Tail stabilised artillery projectile with a tail fairing that can be jettisoned by extracting propellant gases

Abstract

The invention relates to an artillery projectile (1) stabilized by a tail (4), comprising a body (2), a base (3), a deploying tail (4) secured to the base (3), and a cover (5) cooperating with the base (3) and covering the tail (4) in its folded position, the cover (5) being ejectable at the exit of the gun tube (10) in order to allow the tail (4) to take its deployed position. According to the invention, the cowling (5) and the base (3) define between them a borrowed volume (6) capable, upon exiting the gun tube (10), of being put under overpressure, relative to the atmospheric air, by borrowed firing gas during the propulsion phase of the projectile (1) in the tube (10), the cowling (5) thus being ejected at the exit of the tube (10) by a thrust force then applied to the cowling (5) by the borrowed firing gas.

Description

[0001] The field of the invention is that of field artillery projectiles stabilized by tail.

[0002] A tail is commonly used to stabilize a projectile fired from a large or medium caliber smoothbore or rifled gun. Fixed tails and deploying tails are known.

[0003] The deploying tail has the advantage of being less cumbersome in length than the fixed tail, which, to be effective, must be pushed far back from the body of the projectile. In fact, for a smaller footprint, the deploying tail allows for better stabilization, and therefore greater accuracy. In addition, the deploying tail allows firing using a tube of the same caliber as the projectile.

[0004] Artillery projectiles with deployable tails are therefore widely used. For example, French patent FR2221707 B1 describes an artillery projectile with a deployable tail formed of a plurality of fins. In internal ballistics, that is, while the projectile is in the barrel, the fins of the tail are kept in the folded position. As soon as the projectile leaves, the fins must be deployed and locked in the deployed position to ensure the stability of the projectile.

[0005] When the projectile is fired, the tail is exposed to the very high pressure of the firing gas, which risks damaging it.

[0006] To remedy this, French patent FR3094475 B1 discloses a projectile which includes a shroud covering the sides and bottom of the base of the projectile, and therefore covering the pivoting fins housed by the base. This shroud includes an annular bulge or ferrule which is located at the front edge of the shroud and which is sized so as to be able to be applied radially tight against the base of the projectile. When leaving the weapon, the centrifugal force applied to the ferrule and the lack of support by the tube will cause the ferrule, which has been weakened by the passage through the tube, and the front edge of the shroud to burst, which will cause the shroud to separate from the base, favouring the deployment of the fins.

[0007] EP 1 321 737 A2 and US 7 226 016 B2 disclose an artillery projectile according to the preamble of claim 1.

[0008] The present invention aims to improve the prior art by allowing more efficient and on-trajectory removal of the cowling by using the pressure of the firing gas used during the propulsion phase of the projectile in the barrel of the weapon.

[0009] The invention therefore solves both a problem of protecting a projectile tail during the firing phase and a problem of reliability of ejection following firing and on trajectory.

[0010] The invention therefore relates to a fin-stabilized artillery projectile, which projectile is intended to be fired from a gun barrel, the projectile comprising a body, a rear base secured to the body, a deploying rear stabilizing fin secured to the base and capable of taking a folded position in the barrel, folded position in which the fin is received in a receiving space on the base, and a deployed position at the exit of the barrel, and a cowling cooperating with the base and covering the fin in its folded position, the cowling being ejectable at the exit of the gun barrel in order to allow the fin to take its deployed position, the cowling and the base defining between them a borrowed volume capable, upon exiting the gun barrel, of being put under overpressure, relative to the atmospheric air, by firing gas borrowed during the propulsion phase of the projectile in the barrel,the cowling being thus ejected at the outlet of the tube by a thrust force then applied to the cowling by the borrowed firing gas, characterized by the fact that the base delimits an internal cavity centered on the longitudinal axis of the projectile, the borrowed volume being arranged radially between the internal cavity and the receiving space.

[0011] Thus, the empennage is protected by the cowling during the gun firing phase and is able to take its deployed position at the exit of the tube following the effective ejection and on trajectory of the cowling.

