Patent GB-611304-A (GB)
Title: Improvements in or relating to aircraft training apparatus
IPC: G09B9/20
Filed: 1944-09-05
Abstract: 611,304. Ground trainers. DEHMEL, R. C. Sept. 5, 1944, No. 16940. [Class 4] [Also in Groups XXXVII, XXXVIII, XL(b) and XL(c)] Aircraft training apparatus for controlling and indicating simulated flight conditions comprises a plurality of flight controls each adapted to operate one or more variable electrical means connected in electro-mechanically interconnected circuits so as to modify the current characteristics of each other, and a plurality of "light" condition indicating devices responsive to the circuits. The conventional " stick " control 10, Figs. 1, 2, rudder 11, throttle 13 and stabilizer control 440 operate potentiometers connected in circuits, some of which are interconnected, to operate a steering motor SM, air-speed motor ASM and altimeter motor ALTM. These motors individually or in combination actuate the conventional " flight " indicating instruments, and move a recording head over a chart 585 to trace the path of a simulated flight. The students' cockpit may be oriented in simulation of the actual movement of an aircraft, and sound effects corresponding to the engine noise at varying speeds used. The response sensitivity to the controls is made variable to simulate various aircraft types and irregular movements of the " craft " corresponding to rough air conditions are introduced. Flight controls : The stick control 10, Fig. 1, when moved fore and aft, actuates potentiometers 447, 478; 594, 739, 590, while lateral movement thereof actuates potentiometers 400, 443, 508, 716 through gearing 141. The rudder 11, Fig. 2, actuates through gearing potentiometers 402, 472, 506, 715. The throttle 13, Fig. 1, actuates through a rack and pinion 45 potentiometers 449, 476, 592, Fig. 2, while the stabilizer 440 actuates the slider of a potentiometer 445, Fig. 6 (not shown). Course charting head, Figs. 1, 2, 32.-The head 14 representing the location of the aircraft on the range is steerably mounted in the pantograph 15 at 78. The tractive wheel 65 of the head 14 is driven about its own axis 69 by the air speed motor ASM through gearing, a shaft nested within the pivot 64 of the pantograph, a chain 73, sprocket 74, Fig. 32, flexible shaft 75 and mitre gears 76. The head 14 is thus advanced in accordance with the air-speed. At the same time the head is oriented by the steering motor SM through gearing 439, 432 and shaft 61 which through mitre gears drives a sleeve on the pantograph pivot 64 which through a chain 82 drives the sprocket 83 rigid with the housing of the head 14. The head 14 may serve as an indicating device or used to record the " flight " on a motor driven chart 585. The path of the head 14 is also traced on a reduced scale on a map 79 by a pencil 67. Steering motor SM, Fig. 5, control.-In the central or neutral positions of the aileron and rudder controls 10, 11, the two grids 411, 417 of the double triode 409 are similarly biassed from source 404 and the alternating modulation components of the two anode currents, produced by including the transformer secondary 407 in the grid circuits, balance out in transformer 416. Movement of either control 10, 11 operates the corresponding potentiometer 400, 402 to upset the balance whereupon one of the normally blocked thyratrons 426, 427 will fire-dependent on which grid 424, 425 is rendered less negative synchronously with the positive half-cycles supplied to the plates 428, 429 from source 406. The steering motor SM also energized from the source 406 is then driven in a sense and at a speed determined by the sense and magnitude of the movement of the operative control 10 or 11. Conjoint operation of these controls increases the speed of the motor provided they are deflected in the same sense whereby aeronautical manoeuvres such as slips and skids may be simulated. The different responses of heavy and light aircraft may be simulated by adjusting the sensitivity of the circuit, e.g. by shunting a rheostat 430 across the transformer 416. A condenser 431 and variable resistance 418 introduce an adjustable delay in the response of the motor SM to movement of the stick control 10 to simulate the lagging action characteristic of actual aircraft and a resistor 432 enables simulation of the recovery tendency of actual aircraft in shallow turns. Rheostat 433-434 reduce the response delay to stick control when the controls 10, 11 are deflected in opposite senses, simulating the " hang " of an aircraft on to its controls under opposite control dispositions. The motor SM, in addition to orienting the course charting head, drives through gearing 439, Fig. 3, and shaft 367 a tachometer graduated to indicate rate of turn, and mounted on the instrument panel 7. It also drives a compass 5, Fig. 23. Altimeter motor ALTM, Fig. 6 (not shown).