Patent GB-411620-A (GB)
Title: Improvements in or relating to automatic steering or stabilising devices, particularly for aircraft
IPC: G05D1/08
Filed: 1933-03-13
Abstract: 411,620. Automatic controls for aircraft and other vehicles. BOYKOW, J. M., 2A, Fontanestrasse, Lichterfelde, Berlin. March 13, 1933, Nos. 7596 and 7597. Convention dates, March 12, 1932 and May 6, 1932. [Class 4.] In an automatic steering device for aircraft and watercraft in which a switching device for the rudder servomotor is adjusted by a measuring instrument influenced by disturbances of the equilibrium of the vehicle, the switching element is connected by a spring attached to the end opposed to that carrying the contact to an inelastic damping element the moving velocity of which is proportional to the force exerted by the spring. Transverse stabilization. The switching device, Fig. 3, comprises a contact arm 8 carried by an axle 7 and contact track 5 carried by an axle 1 on which is mounted a pulley 3 for the aileron control cables. The contact arm 8 is actuated by an electromagnetic turning device comprising a rotor 6 and stator 6<a> the coils of which are energized according to the stabilizing values. The contact arm 8 is connected to the rotor 13 of a hydraulic damping device by means of a spring 10 and a crank lever 11. When contact is established between the parts 8, 5 the motor 57 is started and drives the axle 1 and pulley 3 through worm gearing 55, 56. The axle of the motor 57 is coupled to an eddy current brake having coils 60, 61 one of which is permanently connected to an electrical source and the other, which is oppositely wound, is connected in series with the field coils of the stator 6<a> whereby the braking effect is made inversely proportional to the stabilizing value. Alternatively a hydraulic or pneumatic brake may be used and be similarly regulated. The electromagnetic turning device 6, 6<a> is influenced by a gyroscope, Fig. 4, having its axis of rotation transverse of the craft and mounted for precession about a vertical axis 19 and a horizontal axis 18. The precession axis 19 may be coupled direct to axle 7 but in the form shown precession about this axis is arranged to apply pressure to crystal or carbon resistance columns 21 through rod 25 and bell-crank lever 23. These resistances 21 are arranged in the exciting circuit of the turning device 6, 6<a> in the manner shown on the right hand side of Fig. 1. In order to prevent a constant deviation of the aircraft from its normal altitude a pendulum 31, may also be employed to influence the stabilizing device. The pendulum deflections are damped by a dashpot. Turning moments proportional to the turning velocity of the aircraft are exercised upon the pendulum by a turning device 33, 33<a> of which the stator field coils are arranged in series with the resistances 21. The coils 6<a> are supplied with additional current, when the pendulum is deflected, through a variable resistance 36 and contacts 31, 35. Course stabilization. The switching device used for course stabilization is the same as that previously described but with the addition of the parts shown in the left hand side of Fig. 3 ; these comprise a contact-carrying arm 39 fixed to the spindle of the damping device 13, a brush arm 38 fixed to the spindle of a second similar damping device 37, and an electromagnetic turning device 40, 40<a>. Precession of the gyroscope about the axis 18 causes pressure on one or other of resistance piles 22 which are mounted on the gimbal ring 17, Fig. 4, and current is thus supplied to the device 6, 6<a> shown to the left of Fig. 1. If now the contact track 39 is displaced relatively to brush 38 current is supplied also to the field coils 40<a> and to coils, not shown, wound around but separate from the coils 6<a> as may be seen from the wiring diagram on the left side of Fig. 1. The damping device 37 thus begins to operate if the sum of the deviations of the aircraft from its normal position tend to the same side, and the aircraft will be returned to its right course when the positions of the damping elements again correspond to each other. Longitudinal stabilization. Three means are described for influencing the steering motor for pitch control. Firstly a spring balance, Fig. 8, comprising a weight 49 carried by an arm 51 pivoted about a fore and aft axis. Weight 49 is balanced by spring 50 but moves up or down under the influence of vertical accelerations whereby one of two resistances 52 will be compressed and the supply of current to field coils 6<a>, Fig. 2, regulated to apply elevator correction. This device also applies a correction for centrifugal acceleration experienced in turns. Secondly a device responsive to changes in air speed comprising a spring loaded wind vane, applies pressure to resistance columns 48. An air speed responsive device may regulate the flow of current to field coils 43<a>, Fig. 6, of a spring balance comprising a rotor 43 adapted to turn a spring centralized lever 42, the arms of which act through damping devices 44 on resistance columns 45. Resistances 45 also control the flow of current to field coils 6<a>, Fig. 2, but only when a pendulum 31, Fig. 2, is out of centre. The device shown in Fig. 6 may be combined with the wind vane and both devices may also be combined with that of Fig. 8. When a hydraulic or pneumatic rudder motor is used the throttle valve is adjusted electromagnetically according to the pressures exerted on the carbon resistances.