[0012] In addition, such an internal cavity is a central area available inside the base which allows the presence of elements, such as electronic communication equipment, a tracer composition, a gas generation drag reduction device, or any other element which must be imperatively positioned on the longitudinal axis of the projectile.

[0013] Advantageously, the borrowed volume opens onto the exterior of the projectile via at least one filling opening capable of putting the borrowed volume into communication with the internal volume of the tube at the rear of the projectile, the filling opening(s) being provided in the cowling and / or in the base.

[0014] In other words, the filling of the borrowed volume can be done, depending on the desired kinematics, either directly by one or more filling openings made in the cowling, for example by an axial opening arranged in the bottom of the cowling, or by one or more openings made in the base, or by openings made both in the cowling and in the base, the or each opening opening on the one hand into the borrowed volume and on the other hand, in use, into the internal volume of the tube at the rear of the projectile.

[0015] Advantageously, the cowling comprises a bottom arranged at the free rear end of the base and a side extending from the bottom, towards the front of the projectile and along the tail in the folded position so as to surround the tail, the bottom comprising a thrust face orthogonal to the longitudinal axis of the projectile, the borrow volume being delimited at the rear by the thrust face.

[0016] Thus, the borrow volume is arranged at the rear end of the projectile.

[0017] Advantageously, the base is a cylindrical base with an axis coincident with the longitudinal axis of the projectile, the side of the cover comprising a tubular wall whose external diameter corresponds to the external diameter of the base, and the borrowed volume being an annular volume around the longitudinal axis of the projectile.

[0018] The borrowed volume may be divided into several separate sub-volumes, including several sub-volumes in the form of ring sectors.

[0019] Advantageously, the cowling, where appropriate the side of the cowling, comprises at least one collar carried by the front edge of the cowling and extending coaxially with the longitudinal axis of the projectile, collar capable of releasably engaging in a corresponding groove in the base. Such a temporary collar-throat connection allows correct positioning of the cowling on the base, without requiring a tool.

[0020] According to an optional particular configuration, the empennage comprises several deployable fins and the cowling is divided into several segments, each segment covering a fin in the folded position, a borrow volume being arranged axially between each segment and the base.

[0021] Advantageously, the bottom of the cowling comprises an annular plate carrying the thrust face and having a central orifice and an internal tubular rim formed at right angles to the plate at the central orifice and extending axially opposite the side of the cowling, the free end of the internal tubular rim cooperating with a stop face of the base, and the borrow volume being delimited radially between the internal tubular rim and the receiving space and being delimited axially between the annular plate and the stop face of the base. The tubular rim and the side of the cowling allow the cowling to be guided along the base when an axial thrust is generated on the cowling.

[0022] The hood can be made of metallic materials such as steel or carbon fiber composite for example.

[0023] The invention will be better understood by reading the following description, a description made in light of the attached drawings, drawings in which: [ Fig. 1 ] represents a partial and schematic sectional view of a projectile according to the invention, in the gun barrel, before firing; [ Fig. 2 ] represents a partial and schematic sectional view of the projectile of the Figure 1 , at the exit of the gun barrel, during a shot; and [ Fig. 3 ] represents a partial and schematic sectional view of a region of the firing gas borrow volume of the projectile according to the invention, showing different modes of arrangement of the filling opening(s) of said borrow volume.

[0024] According to the Figure 1 , a projectile 1 according to the invention comprises a body 2 carrying, at its rear part, a base 3, a tail unit 4 secured to the base 3 and a cover 5 for protecting the tail unit 4.

[0025] Body 2 has a front part (not shown) and a rear part. For the sake of clarity, the terms front and rear are defined by considering the direction of fire of projectile 1.

[0026] The base 3 closes the rear part of the body 2. The base 3 is in the form of a substantially cylindrical single-piece piece, with an external diameter equal to that of the rear part of the body 2. The longitudinal axis A0 of the base 3 coincides with the longitudinal axis A1 of the projectile 1.

