EP0690284B1 - Deploying device for a projectile wing - Google Patents

Description

The present invention relates to a device for deployment of a projectile stabilization wing, including a projectile fired by a recoilless weapon.

Certain projectiles, notably those fired by a tube smooth like that of a recoilless weapon, have stabilization fins at their rear. These fins are folded back when the projectile is in the tube launch and they deploy at the exit of this one.

The known deployment devices put the most often using springs which are kept in good condition tension when the fins are folded along the body of the projectile and which relax by deploying the fin at the exit from the launch tube.

Patent FR7803397 describes such a device for deployment.

The disadvantage of such devices is that they impose the maintenance of several springs (one per wing) during the entire storage time of the projectile.

The mechanical characteristics of the springs deteriorate over time and as a result, on the one hand a decrease deployment efficiency, and secondly asymmetries when opening the fins, which harm stabilization of the projectile on trajectory therefore at the shot accuracy.

In addition, the installation of springs imposes the housing housing for the projectile body these, and poses problems during assembly and control, which increases manufacturing costs.

The patent GB2136930 which represents the preambles of claims 1 and 4, describes a sub-calibrated projectile in which the deployment of the fin is ensured by the aerodynamic flow exerted on the front end fin. The efficiency of such a system is reduced and the deployment symmetry is not guaranteed.

It is the object of the invention to propose a device deployment of stabilization fins for a projectile which does not have such disadvantages and which ensures lower cost efficient and symmetrical deployment of stabilization fins.

Thus the subject of the invention is, according to a first mode of realization, a fin deployment device stabilization for a projectile comprising at least one pallet, made integral with a fin by means drive, and oriented to receive a flow aerodynamics when firing the projectile and transmitting thus an effort resulting in the fin in order to deploy it, device characterized in that it comprises at least two pallets separated by a groove in which is positioned the fin, the groove having a bottom on which the fin comes into support when it is in the folded position on along the projectile body, bottom which constitutes the means which is unlockable so as to separate the deployment device and the fin from a certain opening angle of the latter.

The device will advantageously include a wall front closing the groove at a front part of the device and constituting an axial stop for the end fin.

It may include at least two lateral support feet which are in contact with an external surface of the projectile and which are held by stop profiles carried by the projectile and arranged to prevent displacement of the device in a direction perpendicular to a lateral surface of the fin.

According to a second embodiment of the invention the stabilizer fin deployment device is characterized in that it comprises at least one pallet secured to at least two lateral drive surfaces, each of these drive surfaces being intended for receive support from a different wing of the projectile when the latter are in the folded position along of the projectile body, lateral drive surfaces which constitute the means of training which is unlockable so as to separate the deployment device and the fin from a certain opening angle of the latter.

This device may include a tab intended to come into abutment against a flange secured to the projectile and which constitutes an axial stop for the device.

It may include at least one substantially wall perpendicular to each drive surface and constituting an axial stop for the end of the fin considered.

Each lateral drive surface may include a zone for holding a first lateral surface of the fin.

The device according to the invention may include a external guide surface with circular profile and the diameter is equal to that of a launch tube of the projectile.

An advantage of the invention is that it makes it possible to avoid, to open a fin, the use of potential energy elastic stored in springs.

Another advantage of the invention is that it allows exert maximum force at the start of the opening, when the resistant efforts are also the greatest.

The invention also makes it possible to avoid any drag residual aerodynamics caused by the device. In releasing the fin early enough we also limit rebounds of the latter.

• la figure 1 représente partiellement la partie arrière d'un projectile équipé d'un dispositif de déploiement d'ailettes selon un premier mode de réalisation de l'invention,
• la figure 2 est une vue en coupe transversale de la partie arrière de ce projectile au niveau des dispositifs de déploiement d'ailettes, suivant le plan repéré AA sur la figure 1,
• les figures 3a, 3b et 3c représentent ce premier dispositif de déploiement d'ailettes suivant trois vues orthogonales,
• la figure 4 représente une variante de ce dispositif,
• la figure 5 représente partiellement la partie arrière d'un projectile équipé d'un dispositif de déploiement d'ailettes selon un deuxième mode de réalisation de l'invention,
• la figure 6 est une vue en coupe transversale de la partie arrière de ce projectile au niveau des dispositifs de déploiement d'ailettes, suivant le plan repéré BB sur la figure 5,
• les figures 7a, 7b et 7c représentent ce deuxième dispositif de déploiement d'ailettes suivant trois vues orthogonales.

