US3907433A

US3907433A - Moving target firing simulator and a method of adjustment of said simulator

Info

Publication number: US3907433A
Application number: US407964A
Authority: US
Inventors: Jacques Nault
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-11-03
Filing date: 1973-10-19
Publication date: 1975-09-23
Anticipated expiration: 1992-09-23
Also published as: FR2209448A5; GB1444959A; CH585385A5; DE2354907A1

Abstract

Electromagnetic pulse trains produced by means of a weapon firing mechanism are concentrated by a convergent optical system into a narrow beam which is directed towards a scale-model target provided on one lateral face with spaced photosensitive receivers. A screen provided with an opening which forms an object for the optical system is placed between this latter and a pulse generator. The contour, dimensions and distance between the opening and the optical system, the mean distance between the weapon and the target and the spatial distribution of the receivers on the target are so determined that the envelope of the center of the spot remains practically inscribed within the simplified perimeter of the target face when the spot is displaced around the target with its contour approximately tangent to one photosensitive receiver.

Description

United States Patent [1 1 Nault [76] Inventor: Jacques Nault, 56, avenue Emile Zola, Paris 15 (Seine), France [22] Filed: Oct. 19, 1973 [21] Appl. No.: 407,964

[30] Foreign Application Priority Data Nov. 3, 1972 France 72.38883 [52] U.S. Cl. 356/152; 35/25; 89/41 L; 273/101.1; 356/4 [51] Int. Cl. G01b 11/26 [58] Field of Search 356/4, 152, 165, 166, 172; 89/41 L;35/25;273/101.1, 101.2

[56] References Cited UNITED STATES PATENTS 3,083,474 4/1963 Knapp 35/25 3,169,191 2/1965 Knapp 35/25 3,339,293 /1967 Kuhlo et al. 35/25 1451 Sept. 23, 1975 3,588,108 6/1971 Ormiston 35/25 Primary ExaminerRichard A. Farley Assistant ExaminerS. C. Buezinski Attorney, Agent, or FirmYoung & Thompson [57] ABSTRACT Electromagnetic pulse trains produced by means of a weapon firing mechanism are concentrated by a convergent optical system into a. narrow beam which is directed towards a scale-model target provided on one lateral face with spaced photosensitive receivers. A screen provided with an opening which forms an object for the optical system is placed between this latter and a pulse generator. The contour, dimensions and distance between the opening and the optical system. the mean distance between the weapon and the target and the spatial distribution of the receivers on the target are so determined that the envelope of the center of the spot remains practically inscribed within the simplified perimeter of the target face when the spot is displaced around the target with its contour approximately tangent to one photosensitive receiver.

14 Claims, 24 Drawing Figures US Patent sfipt. 23,1975 Sheet 2 6 3,907,433

US Patent Sept. 23,1975 Sheet 3 of6 3,907,435

j 1 Q? QR US Patent Sept. 23,1975 Sheet 4 6 3,907,433

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Sheet 5 of 6 US Patent Sept. 23,1975

US Patent Sept. 23,1975 Sheet 6 @1 6 3,907,433

MOVING TARGET FIRING SIMULATOR AND A METHOD OF ADJUSTMENT OF SAID SIMULATOR This invention relates to a simulator for firing at a moving target as well as to a method for adjusting said simulator.

There already exists a large number of moving target firing simulators of the type comprising a weapon in which an electromagnetic wave generator associated with an optical system emits flashes in the direction of the target. This latter can be either real or constituted by a model which carries one or a number of photosensitive receivers,

By way of example, there rigidly one known type of firing simulator which can be mounted on a real tank for the purpose of firing at other rear tanks which carry photosensitive receivers. In one design of this type, the simulator comprises a convergent optical system having a plane mirror for concentrating the waves emitted in the direction of the target into a narrow beam, a servocontrolled gyrostabilized equipment unit for displacing the mirror both in angle of elevation and in direction, and a fire control computer. The electromagnetic pulse trains are emitted parallel to the firing axis and directed towards the point which it is assumed that the moving target is intended to reach, taking into account the parameters transmitted to the computer by the tank crew. The computer delays the emission of the pulse trains after ignition of the charge by a time interval equal to the real flight time of the projectile in order to ensure better simulation of real firing.

There is also a known design in which the pulse emitter is housed within the gun barrel of a real tank; the firing axis coincides in this case with the axis of the optical system which is combined with the pulse emitter. As a complementary feature, a delay circuit triggers the pulse with a time-lag corresponding to the time of flight of a real projectile up to the target. This system further comprises a target-stopping mechanism which is operated by the photosensitive detector when this latter records a direct hit. This mechanism can also cause the emission of smoke and sound signals when the target is hit.

In another design, the optical system of the simulator comprises orientable prisms which serve to deviate the axis of the emitted electromagnetic beam through a predetermined angle with respect to the firing axis. The gunner then sets his sights on the point which the target is intended to reach while taking into account the time of flight of a real projectile, the effect of firing of the charge being to cause simultaneousemission of the electromagnetic pulse train.

Simulators of this type suffer from a certain number of disadvantages. Their optical systems cannot be adapted to different types of targets each having a predetermined contour (tanks of different classes, armored vehicles of various types), with the direct result that firing accuracy is adversely affected. Moreover, the photosensitive receivers are mounted on the target in a more or less erratic fashion, the number of receivers being in any case the outcome ofa compromise inasmuch as some direct hits will not be recorded if the number is to small whereas on the other hand, if the number is too large, shots which do not in fact reach the target are liable to be detected as direct hits by reason of the appreciable dimensions of the spots formed by the intersection of the electromagnetic beams with the target.

