US3496869A

US3496869A - Sabot projectile

Info

Publication number: US3496869A
Application number: US656856A
Authority: US
Inventors: Walter Engel
Original assignee: Oerlikon Buehrle Holding AG
Current assignee: OC Oerlikon Corp AG Pfaeffikon
Priority date: 1967-07-28
Filing date: 1967-07-28
Publication date: 1970-02-24
Anticipated expiration: 1987-02-24
Also published as: FR1576031A; GB1224362A; DE1703816B2; BE718414A; CH494389A; DE1703816C3; DE1703816A1; NL137889C; NL6810720A; SE347813B

Description

Filed July 28, 1967 2 Sheets-Sheet 1 Feb. 24, 1970 w. ENGEL 3,

SABO'I' PROJECTILE 22 In venfbf Wei/fer In 8/ 2 fifforn y s Feb. 24, 1970 w. ENGEL SABOT PROJECTILE Filed July 28, 1967 2 Sheets-Sheet z n, v I I i h a 7 firms/776k Wa/fk' lzll ge/ 3,496,869 SABOT PROJECTILE Walter Engel, Dubendorf, Switzerland, assignor to Oerlikon-Buhrle Holding Ltd., Zurich, Switzerland Filed July 28, 1967, Ser. No. 656,856 Int. Cl. F42b 13/16 U.S. Cl. 102-93 7 Claims ABSTRACT OF THE DISCLOSURE The sabot of a sabot projectile has a rear part, a jacket and a driving band. Jacket and driving band are made in a single piece, and the connection between the rear part and the driving band with jacket is formed by adjacent cone surfaces whose apices point rearwards, so that the driving band is pressed against the rear part by the gas pressure. The outside diameter of the driving band is preferably greater than the greatest inside diameter of the gun bore from which the sabot projectile is fired.

The present invention concerns a sabot projectile and a gun bore from which the projectile is fired.

An object of the invention is to provide a sabot projectile wherein the sabot is not destroyed by the gas pressure when the projectile is fired.

A further object of the invention is to provide a sabot projectile wherein the connection between the driving band of the sabot and the jacket and also the connection between the rear part and the driving band are so designed that they are not destroyed by the gas pressure when the projectile is fired.

It is a further object of the invention to provide a sabot projectile wherein the said connections between driving band, jacket and rear part prevent any unwanted entry of gas when the projectile is fired.

With the above and other objects in view which will become apparent from the detailed description below, some preferred modifications of the invention are shown in the drawings in which:

FIG. 1 shows a sectional view with parts in elevation through a sabot projectile taken along section line II in FIG. 2;

FIG. 2 shows a cross-sectional view along section line IIII in FIG. 1;

FIG. 3 shows a cross-sectional view along section line IIIIII in FIG. 1;

FIG. 4 shows a partial sectional view through a gun bore;

FIG. 5 shows a partial sectional view through a cartridge chamber of a gun bore and the jacket of the sabot, along section line V-V in FIG. 4;

FIG. 6 is a partial sectional view through a modified sabot projectile illustrating a modified core support system, and

FIG. 7 is a similar view showing a further modification.

The subcaliber core 1 shown in FIG. 1 consists preferably wholly or partly of tungsten carbide and has a substantially cylindrical shape with an ogive 2. The rear of the core 1 rests with its forward-opening cone surface 7 on a similarly shaped bore surface 8 of a sabot rear part 4. This rear part 4 has a sleeve-shaped extension 5 into which the rear of the core 1 extends. A small space is provided between the rear end face 9 of the core 1, which is perpendicular to the longitudinal axis, and the base surface 11 terminating the bore 8 of the rear part 4.

The rear part 4 consists preferably of an aluminium alloy, such as Perunal. The outside diameter of the core 1 is smaller than the inside diameter of the extension 5. 70

The core 1 is provided in its rear portion with an annular groove 12. Arranged in this groove is a locking ring 14 consisting of three segments. This locking ring 14 rests on 3,495,869 Patented Feb. 24, 1970 a groove flank 13 perpendicular to the projectile axis. The outside diameter of the locking ring is greater than the diameter of the core 1. A sleeve rests on the surface 52 of the locking ring 14 extending beyond the core 1. This sleeve 15 consists of three equal segments. The outside diameter of the sleeve 15 is equal to the inside diam eter of the extension 5. At its forward end the sleeve 15 has a flange 16 which extends into an enlargement of the extension 5 and projects slightly beyond the forward end of the extension 5.

The extension 5 is provided with annular ridges 17 which are spaced at regular intervals measured in axial direction and which are bounded forwardly by a rearwardopening cone surface 10 and rearwardly by a surface 46 intersecting the said cone surface 10. The surface 46 is substantially perpendicular to the axis of the extension 5. From the end face, six radial slots 18 arranged at regular angular intervals extend into the extension 5 (FIG. 3). The slots 18 extend behind the ridges 17 as far as a rearward-opening cone surface 20 of the rear part 4. This surface 20 is intersected by another cone surface 21, extending rearwardly and opening forwardly, the arrangement being such that the diameter of the intersection line of these two

surfaces

20 and 21 is smaller than the outside diameter of the rear sleeve-shaped portion 22 of the rear part 4 which, until the projectile is fired, remains inside the mouth of a carriage, not shown. The cone surface 21 intersects another rearwardly extending and opening cone surface 23, which is intersected by a cone surface 24 which encloses substantially the same angle with the forwardpointing projectile axis as does the cone surface 21. This surface 24 intersects the jacket surface of the portion 22 of the rear part 4.

