627,475. Course recording apparatus. DEHMEL, R. C. Nov. 24, 1944, No. 23455. Convention date, Nov. 25, 1943. [Class 97 (ii)] [Also in Groups XXXVIII and XL (c)] A course indicating or charting device, e.g. for an aircraft or ship, actuated in accordance with the combined effect of a plurality of independently variable speed vectors each represented by an input voltage, comprises means for resolving each input voltage into separate x, y Cartesian co-ordinate speed components, electrically summing the various x components and the various y components, and means responsive to the resultant x, y components, for controlling the course indicating mechanism. The input voltages may, e.g. represent airspeed and wind-drift, and their resultant x, y components be integrated to operate the course indicator which may respond to the Cartesian position co-ordinates so derived or to the polar co-ordinates obtained electrically therefrom. The device may be used in an actual aircraft or in an aircrafttrainer to operate a controller as described in Specification 611,304, [Group XXXVIII], to simulate radio range signals. Deriving airspeed resolute potentials. A potential Ev proportional to the speed of the " craft " is derived, e.g. from the shaft 6, Fig. 1, of the airspeed indicator 1 which drives directly or through a servomotor 2 ... 10, and shaft 11 potentiometers 12, 13, fed from a source 14 of D.C. or A.C., whereby the potentiometer delivers two potentials ŒEv proportional to airspeed. The horizontal component of Ev is derived, e.g. by applying ŒEv to potentiometers 21, 22 the sliders of which are operated by a crank-arm 18 rotating with the pitch element of the artificial horizon 17, whereby the output from sliders 19, 20 is ŒEh=ŒEv cos #, where -# is the angle of elevation of the " aircraft flight. This potential ŒEh, which may be otherwise derived from Ev, e.g. by means of a rotary resolving transformer, Fig. 5 (not shown), is applied to a potentiometer 30, the sliders 29, 31 of which are driven by crank-pins spaced 90 degrees apart in a disc 33 driven through gearing 43 and, if necessary, through a servomotor 35-42, by the element 34, e.g. a compass, responsive to the heading α of the aircraft. The potentials at the sliders 29, 31 are thus proportional to EhN=Eh cos α and EhE= Eh sin α, the resolutes of the " aircraft " horizontal speed along the north and east directions, respectively. These potentials are applied respectively over summing impedances 32, 44 to points 238, 237. Deriving wind-speed resolute potentials. A potential Ew proportional to the wind-speed is derived from a manually set potentiometer 49, 50 and applied to a potentiometer 54. A knob 55 with index 59, manually set to the wind direction B, drives through gear 57, a crank and slide mechanism 60, 61, similar to 33 above, whereby the potentials at the sliders 52, 53 are proportional to EwN=Ew cos # and EwE=Ew sin #, the wind speed resolutes along the north and east directions. These potentials are applied over summing impedances 64, 65 to the points 238, 237. Deriving time integrals of ground-speed resolute potentials. The potential appearing at point 238 is yv=Eh cos α+Ew cos # and represents the sum of the resolutes along the north axis of the craft airspeed and drift, i.e. ground speed. It is applied at point 240 across load impedance 66 and drives an integrator, e.g. a reversible motor 68 through an amplifier 70, e.g. as described in Figs. 5, 6 of Specification 611,304, at a speed proportional to the applied potential, proportionally being enhanced by applying negative feed-back from a generator 72, driven by the motor 68, over a high impedance 74. The motor 68 drives through reduction gearing 76 and differential 81 a shaft 80 the rotation of which is thus proportional to the time integral of the ground speed of the " craft " along the north direction. Similarly, a shaft 83 is driven through a friction clutch 84 by a motor 69 in accordance with the time integral of the ground speed of the " craft " along the east direction. The positions of shafts 80, 83 thus represent at any instant the Cartesian co-ordinates of the " craft " position and rotate the wipers of potentiometers 90, 91, 94, 95 to derive alternating voltages e<SP>1</SP>y and e<SP>1</SP>x corresponding thereto. The Cartesian coordinates of the " craft " ground-speed are indicated by voltmeters 86, 87 connected across the respective feed-back generators 72, 73. Converting Cartesian to polar co-ordinates. To use the signal controller described in Specification 611,304, with the present invention the shaft 104, Fig. 1, must be turned in accordance with the azimuthal direction of the " craft " and the element 105 moved linearly according to its range. The Cartesian coordinate potentials ely, elx are applied to the quadrature windings 205 of a rotary synchronous