Patent GB-549331-A (GB)
Title: Improvements in and relating to apparatus for use in training aircraft pilots
Filed: 1940-12-12
Abstract: 549,331. Apparatus for training aircraft pilots. SPERRY GYROSCOPE CO., Inc. Dec. 12, 1940, No. 17602. Convention date, Dec. 14, 1939. [Class 40 (i)] [Also in Group XXXIII] A device for training aircraft pilots comprises a triangulation device having two limbs adjustable in length and orientation to represent the airspeed and direction and also the wind speed and direction, the third limb being automatically set to show the ground speed and direction, the device also including a marking device to trace the course on a map, &c. The track tracer or crab must follow a path represented by the third arm of a triangle the other arms of which are proportional respectively in length to the wind speed and to the air speed and in directions to the directions of the wind and the trained heading. Azimuthal motion of the pilot trainer is transmitted through a flexible shaft 2 to the triangulation device 3 and drives a gear 4 and sleeve 6 to direct a radial arm 7 into alignment with the trainer heading. The arm 7 carries a screw 9 having a nut 10 which is threaded for movement along the arm 7 and carrying a repeat back slider 17 the radial distance of this slider 17 from the centre line 11 corresponding to the actual air speed of the trainer. The air speed pick off apparatus 78 includes a bellows 12 which actuates a lever 13 in accordance with variations of air speed. The lever 13 engages a potentiometer 14 to control current flow from a supply transformer 15 through the potentiometer 14, transformer primary 16, repeat back slider 17 and potentiometer 18 back to the supply transformer 15. The output of the transformer secondary 16 is supplied to an amplifier 19 whereby the air speed signal is amplified and passed through output transformer 20 to a power amplifier the output of which is supplied through a matching transformer 22 to one of the phase windings of a two-phase motor 23 the shaft of which rotates the shaft 29 through a differential and so drives the screw 9 of the arm 7. The strength of the wind is imposed by means of a screw 39 operating a slider 32 along a frame 33 and the direction of the wind is imposed by moving the base plate 36 to the desired orientation as indicated by the index 37. The third arm 44 Fig. 6 is thus determined and gives the ground speed proportional to its length and its direction in alignment with the arm. The angular position of the arm or link 44 is transmitted to the ground tracer or crab by means of gear 52, Fig. 1, on the rotor shaft of a synchrotransmitter 53 which is connected by cable 54 to a synchro-receiver 55, Fig. 3, to operate gears 57, 58 to orient the crab travelling wheels 60, 61 and gear 59 to orient the tracer wheel 62. The crab is moved at a speed proportional to the ground speed by means of a variable condenser 68 which is adjusted according to the length of the link 44 by means of a rack 65, Fig. 1, gear 66, shaft 31 and gears 67. The condenser 68 is connected in circuit with a variable frequency oscillator 69 the output of which as supplied through a coupled winding 70 is modulated by the output of a fixed frequency oscillator 71. The beat output, proportional to the differences of the frequencies of the oscillators 70, 71, is supplied to amplifier stages 74, 75 arranged in push-pull, the output being fed to small synchronous motors 76, 77 driving the crab wheels 60, 61 to move the crab at a speed proportional to the actual ground speed. Specifications 446,665, and 540,736 are referred to.