 9 to bring the aircraft on to the glide slope. Heading display.-The horizontal position of the path apex is adjusted correspondingly to heading or track information. In all but the "off" position of switch 84, generator 56 generates a flight path on display 48 and heading error signals from the apparatus selected by switch 84 are applied to sawtooth generator 88 to position the path apex horizontally. Ailerons 130 are also controlled automatically. Any roll signal originating in gyro 10 causes CRT yoke 20 to rotate correspondingly. The Specification describes the functioning of the system for VOR, ILS, and compass manual control. Detailed circuits are described for the demodulators, e.g. 26, Fig. 2 (not shown), compass manual control, Fig. 3 (not shown), chopperamplifier 94, Fig. 4 (not shown), control circuits 6 and 7, Figs. 5 and 6 (neither shown) and control circuits 8 and 9, Figs. 7 and 8 (neither shown). Examples of display changes &c. are illustrated in Figs. 1A to 1E (none shown). Limiter 144, Fig. 5. A signal from transistor 311 is limited by a circuit including of transistors 325, 326 potentiometers 322, 323 and a network 328, 329 to prevent high-frequency oscillation of amplifier circuit 112.