Other advantages of the invention will appear on reading the description of different embodiments, description made with reference to the accompanying drawings and in which:

• FIG. 1 partially represents the rear part of a projectile equipped with a device for deploying fins according to a first embodiment of the invention,
• FIG. 2 is a cross-sectional view of the rear part of this projectile at the level of the fins deployment devices, along the plane marked AA in FIG. 1,
• FIGS. 3a, 3b and 3c represent this first device for deploying fins in three orthogonal views,
• FIG. 4 represents a variant of this device,
• FIG. 5 partially represents the rear part of a projectile equipped with a device for deploying fins according to a second embodiment of the invention,
• FIG. 6 is a cross-sectional view of the rear part of this projectile at the level of the fins deployment devices, along the plane marked BB in FIG. 5,
• Figures 7a, 7b and 7c show this second device for deploying fins in three orthogonal views.

Figure 1 shows schematically the rear part a projectile 1 intended to be fired by a launcher without known type of recoil (not shown).

This rear part includes a flange 2 on which are arranged screeds 3 regularly distributed angularly. Each yoke receives a fin 4, mounted pivoting around an axis 5.

The projectile thus represented therefore carries six fins 4 regularly distributed (see figure 2).

The fins 4 are represented here in their position folded along the body of projectile 1, position which is theirs inside the launch tube.

Each fin 4 carries at a front end 4a a deployment device 6 according to the invention (here a only device is shown for clarity of the figure).

According to the first embodiment described, the device 6 comprises two pallets 7a and 7b for receiving the aerodynamic flow that appears when firing along of the body of the projectile between the front part (AV mark) and the rear part (AR mark).

These pallets have substantially the shape of two planes inclined to the axis 8 of the projectile and perpendicular to the lateral surfaces 4b and 4c of the fin 4.

The inclination of the pallets relative to axis 8 of the projectile is chosen such that aerodynamic flow has the effect of removing the device 6 from the body 1a of the projectile.

Because of the mode of action used, the device according to the invention can only be used to deploy fins which in the rest position are folded along the body of the projectile, the free ends of the fins being oriented towards the front part of the projectile and the screeds being arranged at the rear thereof.

Figures 3a, 3b and 3c show in detail the deployment device 6.

This device is made for example in material molded plastic (such as high density polyethylene or polyamide). The material thickness is substantially constant for the whole device. Pallets 7a and 7b are connected to side walls 8a and 8b which are end with lateral support feet 9a and 9b.

The side walls 8a, 8b are flat and substantially parallel to the lateral surfaces 4b, 4c of the fin 4.

The device, after being placed on the projectile, is shaped so as to present opposite aerodynamic flow two channels 6a, 6b whose inlet openings (arranged towards the front part of the projectile) have a surface greater than the openings of outlet (oriented towards the rear part AR), this due the tilt of the pallet.

The support feet 9a, 9b are intended to come into contact with the external surface of the projectile body 1a, they have therefore a cylindrical profile with a diameter equal to that of the body 1a of the projectile.

The two pallets 7a and 7b are separated by a groove 10 in which the fin 4 is positioned.

The groove 10 has a bottom 10a on which the fin comes into support when it is in the folded position on along the projectile body 1a.

The groove 10 is closed by a front wall 11 at the level of a front part of the device 6. When the device 6 is placed on the projectile, the end 4a of the fin is in axial abutment on the wall 11. Thus the fin balances the inertia forces to which subject the pallet when firing.

The width of the groove 10 will be chosen such that it there is no play when installing the device 6 on the fin.

In addition, the feet 9a and 9b of the device are maintained laterally by stop profiles 12 carried by the projectile. These profiles 12 are arranged so as to prevent any movement of the device in a perpendicular direction to the lateral surfaces 4b, 4c of the fin 4.

Alternatively the stop profiles 12 could also play the role of axial stop for the device, it would then suffice to provide a setback on each foot preventing any retreat of the device.

