AU2018200773B2 - Fin-stabilized sub-calibre projectile which can be fired from a rifled barrel and method for the production thereof - Google Patents

Abstract

Abstract To obtain a fin-stabilized sub-calibre projectile (1) which can be fired from a rifled barrel, the sabot (4) of which is lightweight and stable and the penetrator (3) of which has a smaller deflection error after leaving the barrel than is the case with comparable known sub-calibre projectiles, the invention proposes arranging on the penetrator (3) a sabot (4) which transfers the full twist, comprises two guide flanges (7, 8) and the main body (5) of which consists of a light metal alloy, wherein axial bores (17) that are made to pass through the front guide flange (7) and extend to the rear guide flange (8) are provided for weight-saving reasons.

Description

DESCRIPTION

Fin-stabilized sub-caliber projectile which can be fired from a rifled barrel, and method for the production thereof

Field of the Invention

The invention relates to a fin-stabilized sub-caliber projectile that can be fired from a rifled barrel, having a penetrator with a tail fin assembly and having a discardable sabot that is arranged on the penetrator and consists of multiple sabot segments circumferentially joined to one another, which segments are separated from one another after leaving the barrel by the centrifugal forces acting on the projectile during firing. The invention further relates to a method for producing a sub-caliber projectile of this nature.

Background

Projectiles of this nature are known from EP 0 300 373 B1, for example. They often are fired from automatic weapons in the mid-caliber range (20-50 mm). The discardable sabot here consists essentially of a cylindrical main body, made of plastic with predetermined breaking points, which is supported circumferentially over its entire length against the inner wall of the applicable weapon barrel, and a metal insert joined to the rear of the main body. This metal insert is provided with a carrier thread that, in a corresponding thread of the penetrator, serves to transmit to the penetrator the thrust and spin forces acting on the sabot during firing. The relevant main body has a rotating band that transmits the full spin corresponding to the pitch of the spiral flutes of the applicable weapon barrel and the muzzle velocity of the projectile to the sabot and through the carrier thread to the penetrator.

However, it is a disadvantage of prior art projectiles of this nature that the thick-walled design of the main body, which usually is manufactured in an injection-molding process, leads to problems in the production thereof. Because of the relatively long cooling times,

2018200773 13 Jun 2019 long cycle times are necessary in the production of the sabot. Moreover, due to the great wall thickness of the main body, defects such as voids occur frequently in the plastic material, which can then result in deflection errors of the penetrator after exiting the weapon barrel. The larger the caliber of the projectiles is, the thicker the walls of the main body of the sabot are, and the more frequently the above-described problems occur.

A fin-stabilized sub-caliber projectile that can be fired from a rifled barrel is likewise known from DE-OS 2039719, in which the sabot is assembled from multiple sabot segments made of a light metal or plastic that are held together by means of suitable rotating bands.

For reasons of weight saving, the sabot of this projectile has a main body that has a front guide flange that can be supported against the inner wall of the barrel and a rear guide flange arranged at an axial distance. The connecting section of the sabot located between the two guide flanges has a smaller outside diameter than the guideflanges.

For force transmission to the penetrator of the gas pressure forces acting on the sabot when the projectile is fired, an annular groove recessed into the penetrator is located in the region of the rear guide portion of the main body, in which groove a multi-part carrier member of the sabot that is matched to the groove shape of the penetrator engages. Both the rotating bands and the carrier member are designed such that the full spin is not transmitted from the two rotating bands to the sabot during firing of the projectile because of slip between the rotating bands and the sabot, and the full spin of the sabot likewise is not transmitted from it to the penetrator due to slip between the sabot and penetrator.

One disadvantage of projectiles of this nature is that the sabots, and hence also the penetrators, have considerable differences with regard to their spin rate when leaving the barrel. However, the smaller the centrifugal forces are that act on the sabot at

2018200773 13 Jun 2019 emergence from the barrel, the smaller the speed and symmetry are in the discarding of the sabot segments, which can likewise result in deflection errors of the penetrators and thus in an increase in projectile spread in the target area.

Using EP 0 300 373 B1 as a starting point, at least some embodiments of the invention provide a fin-stabilized sub-caliber projectile that can be fired from a rifled barrel, the sabot of which is light and stable and the penetrators of which have smaller deflection errors after leaving the barrel than is the case with comparable prior art sub-caliber projectiles. In addition, a method for the production of a projectile of this type is to be disclosed.

Any reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that that document or matter was known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims.

