GB2095799A

GB2095799A - An aiming device for use in firing at moving targets

Info

Publication number: GB2095799A
Application number: GB8109647A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-03-27
Filing date: 1981-03-27
Publication date: 1982-10-06

Abstract

When firing at a movable target (1), the gun (8) must be swung through a lead angle and aimed in front of the target when the target to be fired on is sighted on with optical means (3). The present invention makes possible very simple aiming of the gun with the aid of a fixed aiming mark and accurate shooting in that the gun, while following a target, is automatically aimed at a lead point in the plane of flight when the optical axis of the sight is directed on to the target. The optical axis of the sight (3) is adjusted relative to the gun barrel (8), by calculating mechanism (4) which calculates the lead angle. Temporary storage of the relevant updated factors is initiated at intervals determined by a pulse generator, which may be associated with a range finder 5. <IMAGE>

Description

SPECIFICATION An aiming device for use in firing at moving targets The invention relates to an aiming device for use in firing at moving targets, particualrly aerial targets, in which the lead angle or the components of the lead angle are determined fully automatically during aiming.

A device according to the invention is suitable for use as an aiming device for use with both manually aimed and motor-driven guns and may be mounted either directly on a gun or, for example, in the case of vehicle-mounted weapons, alongside the gun. A range-finder for determining the range of the target may be rigidly connected with the aiming device and also mounted on the gun, this rangefinder having, for example, the form of a laser- or radar-range finder arranged parallel to the optical axis of the aiming device. Alternatively, the range-finder may be arranged separately and arranged for transmitting ranges measured by it to several guns provided with respective aiming devices.

The aiming device is based on the sighting principle, first mentioned by Kuhlenkamp in 1938 and then in 1 943 in his book on the theory of predictors, which involves the determination of a so-called "plane of flight" that remains constant during rectilinear flight. Aiming devices are already known in which the position of the plane of flight, which is defined by a flight path that is assumed to be rectilinear and the location of the gun station, is determined by two sighting beams corresponding to the lines of sight from the gun to the aerial target at two different moments of time and in which the first sighting beam is somehow retained or stored.In addition to earlier devices, which operate mainly with mechanical parts, such as described for example in German Patent Specification No. 953 047 and Swiss Patent Specification No. 369 383, an aiming device has also already been proposed which is combined with an electronic-calculating machine whereby the factors for determining the plane of flight and the lead angle are calculated by solving known equations by means of which the relationships between the lead angles and the target-observing elements are established. One such device is described in Swiss Patent Specification No. 585 386, in which also some known formulae and equations are set forth.

All these aiming devices, however, have various defects which are predjudicial to their use, particularly for engaging fast-flying targets. The aiming devices referred to, use as an aiming aid the representation of the line of intersection of the plane of flight with the plane of sighting. On this line of intersection, which appears in the optical system of the sight as the so-called apparent flight path, must lie the centre of the sight, the image of the point of future impact, and the image of the target at which the sight is directed. When engaging fast-flying targets, a large field of view is therefore necessary. The scope of use of such devices is, therefore, limited, when substantial lead angles are involved, by the limited field of view of the optical means that are required for sighting the target.

Other disadvantages of the known aiming devices consist in the fact that the calculating mechanism portion thereof must be supplied from time to time not only with the directional data obtained by the process of aiming the weapon but also with stored values for the anticipated velocity and range of the target as well as the angle of dive (or climb) or other quantitative data, as a result of which substantial errors in the determination of the lead may be produced.

The present invention avoids the above-mentioned defects of the known aiming devices and operates fully automatically by continuously determining the lead angle by direct sighting of a target during the aiming process in a similar manner to that in the case of the so-called fire-control systems.

The aiming device according to the invention differs, however, from the known fully automatically operating fire-control systems with electronic calculation of the lead angle in that it does not carry out any direct determination of the target speed and uses a greatly simplified method of calculating the lead angle, which is restricted to ensuring the high degree of accuracy, which in the fire control systems is required for determining the lead point, only in connection with the determination of the plane of flight, while the determination of the position of the lead point itself in the plane of flight is effected with a certain degree of tolerance in the azimuthal direction, which is selectively variable and enables the accuracy of the determination of the lead point to be suited as well as possible to different methods of fire.

