Patent GB-727173-A (GB)
Title: Improvements in or relating to control systems for airplanes
Inventor: FEENEY THOMAS AQUINAS
IPC: B64C13/00
Filed: 1952-11-11
Abstract: 727,173. Aircraft controls. NORTHROP AIRCRAFT, Inc. Nov. 11, 1952, No. 28370/52. Class 4. An aeroplane control system comprises a pilot's control assembly including a pilot's stick mounted to rotate about intersecting longitudinal and lateral axes, a pair of driving gear sectors mounted to be rotated by the stick about one of said axes, a pair of driven gear sectors meshing with said driving gear sectors and mounted to rotate about the other of said axes, a driving lever connected to'move with each of said driven gear sectors, a driven lever connected to move with each driving lever, and controlling an aircraft surface, said driven levers being mounted coaxially, and being coradial when the control stick is in neutral, and elastic means interconnecting said driven levers to urge them coradial when the levers are separated due to rotation of said stick about said longitudinal axis. Dual control mechanism is described, Fig. 2, the control sticks 22, 122, being mounted on forks 20 pivotally mounted about an axis B-B on blocks 17 freely rotatable about an axis A-A. Driving gear sectors 25, 26 are formed on the fork, meshing with driven gear sectors 15, 16 fast to independently rotatable cylinders 14, 12 on the shaft 10. Fast to these cylinders are driving levers 30, 29 connected by links to driven levers 45, 44. Pulley 41 is rotated with lever 45, and pulley 42 with lever 44, and pulley 42 controls the cables 5a, 5b connected to levers 55 controlling the servo motors for the left hand elevon, and similar apparatus for the right elevon is controlled by pulley 41. Levers 55 shift a fluid pressure valve 67 to actuate each servomotor 61, and mechanical feed back for the elevon is provided by link 60. Rotation of the control stick about axis A-A rotates gears 15, 16 in the same sense to operate the elevons together, while rotation about axis B-B operates the elevons differentially. As seen in Fig. 3, the two levers 44, 45 are mounted on an axis 37 on each side of a block 100 bearing two reinforced leaf springs 102. Each lever has two rollers 104 contacting the inside of each leaf spring, so that when the levers 44, 45 move together there is no constraint, but when they separate for aileron action, the leaf springs are forced apart, one by each lever, to provide a centering force. Also shown in Fig. 2 are two levers 50, one depending from each block 17, and connected at their ends by a cable 51 and turnbuckle 52, tightening of which eliminates backlash from the system. Fastened to one lever 50 is a rod 84 secured to a lever 82 fast to a shaft 81. This shaft is subjected to a centering torque from a double acting spring box 77 and by the action of a cam 86 urged by the rod of a ram air pressure bellows 94 into contact with a cam follower lever 85 fast to shaft 81, providing elevator centering action for high and low airspeeds. An alternative control stick assembly is shown in Fig. 5, where the control stick 22 when rotated about a longitudinal axis rotates cylinder 110 about the same axis, so that bevel gears 121, 122 rotate gear sectors 117, 119 in the same sense, and when rotated about a lateral axis, rotates cylinder 110 about the same axis, the bevel gears then rotating gear sectors 117, 119 in opposite senses. One cable lead requires to be crossed in this case. The spring block 100 is then mounted between pulleys 123 and 124 having rollers engaging the leaf springs. Specification 614,102 is referred to.