Guided Munitions Protected by an Aerodynamic Cap

Abstract

In the field of steered munitions intended to destroy a target after at least one flight phase followed by a target approach phase, a munition comprises a munition body of cylindrical shape of longitudinal axis having, on the same side as a front end of the munition which is the end intended to be directed toward the target, a front body comprising an optic of a guidance device that guides said munition toward the target, a cap for protecting the optic, secured to the munition body, characterized in that the protective cap comprises at least one recess having a pyrotechnic device intended to destroy said protective cap so as to free the optic and make the munition guidance device operational during the target approach phase. Application: steered or guided munitions such as those of the rocket or projectile type, or missiles.

Description

The invention relates to guided munitions comprising a protective cap that protects a guidance device guiding the munition toward a target that is to be destroyed.

Guided or steered munitions, such as those of the rocket or projectile type or missiles are equipped with guidance electronics and optical systems in order, after a phase of flight followed by a target approach phase, to ensure a high degree of reliability and precision with which the munition hits the target.

For example, certain types of missile or guided rocket are steered using a laser beam. A missile optic detects the laser beam illuminating the target and a missile on-board computer determines the flight parameters for reaching the target.

In general, the guidance optic is situated at the front end of the missile, or of the steered munition more generally, i.e. is situated at that end of the munition that is directed toward the target, comprises a protective cap, firstly for protecting the guidance optic from impacts with bodies present in the air during the flight phase, and secondly for preventing the temperature of the missile steering electronics associated with the guidance optic from heating up as a result of the aerodynamic friction against the head (or nose) of the munition.

This cap can thus protect the munition guidance optic, as appropriate, during a firing phase, for example when passing through a diaphragm; during a ballistic phase, in the case of a rocket or of a projectile; or during a cruising phase, in the case of missiles.

In the state of the art with guided munitions, either the guidance optic is directly exposed to impact with bodies present in the air and to aerodynamic friction or it is protected by a cap that can, on approaching the target, be detached from the munition body, at the risk of the protective cap detached from the munition body damaging the tail assembly that is deployed at the rear of the rocket or of the missile.

In order to alleviate the disadvantages of steered munitions of the prior art, the invention proposes a steered munition intended to destroy a target after at least one flight phase followed by a target approach phase, said munition comprising a munition body of cylindrical shape of longitudinal axis ZZ′ having, on the same side as a front end Eav of the munition which is the end intended to be directed toward the target, a front body comprising an optic of a guidance device that guides said munition toward the target, a cap for protecting the optic, secured to the munition body, characterized in that the protective cap, in the shape of an ogive of axis of revolution XX′ coincident with the longitudinal axis ZZ′, being made of a material that can be shattered into multiple fragments, comprises at least one recess forming at least one cavity containing a pyrotechnic device intended to supply propulsive energy directly to the walls of the cavity to shatter the protective cap into multiple fragments, in order to free the optic and make the munition guidance device operational during the target approach phase.

Advantageously, the protective cap comprises walls having weakening grooves so as to promote regions along which said walls rupture when the protective cap is being destroyed.

In one embodiment, the steered munition comprises, between the protective cap and the front body of the munition body, a shield that protects the optic of the guidance device.

In an another embodiment, the protective shield comprises a shield body of circular cylindrical rounded shape having two main faces and a circular edge of axis coaxial with the longitudinal axis ZZ′, the rounded shape of the shield body conforming to the shape of the surface of the front body of the munition body.

In another embodiment, the steered munition comprises a clamping band that secures the protective cap to the munition body, the clamping band comprising, on the same side as the front end Eav of the munition, a circular edge of tapering shape.

In another embodiment, the surface of the front body, of rounded shape, has no discontinuity and no roughness so that it exhibits a continuous aerodynamic profile.

In another embodiment, the front body of the munition body comprises, on the same side as the front end Eav, a front body part of circular cylindrical shape of diameter D1, of axis of revolution collinear with the longitudinal axis ZZ′, the front body part comprising a munition front body wall of rounded shape including the optic of the guidance device, the rounded portion of the munition front body wall being directed toward the front end Eav to give the munition a continuous aerodynamic shape when it has been rid of the protective cap.

