EP0077273B1 - Fire control system for a direct shooting weapon mounted on an aircraft with rotating air foil - Google Patents

Description

The present invention relates to a fire control system for a straight-fire weapon, in particular a cannon, mounted on a rotary wing aircraft, such as a helicopter.

We know that fire control for cannon mounted on aircraft has been the subject of numerous studies. For example, patent US Pat. No. 2,724,998 describes a fire control system for a tensioned weapon mounted on an airplane, capable of being actuated by the pilot himself, and comprising an electromechanical calculation device, said weapon being rotatably mounted around two transverse axes, by means of motor means controlled by said calculating device, of the type comprising a sighting system on which a target and a reticle are likely to appear simultaneously, said reticle being able to be moved over said sighting system by a pilot command, as well as means for determining the coordinates of the position of said reticle with respect to an axis system linked to the aircraft and transmitting them to said electromechanical calculation device at least when on said system of aiming said reticle is brought into superposition on said target.

On the other hand, the fire control of such a straight-fire weapon from a helicopter is a relatively new field, in which the studies carried out on airplanes cannot be purely and simply transposed. Indeed, on the one hand, the particular flight characteristics of a helicopter and, on the other hand, the possibility of providing on a helicopter a mounting of a mobile weapon around two axes, for example rectangular, make driving original. of firing a weapon mounted on the helicopter relative to a firing line of the same weapon mounted on an aircraft (on which, in general, said weapon is mounted with fixed axes relative to the fuselage).

In addition, on a combat helicopter, unlike what happens on a combat aircraft, the barrel generally mounted in a turret so as to make it orientable in elevation and deposit with large angular deflections, cannot be, without special provisions , served by the pilot; such an additional load would be incompatible with the handling of the helicopter, the natural instability of which is known to make flight much more delicate and absorbent than that of a fixed wing airplane. Consequently, in this type of armed helicopter, the aiming of the cannon is usually carried out either by the co-pilot or by a specially designed servant.

The subject of the present invention is a fire control system for a tight-shot weapon mounted on a rotary wing aircraft capable of being actuated by the pilot himself and allowing total decoupling between the aiming carried out by the pilot and the corrections shooting.

To this end, according to the invention, the firing control system for a tensioned weapon mounted on a rotary wing aircraft, capable of being actuated by the pilot himself, and comprising a calculation device, said weapon being rotatably mounted around two transverse axes by means of motor means controlled by said calculating device, of the type comprising a sighting system on which a target and a marker may appear simultaneously, said marker being able to be moved on said tracking system aiming by a pilot command, as well as means for determining the coordinates of the position of said reference point with respect to an axis system linked to the aircraft and transmitting them to said calculation device at least when on said aiming system said reference point is superimposed on said target, is characterized in that said calculation device is an electronic calculator and in that said aiming system is of the semi-transparent mirror type allowing nt appear by transparency the target and forming the image of a light symbol generated by an electro-optical device, said image constituting the reference, while said electro-optical device forms said means for determining the coordinates of the reference and transmitting them to the electronic calculator.

Thus, the pilot, after having detected a target can orient the axis of his aircraft towards it, thanks to the flight controls, until the alignment is roughly achieved and the target appears in the field of the mirror. of sight. Then, continuing to drive to maintain and if possible perfect this alignment, by means of a control member, it makes the reference mark coincide with the target on the aiming system.

Preferably, the system according to the invention comprises means for indicating to the calculator the distance separating the aircraft from the target. These means can be display means controlled by the pilot or be constituted by a telemetric system.

Thus, the calculator receives the coordinates of the sighting frame, that is to say those of the target, when the coincidence is obtained by the pilot. It also receives information concerning the distance separating the aircraft from the target. Furthermore, the calculator receives gyrometers, gyroscopes and / or on-board anemometric sensors, information concerning the attitude and the variations in attitude of the aircraft, as well as its relative speed with respect to the ambient air. All of this data is used to predict the movement of the target and determine the orientation to give to the weapon.