Furthermore. simulators which are intended to oper ate on real vehicles are particularly costly (especially the on-board computer simulator) since they can be employed only during field operations.

The primary function of the simulator which is contemplated by the invention is to train personnel for sub sequent service in the operation of ballistic missiles such as anti-tank rocket launchers, for example. Although this must not be considered as a limitation of the invention, the simulator is intended in particular for limited-firing exercises in which the target is constituted by a small-scale model of a real target, the range and the velocity of motion of the model being reduced in the same proportion.

The chief object of the invention is to reduce the cost and duration of target-practice exercises by simulating real-firing conditions as closely as possible and to eliminate any hazards to personnel.

The moving target firing simulator of the type contemplated by the invention comprises a weapon having a firing axis and equipped with a generator which produces electromagnetic pulse trains of short wavelength and is controlled by the firing mechanism of the weapon, a convergent optical system for concentrating said pulse trains into a narrow beam and means for displacing the axis of said beam through a predetermined angle with respect to the firing axis.

In accordance with the invention, the simulator is characterized in that it comprises a screen pierced by an opening which forms an object for the optical system, said screen being placed between the pulse-train generator and the optical system, that the contour and the dimensions of said opening the distance between said opening and the optical system, the distribution of the photosensitive receivers on one lateral face of the target, are so determined that the envelope of the center of the spot remains practically inscribed within the simplified perimeter of the lateral face of the target when the spot is displaced around said target with its contour approximately tangent to a photosensitive receiver.

The waves employed by way of example can be light waves within the visible region of the spectrum or waves within the ultraviolet or infrared regions. In addition, these waves can be monochromatic and have both time and spatial coherence as in laser radiation. The optical system and the photosensitive detectors are clearly adapted to the nature of the waves employed.

In a training exercise, the instructor sets the angular displacement of the wave-beam prior to firing and without the firers knowledge, in such a manner as to ensure that said displacement is equal at absolute value and in opposite direction to the theoretical firing-angle correction corresponding to the conditions of range and velocity which he intends to impart to the target, and to the postulated velocity of a real projectile. The firer in turn sets up an estimated correction on the firecorrector of the weapon and, if this correction is accurate, the wave beam which is produced by the firer strikes the target and is detected by the photosensitive receiver.

In a preferred form of construction, the photosensitive receivers are arranged in spaced relation along a line and within a region located internally of said line, said line being such as to limit the area swept by the spot within the amplified perimeter so that the surface swept by the spot covers practically the entire target face when said spot is placed in successive positions in which its center coincides with each receiver in turn.

The invention is also directed to a method of adjustment of the firing simulator.

In accordance with the invention, the method essentially consists of determining the contour and the dimensions of the opening pierced in the screen which is associated with the optical system, the distance between said opening and said optical system, the mean distance from the weapon to the scale model which serves as a target, and the distribution of the photosensitive detectors on the target so that the envelope of the center of the spot should remain practically inscribed within the simplified perimeter of the target face when the spot is displaced around the target and its contour is maintained approximately tangent to a photosensitive receiver.

In many cases, the spot has two axes of symmetry which are not necessarily orthogonal. Under these conditions, each axis has a length substantially equal to the minimum dimension of all the contours, which are simplified if necessary, of the lateral faces of the target as measured parallel to the direction of the axis aforesaid.

The number of receivers on each lateral face of the target is equal at a maximum to the product of the ratios between the maximum dimensions of said face as measured parallel to each of the axes of the spot and the lengths of the corresponding axes of said spot. The distances as measured parallel to the axes of the spot between the receivers and the apparent contour of the target are great at least equal to the length of the corresponding half-axis of the spot.

The effect thereby achieved is to reduce to a minimum the number of photosensitive receivers required to record any direct hit and only those hits which are actually on the target.

The beam can be angularly displaced either by moving the wave-train generator in a transverse direction with respect to the optical axis or by means of an adjustable optical deflector which is placed between the generator and the convergent optical system.

Further properties and advantages of the invention will become apparent from the detailed description given hereinafter.

A number of embodiments of the invention are illustrated in the accompanying drawings which are given by way of example without any limitation being implied, and in which:

FIG. 1 is a diagram illustrating the principle of operation of the invention;

FIG. 2 is a schematic representation of the detection and operation circuit which is actuated by a photosensitive receiver;

FIG. 3 is an axial sectional view ofa first embodiment of a firing simulator in accordance with the invention;

FIGS. 4 to 8 are sectional views taken along lines lVlV to VIII-VIII of FIG. 3;

FIGS. 9 to 11 are profile, front and top views respectively of a target equipped with photosensitive receivers;

FIG. 12 is a view of a larger scale and similar to FIG.

FIG. 13 is a fragmentary axial sectional view of a second embodiment of the invention;

FIG. 14 is a fragmentary sectional view taken along line XIV-XIV of FIG. 13;

FIG. 15 is a transverse sectional view taken along line XV-XV of FIG. 13;

FIGS. 16 to 23 are diagrams illustrating the shape of the spot and the distribution of the receivers in various simple cases; 7

FIG. 24 is a diagram which is similar to FIG. 1 and shows the parameters to be determined for the adjustment of the firing simulator.

In FIG. 1 which illustrates the principle of operation of the firing simulator in accordance with the invention, there is shown diagrammatically a moving target 1 constituted by a'small-scale model ofa tank which is advancing in the directionf. A predetermined number of photosensitive receivers are placed on said target.