In another embodiment the protective cap, in the shape of an ogive, of axis of revolution XX′, comprises a first recess opening onto a second recess of circular cylindrical shape of diameter equal to the diameter D1 of the front body part of the munition body, the first recess of the cap forming, with the rounded-shaped front body wall, centered on the longitudinal axis ZZ′, a first cavity containing the protective shield.

In another embodiment, the pyrotechnic device comprises a propulsive charge and an igniter, the igniter comprising electrical contacts for activating it.

In another embodiment, the first cavity contains the pyrotechnic device.

In another embodiment the protective shield comprises, near its circular edge, a support for supporting the igniter in a plane parallel to the longitudinal axis ZZ′, the igniter support acting as a spoiler intended to generate a transverse force when it is subjected to the aerodynamic forces as the cap is being destroyed, and as out-of-balance weight in the case of a munition that spins on itself.

In another embodiment, the protective cap further comprises, at the same side as the front end Eav, a third recess of cylindrical shape of axis collinear with the longitudinal axis ZZ′, and separated from the first recess by a dividing wall in a plane perpendicular to the longitudinal axis ZZ′, the third recess being closed by a nose cone to form a second cavity containing the pyrotechnic device intended to destroy the protective cap.

In another embodiment, the protective shield comprises, near its circular edge, a spoiler intended to generate a transverse force on the shield body when it is subjected to the aerodynamic forces and to cause it to be ejected from the body of the munition, said spoiler also acting as an out-of-balance weight in the case of a munition that spins on itself.

In another embodiment, the protective cap comprises a cap connection part extended by a cap end ring having a cap edge of diameter D5 greater than the outside diameter D4 of the cap connection part so as to form a first cap shoulder so that the clamping band can prevent translational movement of the cap along the longitudinal axis ZZ′ on the front body of the munition body.

In another embodiment, the munition comprises two layers of electric conductors intended to activate the igniter:

• • a first layer having one end bonded to one of the main faces of the shield on the same side as the front body of the munition body, a central part bonded to the other main face of the shield on the same side as the first recess of the cap, the other end of the first layer, in the first cavity being electrically connected to the electrical contacts for the activation of the igniter, the first layer passing from one main face of the shield to the other along a groove on the edge of said shield,
  • a second layer of electric conductors, on the same side as the munition body, in electrical contact with the end of the first layer on the same side of the front body of the munition body.

In another embodiment, the front body part is extended toward the rear body of the munition by an intermediate body of circular cylindrical shape of the same axis of revolution ZZ′ as, and of diameter D2 greater than the diameter D1 of, the front body part, so as to form a first body shoulder, the intermediate body being extended by the rear body of the munition of diameter D3 greater than the diameter D2 of said intermediate body, so as to form a second body shoulder.

In another embodiment, the protective cap, secured to the body of the munition by the clamping band, comprises a cap central part of conical or ogive shape extended, on its larger-diameter side, by a cap connection part that connects the cap to the munition body, of circular cylindrical shape, of outside diameter D4 smaller than the diameter D2 of the intermediate body, the cap connection part being extended by a cap end ring having a cap edge of diameter D5 greater than the outside diameter D4 of the cap connection part and less than the diameter D2 of the intermediate body so as to form a first cap shoulder intended to prevent translational movement of the cap.

In another embodiment, the cap edge and the first body shoulder each have a respective hole for the insertion of a pin that angularly indexes the cap and the munition body, the internal wall of the first recess of the cap comprising a tooth inserted in the groove situated on the circular edge of the protective shield, the angular indexing pin and the tooth inserted in the groove of the protective shield providing electrical contact between the two layers and orienting the spoiler of said protective shield at an advantageous clearance angle.

In another embodiment, the cap comprises a series of longitudinal weakening grooves along the walls of the first and second recesses, these grooves being evenly distributed about the axis of revolution XX′ of the cap, the cap further comprising a circular weakening groove along the periphery of its external surface some distance from the cap edge such that said circular weakening groove is located at the tapering end of the clamping band when the cap is mounted on the munition body.

In another embodiment, the cap moreover comprises another circular weakening groove along the periphery of the internal surface of the cap formed by the wall of the second recess, some distance from the cap edge such that said other weakening groove is located at the end, of diameter D1, of the front body part on the side of the front body wall when the cap is mounted on the munition body, the axis XX′ of the protective cap then coinciding with the longitudinal axis ZZ′ of the munition.

