GB886136A - Improvements in or relating to visual indicating devices for use in aircraft - Google Patents

Abstract

886,136. Attitude indicating instruments on aircraft. SMITH & SONS (ENGLAND), Ltd.. S. April 28, 1960 [Jan 20, 1960]. No. 2077/60.Addition to 853,034. Class 4. [Also in Group XL(c)] An aircraft control cabin is provided with apparatus comprising a first visual indicating device capable of providing a moving optical stimulus in the form of one or more light sources which may be made or appear to move along a line approximately parallel to a direction fore- and-aft of the aircraft, the line lying within the periphery of the pilot's field of view and to one side of his line of sight when looking in said direction, a second visual indicating device capable of providing a moving optical stimulus in the form of one or more light sources which may be made to move or appear to move along a line lying transversely of said direction, the line lying within the top or the bottom of the periphery of the pilot's field of view when looking in said direction, means for actuating the first visual actuating device to provide a moving optical stimulus the rate and direction of which are indicative of the magnitude and sense of any departure of a first quantity from a desired value and means for actuating the second visual indicating device to provide a moving optical stimulus the rate and direction of which are indicative of the magnitude and sense of any departure of a second quantity from a desired value. The cockpit, Fig. 3, comprises windscreen 9, instrument panel 10 and pilot's seat 8 and said first visual indicating device is duplicated as at 2 and 3 and the second indicating device is shown at 1. In Fig. 1, which shows the devices in plan view, each device comprises a cylinder coated or formed with light and dark coloured helices mounted for rotation within a casing, Fig. 2 (not shown). The external surface of each cylinder may be illuminated from within the casing or the light coloured areas may be helical slots cut in the wall of the cylinder, which is then provided with internal illumination. Cylinder 1 is driven by a motor 15 which drives also a tachometer generator 18 to generate a voltage proportional to the speed of the motor, the motor being energised from an amplifier 19 which receives an input from a signal combining device 20. One input is derived at tachometer 18 and the other, fed over line 21 through signal shaper 37 and signal combining device 27, is a bank error signal derived from gyro vertical 25 giving actual bank angle and a bank demand signal over line 28 derived at a signal combining device 29 through limiter 30 which prevents the demand signal from exceeding a predetermined safe limit. Device 29 has two inputs, one from a compass 31 giving aircraft deviation from a desired course and another from a switch 32 which may be open or connected to the output of either a V.O.R. or I.L.S. system, giving lateral displacement of the aircraft from a selected radio beam. A third input to device 27 is coupled through signal shaper 35 from a rate gyro 36 which gives a signal representing aircraft rate of roll so as to subtract from the bank demand signal on line 28. Consequently, the speed and direction of rotation of cylinder 1 indicates the direction and extent of stick movement to be imposed by the pilot to restore the aircraft to its correct attitude. Devices 2 and 3 are operated by a motor-generator system similar to that used for device 1, the speed and direction of rotation of the devices being synchronised by synchro-transformer 45 and synchro transmitter 46. Signal combining devices 42 and 43 receive a pitch error signal over line 44 from signal shaper 47 and signal combining device 48. This receives one input from a gyro vertical 49 (which may be the gyro vertical 25) representing actual pitch attitude of the aircraft and another input in opposition representing pitch demand derived at a signal combining device 50 through limiter 51 which is provided to prevent application of pitch demand signals greater than a predetermined safe limit. Device 50 has two inputs, combined additively, one from a datum pitch attitude setting device 52 and the other taken through a switch 53 either from a height error signal generator 55 e.g. a barometric capsule giving a difference reading from a pre-selected altitude reading or from an I.L.S. receiver 56 which gives an indication of the deviation of the aircraft from a predetermined glidepath, which will normally form part of the receiver 33. The speed and direction of rotation of cylinder 2 indicate the direction and extent of stick movement to be imposed by the pilot to restore the aircraft to its correct pitch attitude.