Patent GB-611560-A (GB)
Title: Simulated flight control loading and centering means for grounded aviation trainer
IPC: G09B9/28
Filed: 1946-05-01
Abstract: 611,560. Ground aviation trainers. LINK AVIATION DEVICES, Inc. May 1, 1946, No. 13209. Convention date, June 27, 1945. [Class 4] A ground aviation trainer is provided with pneumatic means for simulating the resistance to movement of the controls, or control loading, resulting from the aerodynamic effect of the slipstream on the control surfaces, and also for simulating trimming of the control surfaces. The invention is described as applied to a trainer of the type in which a dummy fuselage is provided with pneumatically - operated mechanism controlling its pitching, banking and turning movements, as described in Specifications 370,128 and 481,376. Simulated elevator control loading and trimming, Fig. 2.-The handwheel 30 through its shaft 32 is attached to pivotally-mounted members 38, to which is secured the centre plate 56 of a double bellows 52a, 52b. The member 56 is connected by a spring-loaded link 99 to a rotary control valve 63 which is connected by pipes 62, 64 to the bellows 52a, 52b, and by a pipe 73 to a regulator bellows 74, which in turn is connected to the airspeed regulator bellows 82 by a pipe 81. Upon moving the hand wheel and shaft horizontally in a fore-and-aft direction to operate the pitching control bellows, the link 99 operates the valve 63 to put one of the bellows 52a, 52b into communication with the vacuum source, and the other into communication with atmossphere, a force resisting movement of the hand wheel thus being transmitted to the latter by the centre plate 56. If the wheel 30 is released it returns to its neutral position under the action of the bellows, and the control valve returns to its central setting. In order to simulate the increased loading as the hand wheel 30 is moved further from its neutral position, the upper plate 76 of the bellows 74 is connected to one of the pivoted members 38 through a linkage 116, 117, 118, a roller 125 and cam plate 126, and a spring 78, whereby increasing movement of the wheel and members 38 results in corresponding increases in the tension of the spring 78 and degree of vacuum in the bellows 74, to increase the resistance imposed upon the hand wheel. The effect of variation of airspeed on elevator control loading is simulated as the result of variation in the vacuum in the airspeed regulator bellows 82. The simulated trimming mechanism comprises a hand wheel 130 which, through a screw and nut 133, 134, operates links 135, 140 respectively connected to the control valve 63 and the cam plate 126. With the hand wheel 30 in the displaced position, the wheel 130 may be rotated to turn the control valve 63 to its central position, thus neutralizing the bellows 52a, 52b to relieve the force imposed upon the control. Trimming also results in the normal or neutral tension being applied to the spring 78 controlling the bellows 74. Simulated aileron loading and trimming (Fig. 3).-The hand wheel shaft 32 carries a pinion 170 meshing with a toothed sector 171, the latter being provided with an arm 172 connected by links 173, 174, 177 to the centre plate 166 of a double bellows 163a, 163b, the plate being connected by a spring-loaded link 178 to a rotary control valve 168. Rotation of the hand wheel from its neutral position causes operation of the valve 168 and bellows 163a, 163b, the latter giving rise to a force resisting rotation of the hand wheel. The plate 166 is connected by a linkage 200, 201, 203, a cam 215 and cam plate 213, and a spring 211, to a bellows 182 which serves to increase the control loading as the wheel 30 is rotated. Trimming is simulated by means of a control wheel 220 on a shaft 221 carrying a gear wheel 222 meshing with a pinion 223 connected to a flexible shaft 224 which in turn is connected to the control valve 168 by a link 229, and the cam plate 213 by a linkage 231, 232, 235, 236. Operation of the control 220 enables the valve 168 to be centralised, to neutralize the loading of the bellows 163a, 163b when the hand wheel has been turned through any angle. Simulated rudder loading and trimming (Fig. 4).-The rudder pedals 256 are connected by links 265, 274 to bellows 267, 275 respectively, and by links 259 to the rudder bar 260 which, through a link 282 operates a rotary valve 279 connected to the bellows by pipes 278, 280. Movement of either pedal results in operation of the bellows to oppose the pedal movement. A thumb wheel 290 is provided for trimming purposes, the wheel being connected to the control valve 279 through gearing 291, 292, 293, and a linkage 297, 304, 305, 306.