EP0905473B1 - Large-calibre long range projectile for artillery - Google Patents

Description

The technical field of the invention is that of projectiles, in particular artillery projectiles from large caliber campaign with long range.

Increasing the range of artillery projectiles has always been sought after. So it is known to put in place on the rear of the ballistic trajectory projectiles a gas-generating composition block (called a usually block "base-bleed") which is intended to reduce the pellet trail by a generation of gases from the combustion of a composition such as a propellant. The base-bleed increases the range of projectiles only on the order of 5 to 10% and generates dispersions harmful to the shot accuracy.

It has also been proposed to increase the accuracy shooting, to make a course correction or a terminal guidance. But the trajectory projectiles ballistics being gyrostabilized, it is very difficult to perform trajectory correction or terminal guidance correct. In addition, only the accuracy is improved, the range still being relatively small.

Patent WO8100908 proposes an artillery projectile with a base-bleed fitted with a belt, fins guidance and stabilization stabilizer. This projectile is gyro-stabilized for part of its trajectory during which the base-bleed block is operational, then the base-bleed is ejected, allowing the tailplane to deploy stabilization that slows the rotation of the projectile. The projectile thus finds itself on a stabilized trajectory by the tail. Then a terminal guide can be carried out thanks to the guide fins.

Such a concept has several drawbacks. First the transition from the gyrostabilized trajectory to the trajectory stabilized by empennage generates many constraints. The tail unit receives very strong stresses mechanical during its deployment which can generate a loss of projectile stability and / or significant dispersions. Then the range of such a projectile, as it has been explained before, is relatively weak.

It is more advantageous to use a projectile hovering which will be stabilized by empennage as soon as it leaves the gun barrel. In addition, the increase in capacity carrying the projectile (under ammunition and guidance / piloting) involves reducing its thickness by wall, which is allowed by the choice of stabilization by tail fin preferably gyroscopic stabilization.

Concretely a hovering projectile must therefore have a large elongation (length to diameter ratio greater or equal to 10) and will have a relatively thin wall (of 5 to 10mm) to reduce the mass of the projectile while increasing the carrying capacity.

The GB1516073 and DE3730359 patents describe cannon fired and stabilized by tail.

The one proposed by GB1516073 has a rear shoe with a slip belt and ensuring the maintenance of fins in the folded position. The guide in the tube the weapon of the front part of the projectile is provided by centering bosses.

Such a concept is not suitable for the realization of a long-range hovering projectile having a wall relatively thin.

Indeed, the front guide bosses provided by GB1516073 increase the mass of the projectile and increase its aerodynamic drag on trajectory. In addition they must be attached to a relatively thick projectile wall.

Patent DE3730359 proposes a training shoe distributing the forces between the rear of the projectile (by through a sliding piston) and the front of the projectile on which the shoe hangs by teeth at the level of drive grooves made on the projectile.

Such a shoe is of complex realization and its separation from the projectile at the exit of the barrel is delicate due to the presence of grooves and teeth.

The wall of the projectile also has a structure complex and must include a reinforced thickness at the level of the hoof drive grooves.

It is the object of the invention to propose a projectile long-range artillery not having such disadvantages.

Thus the projectile according to the invention has a structure simple and inexpensive to make.

It ensures that a firing range is obtained important with a reliable separation of the hooves drive and projectile at the exit of the tube tear.

The projectile can have a significant elongation (greater than or equal to 10) and a wall thickness relatively thin (around 5 to 10mm) while being able to be fired by an artillery cannon. This results in a scope increased and a large carrying capacity.

Thus the invention relates to an artillery projectile intended to be fired from a large barrel tube caliber and comprising a body fitted at the rear with a deployable stabilization stabilizer, the body being under-calibrated and carrying at least a first guide shoe ejectable fitted with a slip belt designed to reduce the speed of rotation of the projectile, characterized projectile in that it comprises a second guide shoe positioned at the front of the projectile, second shoe made up of at least two segments linked to the body by a means of temporary liaison which consists of at least one shear pin, the shear being caused by a relative recoil of the second hoof relative to the body of the projectile during longitudinal acceleration of the projectile in the barrel tube, the second shoe being ejected at the outlet of the tube.

According to another characteristic of the invention, the second shoe has an internal profile complementary to a external profile of the front part of the projectile, and there are an axial clearance between the internal profile of the second shoe and the external profile of the front of the projectile so as to allow the relative recoil of the second hoof relative to the body of the projectile during its longitudinal acceleration in the barrel tube.

According to another characteristic of the invention, the first guide shoe or rear shoe is positioned at the level of a rear part of the projectile body and it maintains the deployable stabilization stabilizer, the deployment of the latter taking place during the ejection of the rear shoe at the tube outlet.

