Patent GB-711294-A (GB)
Title: Apparatus for instruction or training in navigation
Inventor: RINGHAM GORDON BOY
IPC: G01C21/22
Filed: 1951-09-13
Abstract: 711,294. Electric analogue computing systems. COMMUNICATIONS PATENTS, Ltd. Sept. 12, 1952, [Sept. 13, 1951.] No. 21552/51. Class 37. [Also in Group XXXVIII] In navigation training apparatus, the simulated movement of a craft is traced on a conical projection chart wherein the meridians are radial lines from a fixed point, and the latitudes are arcs of concentric circles with this point as centre, by a pen associated with mutually perpendicular lead screws moved by N-S, E-W signals derived from flight controls, the control settings being operated in accordance with a desired heading relative to a magnetic compass system which is corrected in accordance with the position of the pen on the chart so that a straight course may be obtained by a constant compass heading and is recorded on the conical projection chart by a curved line which cuts the meridians at a constant angle. The simulated movement of the craft is indicated by the recording pen 5 moving over the chart 4 under the Influence of a representative N-S potential derived from a flight computer applied to an amplifier 7 feeding a motor 11, driving the pen 5 up or down a lead screw 6, and a representative E-W potential from the flight computor, displacing the lead screw 6 laterally via an amplifier 16 and a motor 20 which drives a horizontal lead screw 15. The lead screws are mechanically coupled with the sliders 25, 30 respectively of potentiometers 26, 31 which feed voltages biased by voltages from prefixed potentiometers 27; 32 into amplifiers 28, 33 feeding coils 35, 34 respectively of a magnetic resolver, potentiometer 27 being set in dependance on the ratio of the length of the chart 4 and the position of the point at which the meridians converge, and potentiometer 32 being set in accordance with the position of the meridian which is parallel to the vertical lead screw 6. The rotor coil 36 of the magnetic resolver thus feeds a signal into a motor 38 which rotates to eliminate the signal by driving rotor coil 36 and also the rotor 42 of a doublewound selsyn unit 40, the angle of rotation being that between the meridian and the vertical on the chart at the location of the pen 5. The stator 44 of unit 40 is connected to the stator of another selsyn unit 45 whose rotor 46 is given a rotation representing the heading angle of the flight control and rotor 42 of unit 40 is connected to the stator of a further selsyn unit 47, so that its rotor 48, which controls the magnetic compass system by which the flight controls are adjusted, is given an angular correction dependent on the position of the pen 5 on the chart 4. Thus, as the pen moves over the chart, a correction angle is fed by rotors 42, 48 to the compass, and the flight controls will be manually altered to maintain a constant heading relative to this compass, whereby the perpendicular components of movement applied to the pen are altered to cause it to move along the correct curve which indicates the initial heading. The motors 11, 20, 38 are provided with negative feedback from their amplifiers 7, 16, 37 respectively to eliminate hunting.