Patent GB-810957-A (GB)
Title: Improved flight training apparatus for simulating low level flight
IPC: G09B9/20
Filed: 1956-04-17
Abstract: 810,957. Flight training apparatus. CURTISS-WRIGHT CORPORATION. April 17, 1956 [April 21, 1955], No. 11682/56. Class 4. Training apparatus for simulating the effect of low level flying on the control of an aircraft during landing or take-off comprises a servo 1 for computing altitude of flight between ground level and 200 ft. thereabove, the servo being conventional with an amplifier 2, motor 3 and feedback generator 4 which drive through gearbox 15 slider contacts 10, 11, 12, 13 and 14 of potentiometers 5, 6, 7, 8 and 9. The inputs to amplifier 2 comprise a feedback voltage from phase 19 of generator 4 ; an answer voltage from contact 10 of potentiometer 5; an input on line 29 representing sea-level barometric pressure from potentiometer 26 under the control of an instructor-operated knob 27 ; an input on line 34, representing altitude of a simulated runway, from potentiometer 31 under the control of an instructor-operated knob 32, and an input representing altitiude determined according to vertical airspeed derived from potentiometer 22 which forms part of a servo 23 for computing such altitude. The other potentiometer 65 of servo 23 provides a signal picked off at 64 and fed to the card of a potentiometer 62 forming part of a servo for calculating true airspeed, the output from potentiometer 62 energising a simulated airspeed indicator 68. The other potentiometer 91 of the true airspeed servo provides a signal at 92 which is fed to the amplifier 94 of a pitch servo to operate a simulated pitch indicator 95. The potentiometer 91 is energised by the secondary winding 89 of a transformer 88, the primary winding of which is coupled to the amplifier 72 of a servo for calculating the pitching moment of the simulated aircraft as effected by low level flight. The amplifier 55 of the true airspeed servo is provided with one input on line 61 representing the effect of flap position derived from potentiometer 56 as adjusted by a trainee-operated control 60 and another input on line 54 representing the effect of induced drag on airspeed derived from a potentiometer 49 which is energised from contact 14 on potentiometer 9 of servo 1 to reflect a reduction in induced drag when the aircraft is in close proximity to the ground. The contact 51 of potentiometer 49 is operated by a servo 50 for calculating normal acceleration of the aircraft. Reverting to amplifier 72 of the pitching moment servo, the primary input is derived over line 86 from potentiometer 85 controlled by a pilot's simulated elevator control member 86<SP>1</SP>, the remaining inputs being one derived from a potentiometer 75 which is energised over line 78<SP>1</SP>, potentiometer 6 of servo 1 and line 79 from the secondary winding 60 of a transformer 81 forming part of a servo for determining thrust coefficient and is controlled by an instructor-operated dial 77 to simulate the effect on pitching moment by movement of the C. G. position ; a further input over lines 73, 70 and 44 from the secondary winding 41 of a transformer 42 forming part of a lift coefficient servo to supply a signal representing moment coefficient as a function of the lift coefficient and another input over line 71 from potentiometer 8 of servo 1 to supply a signal which reflects an increase in stability of the simulated aircraft near the ground due to the fact that the downwash effect on the tail unit of air flowing over the wing is counteracted by proximity of the ground. Potentiometers 7, 8 and 9 of servo 1 are energised from secondary winding 41 of transformer 42 and potentiometer 7 supplies a signal over line 38 to amplifier 39 of the lift coefficient servo which takes account of the increase in coefficient of lift due to low level flight. A circuit is provided to energise a relay 96 for detecting when the simulator in its supposed flight touches the ground. The circuit is controlled by cam-operated switches 98, 100 and 102 respectively controlled by altitude servo 1, acceleration servo 50 and a servo h‹ which computes rate of climb of the simulated aircraft.