Patent GB-1232631-A (GB)
IPC: G09B9/20
Filed: 1968-04-24
Abstract: 1,232,631. Flight simulation analogue computer. GENERAL PRECISION SYSTEMS Inc. 24 April, 1968 [24 April, 1967], No. 19504/68. Heading G4G. Construction.-In a flight simulation computer (Figs. 1A, 1B), potentiometers 11, 12, 13, 14, 16 and 17 linked to controls develop voltages representing roll, rudder, pitch, mixture and throttle opening, while resistors 18, 19 selectable by switch 21 develop voltages to represent flap conditions. The mixture voltage is applied over threshold circuit 15 to throttle potentiometer 16 ganged with throttle potentiometer 17, and the inputs are applied to thrust generator 45. Roll generator 31 having feedback path 32 receives inputs from potentiometer 11, from thrust generator 45, a dynamic pressure input 35, a sideslip input 36, and a sine roll angle input from potentiometer 107 to produce at its output 37 a roll moment signal. Yaw generator 41 having feedback path 42 receives a rudder input from potentiometer 12, a sideslip input 43, and a dynamic pressure input 44 to produce at its output a yaw moment signal. Pitch generator 51 having feedback 52 receives pitch input from potentiometer 13, dynamic pressure input 53, thrust input from thrust generator 45, flap input from switch 21, and lift coefficient input from generator 61 to produce a pitch moment output at 58. Lift coefficient generator 61 received inputs from flap switch 21, angle of attack input from generator 71, and a constant reference signal + C 20  to produce lift coefficient output at 65. Angle of attack generator 71 receives a pitch moment input 59 and a true airspeed, weight and lift signal at 73. A roll motor 79 driven from bank generator 75 receiving roll moment signal and input 76, a yaw motor 85 driven from yaw generator 81 receiving yaw moment signal and input 83, and a pitch motor 95 driven from pitch generator 91 all drive the trainer in corresponding degrees of freedom, and the roll motor also drives potentiometers 101 to 118. The ends of 101, 102, 103 are grounded while the centre of 101 is connected to yaw generator output, and the slider of 101 is connected to the input of yaw generator 81. The centre of 102 is connected to a D.C. source and its slider to the centre of potentiometer 124 driven by pitch motor 95; the slider deriving signals for angle of attack computation. The centre of 103 is energized from output of angle of attack generator 71, also energizing lift coefficient generator 61. The output of pitch moment generator 51 energizes potentiometer 104 antiphasedly, and the slider energizes the remaining input of the yaw generator 81. The ends of potentiometer 105 are grounded and its centre is energized from output of pitch moment generator 51, while the slider energizes input 93 of pitch generator 91. The output of yaw generator 41 energizes potentiometer 106 antiphasedly, its centre is grounded, and its slider energizes input 92 of pitch generator 91, while the ends of potentiometers 107, 108 are D.C. energized in opposite sign and their centres are grounded. Potentiometers 122, 123, 124 are driven by pitch motor 95, and 122 is D.C. energized in opposed polarity with centre grounded, while 123 is antiphasedly energized from the output of yaw generator 81 with centre grounded. The slider of 123 energizes input of bank generator 75. Airspeed signals are developed by generator 131 having inputs from the slider of 122 and from the slider of 113, and also from the output of thrust circuit 45 and also from a signal representing [dynamic pressure x lift coefficient<SP>2</SP> + drag constant] from multiplier 142; such signals being applied to the several feedback paths 32, 42, 52 of the roll, yaw, and pitch moment generators 31, 41, 51. Altitude and constant reference signals are applied through subtraction network 139 to multiplier 138 also receiving input from airspeed squaring circuit 137 to produce a dynamic pressure signal on line 53, while the lift coefficient signal from 61 is applied to multiplier 141 with a dynamic pressure signal from 138; and is also squared at 144 and applied to multiplier 142 with a dynamic pressure signal from line 53 + a constant drag signal CDO; the product signal being applied to airspeed generator 131. Instrumentation (Fig. 13) is driven from the simulator including heading gyro 151 from yaw power amplifier 84 over line 86, rate of climb meter 152 from multiplier 161 whose inputs are derived from potentiometers 103, 122, and altimeter 153 from the multiplier 161 over integrating amplifier 163. Signals from an altimeter driven potentiometer are applied over line 162 to subtractor 139 (Fig. 1A) and to differencing circuit 149, together with a constant signal, to energize multiplier 164 together with signal from airspeed generator 131 over line 136; the output operating airspeed indicator 154. Divider 166 receives dynamic pressure and airspeed signals over lines 53, 136, whose output is applied to