Patent GB-548190-A (GB)
Title: Improvements in and relating to gyroscopic apparatus, more especially in automatic pilots for aircraft
IPC: G01C21/18
Filed: 1940-03-13
Abstract: 548,190. Automatic control systems for aircraft ;  gyroscopic apparatus. SPERRY GYROSCOPE CO., Inc. March 13, 1940, No. 4753. Convention date, March 18, 1939. [Classes 35 and 38 (iv)] [Also in Group XX] A gyro-vertical has means whereby erecting torques may be applied thereto in dependence on the relative positions of gravity responsive means and a craft on which it is mounted or in dependence upon the relative positions of gravity responsive means and the gyroscope and means are provided whereby either type of control may be selected. An automatic pilot comprising such a system may comprise a side-slip detector to eliminate side-slip by exercising control on the rudder through a course-changing motor. A gyro-vertical 1, having pick-offs 18, 181 such as inductive means of the kind described in Specifications 360,428 and 417,995, [Group XXXVIII], whereby ailerons 27 and an elevator 271 are controlled through amplifiers 241 and servomotors 25, 251 to stabilize an aircraft in respect of longitudinal and transverse axes, is associated with gravity responsive means 11, 12 operating independently of the gyroscope whereby precessive torques. may be applied to erect the gyroscope. These are preferably mercury levels co-operating with pairs of electrical contacts fixed relatively to the craft through which are selectively energized electromagnets 15, 151 and 17, 171 of an induction-type erecting device of the kind described in Specification 492,670. The gravity responsive means are each maintained parallel to the horizontal plane of the aircraft when switches 28, 281 have been thrown to cut out the automatic stabilization of the craft by follow up motors 29, 291 geared to the mercury levels and energized from the pick-ups 18, 181 respectively. Bank and tilt indicators 32, 33 may be operated electrically from transmitters 31, 311 coupled to the axes of the levels. To disable the gravitational control during a turn a switch 34, normally in the left-hand position, is reversed whereupon the correct banking angle is given to the craft by corrections causing the mercury level 11 to control the ailerons 27. At this time the level may be fixed parallel to the craft by a cam operating a wedge 72 causing a scissors device to close upon a pin fixed eccentrically to the axis of the level. To change the flight attitude without severing the gyroscopic control a small " joy stick " 37 may be used to energize selectively the follow up motors 29, 291. Fig. 3 shows a gyroscopic control adapted to secure correctly banked turns and involving initiation of a turn by first imposing a banking angle on the craft. A platform 41, carrying the gimbal mounting of the gyroscope and the inductive pick-offs, only one 19<SP>1</SP> of which is shown, is itself mounted on gimbals and adapted to be correctly levelled by knobs 48, 48; co-operating with sectors 50, 50<SP>11</SP>; on one gimbal ring and liquid levels 45, 451 on the platform. A turn in azimuth may be determined by the setting of the knob 48, the sector 50 being marked with rate of turn indications. The correct rate of turn for the banking angle then imposed by the automatic pilot is obtained by an auxiliary pendulum 52 which operates a reversible motor 56 to adjust a potentiometer 59 determining the speed of a course adjusting motor 60 associated with the directional gyroscope 66 controlling the vertical rudder 55. Follow-up means such as 68 are associated with all the control surfaces though shown only on the rudder 55. Specification 548,195 also is referred to.