GB1294921A - - Google Patents

Abstract

1294921 Aircraft altitude display apparatus F J WALKER 7 Jan 1970 865/70 Heading B7W Display apparatus for assisting a pilot of an aircraft during a landing manoeuvre, comprises an altimeter having hands showing instantaneous altitude and an indicator device superimposed thereon showing the desired altitude with respect to time in order to achieve a predetermined landing manoeuvre. An altimeter 20, having a thousands-of-feet hand 24 and a hundreds hand 26 has positioned concentrically in front thereof two rings 30, 28 respectively carrying indicia 34, 32 to indicate desired altitude. The rings are driven at a predetermined speed by an electric motor 36, reversible by a switch 104 and energized on a line 90 from power source 62 under the control of a double-throw momentary operation switch 80. The duration of operation of motor 36 is controlled by a timer device 118 comprising a constant speed motor 120, normally disengaged clutch 128 and a spring biased switch arm 138 which contacts a limit switch 68 and a switch 146 for energizing a visual and audible warning device 164, 166. Settable calculating apparatus 170 for determining the movements of rings 28, 30 during an approach manoeuvre comprises concentric rings 172, 174 respectively sealed logarithmically in desired range of altitude change in feet and the desired time for an altitude change. The rings are set against an index 194 by knobs 182, 192 which in turn operate through logarithmic linearizing gears to respectively rotate the wiper 88 and casing 85 of a potentiometer 86, the output from which is fed on line 90 to switch 104 to energize motor 36. A simplified embodiment (Fig. 4, not shown) is described in which apparatus 170 is dispensed with and the required rate of altitude change is calculated either mentally or by a separate slide rule.