Patent GB-1536668-A (GB)
Title: Apparatus for aiming a weapon at a moving target
IPC: F41G5/08
Filed: 1975-12-10
Abstract: 1536668 Apparatus for aiming a weapon SPERRY RAND CORP 10 Dec 1975 [11 Dec 1974] 50670/75 Heading F3C Apparatus for aiming a weapon 11, Fig. 5, at a moving target Z, Fig. 1, comprises, in combination, a sighting device 1, Fig. 2, and a computer 2, 3, the sighting device 1 having means for rendering visible within its field of view a target sight line S, Figs. 3 and 4, extending from the lead point V and representing the apparent path of the moving target Z, a target mark T positioned in the target sight line S at a distance from the lead point V representing the calculated lead angle, and means for transmitting to the computer its azimuth and sight angle coordinates. The computer is for receiving signals representing target distance, target velocity and the ballistic characteristics of ammunition for the weapon, for receiving from the sighting device 1 and storing, azimuth and sight angles and to compute therefrom and transmit to the sighting device 1, control signals for setting the target sight line S and target mark T. The means for rendering the target sight line S and target mark T visible in the sighting device 1 comprise an opaque reticle 23, Figs. 6 and 7, having a transparent radial slot 35 and mounted for rotation about a central axis 27, a movable target marker 28 positioned to intersect the radial slot 35, digital-to-rotational converters which receive signals from the computer to rotate the reticle 23 and the target marker 28, and a reflex optical system for superimposing an image of the reticle 23 and the target mark T on the field of view of the sighting device 1. In an embodiment G, Fig. 1, represents the site of the weapon and a is the path of a target. G and a define the flight plane. The projection of a on a horizontal plane is indicated by a<SP>1</SP>. M1 is a point on a at which the target has been sighted from G. S1 is a first sighting beam and has an azimuth angle α 1  from the zero direction N and an elevation angle # 1  from the horizontal plane. When the projectile is fired the target is located at Z, the gun having been directed to the lead point V and raised by the super-elevation angle B. S2 is the second sighting beam, having an azimuth angle α 2  and an elevation angle # 2 . The lead angle # is between S2 and line GZ. The sighting device 1, Fig. 2, is provided with means (not shown) to sense and measure the azimuth and elevation angle of the target along with means to convert angular movement into digital or analog signals. The computer has a memory unit 2 and computing means 3, the unit 2 storing data obtained from measuring the azimuth angle α 1  and elevation angle # 1  of the first sighting beam S1. Data input means 4 feeds the target distance into 3 and data input means 5 feeds the target velocity into 3. This allows the computer to determine the lead angle #. The sighting device 1, Fig. 5, being mounted on gun 11 by parallel guide 13 having levers 15, 17 and 19, follows motions of the gun. The computer controls the location of the sighting device relative to the super-elevation angle B, via means 20.