[0027] The base 3 comprises, along its longitudinal axis A0, a stepped internal cavity 30, delimited laterally by a side wall 300 of the base 3, the internal cavity 30 comprising a first recess 301 of large diameter, on the front end side of the base 3, and a second recess 302 of smaller diameter, on the rear end side of the base 3. Such an internal cavity 30, in particular the first recess 301, allows the arrangement of elements in the base 3 and along the longitudinal axis A1 of the projectile 1.

[0028] An annular bead 31 is formed on the outer surface of the side wall 300, in the vicinity of the front end of the first recess 301. This bead 31 comprises, on its face directed towards the rear end of the base 3 and in the vicinity of its outer edge, an annular groove 310.

[0029] The base 3 also comprises, on its periphery, housings or receiving spaces 32 intended to receive the fins 40 of the tail 4 in the folded position. Each receiving space 32 is formed between the annular bead 31 and the side wall 300. Thus, in the folded position, each fin 40 extends along the base 3, the longitudinal axis A2 of the fin 40 then being parallel to the longitudinal axis A1 of the projectile 1.

[0030] An annular cavity 33 opening at the rear end of the base 3 is formed in the side wall 300, and extends around the second recess 302. In other words, the annular cavity 33 is formed between the second recess 302 and the receiving space 32, and is thus defined laterally internally by the side wall 300 of the base 3 and externally by a tubular wall 33a. The bottom of the annular cavity 33 defines a stop face 34 against which the cowling 5 is intended to come to bear.

[0031] The empennage 4 comprises several pivoting fins 40 which, in the folded position, are sheltered by the base 3 and received in the reception spaces 32 arranged on the base 3. These fins 40 are called upon to unfold towards the outside of the projectile 1, and therefore to take a deployed position, after exiting the tube 10 by means not described. The number of fins 40 as well as their distribution around the base 3 can be variable.

[0032] The protective cowling 5 covers the receiving spaces 32 and therefore the pivoting fins 40, in the folded position of the fins 40. In particular, in the connected state of the cowling 5 and the base 3 in the tube 10, the cowling 5 comprises a bottom 50 arranged at the free rear end of the base 3 and a side 51 formed in one piece with the bottom 50 and extending from the bottom 50, towards the front of the projectile 1 and along the tail 4 in the folded position, so as to surround the tail 4.

[0033] In the embodiment shown, the bottom 50 comprises an annular plate 500 with an outside diameter substantially equal to the outside diameter of the base 3. The annular plate 500 has a central orifice whose diameter corresponds to the outside diameter of the side wall 300 of the base 3 at the second recess 302. A seal 53 is mounted in an annular groove formed on the side wall 300, at the second recess 302. The interface between the bottom 50 and the base 3 is sealed. The annular plate 500 extends orthogonally to the longitudinal axis A1 of the projectile 1, in the plane of the rear free end of the base 3. The annular plate 500 is therefore in contact with the rear end of the tubular wall 33a of the annular cavity 33 of the base 3.The face of the annular plate 500 oriented towards the receiving spaces 32, and therefore towards the annular cavity 33 of the base 3, and in contact with the base 3, defines a thrust face 52 of the cowling 5.

[0034] The bottom 50 further comprises an internal tubular rim 501 formed at right angles and in one piece with the annular plate 500, at the level of the central orifice. Thus, the internal tubular rim 501 extends parallel to the longitudinal axis A0 of the base 3, the central axis of the tubular rim 501 coinciding with the longitudinal axis A0 of the base 3. The front free end of the internal tubular rim 501 comes into contact with the abutment face 34 of the base 3. The internal face of the tubular rim 501 cooperates with the side wall 300 of the base 3. The thickness of the tubular rim 501 is less than the radial dimension of the annular cavity 33 of the base 3, so that an annular volume space is formed between the tubular rim 501 and the tubular wall 33a of the annular cavity 33, this annular volume space constituting a borrow volume 6.