The simulator also comprises a weapon 2, the external shape and dimensions of which are those of a real antitank weapon. Said weapon 2 comprises a normal corrector for firing at a moving target, said corrector being designed to produce an angular displacement as a function of corrections estimated and set up by the firer; the horizontal projection between the sighting line V which joins the weapon to the target and the firing axis T is shown at A and said firing axis is angularly displaced in the direction fof motion of the target.

As contemplated by the invention, the weapon 2 is equipped with an electromagnetic wave train generator which, in the example herein described, is a light-flash generator triggered by. the firing mechanism of the weapon and a convergent optical system so arranged as to form a narrow light beam P starting from a flash. Means are additionally provided for displacing the axis P of the beam through a predetermined angle with respect to the firing axis T. FIG. 1 shows the horizontal projection P of this angular displacement.

The system operates as follows:

During a target practice, if the instructor desires to simulate firing at a real tank which moves at predetermined values of distance, velocity and direction, he determines by means of firing tables the theoretical angular corrections corresponding to these postulated conditions of distance and velocity and to the initial velocity at which a real projectile would travel. Without the knowledge of the firer, he then produces action on the weapon in such a manner as to ensure that the light beam P which will be emitted at the moment of fictitious firing is displaced with respect to the firing axis T through an angle which is equal at absoslute value to the resultant of these theoretical corrections and of opposite direction, the beam P being displaced to the rear of the firing line with respect to the direction of motion of the model 1.

The instructor then causes the model 1 to move at a distance and velocity which are reduced with respect to the postulated conditions of the real tank in a ratio equal to the coefficient of reduction of the model 1. So far as the firer is concerned, said model therefore has the same apparent contour as the real tank would have under the postutated conditions; the distance and velocity estimated by the firer according to the movements of the model are those which he would estimate in real firing under the conditions postulated by the instructor. The firer then sets up on the normal fire corrector of the weapon 2 the angular corrections corresponding to the distance and the velocity which he has estimated, aims at the model and actuates the firing mechanism of the weapon, thereby causing the emission of the light beam P.

If the resultant of the corrections set up by the firer is equal at absolute value to the angular displacement produced by the instructor, the beam P whose velocity of propagation is practically infinite in comparison with the velocity of a real projectile, strikes the model and is detected by one of the photosensitive receivers which are mounted on said model.

The simulator further comprises a chain of operational elements, one particular embodiment of which is shown in FIG. 2.

The photosensitive receivers which are photoelectric cells 3 in the example described are connected to an amplifier 4, the output of which actuates a relay 5 through an adjustable delay circuit 6. When the relay 5 is energized, it causes either stopping or changing of speed of the motor 7 of the model which is controlled by a remote-control circuit 8 either by cable or by radio waves. Prior to firing, the instructor sets the timedelay of the circuit 6 at a value equal to the actual time of flight of the real projectile under the conditions which it is desired to simulate.

The relay 5 is also connected to a circuit 9 which has a fixed timedelay of the order of a few seconds and controls a second relay 11. When energized, said second relay cancels the action of the first delay 5 and puts back the motor 7 under the control of the remotecontrol circuit 8.

When there is a direct hit, the light beam P is detected by a photoelectric cell 3. After a time-delay equal to the actual time of flight of the projectile under real tiring conditions, the relay 5 causes the model to stop or modifies the movement of this latter. In order to complete the illusion of real firing, the relay 5 can also trigger the emission of visual or sound signals such as glows and sounds of explosions. After a fixed timedelay as determined by the circuit 9, the relay 11 re moves the inhibitiion which had been introduced by the relay 5 and the motor 7 can again be controlled by the remote-control circuit 8 for another shot.

The fixed and adjustable time-delays of the chain of FIG. 2 can be obtained by any mechanical or electrical means well known to those versed in the art.

A first embodiment of the simulator weapon will now be described with reference to FIGS. 3 to 8.

The light-flash generator and the optical system are mounted within a cylindrical tube 21 whose axis coincides with the firing axis of the weapon.

The light generator comprises a lamp 22 which is capable of emitting a flash of high intensity and short duration and which is secured to a support 23. The lamp 22 is placed within an enclosure consisting of a reflector 24 and closed at the front end by means of an opaque screen 25 pierced by an opening 26 which performs the function of object for the optical system. An electronic triggering device of conventional type which is not illustrated serves to cause the emission of a flash by means of the trigger of the weapon.

In this embodiment, the flash generator is capable of displacement in two directions substantially at right angles to the firing axis.

To this end, the enclosure containing the lamp 22 is secured by means of a screw 27 which passes through a button-hole slot to a slide unit 29 which comprises a block 31 fitted with a stud 32 and a back-plate 33 which is attached to said stud by means of screws 28.

A disc 34 having a flange 35 which is attached to the tube 21 at right angles to the axis of said tube has a first slot 36 with rectilinear edges placed at the level of the opening 26 and a second slot .37 also having rectilinear edges which are parallel to those of the first slot. The lug 32 of the slide unit 29 is engaged in said second slot 37 and guided by this latter in its movement of displacement.

The reflector 24, the screens 25 and the slide unit 29 are limited by circular arcs having a radius substantially equal to the internal radius of the tube 21 in such a manner as to conform to the shape of said tube in the end positions of the light-flash generator.

