Patent GB-762826-A (GB)
Title: Improved simulated control loading for flight training apparatus
Inventor: SHERMAN ALBERT JOSEPH
IPC: G09B9/28
Filed: 1954-10-27
Abstract: 762,826. Flight training apparatus. CURTISSWRIGHT CORPORATION. Oct. 27, 1954, No. 31063/54. Class 4. In flight training apparatus a simulated control member is loaded by a resisting force responsive to quantities representing the displacement of the simulated control, simulated airspeed and trim setting and other quantities representative of the pressure applied by a student to the control member and of the degree of movement of a member which adjusts the magnitude of the resisting force, whereby the load applied to the control member by the student is balanced by a loading force representative of simulated airspeed and control trim setting. A control member 1 is connected to a rod 12 which carries a plunger 13 operating within a cylinder 16. This carries a diaphragm 18 and an adjustable cap 17 to locate loading springs 14, 15. The cylinder carries a rod 33 forming the piston rod of a piston and cylinder assembly 10 which is connected by conduits 36, 37 to a control valve 9. The valve has an axially movable stem 40b operated by a motor 8 and the hydraulic circuit is completed by a motor driven pump 50 and a reservoir 48. The wiper arm of a potentiometer 3 is mechanically coupled to the member 1 for operation thereby and the ends of the potentiometer on either side of an earthed centre tap are energized by voltages of opposite polarity variable according to the square of simulated airspeed (vi<SP>2</SP>) and derived from a double potentiometer 64, 65 each section of which is contoured for deriving voltages according to a square function, the wiper arms 66, 67 being manually adjustable by a control 68. The double potentiometer 64, 65 energizes also a potentiometer 6 which is adjusted by a control 63 to develop a signal representative of amount of trim and the signals derived from potentionmeter 3 representing control member displacement and simulated airspeed and the trim signal from potentiometer 6 are fed to a summing amplifier 7. A potentiometer 4, secured to cylinder 16 and energised by voltages E of opposite polarity, co-operates with an insulated wiper arm 20 on the rod 12. The arm 20 picks off a voltage indicative of the pressure actually applied by the student on the member 1 and feeds it through conductor 26 to amplifier 7. A further potentiometer 5 has its wiper arm connected to the stem of the valve 5, the derived signal being fed to amplifier 7. The output from the amplifier is fed to the control winding 54 of motor 8 which remains inoperative if the loading force applied by the springs 14 or 15 to the member 1 is correct for the values of airspeed and trim selected by controls 68, 63. Should the loading force be incorrect the inputs to amplifier 7 will unbalance and an output signal will result which will energise motor 8. This will operate valve 9 to admit pressure liquid to the cylinder 10 on the appropriate side of piston 32 to adjust the position of cylinder 16 thereby adjusting the loading of springs 14, 15 to a correct value. A further embodiment is described wherein member 1 is connected to an endless cable incorporating tension loading springs.