The invention will be better understood with the aid of an example of how a guided munition according to the invention is embodied, in the particular case in which this munition is a rocket, and with reference to the indexed drawings in which:

FIG. 1 is a partial view in axial section of one example of how a guided rocket according to the invention is embodied;

FIG. 2 a is a partial view in cross section of a protective cap of the rocket of FIG. 1;

FIG. 2 b is a partial perspective view of the cap of FIG. 1;

FIG. 2 c is a view of detail A of the cap showing weakening grooves;

FIG. 3 a is a perspective view of the rocket body of FIG. 1 comprising a protective shield;

FIG. 3 b shows just the protective shield of the rocket body of FIG. 3a;

FIG. 4 a shows the rocket of FIG. 1 after the cap has been destroyed and before the protective shield has been ejected;

FIG. 4 b shows the rocket of FIG. 1 after the cap has been destroyed and after the shield has been ejected;

FIG. 5 shows an alternative form of embodiment of the rocket of FIG. 1 according to the invention;

FIG. 6 is a perspective view of the rocket body of FIG. 5 comprising a protective shield.

FIG. 1 is a partial view in axial section of one example of how a guided rocket according to the invention is embodied.

More specifically, FIG. 1 is a partial view in cross section of the front end Eav of a guided rocket according to the invention. The front end Eav of the rocket is the end that is directed toward the target when the rocket is launched (the head or nose of the rocket) and which, therefore, has an aerodynamic shape for optimal penetration through the air. The other end of the rocket, which has not been depicted in the figures, is the rear end of the rocket and generally comprises a tail assembly.

The rocket of FIG. 1, of circular cylindrical shape of longitudinal axis ZZ′, essentially comprises:

• • a rocket body 10 having a front body 14 and a rear body 16 essentially forming the rocket body 10,
  • on the same side as the front body 14 of the rocket, a protective cap 20 in the form of an ogive of axis of revolution XX′,
  • a clamping ring 22 that secures the protective cap 20 to the rocket body 10,
  • between the protective cap 20 and the front body 14, a protective shield 24 protecting an optic 26 in the front body 14 of the rocket, of a homing head of the rocket, not depicted in the figures.

The front body 14 of the rocket comprises, on the same side as the front end Eav, a front body part 28 of circular cylindrical shape of diameter D1, of axis of revolution collinear with the longitudinal axis ZZ′. The front body part 28 is extended toward the rear body 16 of the rocket by an intermediate body 30 of circular cylindrical shape with the same axis of revolution ZZ′ and of diameter D2 greater than the diameter D1 of the front body part 28, so as to form a first body shoulder 32. The intermediate body 30 is extended by the rear body 16 of the rocket, of diameter D3 greater than the diameter D2 of said intermediate body 30, so as to form a second body shoulder 34.

FIG. 2 a is a partial view in cross section of the protective cap 20 of the rocket of FIG. 1, FIG. 2b is a partial perspective view of the cap of FIG. 1, and FIG. 2c is a view of detail A of the cap, showing weakening grooves.

The protective cap 20, secured to the rocket body 10 by the clamping band 22 (see FIG. 1) comprises a cap central part 40 of conical or ogive shape extended, on its larger-diameter side, by a cap connection part 42 that connects the cap to the rocket body 10, of circular cylindrical shape, of outside diameter D4 smaller than the diameter D2 of the intermediate body 30.

The cap connection part 42 is extended by a cap end ring 50 having a cap edge 52 of diameter D5 greater than the outside diameter D4 of the cap connection part 42 and less than the diameter D2 of the intermediate body 30 so as to form a first cap shoulder 54 so that the clamping band 22 can prevent translational movement of the cap 20 along the longitudinal axis ZZ′ on the front body 14 of the rocket.

The protective cap 20 further comprises a first recess 60 opening onto a second recess 62 of circular cylindrical shape of diameter equal to the diameter D1 of the front body part 28 of the rocket.

The protective cap 20 and the front body part 28 inserted in the second recess 62 of diameter D1 are in contact, firstly via their respective circular cylindrical surface, these being the internal surface of the cap 20 and the external surface of the front body part 28.