The optical system for forming the light beam comprises a convergent assembly represented schematically by a lens 38. Said lens is fastened by means of threaded studs 41 within a cylindrical sleeve 39 which is coaxial with the tube 21 and projects to a slight extent from said tube at forward end of the weapon. The sleeve 39 has a groove 42 which is ssubstantially at right angles to the axis of the sleeve and extends over approximately one-half the periphery of the sleeve. The head of a screw 43 which is attached to the tube 21 is engaged within said groove 42. A lock-screw 44 which passes through the tube 21 serves to secure the sleeve 39 in a predetermined angular position with respect to the tube 21. The optical axis of the lens 38 coincides with the axis of the sleeve 39 and with the firing axis of the weapon( The end portion of the sleeve 39 which is directed towards the rear of the weapon is cut diagonally. A stud 45 which is substantially at right angles to the axis of the sleeve is fixed at the extremity of said end portion and engaged within a bore 46 formed in the block 31 of the slide unit'29.

In order to set up the vertical angular displacement prior to firing, the instructor displaces the screen 25 in the vertical direction by means of the button-hole slot 20 and locks said screen in position by tightening the screw 27.

In order to set up the horizontal angular displacement prior to firing, the instructor takes hold of the projecting portion of the sleeve 39 and causes this latter to rotate about its axis, the movement being guided by the head of the screw 43 and the rectilinear edges of the groove 42. In this movement, the distance between the lens 38 and the flash generator remains unchanged. Correspondence tables are pre-established between the theoretical firing-angle correction (angle B) and the angle of rotation of the sleeve 39 which can thus be graduated directly in values of angular correction. Said sleleve is then locked in position by the screw 44. The corresponding tables can be drawn up experimentally by replacing the lamp 22 by a source of continuous light such as an iodine lamp and by measuring the displacements of the spot on the screen.

The movement of rotation of the sleeve 39 is accompanied by the stud 45 and the slide unit 29 which comes, for example, into the position shown in chaindotted lines in FIG. 5. The slide unit 29 and the flash generator are subjected to a rectilinear displacement substantially at right angles to the optical axis of the lens 38 and to the firing axis by means of the guiding action produced on the lug 32 by the slot 37. The opening 26 which performs the function of object for the lens 38 is thus displaced transversely with respect to the optical axis of said lens, thereby causing the angular displacement of the light beam P which emerges from the lens 38 at the moment of firing. The slot 36 permits the passage of the incident light cone in all positions of the slide unit 29.

The opening 26 has a shape of the elliptical type and has both a horizontal axis and a vertical axis. The lens 38 forms a real image of said opening 26, said image being located at a distance from the weapon which is comprised within the range of distances which are contemplated for the traveling motion of the model I.

In FIGS. 9 to 11, the apparent contour of the model 1 is shown respectively in a profile view, a front view and a top view.

In FIGS. 9 and 10, there are further shown in thin lines the simplified apparent contours of said model when this latter is located at a mean distance or at extreme firing distances.

There is also shown the luminous spot 51 formed by the intersection of the light beam P with the

apparent contour

52 or 53 of the model when this latter is located at a mean firing distance. The dimensions of the opening 26 and the distance of this latter with respect to the lens 38 are chosen such that the vertical axis of the luminous spot is substantially equal to the minimum vertical dimension C of the

contours

52 and 53. Similarly, the horizontal axis H of the spot 51 is substantially equal to the minimum horizontal dimension D of the

contours

52 and 53.

Recesses designated by the general reference 54 are located at intervals on the lateral faces and the front and rear faces of the model. A photosensitive receiver which is a photoelectric cell in the example described is housed at the center of each recess.

Broadly speaking and in the case of any type of target, it is intended in accordance with the invention to determine the shape and the dimensions of the spot 51 as well as the spatial distribution of the photosensitive receivers on the model in order to ensure that all direct hits, that is to say shots which would in fact reach the target in real firing, and only direct hits, are detected by at least one photosensitive receiver, the number of said receivers being reduced to a minimum which is clearly a function of the desired precision. In the following description, more light will be thrown on this concept of desired precision.

In order to determine the shape and the dimensions of the spot, the following procedure is adopted:

The initial operation consists in delineating the apparent contour of each lateral target face. These contours can be slightly simplified as has been done in FIGS. 9 to 11, in other words, it is agreed beforehand not to detect shots which reach certain peripheral portions of the target such as, for example, that portion of the model tank which corresponds to the gun (as shown in FIGS. 9 and 11). It is also agreed to detect shots which fall outside but in the immediate vicinity of certain portions of the target such as the portions corresponding to the tank tracks. These simplifications make it possible to reduce the number of receivers but evidently reduce what has been referred-to earlier as the precision of the device.

The general shape of the spot is determined with a view to ensuring that its contour conforms as accurately as possible to the simplified contours of the different target faces.

The dimensions of the spot are accordingly chosen so as to be as large as possible, taking account of the following limitation:

The spot must be contained within the simplified contour of any particular lateral face of the target except in some instances of slight overstepping when it is displaced in a direction parallel to itself, one edge of said spot being intended to follow an arc of the contour of said face and the operation being repeated in the case of each lateral face of the target.

The shape and the dimensions of the spot then make it possible to determine in a consistent manner both the shape and the dimensions of the opening 26 which performs the function of object in the optical system.

The number and distribution of the photosensitive receivers on each lateral face of the target are accordingly determined in accordance with the following rules.

The image of the spot as this latter moves in a direction parallel to itself in order that its center should follow the simplified contour of one lateral face of the target sweeps within said contour an area which is limited by a line S. There are shown in FIGS. 16 to 22 schematic examples of target faces on which the areas thus swept are shaded. The line S delimits a given internal domain D. The spots are represented in FIGS. 18, 20 and 23.