By immobilizing the device, on the one hand in relation to the fin and secondly with respect to the body of projectile, we avoid the bending of the fin during its course inside the launch tube, which avoids vibrations from the tip of the fin at the outlet of the tube and improves the deployment process and stabilization of the projectile.

Figure 2 shows in section along the plane AA of the figure 1 the projectile 1 placed in a tube of launch 13.

As shown in this figure, the device 6 has an external guide surface 14 whose diameter is equal to that of the launch tube 13. The device thus improves the guidance of the projectile in the tube launch.

The operation of the device is as follows.

When the projectile is fired, the fins are firmly held by the device throughout the course inside the launch tube.

At the exit of the tube the aerodynamic flow penetrates in the openings 6a and 6b and exerts a force on the pallets 7a and 7b. This effort removes devices 6 from body of the projectile which has the effect of causing fins 4 via the bottom 10a of the grooves 10 and bulkhead 11.

All fins are symmetrically open this mainly because, thanks to the device according to the invention, the force applied to the fin is of origin aerodynamic and it is maximum at the start of the opening. The symmetry is also favored by the absence of vibrations of the fin obtained thanks to the transverse setting provided by the stop profiles 12.

The device according to the invention therefore makes it possible to avoid problems with known deployment springs whose mechanical characteristics are likely to deteriorate during storage of the projectile.

Beyond a certain deployment angle, the resulting aerodynamic forces as well as the centrifugal force which are exercised on the device 6 manage to overcome the friction between the fin and the groove 10 and entrain the separation of the device and the fin.

So during deployment, the devices are automatically ejected and do not interfere with the flight of the projectile by causing aerodynamic braking.

It is possible to determine the opening angle of the fin from which the device is ejected in playing on the dimensions of the contact surfaces fin / groove (for example by giving the groove a shape not parallel to the lateral faces of the fin).

It is also possible to determine the angle at which produces the ejection of the device by playing on the position of the front wall 11 and / or on the shape of the end of the fin.

In this case the action of the centrifugal force is added that of the tilting torque of the device with respect to the fin which is generated by aerodynamic forces.

FIG. 4 thus shows by way of example a device in which the bottom 11 is set back relative to the inlet openings of channels 6a, 6b.

Figure 5 shows schematically the rear part a projectile 1 equipped with a deployment device 15 according to a second embodiment of the invention which is for projectiles equipped with an even number of fins.

This device includes a pallet 7 intended to receive the aerodynamic flow that appears when firing along of the body of the projectile between the front part (AV mark) and the rear part (AR mark).

The inclination of the pallet relative to axis 8 of the projectile is still chosen such that the flow aerodynamics has the effect of removing the device 15 from the body of the projectile.

Figures 7a, 7b and 7c show in detail what deployment device.

It is also preferably made in terms of molded plastic.

Pallet 7 is connected to side walls 8a and 8b which end with lateral support feet 9a and 9b.

As in the previous embodiment, the walls side 8a, 8b are planar and substantially parallel to lateral surfaces 4b, 4c of the fin 4.

Thus the device, after its installation on the projectile, is shaped so as to present, in view of the aerodynamic flow, a channel 15a whose the entry opening (arranged towards the front part of the projectile) has a surface larger than that of the opening outlet (oriented towards the rear rear part).

The support feet 9a, 9b come into contact with the external surface of the projectile body 1a, they have a profile cylindrical with a diameter equal to that of this body.

They each carry a lateral drive surface 16a, 16b which is intended to receive the support of a fin 4.

Each surface 16a, 16b therefore receives a different fin when the latter are in the folded position on along the body 1a of the projectile.

The feet 9a, 9b also carry holding zones 17a, 17b which are each in contact with a surface lateral of the fin considered.

As is more particularly visible in Figure 6, three devices 15 according to the invention make it possible to deploy six fins.

Each fin is held laterally on one side by a holding zone 17 carried by one of the devices 15 and on the other by a stop profile 18 secured to a flange 19 also made of plastic and made secured to the projectile body, for example by bonding.

As shown in Figure 5, the flanges are axially offset from the device, so that the flanges do not prevent the opening of the fin.

The dimensions of the devices 15 and the flanges 19 will be chosen so that there is no play during the placement on the fin.

Such an arrangement makes it possible to immobilize the ends fins which avoid vibrations during shooting and improves the deployment process and stabilizes the projectile.