The clamping band 22 (see FIG. 1) coaxial with the longitudinal axis ZZ′ has two ends, one end of tapering shape, on the same side as the front end Eav, and another end on the rocket body side, an external surface 80 forming part of the exterior surface of the rocket and internal circular cylindrical surfaces.

The clamping band further comprises:

• • on the same side as the end of the body of the rocket, a first internal clamping surface 82 via which the clamping band 22 is secured to the circular cylindrical surface of diameter D2 of the intermediate part 30 of the rocket body 10. The clamping band 22 is kept in position secured to the rocket body 10 by known clamping means,
  • on the same side as its tapering end, a second, circular cylindrical internal surface 90 coaxial with the axis ZZ′ of the same diameter D4 as the cap connection part 42 and able to slip over said cap connection part 42.

The internal surface 90 of the clamping band 22 of diameter D4 is connected by a first band shoulder 94 to a third circular cylindrical internal surface 96 coaxial with the axis ZZ′, and then, via a second band shoulder 98, to the first internal clamping surface 82.

The cap 20 is held in its transverse position on the front body part 28 of the rocket body 10, in both directions along the axis ZZ′, by the clamping band 22, the first band shoulder 94 butting against the first cap shoulder 54 and the cap edge 52 butting against the first body shoulder 32.

The first recess 60 of the cap 20 forms, with a front body wall 110 of rounded shape centered on the longitudinal axis ZZ′ of the end of the front body 14 (see FIG. 1), a first cavity 104 containing the protective shield 24. The rounded portion of the front body wall 110 is directed toward the front end Eav to give the rocket an aerodynamic shape when it has been rid of the protective cap 20 and of the shield.

The protective cap 20 further comprises, on the same side as the front end Eav, a third recess 120 (see FIG. 2) of cylindrical shape of axis collinear with the longitudinal axis XX″ separated from the first recess 60 by a dividing wall 124 in a plane perpendicular to the longitudinal axis XX′. The third recess 120, opening on the same side as the front end Eav of the rocket, is closed by a nose cone 126 so as to form, with the third recess 120, a second cavity 128 containing, according to a key feature of the guided rocket according to the invention, a pyrotechnic device intended to destroy the protective cap 20.

In the embodiment of FIG. 1, the pyrotechnic device essentially comprises a propulsive charge 130 and an igniter 132 comprising electrical contacts 162 for activating it.

The nose cone 126 is rounded at its end to give the protective cap 20 the desired aerodynamic shape.

The cap 20 comprises a series of longitudinal weakening grooves 140 along the walls of the first 60 and second 62 recesses (see FIGS. 2a and 2b). These longitudinal grooves are evenly distributed about the axis of revolution XX′ of the cap.

The cap 20 further comprises a circular weakening groove 144 along the periphery of its external surface some distance from the cap edge 52 such that said circular weakening groove 144 is situated at the tapering end of the clamping band 22 when the cap is mounted on the rocket body 10. The cap moreover comprises another circular weakening groove 145 along the periphery of the internal surface of the cap which is formed by the wall of the second recess 62, some distance from the cap edge 52 such that said other weakening groove 145 is situated at the end, of diameter D1, of the front body part 28 on the same side as the front body wall 110 when the cap 20 is mounted on the rocket body 10. The axis XX′ of the protective cap 20 then coincides with the longitudinal axis ZZ′ of the rocket.

The series of longitudinal weakening grooves 140 and the circular weakening grooves 144, 145 along the walls of the cap 20 have the purpose of making it easier for the cap to disintegrate when the pyrotechnic charge 130 is set off, thus clearing the periphery of the shield 24. This disintegration of the protective cap extends from the other circular weakening groove 145 at the end of the front body part 28 of diameter D1, on the same side as the front body wall 110, as far as the circular weakening groove 144 level with the tapering edge of the clamping band 22.

FIG. 3 a is a perspective view of the rocket body of FIG. 1 comprising the protective shield. FIG. 3b shows just the protective shield of the rocket body of FIG. 3a.

The protective shield 24 comprises a shield body 25 of circular cylindrical rounded shape having two main faces, a rounded circular edge 27 and, near the circular edge 27 of the shield, a spoiler 150. The protective shield is produced in such a way that its circular cylindrical rounded shape of the shield conforms to the shape of the front body 14 of the rocket (see FIGS. 1, 3a and 3b).

