GB663269A - Improvements in power operated flying controls for aircraft - Google Patents

Abstract

663,269. Controlling aircraft. SAUNDERS-ROE, Ltd., SWAIN, A. E., and WALKER, G. E. Feb. 27, 1950 [Jan. 27, 1949], No. 2162/49. Class 4. A power operated flying control system for aircraft of the type comprising a control surface, an operating member movable in opposite directions from a neutral position to impart movement to the control surface, a feel generator for imposing on the operating member a resistance to movement thereof which increases progressively with displacement of the operating member from its neutral position and control mechanism for varying the amount of resistance so imposed bv the feel generator is characterised by the provision of a trimmer for adjusting the neutral position of the operating member by applying trim. to the feel generator (i.e. by varying its datum) the trimmer being so arranged that the control mechanism for varying the amount of resistance imposed by the feel generator to movement of the operating member serves also to vary the rate of application of trim to the feel generator by the trimmer in such a way that the rate of application of trim is decreased as the resistance imposed by the feel generator is increased and vice versa. In the embodiment shown, the input shaft 16, which is rotated by movement of the pilot's control member, is coupled by gearing 54 to a drum 55 coupled by a cable 56 to a power unit (not shown) for moving the control surface. To the end of the shaft 16 is fixed a first lever 131 of the feel generator, which lever receives a pivotal movement determined in amplitude by the movement of the control member. Parallel to the shaft 16 are a torque shaft 36 and a torque tube 37 which are attached together at their right hand ends. To the other end of the torque shaft 36 is fixed a bifurcated lever 135 extending towards and beyond the shaft 16. To the other end of the torque tube 37 is fixed a trimming lever 138. The lever 135 has therein slots 134 which receive a coupling pin 132 extending through a slot 57 in the lever 131 and also through a cam slot 58 in a cam slide 59. As the lever 131 rocks the pin 132 will be caused to travel along the slots 57 and 58 which latter slot will impart a rotational movement to the lever 135 and the torque shaft 36. The trimming lever 138 has therein a rectangular slot 139 engaged by a square projection 145 on a nut 146 carried by a threaded shaft 147. The shaft 147 is mounted in a carriage 141 which is movable transversely of the torque tube to vary the distance of the abutment 145 from the torque tube 37. The shaft 147 is driven through bevel gears 152 from a splined shaft 60 in turn driven by an electric motor 51. Response both of the feel generator and of the trimming adjuster to changes in airspeed is obtained by a capsule 50 connected to a pitot head so that expansion or contraction of the capsule operates contacts 61, 62, 63 to cause an electric motor 49 to rotate in one direction or the other to drive a threaded shaft 64 and, by means of gears 68 and a chain drive 69, a pair of parallel threaded shafts 66, 67. The shaft 66 engages nuts 70 on the cam slide 59 and the shaft 67 engages nuts 71 on the carriage 141 supporting the abutment 145 for the torque tube and the shafts are oppositely threaded so that, in response to changes in airspeed, the cam slide 59 and the abutment 145 will be moved in opposite directions. When the airspeed increases, the cam slide 59 will be moved to the right, bringing the pin 132 opposite a more sharply curved portion of the cam slot 58, with the result that the feel generator imposes a resistance to movement of the control member which increases progressively with increase in airspeed. At the same time the abutment 145 will be moved to the right, thereby increasing the effective length of the trimming lever 145. Consequently the rate of application of trim will decrease with increase in the airspeed. In a further embodiment (Fig. 3, not shown) the levers 135 and 138 lie substantially vertical and extend in opposite directions from the axis of the torque shaft 36. In a still further embodiment, Fig. 5 (not shown), a hydraulic transmitting mechanism is employed. Specifications 619,984, 619,987 and 619,988 are referred to.