GB2195419A - A projectile - Google Patents

Abstract

A projectile (2) which can be fired in a spin-stabilised manner from a barrel (11) by means of gas pressure from a propulsion charge and can be steered in flight is intended to be designed, in the interests of achieving defect-free unfolding capabilities for sliding surfaces and control surfaces which are overcalibre and are therefore folded in during firing, to have only a reduced initial spin with respect to the geometry of the traction-field profile on the inner wall (14) of the barrel. For this purpose, the projectile tail structure (1) is equipped with a sealing ring (4) which can rotate while being frictionally locked thereto and has a sliding ring (9) which is extrusion-coated with a plastic body (10). Inserts in the form of bent flanges (18) ensure the adhesion, which is rigid in terms of movement, between the plastic body (10) and the sliding ring (9) while the sealing ring (4) is being stressed in shear and torsion in the barrel (11) and while it is being stressed centrifugally after emerging from the muzzle of the barrel. <IMAGE>

Description

SPECIFICATION Projectile This invention relates to a spin stabilised projectile.

Such a projectile is shown in German Patent Specification No. 3026409. To increase the flight range as compared with the purely ballistic trajectory curve the rear part of the projectile body is provided with gliding surfaces.

Its tail structure carries control rudders for homing in on the target in the end phase of the flight. During storage and for launching from a barrel, the gliding surfaces (supercalibre in the functional position) are folded into the body and the (similarly supercalibre) control rudders are folded onto or into the tail structure.

An object of the present invention is to equip a spin stabilised projectile in the rear region of its tail structure-and preferably behind control rudders-with a kind of propelling cage, in order to make feasible, by means of propelling-charge gas pressure, a ballistic firing of the projectile from a weapon barrel.

In this regard, the departure spin of the projectile should not be greater than necessary for stabilisation of the projectile at the start of the firing path (since unfolding of the gliding surfaces should occur as soon as possible after reaching an initial stable ballistic flightpath, and a spin which is too high could disturb the unfolding function by virtue of the centrifugal forces and the tangential projectile incident flow) but a (to be preferred in the interests of standardisation) customary weapon barrel is equipped with a thrust field profile (Zug-Feld-Profil) which would lead to an unnecessarily or even prejudicially severe departure spin of the projecticle.

If, upon firing, a propelling cage rotates in the barrel relative to the projectile, the projectile spin is less than the cage spin caused by the thrust field profile in the weapon barrel.

However, it should be ensured that departure factors upon exit from the weapon barrel do not lead to a mechanical destruction of the propelling cage; because (differently than upon firing a propelling-cage penetrator from the cannon of an armoured vehicle) the artillery crew here would not be adequately protected against risks of injury which could result from a propelling cage disintegrating directly in front of the weapon barrel.

In recognition of these factors, an object of at least one embodiment of the present invention is also, therefore, to provide a projectile which appears to meet the listed requirements.

According to the present invention there is provided a projectile which can be fired in a spin-stabilised manner from a barrel by means of propelling-charge gas pressure and which can be guided in flight, characterised in that the projectile is equipped with a sealing ring which, in sliding-friction locking retention, coaxially surrounds an axially-limited region of the projectile tail structure.

In an embodiment of the present invention there are cylindrical friction sliding-contact surfaces between the tail structure and the sealing ring, at the co-operating cylinder surfaces, which can be designed as a material coupling/pairing which tends to display optimum mechanical and thermal stressability.

For the sealing action in the barrel, possibly along with calibre bridging, a slide ring on the tail structure may be, advantageously, cast around or sprayed around with plastics material, which material is chosen for optimum stability in view of the thermal and mechanical stresses when'sealing the propelling-charge gas-pressure chamber relative to the barrel inner wall. In the interests of providing low wear of the barrel inner wall, and also for barrel stability and bearing in mind the gaspressure sealing properties as well as the mechanical torsional force transmission, the use of fibre-reinforced plastics material is expedient.Flange-shaped inserts embedded in the plastics material of the sealing ring, which inserts are fastened to the slide ring and are made from mechanically stiffer (more rigid) material than the plastics body (serving for the calibre bridging and propelling-gas sealing), serve both for surface enlargement for adhesion of the plastics material on the slide ring and for stiffening the plastics-material body in the axially-parallel, i.e. firing, direction. A particularly high safety against radial blasting off (discharge) of parts of the plastics-material body upon exit from the weapon barrel results if these inserts extend parallel to the longitudinal extent of the shell (projectile).

Additional alternatives and further developments as well as further features and advantages of the present invention should be apparent from the claims and from the following description of a preferred example of a projectile in accordance with the present invention which will now be described, by way of example only, with reference to the sole figure of the accompanying drawing which shows, in a manner which is restricted to that which is essential for understanding the present invention, in a highly abstracted manner but approximately true to scale, in broken-away representation, in axial longitudinai section, a part of the tail structure of the projectile with a sealing ring encircled thereon.