Advantageously, the rear shoe may include a push piece receiving the slip belt and a piece tubular covering the rear part of the projectile body while maintaining the stabilization stabilizer in its folded position.

According to an alternative embodiment, the rear shoe may be ejected by a pyrotechnic charge placed between the rear shoe thrust part and the rear part of the body of the projectile.

The tubular part of the rear shoe may have longitudinal weakening zones, intended to break when ejecting the rear shoe in order to increase the aerodynamic drag of it.

According to another characteristic, the projectile may have front control surfaces deployable.

According to another characteristic, the projectile may have a rear thruster.

The rear shoe can then be ejected at the exit of the barrel tube by the pressure generated by the propellant.

Advantageously, the second guide shoe will ensure the guidance in the tube by the contact of its cylindrical surface external with the internal surface of the barrel of the weapon on a length between one and twice the size of tear.

• La figure 1 représente une vue externe d'un projectile d'artillerie selon l'invention.
• La figure 2 représente le projectile d'artillerie selon l'invention avec les sabots avant et arrière éjectés.
• La figure 3 représente une coupe partielle de la partie avant du projectile selon l'invention.
• la figure 4 représente une coupe partielle de la partie avant du projectile après désolidarisation du sabot et du corps.

Other advantages of the invention will appear on reading the description of a particular embodiment, description made with reference to the accompanying drawings in which:

• FIG. 1 represents an external view of an artillery projectile according to the invention.
• FIG. 2 represents the artillery projectile according to the invention with the front and rear sabots ejected.
• FIG. 3 represents a partial section of the front part of the projectile according to the invention.
• Figure 4 shows a partial section of the front part of the projectile after separation of the shoe and the body.

Referring to Figure 1, an artillery projectile heavy gauge campaign 1, according to the invention, is consisting of a body 2 carrying in the rear part 5 a first ejectable shoe 6 (or rear shoe) and in the front part 3 a second ejectable shoe 4 (or front shoe).

The front shoe 4 is composed of several segments 7, here three in number, linked to the projectile body 2 by radial pins 8. Each segment 7 can be produced in an organic material, for example of the thermoplastic type charge.

The rear shoe 6 comprises on the one hand a piece of thrust 9 carrying on its periphery a slip belt 10, and on the other hand a tubular part 11 covering the rear part 5 of the projectile body. The tubular part 11 is made integral with the thrust piece 9, for example by collage. The push piece 9, made of steel, is intended to receive propellants during the phase gun. The tubular part 11 is itself made of thermoplastic.

The front 4 and rear 6 shoes are intended to ensure guiding the projectile inside a barrel tube of a weapon not shown. In particular the front shoe provides contact guidance over its entire surface external cylindrical on the wall of the tube. The length of guide of the front hoof is of the order of the caliber of the weapon this which improves guidance for a large projectile elongation.

This type of structure composed of a front guide and a rear guide which are relatively far apart one of the other is particularly suitable for a projectile great length.

The body 2 is therefore undersized relative to the diameter internal core of the barrel tube, which increases the initial speed while decreasing the coefficient of aerodynamic drag of the projectile and therefore increase its scope.

The body 2 is intended to transport a payload not shown, which may be submunitions intended to be dropped above a target.

To stabilize a projectile on its trajectory, we uses either the gyroscopic effect or a tail.

Field artillery projectiles are usually drawn from large barrel tubes caliber, type 155 mm, with internal stripes intended to give them a high speed of rotation in order to stabilize them on the trajectory. These projectiles are so-called gyro-stabilized.

The artillery projectile according to the invention is intended to carry a large volume payload, by example several submunitions. This carrying therefore requires a long length of projectile which prohibits a stabilization of the projectile by gyroscopic effect.

The stabilization of the projectile 1 according to the invention is ensured by a tail 12 (see fig 2) placed in part rear 5 of body 2 and which deploys at the outlet of the tube gun.

The slip belt 10, of the type described in FR2606869, is intended to take the scratches from the barrel tube and to slide on the thrust piece 9 in order to reduce the speed of rotation of the projectile. So at the out of the barrel tube, the projectile is only subjected to a low roll speed of the order of 10 turns / s.

This low rolling speed of the projectile allows advantageously the deployment of the tailplane at the outlet of tube in good conditions, under low stresses which do not disturb the stability of the projectile.

The stabilization stabilizer 12 consists of four flat blades made of very high limit steel elastic. Each blade is articulated at its root and lockable in the deployed position.

The blades of the empennage 12, shown in position deployed in Figure 2, were originally wound on the exterior of the rear part 5 of the body 2 of the projectile and held in position by the tubular part 11 of the shoe 6.

The attachment of the rear shoe 6 and the body 2 is ensured by the support of the blades of the empennage 12 on the internal surface of the tubular part 11 of the shoe 6. The blades are kept constrained in the coiled position by the shoe 6.

