GB927180A - Improvements in or relating to visual indicating instruments - Google Patents

Abstract

927,180. Indicating apparatus. S. SMITH & SONS (ENGLAND) Ltd. Dec. 15, 1961 [Sept. 29, 1960], No. 33440/60. Class 106 (4). [Also in Group XXXIII] A visual indicating instrument, particularly an attitude indicator for an aircraft, comprises a circular viewing aperture 1 symmetrically positioned within the front face of the casing 2. A conventional roller blind 3, with horizon line 4, is mounted on rollers (not shown) so that line 4 may be moved to indicate pitch and roll with respect to datum marks 5, and a datum mark 7 which moves with the roller blind mechanism registers with a fixed bank scale 6. A transparent screen in front of the roller blind is marked with concentric rings 8, the inner ring being thicker than the remainder. Two flight director indices 9 and 10 are mounted on wires 11 and 12, respectively, for planar movement in directions normal to their lengths by separate mechanisms (not shown) which may be screw jacks driven by electric motors in accordance with a combination of signals representing the aircraft's deviation from a glide path defined by the glide path and localizer beams of a conventional I.L.S. system. The indices are of length equal to or less than half the diameter of aperture 1 and in their undeflected positions they intersect over the thick circle 8. The advantage of the short length of the indices is that if either is moved more than half the full length of the other they do not intersect and it immediately becomes apparent to the pilot the correct action necessary to bring the aircraft on to course. The indices 9 and 10 may be of equal or unequal length.