transformer 107 operating either as a synchronous receiver in which the primary winding 108 is energized from the source supplying the potentiometers 90, 91, 94, 95, or as a servomotor in conjunction with amplifier 109 and motor 111. In either case the shaft 104 is set automatically to the azimuth angle #, equal to tan<SP>-1</SP> e<SP>1</SP>x/e<SP>1</SP>y. Potentials proportional to e<SP>1</SP>y.cos # and e<SP>1</SP>x.sin # are derived from potentiometers 113, 114, fed with the voltages e<SP>1</SP>x, ely, the wipers 115, 116 being operated by a crank and slide mechanism 118, 122, 123, driven by shaft 104. These potentials are applied to impedances 124, 125. The sum voltage, i.e. the range voltage er appearing across load impedance 126 is applied through an amplifier 127, e.g. as described in Specification 611,304, to drive a motor 128 which moves the signal controller element 105 through a lead screw 129. The range voltage er across impedance 126 is balanced by a voltage derived from a potentiometer 132 by a wiper moving with the nut 130, the circuit constants being so arranged that the displacement of the nut corresponds to the range voltage. Signal-controller, operation. The range mechanism 105 including the motor 128, may, as disclosed in Specification 611,304, be rotated bodily with the shaft 104 to effect simulation of the various radio range, marker and other radio signals as therein described. The Z and fan marker signals may alternatively be derived from the Cartesian co-ordinate integrators by contacts such as 140, 141 radially disposed with respect to the Cartesian coordinate shafts 80, 83 and circumferentially adjustable, respectively, to the latitude and longitude of the corresponding marker on the range. These contacts are arranged to close the marker circuit when the brushes 142, 143 driven by the shafts 80, 83 simultaneously engage their respective contacts 142, 143. These contacts may be coupled to the filament circuit of a valve controlling the student's headphones, Figs. 8, 9 (not shown), to effect realistic surging in and out of the marker signals. Flight path recording. This is effected by a stylus carried by the nut 130, Fig. 1, on a chart carried by a disc rotating with or relative to the shaft 104, Fig. 2 (not shown). Alternatively the chart may be unwound from one roller to another by one of the Cartesian co-ordinate shafts 80, 83 and the stylus moved rectilinearly at right angles to the chart movement by the other shaft, Fig. 3 (not shown). Hand wheels 82, 85, Fig. 1, permit adjustment of the shafts 80, 83 relative to their driving motors so that the starting position of the " crafts " may be varied. In addition, a differential may be inserted between the compass 34 and the servotransmitter operated thereby to permit rotation of the co-ordinate axes through any desired. angle. Fig. 11 (not shown), illustrates an arrangement for automatically changing the scale factor of the operating mechanism as the range of the craft represented by nut 130, Fig. 1, passes through a predetermined value. Erroneous operation of the various circuits, e.g. the marker signals due to the scale change are avoided by relay operated switches, and the stylus and marker circuits are rendered inoperative during the switch over. The chart may, alternatively, be moved in two mutually perpendicular directions by the shafts 80, 83, Fig. 7 (not shown), the stylus being stationary. In this case the chart may carry a terrain picture for use with the optical projection system described in Specification 613,010, [Group XXXIII]. Modifications. The invention may chart the true or simulated course of air or water craft, land vehicles, or other conveyances at a remote position, and may be used with any type of grounded aviation trainer. When used in an aircraft the wind speed and direction settings may be derived automatically. The crank and slide mechanisms may be replaced by any suitable means, e.g. sinusoidally wound resistances, or a rotary transformer, Fig. 5 (not shown), e.g. may be used. The integrator motors 68, 69, may be replaced by relay operated motors using condenser discharge feed-back, e.g. as in Fig. 10 (not shown). The ground speed and direction may be derived by applying the ground speed Cartesian coordinate potentials to the quadrature windings of a rotary synchronous transformer, Fig. 6 (not shown) which, similarly to the transformer 107, Fig. 1, takes up the appropriate angular position corresponding to the direction of flight. The transformer shaft carries a direction indicator and is electrically connected with a further similar transformer on the same shaft, whereby a voltage is derived proportional to the ground speed which operates an indicator. The optical projection system referred to above may be used for depicting subaqueous objects as seen from a watercraft.