Patent GB-738166-A (GB)
Title: Improvements in or relating to pilot's indicators for aircraft instrument landing or approach systems
Inventor: CALVERT EDWARD SPENCE
IPC: G01S1/02
Filed: 1952-07-30
Abstract: 738,166. Aircraft instruments. MINISTER OF SUPPLY. July 22, 1953 [July 30, 1952], No. 19326/52. Class 4. [Also in Group XL (c)] In an aircraft landing system in which the landing path is defined by an equi-signal radio beacon, signals which are a function of the angular displacement of the aircraft from the landing path and the rate of change of said displacement are displayed respectively on a single indicator by the angular and translational movement of a single pointer. The rate signal may comprise (1) the first derivative of the displacement signal, (2) the algebraic sum of the displacement signal and its derivative or (3) a signal proportional to the heading of the aircraft relative to the landing path as determined by a gyro compass, the heading signal being compensated for ground wind side drift, Fig. 14 (not shown). In cases (1) and (3) the rate signal is zero when the aircraft is heading towards the beacon whereas in case (2) it is zero when flying parallel to the landing path. Signals relative to azimuth and elevation displacements may be displayed on separate indicators or on a common indicator. As shown in Figs. 1 and la, the azimuth indicator comprises a fixed vertical reference index 11 and a pointer 12 pivoted at 13, the horizontal position of the pointer relative to index 11 being controlled by a servomotor 15 which is controlled by the displacement signal from the receiver 17, and the vertical angle between the pointer 12 and the index 11 being controlled by a servomotor 14 which is controlled by the rate signal generated at 18; a miniature aircraft 19 may be mounted on the pointer. A corresponding elevation display is illustrated in Figs. 2 and 2a (not shown). In a modification, Fig. 5, the horizontal displacement of the pivot 53 of a pointer 52 relative to an index 51 is controlled by the azimuth rate signal and the angle between pointer 52 and index 51 is controlled by the azimuth displacement signal; in the corresponding elevation display, Fig. 6, which does not in itself form part of the present invention, the indicia 61 and 62 are displaced vertically from a fixed reference index G.S. by the displacement and rate signals respectively, the horizon being represented by the line 63. A combined azimuth and elevation display utilizing the types of display shown in Figs. 5 and 6, is illustrated in Fig. 16 and in Figs. 7, 15 and 17 (not shown). As shown in side elevation in Fig. 16, the pointer 52 is attached to a spindle 79 extending through a horizontal slot 80 in the spherically-curved dial 81 from bearings 82, 83 in a frame 84 mounted on bearings 85, 86 for rotation about a vertical axis passing through the centre of curvature of the dial, the rotation and displacement of pointer 52 being produced by rotation of spindle 79 and casing 84 respectively by servomotors 54 and 55. The elevation indicia 61, 62 are carried at the ends of radius arms 92, 93 which extend from coaxial worm wheels, Fig. 17 (not shown), whose common horizontal axis intersects the vertical axis of frame 84 at the centre of curvature of dial 81. Alternatively rotation and displacement of a pointer 194, Fig. 18, mounted on a spindle 190 is produced by two moving coils 181, 182 which are secured rigidly together with their axes intersecting one another at right angles at a point centrally thereof, to constitute a moving assembly supported by spindles 183 coaxial with the coil 181 in bearings 184 in a frame 185 which is pivoted coaxially with coil 182 at points 186 in a fixed U-shaped frame 187 which locates the coil assembly 181, 182 centrally between the poles of a permanent magnet. The spindle 190 is rigidly secured to the coil assembly 181, 182 by a C-shaped junction piece 191: