Patent GB-880136-A (GB)
Title: Improvements in or relating to aircraft indicating instruments
Inventor: MAJENDIE ALASTAIR MICHAEL ADAI
IPC: G05D1/06
Filed: 1959-03-03
Abstract: 880,136. Aircraft instruments. SMITH & SONS (ENGLAND) Ltd., S. Feb. 24, 1960 [March 3, 1959], No. 7372/59. Class 4. An indicating instrument for use on an aircraft having vertical thrust means has first and second indices 3 and 4 representing respectively the aircraft and a landing pad on which the aircraft is required to land the index 4 being movable along a line corresponding to a desired landing track and the index 3 being movable along a line at right angles thereto to represent the lateral displacement of the aircraft from the desired landing track, and a third index 5 movable from the point of intersection of said two lines to represent the horizontal component of the thrust applied to the aircraft by the vertical thrust means whereby, in operation of the aircraft with its heading aligned at least approximately with the desired landing track the instrument can provide the pilot with an indication both of the position in plan of the aircraft relative to the landing pad and the quantities availableto him to control said position. The instrument, shown diagrammatically, has a viewing aperture 1 which carries, preferably at its centre, a fixed datum mark 2 in the form of a spot or metal disc. The index 3 is in the form of a cross mounted on an endlass wire 9 so that it can be moved transversely through the mark 2. Index 4 is in the form of a square, to represent the landing pad, mounted on a flexible band 12. Index 5 is in the form of a bead mounted on crossed wires 15 and 16 and a fourth index 6 is provided in the form of a horizontal bar mounted on a transperant band 20 to indicate by its vertical displacement from mark 2, the required acceleration of the aircraft in the direction of the landing track represented by a vertical line 7. In operation to provide a representation in plan of the position of the aircraft relative to the landing pad, the index 3 is moved relative to the mark 2 by a servo mechanism 10 under the control of signals derived from range and direction reponsive radio equipment 11 to represent lateral displacement of the aircraft from a desired landing track, and band 12 carrying index 4 is mounted on and driven by rollers 13 through a servo mechanism 14 actuated by signals derived from equipment 11 so that the distance of index 4 from mark 2 represents the distance of the aircraft along the landing track from the point on that track which lies directly over the pad. The wires 15 and 16 are moved parallel to their axes by servo mechanisms 19 and 17 respectively. Mechanism 17 is energised by a signal derived from a gyrovertical 18 to represent the angle # which the longitudinal axis of the aircraft makes with the horizontal line in the same vertical plane, corrected for the known angle which the direction of thrust makes with the yaw axis of the aircraft. The mechanism 19 is energised by one signal representing the aircraft's bank angle Ï derived at gyro 18, and another signal representing the aforementioned lateral displacement of the aircraft derived from radio apparatus 11, the senses of-the two signals being such that if, for example, the aircraft is flying in a level altitude but displaced to the right of the track represented by line 7, index 5 will appear on the right of line 7. Then, banking of the aircraft to the left to bring it back to the desired track will cause index 5 to become re-aligned with line 7. The band 20 carrying index 6 is mounted on and driven by rollers 21 operated by a servo mechanism 22 so that the vertical displacement of index 6 from datum 2 represents the required acceleration of the aircraft in a direction parallel to the landing track represented by line 7. Servo mechanism 22 is fed with signals from radio equipment 11 representing the aircraft's groundspeed and its distance along the landing track from the landing pad. The signals representing groundspeed are compared in mechanism 22 with signals generated also in mechanism 22 to represent the desired speed as determined by the desiredspeed/ distance relationship and the difference is utilised to move rollers 21 and hence index 6 so that its displacement from mark 2 represents the magnitude of the acceleration required to maintain the desired relationship.