Aiming with the aiming device according to the invention is extraordinarily simple. The aiming is always effected in the same way, independently of the method of fire being used, by direct sighting on the target by means of a fixed sighting mark in the sighting telescope, even when, during continuously aimed firing, additional means for temporarily influencing the lead angle are used during the firing of a series of shots, whereby a to-and-fro spread across the target is achieved.

The aiming device according to the invention for firing at moving targets is characterized by a calculating mechanism for continuously solving the pre-programmed equations for determining the plane of flight, the lead values and the times of flight of the projectile to the target on the basis of data transmitted to it from the range finder and the gun and for determining the super-elevation on the basis of the ballistic data that is stored in it, in which the calculating mechanism contains, stores and relates the directional data continuously transmitted to it from the gun with the temporarily stored azimuthal and elevational angles and with quantities which can be derived therefrom, and for this purpose has a pulse-generator for producing signals for bringing about temporary storage operations and for forming differential aiming values for periods of time which can be selected as desired, a device for measuring the intervals between the pulses as well as means which initiate the calculation of the lead and which control the adjustment of the optical axis of the sighting device automatically, in accordance with the values determined, in relation to the disposition of the barrel of the gun.

The invention will now be described by way of example with reference to the accompanying drawings, in which: Figure lisa diagram schematically illustrating the arrangement of the device, and Figure 2 is a diagram which explains the significance of symbols used in the formulae to represent distances and angles.

In Figure 2, 1 indicates a target viewed from 3 at a first moment of time and 2 the same target a moment, e.g. one pulse, later. The direction 0 represents the freely selectable zero direction from which the azimuthal angle a is measured and r, and r2 represent the ranges from the sighting device to the target at two different moments of time.

A line 6 represents the flight path of the target and a line 7 represents the horizontal projection of this flight path.

A gun, which is to be aimed at the target 2 or at the lead Point T, is indicated by 8 in Figure 1. The gun 8 may be aimed by a gun-layer R with the aid of a manual or other elevating and traversing gear (not shown in detail). The gun-layer R has at his disposal a sighting device 3 which is elevated and traversed, in the same way as the gun 8, without taking the lead calculation into account. In addition, care is taken in known manner to ensure that the axis of the gun barrel is elevated by the superelevation o.

During the aiming process, the aiming components, i.e. the azimuthal angle a and the angle of elevation Aw of the gun 8 aimed at the target 1 (T), which are first applied to both the gun 8 and the sighting device, are continuously transmitted to the calculating mechanism 4. In like manner, the ranges, which are measured from time to time by a range-finder 5 to the instantaneous positions (T) of the target 1, are also transmitted to the calculating mechanism 4.

At the beginning of the aiming process, both the gun 8 and the sighting device 3 are laid in azimuth and elevation onto the target 1. The calculation of the lead angle, which is necessary for engaging and hitting the target, is then started by releasing a first pulse by means of any desired pulseemitting means, causing the values of the azimuthal angle a and the elevational angle A, which are simultaneously being fed in, to be transmitted to the calculating mechanism 4 and also causing a pulse-generator to be set in operation. This pulse-generator may either be a component of the calculating mechanism 4 or be incorporated in the range-finder 5. The second alternative is, for example, advantageous if the ranges are taken intermittently, as for example when using laser-rangefinders, instead of continously.In the calculating mechanism 4, a time-measuring device of any desired kind effects the measurement of the time difference between each two consecutive pulses emitted from the pulse-generator and initially also effects the measurement of the time difference between the switching on of the pulse generator and the emission of the first pulse therefrom.

When the calculating mechanism 4 is switched on, the calculation of the azimuthal lead angle 5 thereby is begun, using a simplified lead angle calculation, e.g. according to the following equation (1):

In this equation, i2 represents the instantaneous angle of elevation of the sighting device 3 and Y2 the positional angle which can be determined from a comparison of the instantaneous azimuthal and elevational angles (a) and (*12) of the sighting device and the instantaneous range measurement (r2) with the previous values of the azimuthal and elevational angles (ai) and (R,) and of the range (r,) recalled from the store of the calculating mechanism 4, for example according to the following equations (2) and (3):

Y2=Yl +Aa (3) In these equations, Aa represents the difference between the instantaneous value of the azimuthal angle (2) and the previous value of the azimuthal angle (ai) which was recalled from the store together with the previous value of the elevational angle (R,).