-This motor is controlled by a circuit similar to that of Fig. 5, responsive to the stick controlled potentiometers 443, 447, the throttle controlled potentiometer 449 and the stabilizer controlled potentiometer 445. Delayed response and sensitivity controls are provided and the elevator (stick) controlled potentiometer 447 is so arranged as to cause the altimeter motor to operate in the direction of increasing altitude until a " stall " occurs. The motor ALTM drives the rate of climb (tachometer) indicator 3, Figs. 2, 23, directly and through gearing 331, 290 the altimeter 4. Air-speed motor ASM, Fig. 7, control.-The motor is energized over contacts of limit relay LIM and potentiometers 472, actuated by the rudder 476 actuated by the throttle control 13, 478 actuated by the elevator (stick) control 10 and rheostat 480 varied manually to vary the average " flying " speed. Relay LIM is released by limit contacts to stop the motor and thus prevent overtravel of the controller head (see below), and of the charting head 14. The motor ASM also drives an air-speed (tachometer) indicator on panel 7 through shaft 47 and a belt drive. Movement of pilot's compartment.-The steering motor SM may be used to turn the pilot's compartment 92, Figs. 1, 2 in azimuth and the motor ALTM to tilt it while the motor ASM may be used for propelling a mobile mount to simulate forward velocity of an airplane. Aeroplane sound.-A motor RPM, Fig. 7, is energized from source 495 over rheostat 592 operated by the throttle control 13, and rheostat 594 operated by the elevator stick 10 and drives a tachometer 596 on panel 7 to indicate engine RPM. In addition the motor RPM drives a sound generating system producing a tone simulating engine noise. For example, the motor may drive an optical disc 597 having a track for modulating the light received by a photoelectric cell 598 from a light source 599, to operate a loud-speaker 600. Other systems may be used provided that both the amplitude and frequency of the tone produced is modified as the motor speed varies. Rough air conditions, simulating, Fig. 7. Closure of a switch 493 on the student's panel 7 or a switch 494, Fig. 1, at the instructor's position, energizes a relay 491 over the contacts 496 of which a motor RAM is energized from source 495. Cams 484, 485, 486 driven at different speeds by this motor operate various series connected contacts so that at various times, apparently at random, additional " disturbing '' potentials are applied to the grid 417 of tube 409, Figs. 5, 7, to operate the steering motor SM thereby producing intermittent and variable turning effects on the trainer instruments. Sporadic potentials are similarly applied to the grid of valve 458 to operate the altimeter motor ALTM intermittently and apparently at random. The air-speed motor ASM is also varied in speed conjointly with the motor ALTM by potential applied over terminal 521. The amplitude of the " disturbing " potentials is adjustable by rheostat 525 and their frequency by varying the speed of motor RAM by rheostat 525. A ball bank indicator B.1, Fig. 7, mounted on panel 7, Fig. 2, comprises an ammeter, and is energized over potentiometer 506 actuated by the rudder, and 508 actuated by the aileron control 10, from source 404. The "disturbing" potentials are applied thereto over terminal 658. Rough air conditions, apart from the manual control thereof by switches 493, 494, are also initiated when "stalling" occurs, the motor RAM being energized over a segment 588 and wiper 587 actuated by the elevator control 10. At the same time wiper 589 similarly actuated introduces resistance 591 into circuit to increase the " rough air " reaction of all instruments. Magnetic compass, Figs. 23, 27.-A spherical magnetic compass element 674 having pole magnets 675, 676 and an azimuth card 677 is supported on pivot 678 in damping fluid 683 and is magnetically constrained to rotate with a permanent magnet 689 carried by a shaft 690 rotatable by shaft 692 driven by a shaft 383, Fig. 23, which rotates in accordance with the course charting head 14 and also responds to rotation of the controller 16 relative to the traversing tale 8, introduced to simulate wind drift or changing of the North reference direction. An adjustable coupling 694 permits adjustment of the orientation of magnet 689 to simulate magnetic variation. The shaft 690 also drives through gearing 699, 700 and a sleeve 698 a non-magnetic yoke 695 carrying coils 696, 697, adapted to be energized through slip rings 704, 705 in proportion to the current flowing in the steering motor SM, Fig. 5. A spinning effect is thereby produced on the compass element 674 simulating that produced on an actual compass during turns. One stationary coil only may be used in lieu of coils 696, 697. In addition a magnetic ring 694 on the compass element co-acts with four solenoids 685, 687 symmetrically disposed around the ring. Two of these, diametrally disposed, are energized with the altimeter motor ALTM, Fig. 30 (not shown) to cause the compass 674 to tilt corresponding to climbing or diving of the " aircraft." The other two solenoid