EP0767356B1 - Spin braking system for a cargo ammunition submissile - Google Patents

Description

The present invention relates to a improvement to a braking system aerodynamics of a submunition ejected from a cargo shell by being rotated, the system of braking comprising several articulated airbrakes which are reported around the body of the submunition and intended for deploy after ejecting the submunition.

Generally speaking, a cargo munition which is fired by the cannon of a field artillery, is consisting of a large caliber shell containing a charge useful which is released at a point in the trajectory of the shell. The payload can be an illuminating load or be made up of one or more submunitions.

A cargo ammunition of this type is in particular described in document FR-A-2 363 077, this ammunition comprising a shell formed of an envelope closed at its front end with a warhead and at its rear end by a base, this base being connected to the envelope by means a mechanical connection intended to break at the time of shell removal.

The cargo shell is usually fired from a barrel with a striped tube to give the shell a movement very fast rotation intended to stabilize it on its path. Under these conditions, at the time of the unloading of the shell, the payload is ejected while also animated by a rapid rotation movement.

However, the submunitions of the new generation take away target detectors and / or navigation systems, the operation of which is based on a low rotational speed of the submunitions after their ejection. For this purpose, we equip the submunitions a braking system consisting of airbrakes articulated which are reported around the body of the submunition and intended to deploy after the ejection of the submunition to slow down its rotational movement.

In addition, these submunitions are increasingly more cumbersome due to the large number of components that they contain, which requires a reduction of the thickness of the shell of the shell thus causing a decrease in its resistance. In this case, the the stripping used is necessarily at low pressure for do not damage the shell and the systems embedded in submunitions.

The shell being gyrostabilized, the submunition (s) which are placed inside the shell are especially subjected to centrifugal forces which tend to spread the airbrakes by pressing them against the wall of envelope or pellet. The result is a force adhesion or friction which will then oppose the ejection force produced by the stripping system for eject the pellet and the submunitions. It may result malfunctions, especially when the unloading is at low pressure.

The object of the invention is to overcome these disadvantages in improving a system aerodynamic braking systems of the aforementioned type, improvement which is characterized in that the braking system also includes a device for holding the airbrakes in their folded position inside the shell, a holding device which is released following ejecting the submunition to allow opening air brakes outside the shell of the shell, the holding device consisting of bars or legs interposed between the airbrakes and the envelope or the shell base, these legs being integral with a support attached against an end face of the submunition.

For example, the support of the support is constituted by a cup, and the legs are connected at one end to the periphery of the cup extending on the same side thereof following a direction substantially perpendicular to the plane of the cup.

The legs are for example angularly regularly spaced around the cup, and their number is such that at least one leg is associated with a airbrake.

Generally speaking, the legs came in the same piece as the cup or are attached to it by a welding or gluing operation.

The legs can advantageously be cylindrical pins.

When the airbrakes of a submunition are located next to the shell of the shell, the effects of the centrifugal force are significantly reduced as a result of significant reduction in the contact surface between the braking system and shell of this shell, this surface of contact being limited to the legs of the device hold, and once the submunition is ejected out of the shell of the shell, the centrifugal force can then exercise on the legs of the holding device for move away from the submunition and allow the opening of airbrakes.

On the other hand, when the shell of the shell is fitted out to receive part of the body of a submunition and that the airbrakes of the submunition come be located opposite the side wall of the base, the base and submunition assembly is ejected from shell of the shell as a result of actuation of the stripping system, known per se.

• les extrémités libres des pattes du dispositif de maintien sont initialement reçues dans des encoches ou des trous ménagés dans le corps de la sous-munition, et
• un moyen élastique est monté à l'état comprimé entre le culot de l'obus et le corps de la sous-munition, la détente de ce moyen élastique, une fois l'ensemble culot et sous-munition éjecté hors de l'enveloppe de l'obus, permettant de séparer le culot de la sous-munition alors que les pattes du dispositif de maintien des aérofreins restent maintenues en place au moyen des encoches ou des trous de la sous-munition pour faciliter la séparation du culot d'une part et retenir en place le dispositif de maintien et empêcher l'ouverture des aérofreins d'autre part.