The factor 5 in equation (1) represents a corrective factor which is dependent in a complex manner from the instantaneous target range (r2), from the speed of the target and from the disposition of the target as well as the ballistics of the gun 8, but which, according to the invention, may be determined as an approximate value from a comparison of the instantaneous aiming values with the aiming values that have been stored from time to time and which can be made to suit the degree of accuracy of approximation which is aimed at.

In order to calculate the elevational lead angle a, use is made of the fact that the lead point must lie in the plane of flight which for a rectilinear flight path is clearly determined by the aiming values (a), (A) and (r). The angle of elevation AT of the lead point and hence the elevation of the gun 8 less the angle of super elevation u is determined in the calculating mechanism 4 for the instantaneous azimuthal lead angle , for example by using the following equation (4)

The elevational lead angle S is thus also known: 8=T i2 For horizontal flight, the angle p is identical with the instantaneous positional angle y2.

for inclined flight however:

Since the azimuthal angle 5 and the elevational lead angle ô, after being determined in the calculating mechanism 4, are automatically fed to the adjusting mechanism of the sighting device 3 with their sign reversed, the gun 8 is always aimed directly at the lead point T in the plane of flight when the sighting device 3 is directed on the target 2.

In the course of following a target, the above-mentioned calculations of the lead angle are repeated each time a new pulse is emitted with a new transmission of a range value.

The corrective factor 5 in the equation (1) for determining the azimuthal lead angle can be made to suit the selected method of fire and the ballistics of the gun and ammunition employed as well as possible by optimising the equation (1) for the said ballistics.

If the gun 8 is being used for calculated barrage firing, it is then usually sufficient to increase to some extent the positional angle (3'2) that has been calculated in the calculating mechanism 4 according to the equations (2) and (3). In the case where calculated barrage firing is used, however, the aiming components of the gun 8 must be kept unchanged from the firing of the first round of the series until the firing of the last round thereof. Usually, however, it is sufficient merely to slow down the aiming movement of the gun and the sighting device during the firing of the barrage.This temporary cessation or slowing down of the traversing and elevating movement of the gun can be brought about in known manner by component parts of the calculating mechanism 4 for the period during which a series of round is being fired, which period can be freely selected and adjusted in the calculating mechanism.

A wide range of variations is possible in the construction and arrangement of the aiming device of the invention, according to the very many different constructional forms of gunsights that exist and to the very many variations that are possible in the equations for determining the plane of flight, the lead angles 5 and a and the azimuthal lead tolerance factor 5.

Thus, in particular, it is unimportant what kind of range-finder 5 is used for measuring the range to the target and whether the measurement and transmission of the range is effected continuously or intermittently. Laser or radar range-finders are preferably used, but, in view of the relatively small influence that the accuracy of the range measurement has on the accuracy with which the lead is determined, it is even possible, with a suitable choice of permissible tolerances, to use optical range finders or merely to make use of range values taken from known so-called preset range programs.

A great advantage of the device according to the invention consists in the fact that not only is the aiming process very simple and certain, but also the tracking of the target is not critical. Thus, for example, particularly when carrying out calculated barrage firing, it can take place jerkily, provided only that care is taken that the directing of the sight onto the target is effected accurately at the beginning of the program for calculating the lead and when a round is fired. in order to facilitate accurate sighting of the target, it is advantageous that the magnification of the sighting device 3 should be adjustable.

Since a large field of view, which involves a low magnification, is desirable only while the initial finding of the target is being carried out, but unlike the situation with other aiming devices is not required during subsequent following of the target, even when substantial lead angles are involved, there is no reason why the optical device 3 should not have a high magnification.

The fact that, with the aiming device according to the present invention, unlike known aiming devices, a large field of view is not necessary, facilitates the use of periscopic sights which is advantageous when the device is used in conjunction with vehicle-mounted guns.

The sighting device 3 may obviously be provided in known manner with a sun shield protective device.

