Patent GB-855783-A (GB)
Title: Apparatus for directing guided missiles
Inventor: SURTEES HOWARD
IPC: F41G7/30
Filed: 1954-04-15
Abstract: 855,783. Sighting devices. FAIREY CO. Ltd. May 20, 1955, [April 15, 1954], No. 11258/54. Class 97(1) Apparatus for directing a guided missile from an aiming point nearer to a target than the launching point includes a device enabling the aimer to observe the position of the approaching missile in relation to a line of sight passing through the aiming point from the target, and arranged to bring images of the approaching missile and the target simultaneously into the same apparent field of view when the missile is approaching the aiming point along the line of sight, so that the aimer can control the missile to approach and pass over him along the line of sight. As shown in Fig. 1 the apparatus employed by the aimer of a guided missile comprises a periscope tower 10 rigidly connected to a control box 11 and mounted by means of a thrust bearing 12 to rotate about a vertical axis on a driving assembly 13 which is rigidly secured to a tripod. The control box 11 has a handgrip for moving the tower and a control column 16 arranged to control the direction of flight of the missile through radio equipment wholly or partly housed within the control box. The housing of the periscope is provided with two holes 17, 18 to receive binoculars (not shown), the right eyepiece of which has a direct view through the tower whilst the left eyepiece views in the reverse direction through a mirror system. The mirror 20 is arranged to be automatically turned about a vertical axis in accordance with a desired programme. The mirror is carried by a vertical shaft driven from a central potentiometer shaft 31 driven by means of a differential assembly; the lower bevel 37 of the differential is driven from an electric motor 40, the upper bevel 36 is rigidly secured to the tower, and the two planet bevels are carried by a spider 39 integral with the potentiometer shaft 31. Thus if the motor 40 is stationary, rotation of the turret causes rotation of the mirror 20 of half the angle through which the turret is turned. Fig. 2 shows the control circuit for the electric motor 40 which drives the mirror 20. The driving assembly includes an amplifier 54 feeding the motor, and four potentiometers 55, 56, 57, 58, the outputs from which are fed to and added together in the amplifier. These potentiometers are ganged together and are manually controllable by means of a knob 59 having a range scale to adjust a number of coefficients determining the programme in accordance with the distance between the launcher and the aimer. A fixed potential is supplied to the potentiometer 50, driven by the potentiometer shaft 31, so that an output proportional to the deviation of mirror 20 from its final position is fed from it to amplifier 54. A voltage proportional to the deflection of the control column, and hence approximately proportional to the acceleration of the missile is fed to the potentiometer 58, the output of which is fed to amplifier 54. A similar voltage is fed to potentiometer 51 whence the output is fed to potentiometer 57, so that an output proportional to control column deflection, deflection of the mirror, and an adjustable coefficient is fed to amplifier 54. A tacho-generator 52 provides an input to potentiometer 55 proportional to the motor speed and, through a differentiator 53, an input to potentiometer 56 proportional to motor acceleration. In operation the aimer turns the knob 59 to the range at which the programme is to start, swings the tower round until the target is visible in the right hand binocular, and signals for the missile to be launched. When the missile is at the pre-set range he starts the motor and then uses the control column 16 to control the missile so that it remains in the centre of the field of view of the left hand binocular. When the mirror 20 comes to rest the missile is directly approaching the aimer along the line of sight and will shortly pass overhead and become visible in the right hand binocular so that it can be controlled to engage the target.