Patent GB-418499-A (GB)
Title: Improvements in or relating to automatic or semi-automatic pilot for aircraft
IPC: G05D1/04
Filed: 1934-04-27
Abstract: 418,499. Controlling aircraft. SPERRY GYROSCOPE CO., Inc., Manhattan Bridge Plaza, Brooklyn, New York, U.S.A.-(Assignees of Bassett, P. R., and Carlson, B. G.) April 27, 1934, No. 12765. Convention date, July 21, 1933. [Class 4.] Aircraft altitude is controlled automatically by means comprising a gyroscope vertical or artificial horizon and an expansible container which can be closed to the atmosphere at will, and including means brought into action by expansion and contraction of the container due to change in atmospheric pressure for altering the relation between the gyroscope and the craft to maintain level flight. As shown, the expansible chamber 2 is mounted in a casing 1 provided with a screened aperture 1<1>. The chamber is provided with an outlet 3<1> which may be closed at will by means of a needle valve 3 and is connected to a lever 8 fulcrumed at 9, actuating a pointer 11, and having a rounded end 13 which normally partially closes two ports 14, 15 communicating with pipes 18, 19 connected to differential link gear within an airtight casing 20 containing the gyroscope vertical 201. The gyroscope 201 is air spun and is mounted on trunnions 53 in a gimbal ring 54 pivoted about a fore-and-aft axis in the casing 20. The gyroscope is used as an indicator of the artificial horizon, a concave disc 57 being connected to the gimbal ring 54 by a bracket 58 to show lateral tilt by graduations 59 and a horizontal bar 60 is secured to a bail 61 pivoted on trunnions 62, 621 and slidably connected to the gyroscope through a pin depending therefrom and engaging a trackway 64 in the bail. A reference index 65, for the bar 60, connected to a pivotal member 71 containing airports 22, 22<1> indicates change of level of the aircraft. By means of a pump air is continually extracted from the casing 20 through an opening 21. Air at atmospheric pressure enters the casing through the ports 22, 22<1> and similar ports (not shown) at right angles thereto on the fore-and-aft axis of the gyroscope by means of which servo motors are controlled by differential air pressure created by relative movement between discs 23 secured one to the gyroscope and the other to the gimbal ring 54 and the airports. To facilitate the introduction of a follow-up device the member 71 is rotatable about an axis in line with the trunnion axis 53. Pipes 44, 44<1> connect the airports through the trunnion to the servo-motors. The altitude control is introduced as a variable link in the follow-up device which from the elevator servo-motor includes a flexible cable 24 turning a pulley 25 which rotates one arm of a differential-gear train 26, another arm of which may be turned from a knob 27 through a shaft 28, bevel gears 29, a worm 30 and a wormwheel 31 and by means of which the craft may be caused to climb or dive at will. The third arm of the gear-train 26 turns the worm 32 which rotates the wormwheel 33 mounted on a stub shaft 34 journalled in a bracket 35. A complementary stud shaft 36 is journalled in an opposite bracket 35<1>. Complementary irregular-shaped plates 37, 38 are secured respectively to the stub shafts 36, 34 by means of lugs 39<1>, 39 extending towards each other from the plates. These plates are hinged at their tops by means of a pin 350 journalled in a central dividing plate 43 forming with flexible walls 45, 45<1> a pair of chambers 40, 41. A curved rod 50 having a central collar 5<1> extends through a hole in the plate 43. Compression springs 46, 46<1> are inserted between the plates 38, 37 and collars 47, 47<1> loose on the rod and bearing against the plate 43. Movement of the plate 43 is limited by set-screws 48, 48<1> and each chamber 40, 41 is provided with a small leak orifice and is connected with the ports 14, 15 through the pipes 18, 19. Since air is continuously exhausted from the casing 20 air will be slowly withdrawn from the chambers 40, 41, so that air will flow to the bellows through ports 14, 15. With the valve 3 closed departure of the aircraft from the desired altitude will cause the container 2 to rotate the lever 3 and close one or other of ports 14, 15 to cause reduction of pressure in one or other of the chambers 40, 41 and consequently movement of the plate 43 which through a link 550 rotates the airports 22, 22<1>. At the same time the follow-up connection is still operative since rotation of the worm-wheel 33 rotates bodily the chambers 40, 41. In a modification, a flexible air container 2<1>, Fig. 5, is linked at one side to a blade pivoted on a bracket 61 and the edges of the enlarged lower end of the blade normally, partially overlie the ports 13<1>, 14<1>. The interior of the bellows communicates with the interior of the casing through passages 64<1>, 651 closable by a valve 66.