Summary

According to a first aspect, the present invention provides a fin-stabilized sub-caliber projectile that can be fired from a rifled barrel, having a penetrator with a tail fin assembly and having a discardable sabot that is arranged on the penetrator and consists of multiple sabot segments circumferentially joined to one another, which segments are separated from one another after leaving the barrel by the centrifugal forces acting on the projectile during firing, wherein:

a) the sabot includes a main body made of a light metal alloy and having a front guide flange that can be supported on the inner wall of the barrel and a rear guide flange arranged at an axial distance, wherein the connecting section of the sabot located between the two guide flanges has a smaller outside diameter than the guide flanges;

b) the sabot and the penetrator are joined together in a positive manner in the region of the rear guide flange;

c) the sabot further includes a sealing and rotating band is fastened onto the

2018200773 13 Jun 2019 outer circumference of the rear guide flange;

d) the main body has multiple axially-extending, longitudinal grooves uniformly distributed over the circumference that laterally border the sabot segments; and

e) the main body has bores that pass axially through the front guide flange and extend to the rear guide flange along the longitudinal grooves.

According to a second aspect, the present invention provides a method for producing a fin-stabilized sub-caliber projectile that can be fired from a rifled barrel according to the first aspect described above, having the features:

- the prefabricated penetrator, which as a blank already possesses the outer contour of the main body as well as the central bore for the penetrator and the thread for positive connection of the penetrator and sabot, is screwed into the sabot until the penetrator rests against the sabot in a positive manner, subsequent to which the sealing and rotating band is introduced into the recess of the rear guide flange, and the rear seal is introduced by means of a plastic injection molding method, after which the tail fin assembly is screwed onto the penetrator as a complete unit; and

- bores are introduced from the front side of the front guide flange in the axial direction to the rear guide flange prior to assembly, for the purpose of weight reduction in the prefabricated penetrator.

The invention is based primarily on the idea of arranging on the penetrator of the subcaliber projectile a sabot that transmits full spin, the main body of which sabot is made of a light metal alloy and, for reasons of weight saving, has a front guide flange that can be supported on the inner wall of the barrel and a rear guide flange arranged at an axial distance, wherein the connecting section of the sabot located between the two guide flanges has a smaller outside diameter than the guide flanges. In addition to this twoflange contour, for reasons of further weight saving the main body has axial bores that pass through the front guide flange and extend to the rear guide flange.

It has proven to be advantageous if the diameter of the axial bores is chosen such that the region between the penetrator and the relevant bore where the main body has its

2018200773 13 Jun 2019 smallest wall thickness acts as a predetermined breaking point along which the sabot segments separate from one another on account of the centrifugal forces that act on them after leaving the weapon barrel.

Brief Description of the Drawings

Additional details and advantages of the invention are evident from the following exemplary embodiments, explained on the basis of drawings. The figures show:

Fig. 1 the perspective view of a sub-caliber projectile according to the invention,

Fig. 2 a longitudinal cross-section through the projectile shown in Fig. 1, and

Fig. 3 an enlarged front view of the projectile shown in Fig. 1.

Detailed Description of the Preferred Embodiments

Labeled with 1 in Fig. 1 and 2 is a fin-stabilized sub-caliber projectile according to the invention that includes a penetrator 3 joined to a tail fin assembly 2, and a discardable sabot 4 arranged on the penetrator 3.

The sabot 4 includes a main body 5 made of an aluminum alloy, which is joined to the penetrator 3 by a threaded connection 6. This threaded connection 6 achieves the result that the thrust and spin forces acting on the sabot 4 within a weapon barrel during firing of the projectile 1 are transmitted to the penetrator 3 without slip.

The main body 5 has a front guide flange 7 and a rear guide flange 8 arranged at an axial distance. Both guide flanges 7, 8 serve to support the sabot 4 on the inner wall of the applicable weapon barrel when the projectile 1 is in the loaded state. The two guide flanges 7, 8 of the sabot 4 are joined by a connecting section 9, which for reasons of weight saving has a smaller outside diameter than the guide flanges 7, 8.

On the outer circumference of the rear guide flange 8, a sealing and rotating band 11 made of plastic is located inside a circumferential recess 10 of the main body 5.

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In addition, the main body 5 has multiple axially-extending, longitudinal grooves 12 uniformly distributed over the circumference, which in this embodiment laterally border four sabot segments 13-16 of the sabot 4 that are connected circumferentially to one another.

For further weight saving in the sabot 4, the main body 5 contains four bores 17 that pass axially through the front guide flange 7 and extend to the rear guide flange 8 along the longitudinal grooves 12. These bores also serve to create a predetermined breaking point 18. To this end, the diameter of the bores 17 is chosen such that the resulting region 18 between the penetrator 3 and the relevant bore 17, where the main body 5 has its smallest wall thickness, can act as a predetermined breaking point along which the sabot segments 13-16 can separate from one another after leaving the barrel. Alternatives for incorporation of predetermined breaking points are known from practice.

At the rear side, the main body 5 is provided with a rear seal 19 made of plastic to ensure propellant gases cannot enter the central bore 20 that accommodates the penetrator or enter the longitudinal grooves 12.