Referring to the drawing, an axially-limited cylindrical region of the tail structure 1 of a projectile 2 carries, on its jacket (peripheral cylindrical) surface 3, and in sliding fit, a sealing ring 4. In the exemplified instance shown, axial positioning of the ring is provided firstly at the front, in other words in the firing acceleration direction 5, by a radially-projecting encircling shoulder 6, and secondly, in the oppo site axial direction, by a thrust disc 8 which is secured to the tail structure 1, for example, by screw connections and which likewise radially projects beyon the sliding-fit jacket surface 3.

The sealing ring 4 rests with its slide ring 9 on the tail-structure jacket surface 3. The slide ring 9 is sprayed around thickly, in other words radially highly bulkily, by a heat-resistant and abrasion-resistant plastics-material body 10 (i.e. ring 9 is encircled by a thick layer of plastics material) which, in the manner of a propelling cage, bridges the radial distance (gap) between the tail structure 1 and the thrust field profile on the inner wall 14 of a firing barrel 11. In this way, a propellingcharge gas-pressure chamber 12 in the barrel 11 behind the sealing ring 4 is sealed off at the front; so that, in known manner, by deflagration of a propelling-charge agent or initiation of another propelling-gas reaction, the projectile can be accelerated in the firing direction 5 and thus be fired from the barrel 11.

During the propulsion through the barrel 11, the guidance jacket surface 13 of the sealing ring 4 cuts somewhat into the thrust field profile of the barrel inner wall 14, whereby on the axial propulsion in the barrel 11, both the sealing ring 4 and (by way of the friction fit of slide ring 9 on the tail-structure jacket surface 3) also the projectile are set rotating. However, in a desirable manner, by virtue of the rotational sliding movement between sealing ring 4 and projectile tail structure 1, the spin which the projectile 2 has upon firing from the barrel 11 is noticeably less than the spin exerted by the barrel internal thrust directly on the sealing ring 4 itself.

In the interests of a good seal and formlocking engagement of the sealing-ring jacket surface 13 to the profile of the inner barrel wall 14, the jacket surface 13 is not continuously cylindrical, but, as is evident from the drawing, has grooves 15 encircling in staggered manner-between which ribs 16 are thereby defined. For kinetic reasons the front region of the sealing ring 4 extends in crosssection somewhat bevelled inwardly, in other words tapered forwardly in frustoconical manner.

The slide ring 9 is produced from a mechanically and thermally highly stressable material, more especially from a metallic material having alloying materials which are diffused into the surface and which have good siding or slip properties. Rearwardly, contrary to the acceleration in the firing direction, the plasticsmaterial body 10 is up against a ring-discshaped supporting wall 20 which is integrally formed in a flange-shaped manner onto the slide ring 9 and which provides the friction coupling with regard to the rearward structurefast thrust disc 8.So that frictional stressing actually takes place only between the relevant portion of the tail-structure jacket surface 3 and the slide ring 9 guided coaxially thereon, radially projecting flanges 18 are secured to the slide ring 9 to ensure a movement-rigid connection between the slide ring 9 and the plastics-material body 10 both during shear and torsion stress on acceleration in the barrel 11 and during the severe pressure drop at the instant of exit from the barrel 11.

Flanges 18 may consist of metal, or of fibre-reinforced plastics materials, and as desired may be spoke-like bars or encircling rings. As a result of the surface enlargement between the slide ring 9 (with the flanges 19 fastened thereon) and the sprayed-around plastics body 10, a very reliable tear-resistant (fracture resistant) and shear-resistant adhesion is ensured. Moreover, such flanges 18 bring about a form-locking connection between the plastics material body 10 and the slide ring 9, which counteracts any tendency to axial (and possibly also radial) relative movement between the two.

Advantageously, as should be evident from the drawing, the flanges 18 extend at their free end, pointing away from the slide ring 9, as angle pieces 19, namely angled approximately parallel to the tail-structure jacket surface 3. In this way, to a particular degree it is ensured that the very severely occurring radial forces at the instant of exit from the muzzle of the barrel 11 do not lead to a radial tearingaway (fracture) of parts of the plastics-material body 10 on the slide ring 9, in other words the sealing ring 4, rotating relative to the projectile 4, remains ballistically secured after leaving the barrel 11-namely its own mass is held together.If the angle pieces 19 as shown point forwardly, in other words deflected by the flanges 18 in the firing direction 5, then this yields the further constructional advantage that the axial thrust, exerted by the barrel inner wall 14 contrary to the firing direction 5, on the plastics-material body 10 relative to the projectile tail structure 1 tends to lead to a bending of the flanges 18 contrary to the firing direction 5, and thus to a lesser display of the front free ends of the angle pieces 19 in the direction of the barrel inner wall 14, in other words to a strengthening of the radial pressure force of the plasticsmaterial body 10 (supported radially against its slide ring 9) into the thrust field profile whereby a slipping through of the sealing-ring jacket surface 13 relative to the barrel inner wall 14 or a leakage of propelling-gas pressure is additionally countered.

