Patent GB-531390-A (GB)
Title: Improvements in and relating to automatic pilots for aircraft
IPC: G05D1/04
Filed: 1939-05-11
Abstract: 531,390. Automatic pilots for aircraft. SPERRY GYROSCOPE CO., Inc. May 11, 1939, No. 14066. Convention date, May 14, 1938. [Class 135] An automatic pilot for aircraft has the control of the ailerons transferred during or immediately preceding a turn from a long-period gravity responsive device such as a gyrovertical to a relatively short-period gravity responsive device, such as a pendulum in order that the craft may be correctly banked. In the form shown in the Figure the ailerons 45 are operated by a fluid-pressure servomotor 44 under the control of a relay valve 43 actuated by opposed diaphragms 29, 29<SP>1</SP>. The diaphragm chambers are connected through pipes 27, 28 and selector valve 20 either with pipes 17<SP>1</SP> 18<SP>1</SP>, leading to nozzles 17, 18 controlled by a semicircular valve 16 or with pipes 7<SP>1</SP>, 81 leading to nozzles controlled by a semi-cylindrical valve 4. The valve 4 is actuated by the gyro-vertical 1 acting through toothed wheels 60, 61, while the casing housing the nozzles which is evacuated through a conduit 6 is rotatably mounted in a ball-bearing and coupled to a diaphragm 10 subject to the pressures in the pipes 7<SP>1</SP>, 8<SP>1</SP>, to give a follow-up action. The valve 16 is directly connected to the short-period gravity device which in this form comprises a wheel 12 having a hollow rim partly filled with mercury and provided with a perforated partition 14 to make it pendulous and also damp its movement. In a modification an ordinary pendulum is used damped by a vane dipping into a liquid bath. The casing housing the nozzles 17, 18 may be rotatably mounted and coupled to a diaphragm similarly arranged. to the diaphragm 10. The valve 20 which is centralized by springs 30, 30<SP>1</SP>, is actuated by a gyroscopic turn indicator 37 connected by a link 40 with the valve spindle. A brake 96 is fitted to prevent the indicator responding to slight yaws of the craft as distinct from a definite turn. A manually operable pin 91 can be pressed into engagement with a conical recess 92 in the turn indicator to restore the selector valve to the straight line flight position before the turn is completed. In a modification a setting knob on the directional gyroscope adapted to be pressed in to cage the gyroscope and rotated to move it to a new position is connected by a lever with the valve 20 so that as the setting knob is pressed in the change-over valve is operated. The lever may be operated when a setting spindle carrying a toothed gear is moved into engagement with a second gear connected to the movable nozzlecarrying casing of the directional gyroscope. In this form the setting spindle may be geared to an indicating disc on the face of the instrument and the movable casing may be geared to a course indicating card. In a further modification the change-over valve 20 is actuated by a bellows arranged in a closed chamber, the bellows and chamber being connected through restricted conduits with pipes connecting each relay diaphragm chamber both with the valve nozzles of a directional gyroscope and those of a rate of turn indicator. Specifications 515,290 and 531,388 are referred to.