GB780668A - Improvements in or relating to aircraft - Google Patents

Abstract

780,668. Aircraft feel simulators. HOBSON, Ltd., H. M., WESTBURY, R., and SMITH, C. P. Nov. 23, 1955 [Dec. 15, 1954], No. 36350/54. Class 4. A hydraulic feel simulator for power operated aircraft controls having a hydraulic jack including a piston and housing movable relatively by a linkage operated by the pilot's control against the hydraulic pressure in the housing which increases with airspeed, comprises a spring system for opposing movement of the control member, and means operative while hydraulic pressure prevails in the housing, to displace the spring system to an ineffective position, the system automatically returning to the effective position on failure of the pressure. In one embodiment, Fig. 4, the control column 10 operates the servo system transmitter 13 by a rod 12 pivoted at 16 to a lever 17 pivoted to the aircraft at 18 and to the jack piston rod 20 at 19. The housing 24'is pivoted to a lever 41 at 40 and is attached to a spring 48 anchored to the aircraft. Lever 41 is pivoted to the aircraft at 42, and at its other end to two rods 145 each secured to a pin 144 working in a slot 143 in lever 17. Each pin 144 is attached to a spring 46 anchored to the aircraft at 47. While there is no hydraulic pressure in the housing, spring 48 acts to urge pins 144 to the position shown, where springs 46 act to centre the control column. While hydraulic pressure prevails in the housing, the jack contracts and raises lever 41, placing the pins in the upper ends of slots 143, where they are substantially ineffective. In Fig. 5, the pin 19 engages two slots 50, each in a rod 51 urged outwardly by a spring 54, the two rods and springs constituting a double acting spring box. While there is hydraulic pressure in housing 24, however, pressure fluid supplied by conduits 56 acts on pistons 52 to compress springs 54, whereby the pin 19 moves freely in slots 50 with lost motion. In Fig. 6, a lever 57 has a pin 244 at one end engaging a slot 43 in lever 17. The other end of the lever has a collar 59 acted on by spring 58 and a piston 61 subject to the hydraulic pressure in the housing 24. While the hydraulic pressure prevails, piston 61 is raised and the pin 244 is near pivot 18, whereby spring 58 is substantially ineffective to centre the column 10, If the pressure fails, the pin moves to the position shown, and spring 58 provides centering forces. Specifications 734,437 and 740,510 are referred to.