GB1164272A - Improvements in Guidance Systems for Projectiles or Missiles. - Google Patents

Abstract

1,164,272. Missile guidance. BRITISH AIRCRAFT CORP. Ltd. 1 Dec., 1964 [12 Dec., 1963], No. 49227/63. Heading H4D. [Also in Division G3] A guidance system for a missile having flight path controls and rotating about its axis during flight, includes a projector external to the missile for aiming a beam of infra-red, visible or ultraviolet radiation at the target and a rotary pattern device for splitting the beam crosssection into sectors and for rotating the sector pattern; a detector responsive to the radiation which is mounted on the missile offset with respect to the missile axis; and means receiving the detector output and responsive to the frequency modulation of the latter resulting from the rotations of the sector pattern and the detector to adjust the flight path controls in response to the frequency modulation and thereby to steer the missile towards the beam axis. In Fig. 1 there is shown a missile 1, a beam of light split by a rotating pattern device into a large number of sectors, and the beam axis 2 about which the beam is rotated and towards which the missile is to be steered. The missile carries two arms 5a and 5b which have at their ends a light detector 3 and a balance weight 4, respectively, and it is also provided with fins 6 and 7 which control the flight path of the missile. In the example shown the directions of rotation of the missile and the sector pattern are the same and consequently the number of sectors of light through which the detector 3 passes is less while the detector is traversing the outer side of the beam than when it is traversing the half rotation which is nearer to the beam axis. This results in the output of the detector 3 being frequency modulated. The missile includes a control unit containing circuits which convert the modulated signal from the detector into a waveform which after amplification controls the movements of the fins 6 and 7. As the missile is spinning about its own axis, due to the fins being given equal and opposite " standing " angles of incidence, the fins must be given an oscillatory movement in order to steer the missile towards the beam axis. This oscillatory movement is at the frequency of rotation of the missile which is also the frequency at which the output of the detector 3 is frequency modulated. When the missile axis coincides with the beam axis, the missile and the sector pattern are rotating in the same direction the whole time and consequently there is no frequency modulation of the output of the detector 3. The system operates if the angular velocity of the missile is greater or less than that of the sector pattern, and/or if the missile rotates in the same or the opposite direction to the sector pattern. The invention can be applied to projectiles of the " bazooka " kind, the arms 5a and 5b and the fins 6 and 7 folding away within the body contour for launching but pivoting outwards as soon as the projectile has left the launching tube.