The calculator is programmed to take into account the movement of the target. If accelerations are involved, it is necessary to measure the distance between the target and the aircraft, not just to estimate it.

Thus, in a simplified embodiment of the system, in which the distance to the target is estimated by the pilot in the manner mentioned above. above, the calculator assumes, in its calculations, that the target follows a rectilinear trajectory at constant speed during the flight time of the projectile fired by the weapon or a trajectory at constant acceleration and determines the position to give to the line of sight of the weapon in a reference linked to the helicopter so that the trajectories of the target and the projectile intersect at the same instant.

Preferably, the movement of the symbol is controlled in bearing by means of a two-axis gyroscope which is left free in elevation. As a variant, the movement of the symbol is controlled by means of a two-axis gyroscope so that, in the absence of control on the part of the pilot, the gyroscope is slaved to keep a fixed direction relative to the helicopter.

• La figure 1 montre schématiquement, partiellement en perspective, un mode de réalisation du système selon l'invention.
• La figure 2 montre en vue de face le système de visée du système selon l'invention.

The figures of the appended drawing will make it clear how the invention can be implemented.

• Figure 1 shows schematically, partially in perspective, an embodiment of the system according to the invention.
• FIG. 2 shows in front view the sighting system of the system according to the invention.

The system according to the invention, shown schematically in Figure 1, is intended to conduct the firing of a gun 1 mounted on a helicopter (not shown) with a longitudinal axis L-L '. The barrel 1, for example integral with a turret (not shown), can rotate around a bearing axis ZZ 'and an elevation axis YY' under the action of motors or jacks 2 and 3, respectively .

This system comprises a clear sight 4, of the semi-transparent mirror type, through which the pilot whose only eye 5 is represented in FIG. 1, can see a target 6, for example an enemy helicopter. The center of the viewfinder 4 passes for example by the axis LL 'of the helicopter provided with the system according to the invention or occupies a fixed position determined relative to it and the plane of said viewfinder is inclined at 45 ° relative to said axis L-L '.

Under the viewfinder 4 is provided an electro-optical device 7, on which a symbol 8 appears, the arrangement being such that the pilot can see simultaneously on the viewfinder 4 the target 6 and the image 8 'of the symbol 8. The position of the symbol 8 on the screen 7 (and therefore that of the image 8 'on the viewfinder 4) can be adjusted according to two perpendicular axes yy' and zz 'one of which is for example in the vertical plane passing through l 'axis L-L', by action on a control button 9, available to the pilot and for example mounted on the handle 10 of cyclic control. Two reference axes, for example engraved on the viewfinder 4 and carrying respectively the marks y ₁ -y ' ₁ and z _l - z' ,, allow the pilot to align with the axis LL 'when it makes optically coincide the image of the axes yy 'and zz' on the viewfinder 4 with said reference axes.

Furthermore, also available to the pilot, there is provided a control button 11, a device 12 for displaying the value at which said pilot estimates the distance separating him from the target 6, when the system does not include any rangefinder performing this measurement automatically.

The system according to the invention finally comprises a microcomputer 13 in connection with the electro-optical device 7, the distance display device 12, the on-board gyrometers 14, the gyroscopes. on board 15 and an anemometric sensor 16, from which it receives information, as well as with motors 2 and 3, to which it addresses orders.

As will be seen, the fire control system according to the invention makes it possible, on the one hand, to facilitate the aiming of the target 6 by the pilot, and on the other hand to decouple the shooting corrections from the aiming.

When it has detected a target 6, the pilot orients the axis L-L 'of its aircraft, using its flight controls, until the target 6 is in the field of its clear sight 4.

In addition, on the clear viewfinder 4 appears the image 8 'of the symbol 8 representing the direction of sight of the pilot.

At first, this direction of sight coincides with the longitudinal axis of the helicopter.