The body 2 has at its rear part 5 a propellant additional 13 intended to increase the range of the projectile.

The additional propellant 13 is constituted, so classic, of a body in high resistance steel comprising an ejection nozzle 14 for the propellant gases. It comprises a propellant charge consisting of a propellant block solid double base type.

At the exit of the barrel, the additional propellant 13 is lit, for example by borrowing propellant gases from the through an axial opening in the plate raised 9. The high pressure gases produced by the propellant charge combustion are ejected through the nozzle ejection 14 by generating an axial thrust. This propellant generation ensures separation and then the ejection, behind the projectile, of the rear shoe 6.

In FIG. 2, the segments 7 of the front shoe 4 are located in a position separated from the body 2. Ejection of the hoof before is effective at the outlet of the tube, after a rupture of the pins 8 as will be explained later, thanks to the aerodynamic forces exerted on the front of the hoof and which allow the spacing of the segments 7.

The front part 3 of the body 2 of the projectile comprises deployable control surfaces 15, here the number of four. These control surfaces are deployable through slots 17 carried out on the body 2. They are deployed on trajectory at a given time as will be explained more far. They are intended to guide the projectile.

The front part 3 also includes a ballistic warhead 16 containing a set of guidance and piloting (not shown), in particular of gyrometers of roll, yaw, pitch, of a satellite locator (GPS) with its antennas, an actuator module for control surfaces with reduction servos, as well as a source of energy and an order processor.

Figure 3 shows a partial section of the part front 3 of projectile 1.

The front part 3 of the projectile 1 carries the front shoe 4 composed of the three segments 7 made integral with the body 2 by radial pins 8.

Segments 7 of the front shoe have a profile internal 17 complementary to the external profile 18 of the warhead 16. When the front shoe 4 is linked to the body 2 by the pins 8, as shown in FIG. 3, an axial clearance 19 persists between the two profiles 17 and 18, the segments 7 of the shoe front being in an advanced position relative to the body 2.

When igniting the propellant charge of the ammunition inside the barrel tube, the pressure generated by the propellant charge combustion gases is exerted on the thrust plate 9 of the rear shoe 6 and pushes projectile 1 inside the barrel tube. The friction forces between the outer cylindrical surface of the front hoof 4 and the gun tube scratches contradict the significant longitudinal acceleration of the projectile, and a shear force is therefore created at the level of the pins 8, causing their rupture.

The segments 7 of the front shoe 4 separate from the body 2 and the front hoof then moves back relative to the body until the profile 17 of the shoe stops against the profile external 18 of the warhead 16 and disappearance of the game 19.

Figure 4 shows this phase at the end of the decline relative of the segments 7 of the front shoe relative to the body 2, when the two profiles 17 and 18 are in contact. In this configuration, the segments 7 of the shoe 4 are separated of the body 2 of the projectile, the pins being broken. In barrel tube outlet, the aerodynamic pressure which is exerted on a conical surface before 20 of the shoe 4 causes opening and then ejecting the segments 7.

Such a front shoe structure 4 ensures a reliable guidance of a projectile of great elongation (greater than 10) due to the guide length important of the front shoe which is in contact with the tube (guide length of the order of size).

The joining by shearable pins allows the keeping the front hoof during the transport and storage with a projectile wall thickness relatively thin (around 5-10mm). Shear pins when fired ensures reliable separation of the sabot and projectile at the exit of the barrel of the weapon by the only effect of aerodynamic forces.

Inside the barrel of the weapon, the relative contact of the profile 17 of the front shoe with the external profile 18 of the warhead allows a good distribution of efforts. This ensures a reliable guidance in the barrel of a large projectile weapon elongation and having a thin wall thickness at the level of the warhead.

There remains no ejection of the hoof protrusion on the body of the projectile which would likely to increase its aerodynamic drag.

• Phase de balistique intérieure dans le tube de canon:
  • mise à feu de la charge propulsive,
  • rupture des goupilles de liaison 8,
  • recul relatif des segments 7 du sabot avant 4 par rapport au corps 2.
• Phase de vol balistique, dès la sortie du tube de canon:
  • éjection des segments 7 du sabot avant 4,
  • allumage du propulseur additionnel 13,
  • éjection du sabot arrière 6,
  • ouverture de l'empennage de stabilisation 12.
• Phase de vol piloté, sensiblement à partir de l'apogée de la trajectoire:
  • ouverture des gouvernes de pilotage 15 commandée par les servomoteurs,
  • guidage-pilotage du projectile en direction de la cible.