In this case and according to other characteristics of the invention:

• the free ends of the legs of the holding device are initially received in notches or holes made in the body of the submunition, and
• an elastic means is mounted in the compressed state between the shell of the shell and the body of the submunition, the trigger of this elastic means, once the base and submunition assembly ejected from the shell the shell, making it possible to separate the pellet from the submunition while the legs of the airbrake holding device remain held in place by means of the notches or holes of the submunition to facilitate the separation of the pellet on the one hand and retain the holding device in place and prevent the opening of the airbrakes on the other hand.

In addition and according to another characteristic of the invention, a connecting element is fixed to the device for maintaining the airbrakes of the submunition on the one hand and on the shell of the shell on the other hand, this device of connection being constituted by a drop-down means, such as a cable or chain for example, to release the legs notches or holes in the submunition, once the pellet itself cleared from the submunition, and allow the opening of the airbrakes by force centrifugal.

In this case also, the effects of force are significantly reduced as a result of significant reduction in the contact surface between the braking system and the shell base, this surface of contact being limited to the legs of the holding device, which facilitates the separation of the base from the submunition.

According to an important advantage of the invention, the holding device holds the airbrakes a submunition in their folded position during interior and exterior ballistics phases of the shell and this, as long as the submunition is not ejected out of the shell of the shell.

According to another advantage of the invention, the friction forces between the braking system and the shell or the shell of the shell, which result from the centrifugal force, are considerably reduced as a result a significant reduction in contact surfaces.

According to another advantage of the invention, a device for holding the airbrakes of a submunition can be considered regardless of the number of submunitions boarded the cargo shell.

According to another advantage of the invention, the holding device is simple and easy in structure to be implemented for a reduced manufacturing cost.

• la figure 1 est une vue en perspective d'un obus cargo équipé d'un système de freinage perfectionné selon l'invention,
• la figure 2 est une demi-vue en coupe partielle de la partie arrière de l'obus pour illustrer les différents éléments constitutifs du système de freinage selon l'invention, en particulier un dispositif de maintien des aérofreins constituant le système de freinage d'une sous-munition lorsque les aérofreins viennent se loger dans le culot après montage de la sous-munition dans l'obus,
• la figure 3 est une vue en perspective éclatée du dispositif de maintien des aérofreins selon un mode de réalisation de l'invention,
• les figures 4 et 5 sont des vues en perspective partielle illustrant les deux étapes successives de fonctionnement du système de freinage perfectionné selon l'invention,
• la figure 6 est une demi-vue en coupe semblable à celle de la figure 2 lorsque les aérofreins d'une sous-munition ne viennent pas se loger dans le culot après montage de la sous-munition dans l'obus, et
• la figure 7 est une vue en perspective d'une variante de réalisation du système de maintien illustré à la figure 3.
• la figure 8 est une demi vue en coupe partielle de la partie arrière d'un obus montrant un dispositif de maintien selon un autre mode de réalisation de l'invention,
• la figure 9 est une vue en perspective du dispositif de maintien illustré à la figure 8.

Other advantages, characteristics and details of the invention will emerge from the explanatory description which follows, given with reference to the appended drawings given solely by way of example and in which:

• FIG. 1 is a perspective view of a cargo shell equipped with an improved braking system according to the invention,
• Figure 2 is a partial sectional half-view of the rear part of the shell to illustrate the various components of the braking system according to the invention, in particular a device for holding airbrakes constituting the braking system of a submunition when the airbrakes are housed in the base after mounting the submunition in the shell,
• FIG. 3 is an exploded perspective view of the device for holding the airbrakes according to one embodiment of the invention,
• FIGS. 4 and 5 are partial perspective views illustrating the two successive stages of operation of the improved braking system according to the invention,
• FIG. 6 is a half-view in section similar to that of FIG. 2 when the airbrakes of a submunition do not come to be housed in the base after assembly of the submunition in the shell, and
• FIG. 7 is a perspective view of an alternative embodiment of the holding system illustrated in FIG. 3.
• FIG. 8 is a half view in partial section of the rear part of a shell showing a holding device according to another embodiment of the invention,
• FIG. 9 is a perspective view of the holding device illustrated in FIG. 8.

Cargo shell 1 illustrated in Figure 1 includes an envelope 2, the front part of which is closed by a warhead 4 and the rear part of which is closed by a base 5. Base 5 is connected to the casing 2 by means a mechanical connection (not shown) intended to be break when the shell 1 is unloaded.

