Patent GB-1429236-A (GB)
Title: Method of gunnery training and firing training apparatus for  use therewith
IPC: F41G3/26
Filed: 1973-06-27
Abstract: 1429236 Teaching warfare GIRAVIONS DORAND 27 June 1973 [27 June 1972] 30609/73 Heading F3C A method of gunnery training comprises the steps of simulating the firing of a projectile from a gun up to a point of impact of the fired projectile by an optical representation of the trajectory as a function of the aiming of the gun and of reference data comprising at least a reference line of sight from the gun and the distance to the target and of introducing into said simulation terrain data defining three ground planes which are distinct from the plane perpendicular to the vertical plane containing line of sight and which are located respectively around the target, in front of the target, and behind the target, with respect to said gun. The three ground planes are perpendicular to the vertical plane containing the line of sight. The simulated projectile trajectory up to the point of impact is determined from the reference data and from the aim of the gun upon the firing of the simulated projectile. A simulated point of impact with the ground may be defined by the intersection of the simulated projectile trajectory and the ground planes away from the target. A simulated impact with the ground may be indicated differently from a simulated impact on the target. Account may be taken of pre-recorded target data in the plane perpendicular to the line of sight. The simulated trajectory and simulated impact may not be displayed if the trajectory passes beyond the target or visible ground obstacle. The trajectory may be indicated in the aiming device of an instructor at the same time as in the aiming device of the firer, so that the instructor may intervene during the simulated firing sequence to cancel the display of ground impact, or the trajectory may be displayed at least partially in the aiming device of an instructor, before simulation in the aiming device of the firer, the instructor determining in part this simulation. Predetermined firing effects may be introduced into the simulation and may be displayed in the field of view of the aiming device of the firer, by superimposition on the observed landscape for example using cine films. These effects may be selected as a function of the simulated firing trajectory either automatically or by the instructor notably to display the simulated impact in different ways, depending on whether it is on the target or with the ground, and at a point seen by or hidden from the firer. Random variations are applied to at least some of the reference, target or terrain data. The method of gunnery training is effected by a simulated firing computer in which are recorded the terrain data, and at least one optical unit for simulating in at least the aiming device of the firer the simulated firing determined by the computer as a function of the firer's aim. Another aiming device may be provided and connected to the computer for introducing reference data from an instructor. Simulated firing can be displayed simultaneously in both aiming devices, alternatively the simulated firing may be displayed to the instructor before simulation in the aiming device of the firer. The simulator also displays special simulation effects on at least the aiming device of the firer, these effects being controlled by the computer or by the instructor. In an embodiment the recorded terrain data defines three ground planes TT1, TT2 and TT3, Fig. 3A, respectively around, in front of, and behind a target 12, with respect to the firer of a gun 11. The characteristics of these planes are estimated by the instructor and fed into the computer memory in the form of three angles of slope P1, P2 and P3, and distances d C1 , d C2  respectively of their lines or intersection from the gun 11. Distances d T1 , d T2  and angle # T , Fig. 3B, are also fed into the computer and a target 12 is placed on the terrain by the instructor at a distance D c , Fig. 6A, from the gun. Additionally the distance Dc, elevation and bearing angles of the target 12 relative to the gun axis, and the dimensions of the targets outline are fed into the computer along with the gun elevation and train angles. The gun is aimed at the target and fired and the computer determines the simulated projectile trajectory with respect to the simplified terrain and impact points a, b, c, d and e, Figs. 3B and 4, are recorded. The special simulation effects by cine films for example are introduced using an optical unit shown in Fig. 5 where a semi-reflecting mirror 14 is placed on the optical axis of eyepiece 13 and makes an angle of 45 degrees therewith. Thus the landscape and target can be seen through the eyepiece 13 as well as a collimated luminous spot produced by lens 15 from a light source 16 and reflected by a servocontrolled mirror 22, whose angular motion determines the spot movement. The image of the light source 16 is reflected to the lens 15 by a mirror 17 mounted on a pivot 18, thereby enabling the image of source 16 to be replaced by images on screens or of firing effects, different one from another and placed around the mirror 17 in positions 19, 20 and 21 by rotation of the pivot 18. Special effects include de-focusing of the eyepiece 13 to simulate smoke, placing an optically distorted glass in front of the eyepiece 13 to cause "waving" as effected by hot air or to cause dazzling.