To summarise there is provided a projectile which can be fired in a spin-stabilised manner from a barrel by means of propelling-charge gas pressure and which can be guided in flight. The projectile is, in the interests of disturbance-free unfurling of gliding surfaces and control rudders which are supercalibre and which are therefore folded in upon the firing, designed to have, with regard to the thrust field profile on the barrel inner wall, only a reduced departure spin. To this end, the projectile tail structure is equipped with a sealing ring which is rotatable thereon in friction locking and which has a slide ring cast around with a plastics-material body.Inserts in the form of angled flanges ensure the movementrigid adhesion between the plastics-material body and the slide ring during the shear and torsional stress of the sealing ring in the barrel and during its centrifugal stressing after exit from the barrel muzzle.

The ring 4 is rotatable relative to the projectile 2 (with its disc 8 fastened in a rotationally-rigid manner thereto), in which respect friction occurs on the surface of the tail structure 1 and on the front surface of the disc 8.

If pressure 5 acts towards the rear side of the disc 8, the projectile 2 with its ring 4 is pushed forwards in the weapon barrel 11. By virtue of the helical inclination of the grooves on the inner surface 14 of the barrel 11, upon this displacement the ring 4 is rotated in the barrel 11. However, the ring 4 does not entrain the projectile in a rotationally-rigid manner, because in the contact areas (at 9 and in front of 8) there is no rigid connection but only a frictional connection. The projectile 2 thus does not rotate in the barrel 11 as quickly as does the ring 4.The period of time it takes for the ring 4, rotated in the barrel 11, also to set the projectile 2 into the rotation motion (and how long after exit from the barrel the ring 4 still displays a different rotation than the projectile 2) depends on the severity of the frictional forces between ring 4 and projectile 2 (with disc 8).

Crucial to the idea of the present invention is that the projectile 2, upon leaving the barrel 11, has only a slight spin which is sufficient for the stabilisation upon exit from the barrel-whilst too severe a spin could for example damage the mechanical suspension of a seeker head or the mechanism for unfurling gliding wings and control rudders.

It is to be understood that the scope of the present invention is not to be unduly limited by the particular terminology employed and the scope of any particular term may extend to any reasonable equivalent or generic term where sensible. The scope of the present invention may extend to any apparatus, method or function or combination thereof related to the projectile or projectile sealing ring.

Further according to the present invention there is provided a projectile which, in use, is spin stabilised, comprising a sealing ring mounted towards or at the rear of the projectile, which ring extends beyond the calibre of the projectile to seal against the inner wall of a barrel when the projectile is ready for firing from the barrel, rotation of the sealing ring relative to a body of the projectile being restricted by a frictional force between the ring and said body.

In particular, the present invention may extend to any spin stabilised projectile having a sealing ring frictionally held on a body of the projectile, which ring does not break up on exit from the firing barrel and which induces a spin on the projectile which is not too high to disturb the unfolding of gliding surfaces.

Claims (11)

1. A projectile which can be fired in a spin-stabilised manner from a barrel by means of propelling-charge gas pressure and which can be guided in flight, characterised in that the projectile is equipped with a sealing ring which, in sliding-friction locking retention, coaxially surrounds an axially-limited region of the projectile tail structure.

2. A projectile as claimed in claim 1, in which the sealing ring has a slide ring which rests on the outer jacket surface of the projectile tail structure and which is enclosed in an axially thickly bulky manner by a heat-resistant and abrasion-resistant plastics-material body into which flanges project, which flanges extend radially from the slide ring and are made from material which is stiffer than the plastics material.

3. A projectile as claimed in claim 2, in which the flanges are angled axially parallel with respect to the tail structure.

4. A projectile as claimed in claim 3, in which the flanges are equipped with angle pieces pointing in the firing direction.

5. A projectile as claimed in any one of claims 2 to 4, in which the plastics-material body consists of composite fibre material.

6. A projectile as claimed in any one of claims 2 to 5, in which the slide ring merges rearwardly into a supporting wall which protrudes radially in a flange-like manner.

7. A projectile as claimed in any one of claims 2 to 6, in which for the frictional locking between the slide ring and the tail-structure jacket surface a metallic material is provided.

8. A projectile as claimed in any one of the preceding claims, in which the sealing ring is axially supported rearwardly against a structure-fast thrust disc.

9. A projectile as claimed in any one of the preceding claims, in which the sealing ring has a plastics-material jacket surface with inlet groove profile.

10. A projectile as claimed in any one of the preceding claims, in which the sealing ring has, in the firing direction, a frustoconicallytapering geometry.

11. A projectile having a sealing ring and tail structure substantially as herein described with reference to the figure of the accompanying drawings.