The photoelectric receivers are distributed along the line S and also within the domain D if necessary. The spatial distribution of any receivers which may be placed within said domain D is determined by forming within said domain a line S (not shown) by the same means which have served to form the line S from the contour of the target face. Said line S can in turn delimit another intemal domain D and so on. The spacing of said receivers is chosen such that, if the image of the spot is placed in successive positions in which its center coincides in turn with one of the receivers, practically the entire surface of the target face aforesaid is covered by the spot in the successive positions of this latter.

In many practical cases, the contour of each target face has a simple geometrical shape or is at least formed by elements which have a simple geometrical shape. The spot itself will also have a simple shape and a symmetry with respect to two axes, not necessarily at right angles, and consequently a center within the precise geometrical meaning of the term.

Under these conditions, the rules given above in regard to the choice of the dimensions of the spot and the spatial distribution of the photosensitive receivers admit of a more simple formulation. In particular:

each axis of the spot has a length substantially equal to the minimum dimension of all the lateral faces of the target as measured parallel to the direction of the axis aforesaid;

the distances from each point of the line S to one lateral face of the target with respect to the simplified contour of said face, said distances being measured parallel to each axis of the spot, are at least equal to the length of the corresponding half-axis. When the spot is displaced around the target while maintaining its contour approximately tangent to a photosensitive receiver located on the line S in accordance with the method contemplated by the invention, the envelope of the center of the spot therefore remains practically inscribed within the perimeter of the simplified taraget face;

the number of photosensitive receivers placed on one face of the target is equal at a maximum to the product of the ratios between the maximum dimensions of said face as measured parallel to the direction of each axis of the spot and the length of the corresponding axis of the spot, each of these ratios being rounded-off to the nearest whole number of high value.

A clearer understanding of the rules mentioned above will be gained from a study of the simple examples shown in FIGS. 16 to 23.

In the case of FIGS. 16 to 18, consideration is given to a target having two first lateral faces with a simplified contour as shown in FIG. 16 and two other lateral faces having a simplified contour as shown in FIG. 17.

Since these two contours are constituted by elements of rectangles, the spot (shown in FIG. 18) is given a rectangular shape with a center 71 and two orthogonal axes represented in dashed lines.

The vertical axis of the spot has a length 2y equal to the minimum vertical dimension a (FIG. 16) of all the faces of the target. Similarly, the horizontal axis of the spot has a length 2b equal to the minimum horizontal dimension b of all the faces.

Each point of the lines S corresponding to each face is located with respect to the simplified contour of the corresponding face at a horizontal distance which is at least equal to h and to a vertical distance which is at least equal to y.

The ratio d/2h between the maximum horizontal dimension of the two first faces and the length of the horizontal axis of the spot is equal to 6, and the ratio c/2v between the maximum vertical dimension of said faces and the length of the vertical axis of the spot is equal to 1.4 which is rounded-off to the higher integer 2. From the rule which has been set forth in the foregoing, the number of photosensitive receivers is equal at a maximum to 12. It is apparent from FIG. 16 that the actual number of receivers which are represented by X can be reduced in this case to 8. But it is readily apparent that, if the dimension e (FIG. 16) were increased, the lengths of the axes of the spot would be unchanged and the number of receivers would be greater than eight while remaining smaller than twelve.

In the case of FIGS. 19 and 20, consideration is given to only one face (FIG. 19) of the target. Since the simiplified contour of this face is made up of elements of parallelograms, the spot (FIG. 20) also has the shape of a parallelogram with two non-orthogonal axes and a center 72.

One of the axes of the spot has a length 2g equal to the minimum dimension 1' (FIG. 19) of the face of the target in the direction of said axis. The other axis of the spot has a length 2j equal to the minimum dimension I of the face in the direction of said second axis.

The points of the line S are located with respect to the contour of the face at distances which are measured parallel to the two axes of the spot and are at least equal respectively to g and to j.

In this particular case, the internal domain limited by the line S has a zero area.

The ratios m/2g and n/2j between the maximum dimensions of the target face as measured parallel to the axes of the spot and the lengths of said axes are respectively equal to 3 and 2.3. By rounding-off the second of these ratios to the nearest integer of higher value, a

maximum number of receivers equal to 9 is obtained by virtue of the rule set forth in the foregoing. It is apparent from FIG. 19 that the acutal number of receivers can be reduced to 5.

FIGS. 21 to 23 relate to a target having two first faces as shown in FIG. 21 and two other faces as shown in FIG. 22. The shape of the spot is illustrated in FIG. 23. The lines S relating to two pairs of faces have a shape which is similar to that of the lines S shown in FIGS. 16 and 17.

This example is given in order to illustrate one instance in which a compromise has been made in regard to the shape of the spot. In fact the faces in accordance with FIG. 21 have rounded corners whereas the faces in accordance with FIG. 22 have right-angled corners.

It is possible to choose a shape of spot and a special distribution of receivers such that all direct hits on each face of the target are detected. This would result, however, in a spot having small dimensions and a large number of receivers.

On economical grounds, it appears preferable to accept a slight reduction in the desired precision by adopting the shape of spot shown in FIG. 23 which has rounded corners as in FIG. 21. It is thus considered of no further interest to make use of the receivers shown for the purpose of detecting shots which fall in the zones shaded in thick lines of FIG. 22.

It is understood that the foregoing rules make it possible to reduce the number of receivers and also to avoid the need to make the spot virtually punctual as this could be achieved only approximately and would result in a complicated and costly. optical system. The accuracy of detection of direct hits nevertheless remains substantially the same as in the case of a virtually puntual spot and a very high correlative number of receivers.

