GB1441127A - Guidance system for an anti-aircraft missile - Google Patents

Abstract

1441127 Guidance system BOFORS AB 25 June 1973 [26 June 1972] 30171/73 Heading F3C A guidance system for an anti-aircraft missile 2, which is launched from a sighting device 3 having a sight line S rotatable about an azimuth axis and an elevation axis perpendicular to the azimuth axis, the sighting device intended to be pointed at a target throughout the guiding operation. The missile launcher 1 is integral with the sighting device 3, and the launcher 1 is parallel to the sight-line S which, as shown, in Fig. 1 contacts a target M at an instant I; in this instant the missile 2 is launched, After the launching the sight-line S is maintained on the moving target M and the deviation of the missile 2 from the sight-line S is continuously determined by equipment (not shown) and passed to flight control means (not shown) to change the missile direction and reduce this deviation. Thus the missile flies in a curved path towards the target. The signals show the deviation in two pre-selected, orthogonal directions relative to the sight-line, generally in the horizontal and vertical directions, the flight control means having the vertical direction indicated by a gyroscope mounted in the missile and, consequently, also having the horizontal direction indicated. Since the sight-line is rotated in azimuth and in elevation away from its direction at the instant of launch the horizontal direction relative to the sight line will diverge further from the yaw control plane of the missile as determined by the gyroscope. Similarly the vertical direction will diverge from the pitch control plane of the missile. This means that signals representing deviations of the missile from the sight-line in the horizontal and vertical directions respectively cannot be used for controlling the flight of the missile in the yaw and pitch planes as determined by the gyroscope as the missile would be formed to move in a helical flight path about the sight-line. The difficulty is overcome by continuously rotating the co-ordinate system about the sight-line during the guidance of the missile towards the target. In use signals representing the deviation of the missile from the sight-line in the horizontal and vertical directions can be converted into the desired yaw and pitch control signals b use of known co-ordinated transforming circuits. Systems for determining the deviation of the missile from the sight-line and for producing control signals representing this direction for the flight control means of the missile include (a) an optical sight, (b) photodetectors and optical means for projecting an image of the missile or of a light source on the missile upon these photodetectors, and (c) a sighting device associated with a radiation transmitter which emits an electromagnetic guidance beam in the direction of the sight-line.