The spoiler 150 of the protective shield 24 is intended to generate a transverse force when it is subjected to aerodynamic forces as the cap 20 is being destroyed. This transverse force ensures that the shield 24 is ejected sideways and frees the optic 26 of the homing head of the rocket.

The shield may be made of metal or of a plastic capable of withstanding the effects of the pyrotechnic charge.

In the rocket embodiment of FIG. 1, the cap 20 has a hole 158 for the attaching of the igniter 132 in the dividing wall 124 between the first 60 and third 120 recesses of the cap, in order to set off the propulsive charge 130 in the second cavity 128 of the rocket.

The rocket comprises two layers of electric conductors intended to activate the igniter 132 (see FIG. 1):

• • a first layer 160 having one end bonded to one of the main faces of the shield 24 on the same side as the front rocket body, a central part bonded to the other main face of the shield 24 on the same side as the first recess 60 of the cap 20. The other end of the first layer 160, in the first cavity 104 is electrically connected to the electrical contacts 162 for the activation of the igniter 132. The first layer 160 passes from one main face of the shield 24 to the other along a groove 29 on the edge of said shield 24.
  • A second layer 170 of electric conductors, on the same side as the rocket body 10, is in electrical contact with the end of the first layer 160 on the same side of the front rocket body.

Pressure of contact between the two layers 160, 170 is applied by a presser 172 housed in a recess of the front body 14 of the rocket comprising a passage 173 for connecting this second layer 170 to activation electronics, not depicted in the figures, that activate the igniter 132.

The first 160 and second 170 electrical layers are in one and the same axial plane passing along the longitudinal axis ZZ′ so that they can be in electrical contact. For this reason, the cap edge 52 and the first body shoulder 32 each comprise a respective hole for the insertion of a pin 174 which angularly indexes the cap 20 and the rocket body 10. Moreover, the internal wall of the first recess 60 of the cap 20 has a tooth 146 inserted in the groove 29 situated on the circular edge 27 of the protective shield 24. The angular indexing pin 174 and the tooth 146 inserted in the groove 29 of the protective shield provide electrical contact between the two layers 160, 170 and orient the spoiler 150 of the protective shield at an advantageous clearance angle.

In the case of a rocket that spins on itself, the spoiler 150 subjected to centrifugal force would create an imbalance and strengthen the transverse component that tends to eject the shield 24.

FIG. 4 a shows the rocket of FIG. 1 after the cap 20 has been destroyed and before the protective shield 24 has been ejected, and FIG. 4b shows the situation after the shield has been ejected. After the shield 24 has been ejected, the optic 26 of the homing head is cleared of any obstacle and forms the new rounded aerodynamic profile of the rocket. It should be noted that this new profile, suited to the steered guidance phase, is continuous and without roughness.

FIG. 5 shows an alternative form of embodiment of the rocket of FIG. 1 according to the invention.

In this alternative form of FIG. 5, the first recess 60 comprise a shield 180 and, in the first cavity 104 formed by the first recess 60 and said shield 180, a propulsive charge 183 and an igniter 184 secured to the shield 180. The second cavity 128 is empty.

FIG. 6 is a perspective view of the rocket body of FIG. 5 comprising a protective shield.

The protective shield 180 comprises a shield body 188 of rounded cylindrical shape conforming to the rounded shape of the front body 14 of the rocket and, on the circular edge 189 of the shield 180, a support 190 for supporting the igniter 184 in a plane parallel to the longitudinal axis ZZ′.

The support 190 comprises a fixing hole 192 for the igniter 184 which is electrically connected to the first 160 and second 170 layers of electrical conductors.

In this alternative form the propulsive charge 183 and the igniter 184 are near the shield 180.

As in the first embodiment of FIG. 1, the support element 190 supporting the igniter 184 of the shield 180 acts as a spoiler intended to generate a transverse force when it is subjected to aerodynamic forces when the protective cap 20 is being destroyed, and as an out-of-balance weight in the case of a rocket that spins on itself.