Once the target '6 is in the field of the clear sight 4, the pilot, by means of the control button 9 placed on its cyclic stick 10 will make the image 8' of the symbol 8 and the target 6 coincide. The pilot's job is then to pursue the target 6 with the symbol 8 throughout the aiming phase of the weapon and the shooting, so as to constantly maintain the coordinates C _b , E _b of the target respectively equal to the coordinates C _a , E _has image 8 '(see FIG. 2).

The control button 9 is a button with “two axes (site and deposit) making it possible to move the image of the symbol on the viewfinder. If the pilot exerts a force on the control button 9, the symbol 8 moves in the corresponding direction. In the absence of action on the button 9, the image of the symbol 8 keeps a fixed position on the clear viewfinder 4 and therefore indicates a fixed direction in a frame linked to the helicopter.

The pilot has two means for refining and continuing the aiming, namely his flight controls and the control button 9. He uses this last button, in particular in the case where the aiming at the flight controls would bring him towards areas of dangerous theft.

• des gyromètres de bord 14 et/ou des gyromètres spécifiques du viseur, qui fournissent les trois composantes par rapport à un système d'axes lié à l'hélicoptère de la vitesse de rotation absolue de la ligne virtuelle hélicoptère-cible.
• des gyroscopes de bord 15 qui fournissent une mesure de l'assiette longitudinale et de l'angle de gite.
• de capteurs anémométriques 16 mesurant les composantes de la vitesse de l'hélicoptère par rapport à l'air.
• du dispositif électro-optique 7 qui fournit la direction de la ligne de visée 17 par rapport à une référence liée à l'hélicoptère sous forme des coordonnées E_a et C_a (voir figure 2).
• du dispositif 12 qui fournit une estimation de la distance le séparant de la cible 6, ce dispositif pouvant être remplacé par un télémètre.

The digital calculator 13 manages the system and calculates the score to be given to the weapon 1. To calculate this score, it receives measurements:

• on-board gyrometers 14 and / or viewfinder-specific gyrometers, which supply the three components with respect to an axis system linked to the helicopter of the absolute speed of rotation of the virtual helicopter-target line.
• edge gyroscopes 15 which provide a measurement of the longitudinal attitude and of the angle of inclination.
• anemometric sensors 16 measuring the components of the helicopter's speed relative to the air.
• of the electro-optical device 7 which provides the direction of the line of sight 17 with respect to a reference linked to the helicopter in the form of the coordinates E _a and C _a (see Figure 2).
• of the device 12 which provides an estimate of the distance separating it from the target 6, this device being able to be replaced by a range finder.

All this information is filtered to arrive in the calculator 13 in the same form and the same frequency.

- The calculator processes this information and deduces the score to be given to cannon 1 so that the shell reaches the target 6. A simple assumption taken into account in the calculator 13 program to calculate the score for weapon 1 is that target 6 moves in a straight line and at uniform speed during the time of the shell's journey. If the helicopter is equipped with a rangefinder, a hypothesis on the acceleration of the target can be taken into account.

The instructions from the calculator 13 give the site sc and the gc deposit to be given to the gun and are sent to the rotation servos 2 and 3 of the latter.

Thus, as long as the pilot maintains the image 8 ′ on the target 6 in superposition, it is certain that the weapon 1 is correctly aimed, in accordance with the program of the calculator 13, so that he can actuate the trigger of said canon.

• 1. Le déplacement du symbole 8 est commandé en gisement par l'intermédiaire d'un gyroscope à deux axes qui est laissé libre en site et qui, en gisement, est asservi à rester au voisinage de C_a=O. Le symbole 8 est donc découplé des petits mouvements en gisement. En site, le pilote ne peut déplacer sa visée qu'à l'aide de son bouton de commande 9 ; en effet, le gyroscope est libre en l'absence de commande du pilote et garde donc une direction fixe par rapport à la terre.
• 2. On commande le déplacement du symbole 8 par l'intermédiaire d'un gyroscope à deux axes de sorte que, en l'absence de commande de la part du pilote, le gyroscope est asservi à garder une direction fixe par rapport à l'hélicoptère en étant découplé des petits mouvements. Le gros avantage de ce type de visée est qu'en l'absence de commande, le pilote voit un symbole qui est stable par rapport au paysage extérieur et qui suit le mouvement moyen de l'hélicoptère. Le pilote peut affiner sa visée aux commandes de vol.