multiplier 167 together with rudder deflection signal from potentiometer 12 (Fig. 1A) and sideslip signal over line 169; the output being applied to adder integrator 168 together with inverted yaw signal from generator 41 over line 48, and output signal from divider 171 receiving airspeed signal over line 136 and a sine roll angle signal from potentiometer 108 over line 118. The quotient signal represents sine-roll angle/airspeed and is added at 168 to yaw signal and dynamic pressure/airspeed x (rudder deflection-sideslip) signal, and integrated. The result is added at 173 to rudder deflection signal, dynamic pressure signal, and feedback signal from multiplier 175 also receiving a lift signal over line 141, and integrated to operate bank instrument 156. Rate of turn indicator 155 is energized from yaw generator 41, and tachometer 157 is driven from thrust generator 45, while altitude gyro 158 is driven by a synchro (not shown) from roll motor 79. The pitch or horizon bar 159 is energized from the slider of potentiometer 122 driven by pitch motor 95. Operation and theory.-The interaction of the several controls and their consequent composite effects on behaviour and handling of an aircraft are simulated, and the controls of the simulated aircraft are linked to the appropriate input members of the analogue circuitry. By mathematics and for the following parameters: it is shown that for roll moment 1. P<SP>V</SP> = #[K i # t  + A(-K 2 # SA  -k 3 #) + q/Vp (K 4 R a - k 5 P a ) + K 6 #]dt, the roll moment generator 31 being stabilized by feedback over 32 which also introduces the division q/Vp, and receiving lateral deflection signals from 25, throttle opening signals from 29 through 45 dynamic pressure signals from airspeed and altitude over multiplier 138, and side slip signals from adder-integrator 168. Sideslip #is subtracted from lateral deflection # SA  and multiplied by dynamic pressure q; then divided by airspeed V p  and multiplied by the difference between roll and heading moments (R A -P A ). The position of 117 driven by motor 79 represents roll related to centre, and the sum of the foregoing quantities is integrated to give total roll moment P A . This modifies the output of bank generator 75 to control the output and sense of roll motor 79. For yaw moment 2. R A  = #[q(-k 7 # SA -k 8 # PR  + KgB) + q/V/p (-K 10 P a - K 11 R a ) - K 12 # PR ]dt; in which yaw moment generator 41 receives dynamic pressure signal q from 138 and rudder deflection signal from 26; to produce the first term. A feedback path combining P A  from 31 V P  from 131 and Ra from 41 to produce an input q/Vp to 41 which together with q to 44 generates the second term; while the output R A  from 41 is inserted at 48, so that positive and negative yaw moment signals are obtained. For pitch moment, 3. Q A  = #[k 13 # t  + q(- k 14  - K 15 # SE  + k 16  # fw - k 17 C 2 ) - q/V p  k 18 Q A K 19 #]dt; in which pitch moment generator 51 receives dynamic pressure signal q and throttle signal from potentiometer 16 through 45, while wheel pitch deflection signal # SE  is applied from potentiometer 13 and flap signal # fw  from switch 21, with lift coefficient C L  from generator 61. Feedback path 52 receives true airspeed signal V p  from 131 and pitch signal Q A  from generator 51. Lift coefficient C L  is derived in 61 by summation of flap signal # fw  from 21, and angle of attack signal a from 1; the output signal plus a constant being applied to multiplier 141 with dynamic pressure q signal to generate an output representing lift, which is added to a cos # cos # signal and applied to 143 for division by airspeed signal V p . The resultant signal is applied to 171 together with pitch movement signal Q A , and for angle of attack, 4. a = #k 20 Q A  + (- k 21  Lift + k 22  cos # cos #)/V p  dt. The cos # and cos # signals are derived from cascaded cosine wound potentiometers 102, 121 respectively driven by roll and pitch motors 79, 95. For true airspeed, 5. V P  = #- k 23  sin # + k 22  α cos # + k 25 # T  + q(- k 26 # fw  + k 27  - k 28 C L 2)dt, wherein generator 131 receives throttle signal from potentiometer 29 through 45, and multiplier 142 derives the product signal of q and the sum of flap signal # fw , drag signal C DO , and the square of lift coefficient C L  derived from 144. The result is applied to airspeed generator 131 together with a signal representing sin # from potentiometer 122 driven by pitch motor 95, and a cos # from potentiometer 103 driven by roll motor 79, and the generator 131 integrates the sum to produce a signal representing Vp. Roll motor 79 driving potentiometers 101 to 108 is controlled over bank signal generator 75 receiving signal from roll generator 31 and a sin # signal from potentiometer 123 driven by the pitch motor. Inputs of yaw generators 81 are derived from potentiometers 101 and 104 driven by roll motor 79 representing Q A  cos # and R A  sin #, while the inputs of pitch generator 91 are derived from pot