It would nevertheless be possible to omit the flanges 19 and to keep only one-sided retention of the fin by the holding zone 17, the result obtained would however be less effective.

Each device 15 finally comprises a rear tab 20 which is intended to come into abutment against a flange 21 of the projectile and which constitutes an axial stop for the device.

The tab also makes it possible to locate, at the level of the rear flange and at equal distance from each fin, the pivot point of the device. Such a provision ensures symmetrical opening of the two fins by the device.

It would be possible as an alternative to replace this tongue by two walls, each carried by a foot 9a, 9b and perpendicular to the drive surface considered 16a, 16b. These walls abutting against the end 4a of the fin during assembly.

As in the previous variant, the device 15 has an external guide surface 14 whose diameter is equal to that of the launch tube 13. The device thus improves the guidance of the projectile in the tube launch.

The operation of this embodiment is analogous to that of the previous one.

The deployment device is still ejected at from a certain opening angle of the fins.

An advantage of this embodiment is that it allows to eject the device very quickly which reduces its action to a simple initial impulse on the fins which end then their opening by inertia and by the effect of their clean trail.

The rapid ejection of the device also presents the advantage of limiting the angular speed of the fin in limit switch which limits the rebounds of the fin and improves the stabilization of the projectile.

Indeed, the distance between the ends of two neighboring fins increases during opening. The fins are therefore quickly released from surfaces 16a, 16b and it is possible to determine precisely the instant of ejection of the device by playing on the dimensions of the drive surfaces 16a, 16b and especially on the length L (see Figures 6 and 7a).

Another advantage of this embodiment is that it reduces the number of devices used for a projectile, therefore the cost of production.

Finally as a variant it would be possible to define a deployment system which would remain united to the fin even after deployment. Such a device would include for example one or more fixed pallets to the side walls of each fin.

Claims (8)

1. A deployment device for the stabilizing fins (4) of a projectile (1) comprising at least one pallet made integral with a fin (4) by drive means, and facing so that it receives an aerodynamic flow when the projectile is fired and thus transferring a resultant strain to the fin (4) so as to deploy it, characterised in that it comprises at least two pallets (7a, 7b) separated by a groove (10) in which the fin (4) is positioned, the groove (10) comprising a bottom (10a) whereupon the fin (4) comes to bear when it is in a folded position along the body of the projectile (1), said bottom constitutes a drive means unlockable so as to separate the deployment device from the fin from a certain angle of opening of the latter.
2. A device according to Claim 1, characterised in that it comprises a front wall (11) closing the groove (10) at a front part of the device and constituting an axial stop for the end of the fin (4).
3. A device according to one of Claims 1 or 2, characterised in that it comprises at least two lateral support feet (9a, 9b) which are in contact with an outer surface of the projectile (1) and which are held by stop profiles (12) carried by the projectile and arranged so as to prevent any movement of the device in a perpendicular direction to a lateral surface (4b, 4c) of the fin (4).
4. A deployment device for the stabilizing fins (4) of a projectile (1) comprising at least one pallet made integral with a fin (4) by drive means, and facing so that it receives an aerodynamic flow when the projectile is fired and thus transferring a resultant strain to the fin (4) so as to deploy it, characterised in that it comprises at least one pallet (7) integral with at least two lateral drive surfaces (16a, 16b), each of these drive surfaces being designed to accommodate a different fin (4) of the projectile (1) when the latter are in their folded position along the body of the projectile, said lateral surfaces (1) constitute a drive means unlockable so as to separate the deployment device from the fin from a certain angle of opening of the latter.
5. A device according to Claim 4, characterised in that it comprises a tab (20) designed to come to bear on a flange (21) integral with the projectile (1) and constituting an axial stop for the device.
6. A device according to Claim 4, characterised in that it comprises at least one wall which is roughly perpendicular to each drive surface (16a, 16b) and constitutes an axial stop for the end of the concerned fin (4).
7. A device according to one of Claims 4 to 6, characterised in that each lateral drive surface (16a, 16b) comprises a holding area (17a, 17b) of a first lateral surface of the fin (4).
8. A device according to one of Claims 1 to 7, characterised in that it comprises an outer guiding surface (14) having a circular profile and wherein the diametre is equal to that of the launch tube of the projectile (1).

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