In some cases, aiming as presented above may be difficult for the pilot, mainly because of the small high-frequency movements of the helicopter. To this end, two improvements can be made in the aiming for better accuracy.

• 1. The displacement of the symbol 8 is controlled in bearing by means of a two-axis gyroscope which is left free in elevation and which, in bearing, is slaved to remain in the vicinity of C _a = O. The symbol 8 is therefore decoupled from small movements in the deposit. On site, the pilot can only move his aim using his control button 9; in fact, the gyroscope is free in the absence of pilot control and therefore keeps a fixed direction relative to the earth.
• 2. The movement of the symbol 8 is controlled by means of a two-axis gyroscope so that, in the absence of control by the pilot, the gyroscope is slaved to keep a fixed direction relative to the helicopter by being decoupled from small movements. The big advantage of this type of sighting is that in the absence of control, the pilot sees a symbol which is stable compared to the external landscape and which follows the average movement of the helicopter. The pilot can refine his aim with the flight controls.

Claims (8)

1. Firing control system for a direct firing weapon (1) mounted on a rotary-wing aircraft, adapted to be actuated by the pilot himself, and comprising a calculating device (13), said weapon (1) being mounted for rotating about two transverse axes Y-Y' and Z-Z', due to driving means controlled by said calculating device, of the type comprising a sighting system (4) on which a target (6) and an adjusting mark (8') can appear simultaneously, which adjusting mark can be moved on said sighting system.by a control of the pilot, as well as means (7) to determine the coordinates of the position of said adjusting mark (8') with respect to a system of axes tied to the aircraft and to transmit them to said calculating device (13) at least when on said sighting system (4) said adjusting mark (8') is superposed on said target (6), characterized in that said calculating device (13) is an electronic computer and in that said sighting system is of the semi-transparent mirror type showing the target in transparency and reproducing the image of a luminous symbol (8) generated by an electro-optical device, said image constituting the adjusting mark (8'), whereas said electro-optical device forms the means (7) to determine the coordinates of the adjusting mark (8') and to transmit them to the electronic computer (13).

2. System according to claim 1, characterized in that it comprises means (11, 12) to indicate to the computer (13) the distance separating the aircraft from the target.

3. System according to claim 2, characterized in that said means (11, 12) are display means controlled by the pilot.

4. System according to claim 2, characterized in that said means (11, 12) are constituted by a range-finder.

5. System according to any one of claims 1 to 4, for an aircraft equipped with gyrometers, gyroscopes and/or anemometric sensors, characterized in that said gyrometers (14), gyroscopes (15) and/or sensors (16) supply to the computer (13) information on the attitude and attitude variations of said aircraft, as well as on its relative speed with respect to the atmosphere.

6. System according to any one of claims 1 to 5, characterized in that in its calculations, said computer assumes that the target (6) follow a rectilinear path at a constant speed throughout the course of the shell fired by the weapon (1) or a path at constant acceleration, and determines the position to be given to the line of sight of the weapon (1) within a system of axes tied to the helicopter so that the paths ot the target and of the shell intersect at the same moment.

7. System according to any one of claims 1 to 6, characterized in that the displacement of the symbol (8) is controlled in bearing via a twin-axis gyroscope which is left free in sight.

8. System according to any one of claims 1 to 6, characterized in that the displacement of the symbol (8) is controlled by a twin-axis gyroscope so that, when not controlled by the pilot, the gyroscope is programmed to keep a fixed direction with respect to the helicopter.

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