Referring once again to the case of the target which is constituted by a model tank, it is seen from FIGS. 9 and 10 that there have ben adopted the simplified contours of the lateral faces of the model which are composed of rectilinear segments and arcs of curves of the elliptical type which, in the case illustrated, are circular half-circumferences. The spot 51 is in turn formed by the elements aforesaid and has two orthogonal axes of symmetry, the lengths of which are chosen as stated earlier.

The recesses 54 which contain the photoelectric cells are spaced along a line S (not shown) which is determined as in the previous examples.

In this case the ratio G/H between the maximum horizontal dimension of the two lateral faces of the model corresponding to FIG. 9 and the horizontal axis of the spot is equal to 2.4. Moreover, the ratio F/C between the maximum vertical dimension of the same lateral faces of the model and the vertical axis of the spot is equal to 1.75. If these two ratios are rounded-off to the two nearest whole numbers of higher value, there is determined by means of the rule given above a maximum number of photoelectric cells which is equal to six and which is equal in this case to the actual number of cells 54a to 54f. This coincidence between the maximum number and the actual number of cells is due to the reg ular shape of the simplified contours of the target faces.

In FIG. 12, there is shown the apparent contour at a means firing distance of the lateral face of the model corresponding to FIG. 9. There are also shown the six essential cells 54a to 54f and the contours of the spots 51 which are centered on each of these cells. It is apparent that the entire group consisting of the six spots covers practically the entire face without projecting beyond the contour to any appreciable extent.

In the case of a given shot, if the center of the light beam P which represents the point of impact of the projectile under real firing conditions is located near the contour of the face but inside this. latter, for example at K, the luminous spot will be represented by the chain-dotted outline 51a. This spot will be detected by the cell 54d and, in consequence, this will be effectively counted as a direct hit.

On the contrary, if the center of the beam P is located at L outside the apparent contour of the model face and therefore at a vertical distance with respect to the nearest cell 540 which is greater than a vertical halfaxis of the spot 51b, and at a horizontal distance greater than a horizontal half-axis of said spot with respect to the cell 54b, it is apparent that the spot 51!) will not be detected by any cell although it covers part of the model face.

It will clearly be understood that additional receivers can be added on condition that they are placed inside the line defined by the centers of the receivers 54a to 54f, this line being intended to satisfy the abovedefined condition of distance with respect to the contour of the model face.

Referring now to FIG. 24, there will now be described a numerical example of execution of the invention in the case in which the simulator is applied to practise firing of antitank rocket launchers.

NUMERICAL EXAMPLE a. Determination of the angle of correction The angle of correction is the resultant of an angle of horizontal correction and an angle of vertical correction.

Practice firing is carried out at a short distance and the target is a model but the reduction factor is applied to all elements of the simulator and does not effect the value of the angle of correction.

The angle of vertical correction is given by the range tables for the weapon considered and is a function of the firing range.

In the present example of training exercises for firing with antitank rocket launchers at a tank located at a distance within the range of approximately 100 and 200 meters and moving at a speed which varies approximately between and 40 km/hr, the angle of horizontal correction B (shown in FIG. 1) is determined as follows:

The velocity of the projectile between 100 and 200 meters is first considered as a constant. Moreover, as in all ballistic firing, it is assumed that the speed and direction of displacement of the target do not vary during the time of flight of the projectile (rocket).

In FIG. 24, the following parameters are defined:

P0 is the distance traversed by the electromagnetic pulses of the beam P (FIG. 1) up to the target,

Vc is a vector representing the speed of the target as this latter moves along an axis Z-Z,

E is the projection of Vc on a line at right angles to Pc,

Tc is the distance between the weapon and the point 0 at which the projectile is assumed to strike the target under real firing conditions and therefore corresponds to the line of fire T of FIG. 1,

M is the angle between V0 and E.

The angle of horizontal correction B expressed in mils is of small value and can consequently be assimilated with its tangent. Its value is given by the expression:

Moreover, since 1 is the time of flight of the rocket and v is the rocket velocity (assumed to be constant), we have:

E V (cos M) X t.

and

P v X t.

From this it is deduced that:

B= (cos M) I000.

The time of flight t of the projectile and the firing distance or range T therefore have no influence on the value of B. Since the velocity v of the projectile is known I00 m/sec in the case of a rocket), the must thus estimate the angle M and the speed V of the target prior to firing. By reason of the limited possibilities of visual estimation of these two parameters and the permissible percentages of errors in the case of a weapon of the rocket-launching type. the choice relating to V and M is reduced to the following values:

V(m/sec)=0 l.5'3 6-9-12 which corresponds approximately to the following speeds in km/hr: 0 5 l0 20 30 40 (in practice, 40 km/hr is an exceptional maximum in the case of an armoured vehicle such as a tank).

M (in degrees) 0, 30, 45, 60, 90.

namely cos M l, 3/2, V 2/2, 1%, 0.

Since the results of the calculations are rounded-off, there are obtained in the case of the angle B the following values expressed in mils:

V, 5 km/hr l0 km/hr 20 km/hr 30 km/hr 40 km/hr 0 de- 15 30 60 90 I20 gree 30 degrees I2 25 5O I00 45 degrees 10 20 40 60 60 degrees 7 I5 30 45 60 degrees 0 0 0 0 0 b. Determination of the configuration of the spot two semicircles which are joined to the short sides of the rectangle as shown in FIG. 23.

