Patent GB-520177-A (GB)
Title: Improvements relating to automatic control apparatus for aircraft
IPC: G05D1/04
Filed: 1938-07-13
Abstract: 520,177. Fluid - pressure servomotor - control systems. SMITH & SONS (MOTOR ACCESSORIES), Ltd., S., and MEREDITH, F. W. July 13, 1938, No. 20801. [Class 135] Control apparatus for aircraft comprises means associated with the rudder for controlling the course in accordance with detected turn in azimuth and means, responsive to lateral acceleration or side-slip, operating course-setting means to control the lateral acceleration or side-slip when the aircraft is banked to effect change of course. To change course it is necessary only to bank the aircraft, the rudder being automatically actuated to suppress side-slip. The apparatus shown in Fig. 1 comprises a frame 12, mounted on trunnions 13 arranged longitudinally of the aircraft, supporting on tranverse trunnions 11 a platform 10 carrying gyroscopes 100. 200. One of the trunnions 13 is provided with a cableoperated pulley 80, and the platform is provided with an arm 15 engaging a slotted sector 16 provided with a cable-operated pulley 81. The gyroscope 100 consists of a rotor 18 mounted in gimbals 19, 20 which operate valves 22, 25 controlling servomotors for the elevator and rudder respectively. The gyroscope 200 consists of a rotor 30 mounted in gimbals 31, 32 the gimbal 32 operating a valve 34 controlling a servomotor for the ailerons. The gimbal 31 operates a valve 36 controlling a precessing-motor 37 connected to the gimbal 32. A bracket 40 on the frame 10 supports nozzles 41, 42, the nozzle 42 co-operating with a blade 43 attached to a weight 44 which is attached by springs 45 to a block 46 on a spindle which is coaxial with the trunnions 13. A contact-arm 48 on the block rides over contacts 50, 51 in circuit with an electromagnet 54 for operating a valve 56 provided with inlets 58, 59 communicating with the nozzle 42 and a pressure-supply respectvely. The valve is provided with a pair of outlets leading to a banktrimming motor 70 which is connected to the gimbal 31. The valve is provided also with a pair of outlets leading to an azimuth-precessing motor 73 which is connected to the gimbal 19. When the electromagnet is energized and deenergized, the inlets 58, 59 are connected through the valve to the motors - 73, 70 respectively. Normally the contact-arm 48 engages an insulating-section, the blade 43 has one edge disposed across the centre of the nozzles 41, 42 and the pressure-difference at the inlets 58, 59 is applied to the bank-trimming motor 70. When the aircraft is banked, side-slip is detected by the weight 44, and the blade 43 is displaced, thereupon, the pressure at the inlet 58 is increased or decreased, 'the;,electromagnet 54 is energized through one of the contacts 50, 51, and the motor 73 applies torque to the gimbal 19. The resulting precession of the gimbal 20 operates the valve 25 and the associated servomotor moves the rudder to turn the aircraft in the direction required to control side-slip. The axis of the jets is arranged above the axis of the frame 12 so that when the frame is tilted to initiate a turn, the jets are displaced relatively to the blade 43 even if the side-slip is zero. To produce a flat turn, the spindle 47 is turned by means of a cable-operated pulley 82, the pulley 80 being held stationary. An alternative apparatus comprises, as shown in Fig. 4, an azimuth gyroscope consisting of a rotor 110 mounted in gimbals 111, 112, the gimbal 112 being mounted in a bracket 113 on a worm-wheel 114 and connected to a piston-valve 116 mounted in a cylinder 117. The worm-wheel is carried by a distributing-member 118 which is rotatable in a block 119 and is formed with grooves 124, 125 and 123 communicating with inlet pipes 120, 122 and an outlet pipe 121 for the cylinder 117. The groove 123 communicates with a pressuresupply 129; and the grooves 124, 125 communicate through pipes 126, 127 with a servomotor 128 having its piston-rod 130 connected to the rudder. To provide a follow-up, the piston-rod is geared to planet wheels 134 which are geared to a worm 137 engaging the worm-wheel, and are also geared to a rotor 143 which is driven in opposite directions by jets 148. 149. When sideslip occurs, a difference in pressure at the nozzles is produced by means such as the blade 43 and associated parts described with reference to Fig. 1, the rotor turns the worm 137, and the rudder is displaced to control side-slip. Specifications 365 186 and 422,813 [both in Group XXXIII], are referred to.