When the projectile 1 is fired, the sealing and rotating band 11 is pressed into the rifling grooves of the applicable weapon barrel by the force of the propellant gases, and causes a rotary motion of the sabot 4 as well as a corresponding rotary motion of the penetrator 3 via the threaded connection 6. As soon as the projectile 1 has left the barrel, the predetermined breaking points 18 tear along the longitudinal grooves 12 as a result of the centrifugal forces acting on them, and the sabot segments 13-16 are discarded at high speed and symmetrically with regard to the flight path of the projectile

1.

A preferred method for producing the projectile disclosed above is described below.

Starting from a blank that already possesses the outer contour of the main body 5 as well as the central bore 20 for the penetrator 3 and the thread for positive connection of the penetrator 3 and sabot 4, the four bores 17 for weight reduction are, if desired, introduced from the front side of the front guide flange 7 in the axial direction to the rear

2018200773 13 Jun 2019

Ί guide flange 8. To prevent slip during transmission of spin between the rotating band 10 and the sabot 8, the base of the recess 10 of the rotating band preferably is provided with knurling on the entire circumference. To protect against sinking into the land I groove profile in the barrel, the sabot is coated by means of an anodic oxidation method. This coating is primarily important at the two guide flanges 7 and 8, and is distinguished by its hardness and abrasion resistance.

The prefabricated penetrator 3 is now screwed into the sabot 4 via threads until it rests against the thread stop 22 of the sabot 4 in a positive manner.

Next, the sealing and rotating band 11 is introduced into the recess 10 of the rear guide flange 8, and at the same time the rear seal 19 is introduced by means of a plastic injection molding method. This is made possible because the rotating band region 10 is connected to the region of the rear seal 19 by means of longitudinal slots 21.

The tail fin assembly 2 is subsequently screwed onto the penetrator as a complete unit.

It is a matter of course that the invention is not limited to the exemplary embodiment described above. Thus, the sabot can be composed of only two or three sabot segments, for example. Moreover, the sealing and rotating bands can also be made of a different suitable material, such as sintered metals, instead of plastic.

7a

2018200773 13 Jun 2019

List of Reference Symbols sub-caliber projectile, projectile tail fin assembly penetrator sabot main body positive connection, threaded connection (front) guide flange (rear) guide flange connecting section recess sealing and rotating band longitudinal groove

13-16 sabot segments bore region, predetermined breaking point rear seal central bore longitudinal slots thread stop

Claims (8)

1. A fin-stabilized sub-caliber projectile that can be fired from a rifled barrel, having a penetrator with a tail fin assembly and having a discardable sabot that is arranged on the penetrator and consists of multiple sabot segments circumferentially joined to one another, which segments are separated from one another after leaving the barrel by the centrifugal forces acting on the projectile during firing, wherein:

a) the sabot includes a main body made of a light metal alloy and having a front guide flange that can be supported on the inner wall of the barrel and a rear guide flange arranged at an axial distance, wherein the connecting section of the sabot located between the two guide flanges has a smaller outside diameter than the guide flanges;

b) the sabot and the penetrator are joined together in a positive manner in the region of the rear guide flange;

c) the sabot further includes a sealing and rotating band is fastened onto the outer circumference of the rear guide flange;

d) the main body has multiple axially-extending, longitudinal grooves uniformly distributed over the circumference that laterally border the sabot segments; and

e) the main body has bores that pass axially through the front guide flange and extend to the rear guide flange along the longitudinal grooves.

2018200773 13 Jun 2019

2. A fin-stabilized sub-caliber projectile according to claim 1, wherein the diameter of the bores is chosen such that the region between the penetrator and the relevant bore where the main body has its smallest wall thickness acts as a predetermined breaking point along which the sabot segments separate from one another after leaving the barrel.

3. A fin-stabilized sub-caliber projectile according to claim 1 or 2, wherein the main body is made of an aluminum alloy.

4. A fin-stabilized sub-caliber projectile according to any one of claims 1 to 3, wherein the positive connection between the sabot and the penetrator is a threaded connection.

5. A fin-stabilized sub-caliber projectile according to any one of claims 1 to 4, wherein the sealing and rotating band is made of plastic.

6. A fin-stabilized sub-caliber projectile according to any one of claims 1 to 5 wherein the main body has a plastic rear seal.

7. A method for producing a fin-stabilized sub-caliber projectile that can be fired from a rifled barrel according to one of claims 1 to 6, having the features:

- the prefabricated penetrator, which as a blank already possesses the outer contour of the main body as well as the central bore for the penetrator and the thread for positive connection of the penetrator and sabot, is screwed into the sabot until the penetrator rests against the sabot in a positive manner, subsequent to which the sealing and rotating band is introduced into the recess of the rear guide flange, and the rear seal is introduced by means of a plastic injection molding method, after which the tail fin assembly is screwed onto the penetrator as a complete unit; and

2018200773 13 Jun 2019

- bores are introduced from the front side of the front guide flange in the axial direction to the rear guide flange prior to assembly, for the purpose of weight reduction in the prefabricated penetrator.

8. A method according to claim 7, wherein the introduction of the sealing and rotating band and the introduction of the rear seal take place simultaneously.