Since the distance Fe is approximately 10 meters (150 meters under real firing conditions), the dimensions of the spot will accordingly be as follows:

major axis 16 cm minor axis: 9.3 cm

Taking into account the essential requirements mentioned above, the determination of the configuration and the dimensions of the spot assumes special significance. ln point of fact, it permits the possibility of calculating the minimum number of photosensitive detec tors and ensuring the most rational distribution of these latter on the face considered of the target in order to obtain practically punctual firing precision.

c. Determination of the opening 26 The spot is homothetic with the opening 26, the dimensions of which are determined in the following manner:

L being one of the axes of the spot mentioned in paragraph b),

fbeing the focal distance of the lens 38,

Pc being the distance between the optical center of the lens 38 and the tank model,

and I being the dimension of the opening 26 which is homothetic with L,

l is determined with a sufficient approximation by means of the following expression:

When P =10 m and f= 0.50 m the minor axis of the opening 26 is therefore:

1,=9.3 O.5/l=4.6 mm

and the major axis:

l 16 X 0.5/ 8 mm.

These dimensions are small. Since they are proportional to the focal distance fof the lens 38, a lens having a sufficient focal distance is chosen and mounted at the extremity of the weapon. This makes it possible to avoid the need to reduce the

dimensions

1,, 1 to an excessive extent in order that is may therefore not be too difficult to form the opening 26.

It is apparent that, in the case of an opening 26 having given dimensions, the dimensions of the spot vary as a function of the distance P between the weapon and the target. These variations, however, may be considered as practically negligible within a given range. In the particular case described, experience has shown that the formed spot remains satisfactory between P 9 m and P,. 12 m, which offers highly adequate possibilities of target practice and training.

The opening 26 can be changed by replacing the opaque screen 25 by a similar screen in which is formed an opening having a suitable contour and dimensions.

In the alternative embodiment which is illustrated in FIGS. 13 to 15, the light-flash generator is stationary and the weapon is provided for the purpose of deviating the light beam P with an optical deflector constituted by an orientable prism 61 having a rectangular cross section.

The prism 61 is placed at the level of the opening 26 which serves as an object for the lens 38 (said lens having been omitted from FIGS. 13 to 15) and between said opening and said lens. The prism 61 produces a deviation of the incident beam through angle of degrees, with the result that the flash generator is disposed laterally with respect to the tube 21 as shown in FIGS. 13 to 15 in order that the beam emerging from the prism 61 should have a direction which is close to that of the optical axis of the lens 38.

The prism 61 is supported by a shaft 62 which is substantially vertical in the firing position. Said shaft 62 is mounted at one end in a bearing 63 which is attached to the tube 21 and at the other end in a footstep bearing mounted in a slide-blcok 64. A threaded micrometric rod 66 engages with the slideblock 64 and serves to subject this latter to a rectilinear movement of translation in a direction parallel to the optical axis of the lens 38 and to the firing axis, this movement being guided by means of slideways 65.

The vertical shaft 62 is regidly fixed to an arm 67 which is substantially horizontal in the firing position. A threaded micrometric rod 68 disposed in meshing engagement with an internally-threaded block 69 which is attached to the tube 61 serves to displace the arm 67 and to cause rotation of the prism 61 about the vertical shaft 62. On the other hand, when action is produced on the rod 66, said shaft 62 is inclined with respect to the vertical central position thereof. this being equivalent to rotating the prism 61 about a horizontal axis.

Thus the beam which is incident upon the lens 38 and consequently also the emergent beam P can be deviated with respect to two rectangular axes.

The invention clearly makes it possible to train personnel at low cost under all real combat conditions and removes any danger. Training may be undertaken in particular on the premises of military barracks and does not entail the need for specially equipped shooting ranges.

it is readily apparent that the invention is not limited to the embodiments which have just been described and many alternative modes of execution may be added to these latter without thereby departing from the scope or the spirit of this invention. The following arrangements are specially worthy of note:

It is possible, for example,to provide the opening 26 of the optical system with example, to variable contour adapted to the type of target, such as a contour which is of the oval type or which is related to an ellipse. The lens 38 can be replaced by a more elaborate optical system of a type known per se, with a view to eliminating the lateral iridescence fringes. of the spot and thus to forming a spot having a perfectly sharp contour. It is also possible to change the opening 26 by means of a rotating disc which replaces the screen 25 and is provided along its periphery with openings having increasing dimensions, or alternatively by means of a device of the diaphragm type. These systems can readily be adjusted at the beginning of a training exercise or even while an exercise is in progress.

1 claim:

1. A moving target firing simulator comprising a weapon having a firing axis and equipped with a generator which produces electromagnetic pulse trains of short wavelength and is controlled by the firing mechanism of said weapon, a convergent optical system for concentrating said pulse trains into a narrow beam di rected to the target, said beam forming at its intersection with said target a spot having a predetermined contour and whose center travels on an envelope when the beam is moved with respect to the target, means for displacing the axis of said beam through a predeterminedangle with respect to the firing axis, and photosensitive receivers distributed on target faces, wherein said simulator comprises a screen pierced by an opening which forms an object for the optical system, said screen being placed between the pulse-train generator and the optical system, and wherein the contour and the dimensions of said opening, the distance between said opening and said optical system, the distribution of the photosensitive receivers on one lateral face of the target, are so determined that the envelope of the center of the spot remains practically inscribed within aa simplified perimeter of the lateral face of the target when the spot is-displaced around said target with the contour of said spot maintained approximately tangent to said photosensitive receivers.

2. A simulator according to claim 1, wherein the photosensitive receivers are arranged in spaced relation along a line and within a region located internally of said line, said line bounding the area swept by the spot within said simplified perimeter in order that the surface swept by the spot should cover practically the entire target face when said spot is placed in successive positions in which its center coincides with each receiver in turn.