A further advantage of the aiming device according to the invention, as compared with other aiming devices which are provided with a calculating mechanism and which are based on the determination and fixing of the position of a plane of flight which remains unchanged while the target is being followed, is that, with the device according to the invention, the plane of flight and the lead angle are clearly and accurately determined within the short time period between two successive pulses emitted by the pulse generator and thus without delay. In this way, successive determinations of the plane of flight are carrried out automatically while the target is being followed, so that the calculation of the required lead, which is based on the assumption that the flight path is rectilinear, also produces, with no appreciable delay, a substantially correct result when an aerial target, after performing a manoeuvre along a curved flight path, is once again following a straight flight path. It is thus possible to relieve the gun-layer of extra work, so that he can concentrate at all times wholly and exclusively on the careful following of the target and correct firing of each round.

Claims

1. An aiming device for use in firing at moving targets, particularly aerial targets, comprising an optical sighting device (3) the optical axis of which is adjustable in both azimuth and elevation with respect to the direction of the barrel of the gun to be aimed and which cooperates via electrical connections with a range-finder (5) and a calculating mechanism (4), characterised in that the calculating mechanism (4) is suitable for continously solving preprogrammed equations for determining the plane of flight, the lead values and the times of flight of the projectile to the target on the basis of data transmitted to it from the range-finder (5) and the gun (8) and for determining the super-elevation on the basis of the ballistic data that is stored in it, in which the calculating mechanism (4) contains stores and relates the directional data continuously supplied to it from the gun with temporarily stored azimuthal and elevational angles and with quantities which can be derived therefrom, and for this purpose has a pulse-generator for producing signals for bringing about temporary storage operations and for forming differential aiming values for periods of time which can be selected as desired, a device for measuring the intervals between the pulses as well as means which initiate the calculation of the lead and which control the adjustment of the optical axis of the sighting device (3) automatically, according to the values determined, in relation to the direction of the barrel of the gun (8).

2. A device according to claim 1, characterised in that the optical sighting device (3) and the calculating mechanism (4) are removably secured as a unit to a sight-carrier connected to the gun.

3. A device according to claim 1, characterised in that the optical sighting device (3) and the calculating mechanism (4) are mounted separately adjacent the gun (8).

4. A device according to claim 1, characterised in that the magnification of the sighting telescope of the optical sighting device (3) is adjustable.

5. A device according to claim 1, characterised in that a periscopic sight is used instead of the sighting telescope of the optical sighting device (3).

6. A device according to claim 1, characterised in that the stores of the calculating mechanism (4) are suitable for storing ballistic data relating to various different kinds of projectiles.

7. A device according to claim 1, characterised in that a laser-telemeter is used for determining the range of the target.

8. A device according to claim 1, characterised in that a radar-telemeter is used for determining the range of the target.

9. A device according to claim 1, characterised in that a range-programming device is used for determining the range value is to be fed into the calculating mechanism.

10. A device according to claim 1, characterised in that the output of the calculating mechanism (4) acts upon the means for adjusting the direction of the optical axis of the sighting device (3), which direction is determined by the gun without correction to allow for lead.

11. A device according to claim 1, characterised in that the calculating mechanism (4) is programmed so that, for the purpose of determining the plane of flight, it is arranged to solve the equation:

12. A device according to claim 1, characterised in that the calculating mechanism (4) is programmed so that, for the purpose of determining the azimuthal lead angle, it is arranged to solve the equation:

1 3. A device according to claim 1, characterised in that the calculating mechanism (4) is programmed so that, for the purpose of determining the elevation lead angle, it solves the two equations:

and iT 2 14.A device according to claim 1, characterised in that it has an element for changing over frbm the manner of operation for continuously aimed firing to the manner of operation for barrage firing and vice versa.

1 5. A device according to claim 1, characterised in that it has means for adjusting and limiting the duration of a period of continuous firing to a selectively adjustable time.

1 6. A device according to claim 1, characterised in that it comprises means for stopping the elevating and traversing movements of the gun (8), during calculated barrage firing, on the firing of the first round of a series of rounds and preventing said movements from being recommenced while the remaining rounds of said series are being fired.

1 7. A device according to claim 1, characterised in that it comprises means for reducing the speed of the elevating and traversing movements of the gun (8), during calculated barrange firing, on the firing of the first round of a series of rounds and keeping the speed of said movements reduced while the remaining rounds of said series are being fired.