[0035] The flank 51 of the cowling 5 is in the form of a tubular wall 510 coaxial with the tubular rim 501. The external diameter of the tubular wall 510 corresponds to the external diameter of the annular plate 500 and therefore to the external diameter of the base 3. The front edge of the tubular wall 510 carries an annular collar 511 which extends parallel to the longitudinal axis A1 of the projectile 1. The collar 511 is dimensioned to engage, in a releasable manner, in the annular groove 310 of the base 3. It should be emphasized that, although in the embodiment shown, the connecting means between the cowling 5 and the base 3 comprises an axial collar 511 and a corresponding groove 310, any other detachable connecting means between the base 3 and the cowling 5 could be used.

[0036] The borrow volume 6 formed between the cowling 5 and the base 3 is delimited axially by the thrust face 52 at the rear and the stop face 34 at the front, and delimited radially by the tubular rim 501 and the tubular wall 33a. The borrow volume 6 is thus constituted by a chamber delimiting an annular internal volume whose central axis coincides with the longitudinal axis A0 of the base. 3.

[0037] The borrowing volume 6 has at least one filling opening 7 opening into the volume delimited by the tube 10 at the rear AR of the base 3, thus allowing the internal volume of the tube 10 at the rear AR of the projectile 1 to be put into fluid communication with the borrowed volume 6. In the embodiment shown in the Figure 1 , a single filling opening 7 is provided through the cowling 5. This is an axial opening passing through the annular plate 500.

[0038] Alternatively, as can be seen schematically in the Figure 3 , a 7' filling opening could be fitted through the base 3, in particular through the wall of the base 3 carrying the abutment face 34. A filling opening 7" could alternatively be arranged both through the cowling 5 and the base 3, in particular through the side wall 300 of the base 3 at the level of the second recess 302 and through the tubular rim 501 of the cowling 5. As a variant, several filling openings 7, 7', 7" of the borrow volume 6 can open at the rear AR of the projectile 1, in particular the three filling openings 7, 7', 7" shown on the Figure 3 . On the Figure 3 , the arrows at the entrance of each filling opening 7 show the path taken by the firing gas G to fill the borrow volume 6.

[0039] Alternatively, the borrow volume 6 can be divided radially into several sub-volumes separated by a wall of the base 3. Each sub-volume has the shape of a ring sector and is arranged radially at the level of a fin 40 of the empennage 4. Each sub-volume then has its own filling opening(s) 7. The cowling 5 can also be divided into several segments, each segment covering a fin 40 in the folded position. Each sub-volume is arranged axially between each segment of the cowling 5 and the base 3.

[0040] Alternatively, for example in the case of a base 3 not having an internal cavity 30 at the rear AR, the bottom 50 of the cowling 5 could be formed as a disc-shaped plate.

[0041] In practice, before firing, the cowling 5 surrounds and covers the tail unit 4, the fins 40 of which are in the folded position in the reception spaces 32, thus protecting the tail unit 4.

[0042] During firing, the firing gas G enters the borrow volume 6 through the filling opening(s) 7.

[0043] At the exit of the gun barrel 10, in other words as soon as the projectile 1 has left the gun barrel 10, the gas borrowed during the firing phase and therefore contained in the borrowed volume 6 will find itself under overpressure relative to the atmospheric air. This overpressure gas will then generate a thrust force P (represented on the Figure 3 ) at the rear of the borrow volume 6, in particular an axial thrust on the thrust face 52 of the cowling 5. This thrust force P causes the detachment of the cowling 5 from the base 3, in particular a separation of the collar 511 from the groove 310, and the displacement of the cowling 5 along the base 3. The cowling 5 is therefore ejected, as can be seen in the Figure 2 , like a piston in a cylinder which moves under the effect of the pressure which is present in the chamber. Once the cowling 5 is ejected, the empennage 4 can be deployed, the fins 40 passing into the deployed position.

[0044] Thus, the present invention makes it possible to protect the deploying tail 4 of the projectile 1 during the firing phase by means of the cowling 5 ( Figure 1 ) while allowing efficient ejection of the cowling 5 on the trajectory at the exit of the tube 10 ( Figure 2 ), using the pressure of the firing gas G used during the propulsion phase of the projectile 1 in the gun tube 10.

