Patent GB-755700-A (GB)
Title: Improved apparatus for simulating aircraft control loading and feel
Inventor: GRANDMONT PAUL EMILE
IPC: G09B9/28
Filed: 1954-09-08
Abstract: 755,700. Flight training apparatus. CURTISS-WRIGHT CORPORATION. Sept. 8, 1954, No. 26064/54. Class 4. In flight training apparatus the control members operated by the student pilot are loaded in accordance with signals representative of indicated airspeed supplied by flight computing mechanism and in accordance with the magnitude of movement of the control members in order to give the pilot a sense of " feel " when operating the controls. The arrangement of the apparatus, is shown in Fig. 3 in which the pilot's seat 13 is mounted on a floor 12 apertured for a control column 10 mounted for universal freedom of movement on a mounting 14, 15, 16. The rock-shaft 16 has a parallel-linkage connection 25, 26, 27 with a torque-applying unit 20 comprising a motorgenerator set 20b, a reduction gear-box 20a and a potentiometer 20c controlled by the linkage 25-27 to show the lateral position of the control column 10. Similar units 21 and 22 are provided for loading the control column 10, during fore and aft movement, and the rudders pedals 11 respectively, one pedal only being shown for clarity. A trim control box 30 mounted adjacent the pilot's seat carries trim controls 31, 32, 33 for the elevator, rudder and aileron respectively. As illustrated in Fig. 2, which is representative of elevator control only, the apparatus comprises a force computer 80 supplied at 56 from a flight computer (not shown) with an input representative of a combined function of the simulated angle of attack and airspeed squared and additional inputs 57 stated to be representative of Mach number. Further inputs are provided as follows. The input 58 is derived from the trim potentiometer 35 through conductor 58<SP>1</SP> by means of the manually-adjustable contact 34 and the potentiometer is energized from the flight computer at its opposite terminals by oppositely phased A.C. voltages representing indicated airspeed squared and it is earthed at its mid-point so that the voltage derived at contact 34 can vary both in sense and magnitude for representing negative and positive trim. The input at 59 is derived from the slider contact 77 of the elevator position potentiometer 21c through conductor 59<SP>1</SP>, this potentiometer being energized at its opposite terminals in the same manner as potentiometer 35. The inputs described are algebraically summed by a force summing amplifier 55 which gives an output to energize the control winding 62 of a two-phase torque motor 63 of the torque device 21b, the secondary winding 64 of the motor being energized from a source of reference A.C. voltage Eac. The shaft of the torque motor is directly connected to the shaft 23 of the gear-box which in turn is connected to the control column 10. The inputs so far described are sufficient to provide a steady loading force acting on the control column 10, but this force is modified in accordance with variations in the velocity and acceleration of the control mechanism by the provision of a pair of generators 65 and 68 driven directly by the motor 63. Generator 65 is an A.C. two-phase type having a reference winding 66 energized by a reference A.C. voltage Eac and an output winding 67 connected through conductor 60<SP>1</SP> to the input 60 of force summing amplifier 55. This input Ew represents velocity feed-back to damp the motor 63 and since the phase of the voltage in winding 67 is opposite to that of the control voltages from the flight computer the damping force decreases as the generator velocity decreases. Further mechanism which provides acceleration feed-back comprises a D.C. generator 68, the output of which is fed to a low-pass filter 78 connected to a differentiating circuit comprising a condenser 69 and resistance 70 the output of this circuit being connected to the movable contact 72 of a vibrator having fixed contacts 73, 74 connected to the opposite terminals of a transformer primary winding 75. The transformer secondary winding 76 is connected through conductor 61<SP>1</SP> to the input 61 of amplifier 55 which represents the acceleration feed-back Eα.