This connection is for example obtained in freely engaging the base 5 in the casing 2 and by axially retaining by fixing means having a fracture leader such as screws or pins.

Shell 2 of shell 1 contains one or more several submunitions 7 which are ejected at the time of shell 1 unloading, i.e. after separation between the casing 2 and the base 5 which is caused by a stripping system known per se.

A belt 9 fixed around the envelope 2 is intended to take the scratches from the launch tube of the cannon firing shell 1 to print the latter a rapid rotation movement intended to stabilize it on its path.

Submunitions 7 which are also rotated by the casing or the base of the shell thanks for example to keys, are by consequently ejected by being animated by a movement of rapid rotation and, for the reasons explained in preamble, this rotation speed is reduced by means a braking system consisting of airbrakes 10 which deploy automatically after the ejection of the submunitions.

Referring in particular to FIGS. 4 and 5, an air brake 10 is for example constituted by a blade 12 articulated climb on the body of the submunition 7. The blade 12 is shaped with a radius of curvature such that can come and fit the body shape of the submunition 7. Several airbrakes 10, four in number per example, are thus distributed around the body of the submunition 7.

Once submunition 7 is housed in the shell 1, the blades 12 conform to the shape of the body of the submunition 7 and the airbrakes 10 are found in a folded position between the body of the submunition 7 and either the inner wall of the envelope 2, or the wall internal of the base 5, as will be explained below.

A holding device 15 is used to retain the airbrakes 10 in their folded position at inside shell 1 to avoid the effects of force centrifugal resulting from the rotational movement printed at shell 1 from the cannon shot. Indeed, the force centrifugal tends to spread the airbrakes 10 to come press against the casing 2 or the base 5 until shell removal 1.

In general, the support system 15 is constituted by a set of lugs or bars 20 which are interposed between the airbrakes 10 and the wall internal of the casing 2 or of the base 5. The tabs 20 are integral with a support 22 which is simply attached against an end face or rear end face of submunition 7.

According to an exemplary embodiment, the support 22 consists of a cup 23. The legs 20 are connected at one end to the periphery of the cup 23, so as to extend substantially perpendicularly to the cup 23 and on the same side thereof. Other said, the legs 20 delimit between them a cylinder and extend along the generatrices of this cylinder.

The legs 20 may have come from the same part with the cup 23 or be fixed to it by a bonding or welding operation.

According to a first illustrated embodiment in Figures 1, 2, 4 and 5, we will consider a cargo shell with a payload consisting of a single submunition 7, of which the airbrakes 10 are located, which is often the case, towards a rear end or rear end of the submunition submunition considering the direction of introduction of the in shell 1. In addition, shell 5 of shell 1 can be arranged, in particular with regard to the length axial of its cylindrical side wall 5a, to receive the rear part of the submunition. In these conditions, once the submunition is placed in shell 1 the airbrakes 10 will be located opposite the side wall 5a from pellet 5.

• la coupelle 23 est coincée entre le fond du culot 5 et une face d'extrémité arrière de la sous-munition 7, et
• les pattes 20 sont positionnées entre le corps de la sous-munition 7 et la paroi latérale 5a du culot 5 et les extrémités libres de ces pattes 20 viennent s'engager dans des encoches 24 ménagées dans la sous-munition 7, un léger jeu ou espace e séparant les pattes 20 et la paroi latérale 5a du culot 5.

The holding device 15 is mounted between the base 5 and the rear part of the submunition 7, so that after assembly, as illustrated in FIG. 2:

• the cup 23 is wedged between the bottom of the base 5 and a rear end face of the submunition 7, and
• the tabs 20 are positioned between the body of the submunition 7 and the side wall 5a of the base 5 and the free ends of these tabs 20 engage in notches 24 formed in the submunition 7, a slight play or space e separating the legs 20 and the side wall 5a of the base 5.

A connecting means 25 is provided between the holding device 15 and the base 5. For example, this means is unrollable and consists of a cable or a chain 27, the two free ends of which are respectively connected to the cup 23 and to the bottom of the base 5. The cup 23 advantageously has a convex shape to delimit a space intended to receive the cable 27.

Finally, an elastic element, such as a Belleville washer 29, is interposed between the bottom of the base 5 and the cup 23 of the holding device 15, this washer 29 being compressed once the base 5 fixed to the casing 2.