The advantage of this alternative form of FIG. 5 is that it simplifies the protective cap 20 and ensures that metallic remains of the pyrotechnic device are ejected with the shield on one side of the rocket together with the fragments of the cap after it has been destroyed.

In another alternative form of embodiment of the rockets of FIGS. 1 and 5, the cap 20 comprises only a pyrotechnic charge activated by a pyrotechnic cord instead of the layers 160, 170 of electrical conductors. This other alternative form avoids the use of an igniter near the propulsive charge and avoids the expulsion, when the cap is being destroyed, of metallic components that could damage the deployed tail assembly of the rocket.

The nose of the rocket, or of the munition in the more general case, contains optical and electronic material which, given a lengthy target approach phase and supersonic speed, needs to be protected by the protective cap. To do this, the material used to create the protective cap is chosen from materials of the ceramic type or from other sintered materials which have the property of being very weakly, if at all, conductive of the heat energy generated by friction against the air into the mechanical structure of the rocket. In addition, the mechanical properties of ceramic materials make them easy to shatter (they are friable/brittle), either by deflagration or by detonation depending on the type of pyrotechnic device chosen.

Through a choice of suitable materials, this invention could be used in a system of the mortar or gun type.

The configuration of the protective shield in the munition according to the invention makes it possible to protect the optic (for example a lens) of the guidance system during flight of the munition up until the point that the shield is ejected, and also during storage and logistics phases and the remainder of the operational (tactical) phase.

This invention also allows a radical change to the aerodynamic profile of the guided munition which in this particular instance changes from an ogive shape to a hemispherical shape.

Claims

1. A steered munition intended to destroy a target after at least one flight phase followed by a target approach phase, said munition comprising: a munition body of cylindrical shape of longitudinal axis ZZ′ having, on the same side as a front end of the munition which is the end intended to be directed toward the target, a front body comprising an optic of a guidance device that guides said munition toward the target, a cap for protecting the optic, secured to the munition body, the protective cap, in the shape of an ogive of axis of revolution XX′ coincident with the longitudinal axis ZZ′, being made of a material that can be shattered into multiple fragments, comprising at least one recess forming at least one cavity containing a pyrotechnic device intended to supply propulsive energy directly to the walls of the cavity to shatter the protective cap into multiple fragments, in order to free the optic and make the munition guidance device operational during the target approach phase.

2. The steered munition as claimed in claim 1, wherein the protective cap comprises walls having weakening grooves so as to promote regions along which said walls rupture when the protective cap is being destroyed.

3. The steered munition as claimed in claim 1, further comprising, between the protective cap and the front body of the munition body, a shield that protects the optic of the guidance device.

4. The steered munition as claimed in claim 3, wherein the protective shield comprises a shield body of circular cylindrical rounded shape having two main faces and a circular edge of axis coaxial with the longitudinal axis ZZ′, the rounded shape of the shield body conforming to the shape of the surface of the front body of the munition body.

5. The steered munition as claimed in claim 1, further comprising a clamping band that secures the protective cap to the munition body, the clamping band comprising, on the same side as the front end of the munition, a circular edge of tapering shape.

6. The steered munition as claimed in claim 1, wherein the surface of the front body, of rounded shape, has no discontinuity and no roughness so that it exhibits a continuous aerodynamic profile.

7. The steered munition as claimed in claim 1, wherein the front body of the munition body comprises, on the same side as the front end, a front body part of circular cylindrical shape of diameter D1, of axis of revolution collinear with the longitudinal axis ZZ′, the front body part comprising a munition front body wall of rounded shape including the optic of the guidance device, the rounded portion of the munition front body wall being directed toward the front end to give the munition a continuous aerodynamic shape when it has been rid of the protective cap.

8. The steered munition as claimed in claim 7, wherein the protective cap, in the shape of an ogive, of axis of revolution XX′, comprises a first recess opening onto a second recess of circular cylindrical shape of diameter equal to the diameter D1 of the front body part of the munition, the first recess of the cap forming, with the rounded-shaped front body wall, centered on the longitudinal axis ZZ′, a first cavity containing the protective shield.

9. The steered munition as claimed in claim 1, wherein the pyrotechnic device comprises a propulsive charge and an igniter, the igniter comprising electrical contacts for activating it.

