GB768440A - Improvements in navigational devices - Google Patents

Abstract

768,440. Electric analogue calculating systems. MINISTER OF SUPPLY. March 3, 1949 [Feb. 19, 1948], No. 4888/48. Class 37. [Also in Group XL (c)] In an aircraft or ship, navigational aid apparatus comprises indicators for deviation of course and for time or distance (R) remaining before the destination (D) is reached, and means for computing (NN + EE),(NE -NE),(N<SP>2</SP> + E<SP>2</SP>) where N, E are co-ordinates for D related to the craft's position and N, E are resolutes of the craft's speed. Resolutes N, E are derived from a sin/cos potentiometer 101, 102 energized by an airspeed analogue voltage and driven in accordance with aircraft heading and applied to amplifiers 105, 106; resolutes of wind velocity being applied at 103, 104. The amplifier output from amplifier 105 drives a motor 107 to adjust potentiometers 109, 110 so that a voltage proportional to N is applied across a bridge circuit 113, 114, 115, 116; ( - N) being fed back at 121 so that 105 is fed in proportion to acceleration. The motor 113 driven by current proportional to N adjusts potentiometers 118, 119, 120 to the new value of N so that the tapping on 118 gives the instantaneous value of NN and so on. The voltage proportional to E is applied from 111, 112 to 119 so that the tapping on this potentiometer provides NE. The voltages NE, NN, EN, EE are so combined in a ratiometer 124, 125, 126, 127 that this device indicates the value of as the departure from the wanted course. By altering connections to 119, 120, 123, 128, 125 the ratiometer device may represent the expression for the time remaining before (D) is reached. In an alternative arrangement, Fig. 2 (not shown), the quantities NN, EE and NE, NE and N<SP>2</SP>, E<SP>2</SP> are combined in high-gain amplifiers before applying them to indicators direct or through an electronic divider or a servomotor.