The operation of the brake system will be explained below with reference to Figures 4 and 5.

Shell 1 is fired while being rotated at high speed. The submunition 7 which is rotated by the shell 1, is therefore subjected to the action of centrifugal force which should have the effect of pressing the legs 20 against the side wall 5a of the base 5 while eliminating the initial play e . However, as the legs 20 are radially maintained on one side by the cup 23 and on the other side by the notches 24 of the submunition 7, the centrifugal force can at most only cause bending of the legs 20, so that only the central part of the lugs 20 is capable of coming into contact with the side wall 5a of the base 5. This contact surface can moreover be limited to the minimum with cylindrical lugs 20. The frictional forces which result from this contact are therefore considerably reduced because, without the presence of these lugs 20, the blades 12 of the airbrakes 10 would come directly into contact with the side wall 5a of the base 5 on a significantly larger surface.

The shelling of shell 1 will then take place at a point in its trajectory following the actuation of a stripping system known per se. This system is by example consisting of a pyrotechnic composition gas generator which is mounted in the warhead 4 and by a initiation chronometric rocket. After initiation of the pyrotechnic composition, the gas pressure resulting from combustion is applied to the front end face of submunition 7 via a piston until breaking the mechanical link between the casing 2 and the base 5.

First illustrated in Figure 4, the assembly consisting of the base 5 and the submunition 7 ejects out of envelope 2 while also being animated of a rapid rotational movement. Forces aerodynamics which are then applied to the base 5, in particular on the free end face of its wall lateral 5a which is no longer in abutment against a shoulder associated with submunition 7, and the trigger on the washer Belleville 29 lead to the separation of base 5 from submunition 7. This separation takes place all the more easily as the frictional forces of the legs 20 on the side wall 5a of the base 5 are reduced. The airbrakes although released from envelope 2 are still retained in their folded position by the maintenance 15. Indeed, under the action of forces aerodynamic, the cup 23 remains pressed against the submunition 7 and the legs 20, which are retained by the notches 24 of submunition 7, cannot deviate or open under the action of centrifugal force. Finally, the cable 27 in progress produces no action on the holding device 15.

Secondly illustrated in Figure 5, the cable 27 is stretched and therefore pulls on the holding device 15, which has the effect of releasing the tabs 20 outside the notches 24 of the submunition 7. The holding device 15 thus frees itself from the submunition 7 with the legs 20 which, under the action of the centrifugal force, move apart to allow opening or the deployment of airbrakes 10 in order to slow down the rotational movement of the submunition.

We will now consider airbrakes of a submunition or more on-board submunitions in a shell, which this time are located next to the envelope of this shell. In this case, the centrifugal force resulting from the rotation of the shell from the moment of barrel, tends to apply the airbrakes against the wall of the shell of the shell. The friction forces which result then oppose the action of the system of unloading which causes the ejection of the submunition (s) after separation of the shell from the shell.

In this case, the airbrakes 10 of a submunition 7 may also be retained in their folded position until the ejection of the submunition 7 by means of a holding device 15 similar to that previously described.

• la coupelle 23 est globalement coincée entre les deux faces d'extrémités adjacentes des corps des deux sous-munitions 7 et 7', et
• les pattes 20 sont positionnées entre les aérofreins 10 et la paroi de l'enveloppe 2.

Referring to FIG. 6 which schematically illustrates two adjacent submunitions 7 and 7 ′ housed in the shell 1, the device 15 for holding the airbrakes 10 of the submunition 7 is such that:

• the cup 23 is generally wedged between the two adjacent end faces of the bodies of the two submunitions 7 and 7 ′, and
• the tabs 20 are positioned between the airbrakes 10 and the wall of the envelope 2.

In this case, however, the free ends lugs 20 do not come to be housed in notches of submunition 7. Indeed, such a provision does not is no longer necessary as the ejection of the submunition 7 does not interfere with the separation of base 5 from the shell 1. In addition, the cable 27 which previously connected the holding device 15 and the base 5 can be omitted.

Once the shell is fired, the centrifugal force resulting from the rotation of the shell and submunitions from the cannon, will also have for effect of pressing the legs 20 against the envelope 2 but on a limited contact surface, which reduces all the more the friction forces which will then oppose the action of the stripping system.