10. The steered munition as claimed in claim 9, wherein the first cavity contains the pyrotechnic device.

11. The steered munition as claimed in claim 9, wherein the protective shield comprises, near its circular edge, a support for supporting the igniter in a plane parallel to the longitudinal axis ZZ′, the igniter support acting as a spoiler intended to generate a transverse force when it is subjected to the aerodynamic forces as the cap is being destroyed, and as out-of-balance weight in the case of a munition that spins on itself.

12. The steered munition as claimed in claim 8, wherein the protective cap further comprises, on the same side as the front end, a third recess of cylindrical shape of axis collinear with the longitudinal axis ZZ′, and separated from the first recess by a dividing wall in a plane perpendicular to the longitudinal axis ZZ′, the third recess being closed by a nose cone to form a second cavity containing the pyrotechnic device intended to destroy the protective cap.

13. The steered munition as claimed in claim 4, wherein the protective shield comprises, near its circular edge, a spoiler intended to generate a transverse force on the shield body when it is subjected to the aerodynamic forces and to cause it to be ejected from the body of the munition, said spoiler also acting as an out-of-balance weight in the case of a munition that spins on itself.

14. The steered munition as claimed in claim 1, wherein the protective cap comprises a cap connection part extended by a cap end ring having a cap edge of diameter D5 greater than the outside diameter D4 of the cap connection part so as to form a first cap shoulder so that the clamping band can prevent translational movement of the cap along the longitudinal axis ZZ′ on the front body of the munition body.

15. The steered munition as claimed in claim 9, further comprising two layers of electric conductors intended to activate the igniter: a first layer having one end bonded to one of the main faces of the shield on the same side as the front body of the munition body, a central part bonded to the other main face of the shield on the same side as the first recess of the cap, the other end of the first layer, in the first cavity being electrically connected to the electrical contacts for the activation of the igniter, the first layer passing from one main face of the shield to the other along a groove on the edge of said shield,a second layer of electric conductors, on the same side as the munition body, in electrical contact with the end of the first layer on the same side of the front body of the munition body.

16. The steered munition as claimed in claim 7, wherein the front body part is extended toward the rear body of the munition by an intermediate body of circular cylindrical shape of the same axis of revolution ZZ′ as, and of diameter D2 greater than the diameter D1 of, the front body part, so as to form a first body shoulder, the intermediate body being extended by the rear body of the munition of diameter D3 greater than the diameter D2 of said intermediate body, so as to form a second body shoulder.

17. The steered munition as claimed in claim 16, wherein the protective cap, secured to the body of the munition by the clamping band, comprises a cap central part of conical or ogive shape extended, on its larger-diameter side, by a cap connection part that connects the cap to the munition body, of circular cylindrical shape, of outside diameter D4 smaller than the diameter D2 of the intermediate body, the cap connection part being extended by a cap end ring having a cap edge of diameter D5 greater than the outside diameter D4 of the cap connection part and less than the diameter D2 of the intermediate body so as to form a first cap shoulder intended to prevent translational movement of the cap.

18. The steered munition as claimed in claim 17, wherein the cap edge and the first body shoulder each have a respective hole for the insertion of a pin that angularly indexes the cap and the munition body, the internal wall of the first recess of the cap comprising a tooth inserted in the groove situated on the circular edge of the protective shield, the angular indexing pin and the tooth inserted in the groove of the protective shield providing electrical contact between the two layers and orienting the spoiler of said protective shield at an advantageous clearance angle.

19. The steered munition as claimed in claim 18, wherein the cap comprises a series of longitudinal weakening grooves along the walls of the first and second recesses, these grooves being evenly distributed about the axis of revolution XX′ of the cap, the cap further comprising a circular weakening groove along the periphery of its external surface some distance from the cap edge such that said circular weakening groove is located at the tapering end of the clamping band when the cap is mounted on the munition body.

20. The steered munition as claimed in claim 19, wherein the cap comprises another circular weakening groove along the periphery of the internal surface of the cap formed by the wall of the second recess, some distance from the cap edge such that said other weakening groove is located at the end, of diameter D1, of the front body part on the side of the front body wall when the cap is mounted on the munition body, the axis XX′ of the protective cap then coinciding with the longitudinal axis ZZ′ of the munition.