Patent GB-723529-A (GB)
Title: Improvements in and relating to gust alleviating devices for aircraft
Inventor: NORTH JOHN DUDLEY
IPC: B64C1/00
Filed: 1951-06-11
Abstract: 723,529. Automatic control systems for aircraft. BOULTON PAUL AIRCRAFT, Ltd. June 11, 1952 [June 11, 1951], No. 13767/51. Class 38 (4). [Also in Groups XXIX and XXXIII] Apparatus for the control of aircraft ailerons 6, Fig. 1, comprises a first differential 8 for each aileron arranged to detect differential movement between the aileron and the pilot-operated member 5, and a second differential 20, 22 into which is fed the output of differential 8 and the movements of a gust alleviating member in the form of a lever 31 moved under the control of a gust detector 34, 35, the output of this differential being applied to a servo-mechanism for operating the ailerons. The lever 5 is rockable by the pilot's hand wheel 1 and is connected by links 7 to the differentials 8, each comprising a lever 9 pivoted at 10 to a lever 11 pivoted at 12 and connected by link 13 to lever 14 pivoted at 18 and connected at opposite ends to the aileron 6 and a servomotor 16. Each lever 11 is connected by a link 51 to one arm of a bellcrank 50 and by a spring link 19 to one end of a lever 20 pivoted at 21 on an arm 22 pivoted at 23. The other ends of levers 20 are connected by links 30 to opposite ends of lever 31, and the free ends of arms 22 are connected by links 24 and hydraulic relays 25 to delivery controlling members 28 of variable delivery pumps 29 which supply the servomotors 16. Thus movements of the ailerons in opposite directions by the servomotors 16 are fed back by links 13 to return members 28 to the neutral position. A vertical gust is detected by a differential of pressure between angularly-spaced pressure heads 34, 35 mounted forward of the nose of the aircraft and causing a pick-up 36 to supply a signal amplified at 37 to a hysteresis electric motor 32, Fig. 2, which turns the lever 31 via gearing 61-63, 55 and overload release clutch 56, 59. Turning of lever 31 causes movement of arms 22 to vary the deliveries of the pumps to move the ailerons synchronously and in the same direction to vary the lift of the wings to counteract the gust. The other arm of each bell-crank 50 is connected by a link to one end of a lever 47 pivoted centrally to arm 46 of a bell-crank, the other arm 44 of which carries a link 43 operating a potentiometer 41, movement of which applies a feed-back signal to the amplifier 37. Movement of the ailerons in opposite directions merely pivots lever 47 about its centre, but movement of the ailerons in the same direction causes lateral movement of the lever 47 with consequent pivoting of bell-crank 44, 46 and actuation of potentiometer 41. Potentiometers 53, 54 may be operated simultaneously to provide indication to the pilot and to a recording camera. The gust-controlled movements of the ailerons are superimposed on the pilot-controlled movements thereof. A three-position lever 68 is provided for the pilot to select (a) direct manual operation of the ailerons, in which case the lever moves link 69 to engage latches 70, 75 in notches 73 in the arms 11, opens by-pass valves 79 to interconnect both sides of servomotors 16, and opens a valve 82 between heads 34, 35, to prevent the establishment of a pressure difference therebetween; (b) power operation of the ailerons in which case the lever disengages the latches, closes valves 79 but leaves valve 82 open; or (c) power operation plus gust alleviation, in which case the lever additionally closes valve 82. In lever positions (a) and (b) the lever 31 is held in its central position by a spring-loaded member 64, Fig. 3, acting on parts 65 of clutch member 56, the member 64 being removed by a solenoid 67 when lever 68 is moved to position (c). Feel is provided by springs 84. Reference has been directed by the Comptroller to Specification 650,305, [Group XXXIII].