3. A simulator according to claim 1 and in which the spot contour is symmetrical with respect to two axes, wherein each axis has a length substantially equal to the minimum dimension of all the simplified contours of the lateral faces of the target as measured parallel to the direction of the axis aforesaid.

4. A simulator according to claim 3, wherein each point of the line aforesaid is located with respect to the simplified perimeter of the corresponding target face at distances which are measured parallel to the axes of the spot and are at least equal to half of the corresponding axis.

5. A simulator according to claim 4, wherein the number of photosensitive receivers placed on one lateral face of the target is equal at a maximum to the product of the ratios between the maximum dimension of said face as measured parallel to each axis of the spot and the length of the corresponding axis of said spot,

each ratio aforesaid being rounded-off to the nearest whole number of higher value.

6. A simulator according to claim 1, wherein the weapon comprises means for moving the pulse train generator in a transverse direction with respect to the optical axis of the convergent system, said optical axis being such as tocoincide with the firing axis of the weapon.

7. A simulator according to claim 6, wherein the weapon comprises a support having'a rectilinear slot located substantially at right angles to the firing axis and a slide unit which is engaged within said slot and supports the pulse train generator.

8. A simulator according to claim 7, wherein the weapon comprises a rotary tubular sleeve which is coaxial with the firing axis and contains the convergent optical system and wherein the sleeve is providedwith a stud substantially at right angles to the slot aforesaid and engaged in a bore on the slide unit.

9. A simulator according to claim 8, comprising a rectangular deflecting prism placed between the pulsetrain generator and the convergent optical system and rotatably mounted about two axes at right angles to each other and to the optical axis of the convergent system, said axis being such as to coincide with the firing axis of the weapon, wherein the prism is mounted on a shaft which is transverse with respect to the tubular sleeve and substantially vertical in firing position, and wherein one extremity of said shaft is rigidly fixed to a supporting slide unit whilst the other extremity is engaged in a bearing which is attached to the tubular sleeve.

10. A simulator according to claim 9, wherein the slide unit is engaged in guiding slideways and meshes with a threaded micrometric rod which is substantially parallel to the axis of the optical system of the weapon.

1]. A simulator according to claim 10, wherein the prism support shaft is fitted with a transverse arm which can be displaced in rotation about a vertical axis in firing position by means of a threaded operating rod attached to the tubular sleeve.

12. A simulator according to claim 1, which comprises a first relay actuated by a photosensitive receiver in order to produce a sound or visual signal and in order to actuate a control system to modify the movement of the target, said simulator comprising means for disconnecting said control system for modifying the movement of said target.

13. A simulator according to claim 12, wherein said simulator comprises a second relay connected to the first relay with interposition of a fixed-delay control circuit.

14. A simulator according to claim 1, wherein the opening which is formed in the screen and determines the contour of the spot has an elongated contour, for example, and may be of the rectangular or elliptical type.

Claims

1. A moving target firing simulator comprising a weapon having a firing axis and equipped with a generator which produces electromagnetic pulse trains of short wavelength and is controlled by the firing mechanism of said weapon, a convergent optical system for concentrating said pulse trains into a narrow beam directed to the target, said beam forming at its intersection with said target a spot having a predetermined contour and whose center travels on an envelope when the beam is moved with respect to the target, means for displacing the axis of said beam through a predetermined angle with respect to the firing axis, and photosensitive receivers distributed on target faces, wherein said simulator comprises a screen pierced by an opening which forms an object for the optical system, said screen being placed between the pulse-train generator and the optical system, and wherein the contour and the dimensions of said opening, the distance between said opening and said optical system, the distribution of the photosensitive receivers on one lateral face of the target, are so determined that the envelope of the center of the spot remains practically inscribed within aa simplified perimeter of the lateral face of the target when the spot is displaced around said target with the contour of said spot maintained approximately tangent to said photosensitive receivers.

5. A simulator according to claim 4, wherein the number of photosensitive receivers placed on one lateral face of the target is equal at a maximum to the product of the ratios between the maximum dimension of said face as measured parallel to each axis of the spot and the length of the corresponding axis of said spot, each ratio aforesaid being rounded-off to the nearest whole number of higher value.

6. A simulator according to claim 1, wherein the weapon comprises means for moving the pulse train generator in a transverse direction with respect to the optical axis of the convergent system, said optical axis being such as to coincide with the firing axis of the weapon.

7. A simulator according to claim 6, wherein the weapon comprises a support having a rectilinear slot located substantially at right angles to the firing axis and a slide unit which is engaged within said slot and supports the pulse train generator.

8. A simulator according to claim 7, wherein the weapon comprises a rotary tubular sleeve which is coaxial with the firing axis and contains the convergent optical system and wherein the sleeve is provided with a stud substantially at right angles to the slot aforesaid and engaged in a bore on the slide unit.

9. A simulator according to claim 8, comprising a rectangular deflecting prism placed between the pulse-train generator and the convergent optical system and rotatably mounted about two axes at right angles to each other and to the optical axis of the convergent system, said axis being sucH as to coincide with the firing axis of the weapon, wherein the prism is mounted on a shaft which is transverse with respect to the tubular sleeve and substantially vertical in firing position, and wherein one extremity of said shaft is rigidly fixed to a supporting slide unit whilst the other extremity is engaged in a bearing which is attached to the tubular sleeve.

11. A simulator according to claim 10, wherein the prism support shaft is fitted with a transverse arm which can be displaced in rotation about a vertical axis in firing position by means of a threaded operating rod attached to the tubular sleeve.