GB763506A - Monitoring apparatus for automatic pilot systems - Google Patents

Abstract

763,506. Automatic control systems. BENDIX AVIATION CORPORATION. May 14, 1954 [June 30, 1953], No. 14249/54. Class 38 (4). An automatic control arrangement for an aircraft having a main control surface 10 and a trim surface or tab 12, includes a safety device for disconnecting the trim tabs 12 from its drive when the load on the main control surface 10 exceeds a predetermined value. As shown, pitch deviation is detected at 13 by an artificial horizon gyro, and applied over amplifier 17 to a servomotor 19 having a follow-up circuit comprising rotor 25 of inductive device 22; servomotor 19 actuates shaft 23 to move link 42 and rotate arm 51 about an axis 52; arm 51 is coupled by springs 53 to the main control surface 10, and is coupled by link 57 to a control tab 11. The springs are such that a variation in pitch first results in a movement of the main surface 10 and control tab 11 as a unit to correct the pitch variation until the loading of the surface 10 is just greater than the torque produced by springs 52; further rotation of arm 51 then results in a deflection of the control tab 11 relative to the surface 10 and in such a direction as to produce a torque on the main surface 10 as to aid the torque exerted by the springs 52. This effect continues until the surface 10 and control tab 11 are again in line and the pitch deviation corrected. Amplifier 17 also feeds a servomotor 60 which is coupled through an irreversible transmission gear 61 to actuate a trim tab 12, so that variation of pitch due to a change in loading of the aircraft (fuel consumption or passenger movement) may be compensated by a permanent deflection of the trim tab 12. The trim tab 12 when deflected exerts a loading on the main surface 10, and should the main surface 10 become locked or motor 19 inoperative, this loading may become so great as to produce undesirable results when the manual or electrically-operated clutches 36, 35 are opened to place the aircraft under manual control at 31. To avoid this overloading, clutch 70 is opened when the angle between the main surface 10 and arm 51 exceeds a predetermined value; to this end, an arcuate contact 75 is carried by the main surface 10, and arm 51 carries a contact 77 rotatable over the arcuate contact 75, so that when the relative displacement exceeds a given angle, clutch 70 is opened and the trim tab 12 is no longer driven. Specifications 632,309, [Group XXIV], and 662,831 are referred to.