[0045] It is understood that the particular embodiments which have just been described have been given for informational and non-limiting purposes, and that modifications may be made without departing from the scope of the present invention.

Claims

1. Artillery projectile (1) stabilized by a tail (4), which projectile (1) is intended to be fired from a gun barrel (10), the projectile (1) comprising a body (2), a rear base (3) secured to the body (2), a deploying rear stabilizing tail (4) secured to the base (3) and capable of taking a folded position in the barrel (10), folded position in which the tail (4) is received in a receiving space (32) on the base (3), and a deployed position at the outlet of the barrel (10), and a cover (5) cooperating with the base (3) and covering the tail (4) in its folded position, the cover (5) being ejectable at the outlet of the gun barrel (10) in order to allow the tail (4) to take its deployed position, the cover (5) and the base (3) defining between them a volume borrowed (6) capable, upon exiting the barrel (10), of being put under overpressure, relative to the atmospheric air,by firing gas (G) borrowed during the propulsion phase of the projectile (1) in the tube (10), the cowling (5) being thus ejected at the outlet of the tube (10) by a thrust force then applied to the cowling (5) by the firing gas (G) borrowed, , characterized by the fact that the base (3) delimits an internal cavity (30) centered on the longitudinal axis (A1) of the projectile (1), the borrowing volume (6) being arranged radially between the internal cavity (30) and the receiving space (32).

2. Projectile (1) according to claim 1, characterized by the fact that the borrowed volume (6) opens onto the exterior of the projectile (1) via at least one filling opening (7, 7', 7") capable of putting the borrowed volume (6) into communication with the internal volume of the tube (10) at the rear (AR) of the projectile (1), the filling opening(s) (7) being arranged in the cowling (5) and / or in the base (3).

3. Projectile (1) according to any one of claims 1 and 2, characterized by the fact that the cowling (5) comprises a bottom (50) arranged at the free rear end of the base (3) and a side (51) extending from the bottom (50), towards the front (AV) of the projectile (1) and along the tail (4) in the folded position so as to surround the tail (4), the bottom (50) comprising a thrust face (52) orthogonal to the longitudinal axis (A1) of the projectile (1), the borrow volume (6) being delimited at the rear (AR) by the thrust face (52).

4. Projectile (1) according to claim 3, characterized by the fact that the base (3) is a cylindrical base with axis (A0) coincident with the longitudinal axis (A1) of the projectile (1), the side (51) of the cover (5) comprising a tubular wall (510) whose external diameter corresponds to the external diameter of the base (3), and the borrowed volume (6) being an annular volume around the longitudinal axis (A1) of the projectile (1).

5. Projectile (1) according to any one of claims 1 to 4, characterized by the fact thatthe borrowed volume (6) is divided into several separate sub-volumes, in particular several sub-volumes in the form of ring sectors.

6. Projectile (1) according to any one of claims 1 to 5, characterized by the fact that the cowling (5), where appropriate the side (51) of the cowling (5), comprises at least one collar (511) carried by the front edge of the cowling (5) and extending coaxially to the longitudinal axis (A1) of the projectile (1), collar (511) capable of engaging releasably in a corresponding groove (310) of the base (3).

7. Projectile (1) according to any one of claims 1 to 6, characterized by the fact that the empennage (4) comprises several deployable fins (40) and that the cowling (5) is divided into several segments, each segment covering a fin (40) in the folded position, a borrow volume (6) being arranged axially between each segment and the base (3).

8. Projectile (1) according to one of claims 3 and 4 or according to any one of claims 5 to 7 taken as dependent on the claim 3, characterized by the fact that the bottom (50) of the cowling (5) comprises an annular plate (500) carrying the thrust face (52) and having a central orifice and an internal tubular rim (501) formed at right angles to the plate (500) at the central orifice and extending axially opposite the side (51) of the cowling (5), the free end of the internal tubular rim (501) cooperating with a stop face (34) of the base (3), and the borrow volume (6) being delimited radially between the internal tubular rim (501) and the receiving space (32) and being delimited axially between the annular plate (500) and the stop face (34) of the base (3).

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