The different stages of operation of the artillery projectile according to the invention are as follows:

• Interior ballistics phase in the barrel tube:
  • firing of the propellant charge,
  • breaking of the connecting pins 8,
  • relative recoil of the segments of the front shoe 4 relative to the body 2.
• Ballistic flight phase, from the exit of the barrel tube:
  • ejection of the segments 7 of the front shoe 4,
  • ignition of the additional thruster 13,
  • rear shoe ejection 6,
  • opening of the stabilization stabilizer 12.
• Pilot flight phase, substantially from the apogee of the trajectory:
  • opening of the control surfaces 15 controlled by the servomotors,
  • guidance-piloting of the projectile towards the target.

The control surfaces 15 are advantageously not open only after peak in order to reduce drag aerodynamics and ensure sufficient stability in flight ballistic.

Thus, the projectile according to the invention, being of the type undersized and equipped with an additional propellant, allows carrying a large payload, of the order of 30 kg to a very long shooting distance of the order of 60 to 80 km.

Of course, without departing from the scope of the invention, other variants can be envisaged.

For example in the case where the additional propellant does not would be lit only during the trajectory, for example by a electric initiation, the rear shoe ejection can be carried out by a pyrotechnic charge 21 placed between the thruster 13 and the thrust plate 9 of the rear shoe 6 and lit as soon as it leaves the barrel tube (see Figure 5). This pyrotechnic charge 21 may be ignited by means of a propellant gas borrowing, for example through a axial opening 22 arranged in the thrust plate 9, a pyrotechnic delay 23 ensuring the ejection of the rear shoe 6 after the exit of the barrel of the weapon.

A pyrotechnic charge of this type can, of course, complete the rear shoe ejection means 6 with the propellant 13 described in Figure 2. Indeed the rise in propellant pressure not being immediate, separation fast hoof by a pyrotechnic charge would present the advantage of releasing the stabilization stabilizer as soon as exit of the barrel tube, thus improving the stabilization of the projectile.

A weakening of the tubular part 11, by longitudinal precuts 24 of its wall (shown in figure 5), can also be envisaged in order to improve its aerodynamic braking as of its ejection at the exit of the tube of cannon. Thus the pressure generated by the load pyrotechnic ejection 21 and / or the propellant 13 will cause the cutting of the tubular part 11 at the areas of embrittlement 24. The tubular part 11 will then open under the shape of petals, thus increasing its braking aerodynamic.

Claims (10)

1. An artillery projectile (1), designed to be fired from a large-calibre gun barrel, which comprises a body (2) whose rear part (5) is fitted with deployable stabilising fins (12), the body being sub-calibred and carrying at least one first ejectable guiding sabot (6) fitted with a sliding drive band (10) intended to reduce the spin rate of the projectile, characterised in that it incorporates a second guiding sabot (4) positioned at a front part (3) of the projectile, second sabot (4) being formed of at least two segments (4) connected to the body by a temporary connecting means formed of at least one shearable pin (8), whose shearing is caused by the relative recoil of the sabot (4) with respect to the body (2) of the projectile during the longitudinal acceleration of the projectile in the gun barrel, the second sabot (4) being ejected upon exiting the barrel.
2. A projectile according to Claim 1, characterised in that the second sabot (4) possesses an inner profile (17) which matches an external profile (18) of the front part of the projectile and in that there is an axial clearance (19) between the inner profile of the sabot and the external profile of the front of the projectile so as to allow the relative recoil of the sabot with respect to the projectile body during its longitudinal acceleration in the gun barrel.
3. A projectile according to Claim 1 or 2, characterised in that the first guiding sabot (6) or rear sabot is positioned at a rear part (5) of the projectile body and in that it holds the deployable stabilising fins (12) in place, their deployment being carried out when the rear sabot is ejected upon exiting the barrel.
4. A projectile according to Claim 3, characterised in that the rear sabot (6) comprises a thrusting part (9) which receives the sliding drive band (10) and a tubular part (11) covering the rear part of the projectile body whilst keeping the stabilising fins (12) in their folded-back position.
5. A projectile according to Claim 4, characterised in that the rear sabot (6) is ejected by means of a pyrotechnic charge placed between the thrusting part (9) of the rear sabot (6) and the rear part of the projectile body.
6. A projectile according to Claim 4 or 5, characterised in that the tubular part (11) of the rear sabot (6) has longitudinal zones of embrittlement (24) which are intended to fracture during the ejection of the sabot so as to increase its aerodynamic drag.
7. A projectile according to any one of Claims 1 to 6, characterised in that it incorporates in its front part (3) deployable piloting ailerons (15).
8. A projectile according to any one of Claims 1 to 7, characterised in that it comprises a rear booster (13).
9. A projectile according to Claim 8, characterised in that the rear sabot (6) is ejected upon exiting the gun barrel by means of the pressure generated by the booster (13).
10. A projectile according to either one of Claims 1 to 9, characterised in that the second guiding sabot (4) ensures the guiding in the barrel by contact of its external cylindrical surface with the inner surface of the barrel of the weapon along a line comprised between one and two times the calibre of the weapon.

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