Following the actuation of the unloading system, the increase in pressure of the gases generated by combustion of the pyrotechnic composition, causes the rupture of the mechanical connection between the casing 2 and the base 5. The pellet 5 emerges from the envelope 2 then is ejected, and the submunition 7 in turn comes out of envelope 2 under the thrust of gas. When the holding device 15 is completely disengaged from the casing 2, the centrifugal force acts first on the legs 20 by moving them away from the body of submunition 7 to release them from the airbrakes 10, and then on the airbrakes 10 themselves which go then open or deploy to slow the movement of submunition rotation 7.

If we maintained the presence of cable 27, it would then be fixed between the holding device 15 of airbrakes 10 of submunition 7 and the body of submunition 7 'ejected just before the submunition 7. The cable 27 would then facilitate the release of the maintenance 15 of the submunition 7.

According to an alternative embodiment illustrated in Figure 7, the cup 23 of the holding device 15 is pierced with a central opening 30.

Figures 8 and 9 show a device holding according to another embodiment of the invention.

In this embodiment the legs of holding 20 are constituted by pins cylindrical, regularly distributed angularly and fixed by welding to the cup 23.

Each pin enters a hole 24 arranged on the body of the submunition 7.

This embodiment has the advantage to be simple to manufacture. In addition, assured maintenance by pins is more rigid than that allowed by thin legs and it also further reduces friction. Indeed, the contact between the pins and, on the one hand the airbrakes 10, and on the other hand the wall internal of the envelope or the base is carried out according to a reduced surface which is that of the generators of pins.

Claims (12)

1. An aerodynamic brake system for a sub-munition (7) ejected from a cargo shell (1) comprising a casing (2) closed off by a base (5) and having a spin motion, such system comprising several hinged airbrakes (10) that are folded around the body of the sub-munition (7) and are intended to deploy or open after the sub-munition (7) has been ejected, characterised in that it also comprises a device (15) to hold the airbrakes (10) in their folded position inside the shell (1), such retention device (15) being released further to the ejection of the sub-munition (7) to enable the airbrakes (10) to open outside the shell (1) casing (2), said retention device (15) being constituted by clips or lugs (20) placed between the airbrakes (10) and the casing (2) or the base (5) of the shell, such lugs (20) being integral with a support (22) made on one end face of the sub-munition (7).
2. Braking system according to Claim 1, characterised in that the support (22) is constituted by a cup (23), the lugs (20) being connected by one end to the periphery of the cup (23) extending on the same side as the latter in a direction substantially perpendicular to the plane of the cup (23).
3. Braking system according to Claim 2, characterised in that the lugs (20) are evenly spaced angularly around the cup (23).
4. Braking system according to Claim 2 or 3, characterised in that the lugs (20) are fastened to the cup (23) by a welding or bonding operation.
5. Braking system according to Claim 2 or 3, characterised in that the lugs (20) and the cup (23) form a single piece.
6. Braking system according to one of Claims 2 to 4, characterised in that the lugs (20) are cylindrical pins.
7. Braking system according to any one of the above Claims, characterised in that when the airbrakes (10) are positioned opposite the lateral wall (5a) of the base (5) of the shell (1) for a sub-munition that is partly housed in the base (5), the free ends of the lugs (20) engage in holes or notches (24) arranged in the body of the sub-munition (7).
8. Braking system according to Claim 7, characterised in that it comprises an elastic means (29) mounted between the base (5) and the sub-munition (7) to separate the base (5) from the sub-munition (7) when the base-sub-munition assembly is ejected from the casing (2).
9. Braking system according to Claim 8, characterised in that the elastic means (29) is constituted by a Belleville washer compressed once the base (5) has been fastened to the shell casing (2).
10. Braking system according to any one of Claims 8 or 9, characterised in that it also comprises a linking element (25) fastened firstly to the retention device (15) and secondly to the base (5), to disengage the lugs (20) from the holes or notches (24) of the sub-munition (7) and free the retention device (15) when the base (5) has separated from the sub-munition (7).
11. Braking system according to Claim 10, characterised in that the linking means (25) are unwindable and constituted by a wire or chain (27).
12. Braking system according to any one of Claims 1 to 6, characterised in that, when the airbrakes (10) are positioned opposite the casing (2) of the shell (1), the retention device (15) for the airbrakes (10) is freed from the sub-munition (7) through the action of the centrifugal force exerted on the lugs (20).

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