The cylindrical portion of the core 1 not extending into the extension 5 is encompassed by a full-caliber jacket 25 made of plastic material and extending to a point forward of the rear end of the ogive 2. The jacket is preferably made of a thermoplastic material designated nylon 6.6, having the following properties: tensile strength 8 kp/ mm. modulus of elasticity E 17,000 kp./cm. compressive strength 11 kp./mm. notch impact strength 130 cm.kp./crn. elongation to rupture 200%.

The forward portion of the jacket 25 is cylindrical; the rear portion is a truncated cone slightly tapering forwardly. The diameter of the forward edge of the truncated cone is greater than the diameter of the cylindrical jacket portion so that the rear portion clearing the cylindrical surfaces forms a collar-shaped extension 26 of the jacket. This extension 26 represents the driving band intended to transmit to the jacket the spin imparted by the surfaces of the lands 28 bounding the grooves 29 of the gun bore 27.

As shown in FIG. 5, before firing, the jacket surface of the driving band 26 rests against a cone surface 31 of the gun bore 27, which forms the rear termination of the lands 28 and into which the bottoms of the grooves 29 extend. The cylindrical jacket portion is centered and guided by the lands 28. The rear portion 33 of the bore of the jacket 25 is enlarged, and the bore step forming a shoulder 34 rests on the end face of the sleeve flange 16. The ridges 17 of the extension 5 have a larger diameter than the portion 35 of the bore of the jacket 25 and engage it in barb-like fashion, The rear portion of the bore of the jacket is so designed that it rests against the

surfaces

20, 21, 23, 24 of the rear part 4, so that its rearmost portion touching the

surfaces

23 and 24 forms a ring 47 of tongue-shaped cross-section.

As shown in FIGS. 1 and 2, radial grooves 36 are cut into the jacket 25 at regular angular intervals from the bore wall and extend from the end face to the level of the rear end of the extension 5. The surfaces of the jacket 25 terminating the grooves 36 at the rear are arranged in the same plane as a groove 37 running round the whole periphery of the jacket and provided with a rounded bottom. The jacket 25 is provided on the outside with recesses 38, which serve weight-reducing purposes and whose bottoms are rounded in circular fashion and whose flanks 39 enclose a substantially right angle. The symmetry planes of these recesses 38 forming radial planes are arranged between the symmetry planes of the grooves 36 (FIG. 2).

A plastic hood 40 extending forwardly from the jacket 25 is formed as a hollow body having a tapering forward portion and a rear portion widening rearwardly in bell fashion to the outside diameter of the jacket 25 of the sabot 3. The hood 40 ends forward of the ogive 2 of the core 1, enclosing the ogive and spaced therefrom and is connected with the jacket 25 by a flange 41 which terminates it at the rear which protrudes inwardly to engage a groove 42 cut round the whole circumference of the jacket 25. The hood 40 is closed forwardly by a thin cover 44 arranged across its longitudinal axis and located at a short distance rearward of the end face 43 and made integral with the rest of the hood. The circular junction 45 of the cover 44 with the hood 40 forms a place of intended rupture. This cover 44 increases the strength of the hood-40 and also prevents any foreign matter from penetrating between it and the ogive 2 of the core 1.

The action of the sabot projectile before and at firing is as follows:

In the handling and transport of the sabot ammunition, the shocks directed towards the ogive 2 of the core 1, often consisting of a thin ballistic hood, are absorbed by the hood 40, but, owing to the stiffness of the latter, are not transmitted to the ogive 2.

When a cartridge, fed by the action of the gun, comes to a sudden stop in the cartridge chamber at the end of the loading process, the core 1, owing to its forwarddirected inertia, comes to rest with its rear groove flank 13 against the locking element 14, and this against the sleeve 15, for whose flange 16 the shoulder 34 inside the jacket 25 forms an abutment. The force of inertia of the core 1 is transmitted by the jacket 25 to the ridges 17 of the extension of the rear part 4 and thus absorbed by the latter. This prevents the jacket being unduly stretched and ripped apart.

At the beginning of the movement of the projectile, after the ignition of the propellant charge, when the driving band 26 is moving along the cone surface 31 of the cartridge chamber, its part marked by double hatching in FIG. 5 undergoes partly plastic and partly elastic deformation. At the same time the lands 28 of the gun bore cut into the driving band 26, so that the side surfaces 30 of the lands 28 impart forces to the jacket 25 causing the latter to spin, The rear portion of the driving band 26, which suffers the greatest deformation, is arranged in axial direction on the level of the cone surface 21 of the rear part 4. The pressure developed by the elastic deformation of the driving band 26 and transmitted to the jacket 25 by the cone surface gives rise to a frictional force which transmits the spin of the jacket 25 to the rear part 4. This coupling action between jacket 25 and rear part 4 can be improved by knurling 48 of the cone surface 21 as indicated by a dash-dotted line on the right of FIG. 1, causing the jacket 25 to mesh with the rear part 4 under the external pressure acting on the jacket,

The radial prestressing of the driving band 26 offers the further advantage that the projectile will still be properly guided and set spinning even when the bore 27 is worn and thus has an excessive inside diameter, as this diameter difference is made good by the elastic expansion of the driving band 26.

In the acceleration of the sabot projectile, the core 1 is pushed with such force rearwards against the chamber formed by the supporting surface 8 of the rear part 4 that the latter undergoes plastic deformation. As a result the subcaliber core 1 moves relatively to the rear part 4 rearwards and is then no longer held free of clearance in axial direction. Further, the core 1 is set spinning by the frictional force acting between it and the rear part 4.

The force acting on the jacket 25 in axial direction forwardly is determined by the size of its surface exposed to the gas. At the beginning of the projectile movement, this surface is composed of the rear annular surface 49 and, as the gas can penetrate between the surface 24 of the rear part and the jacket surface 50, of the surface which is determined by the projection of this jacket surface 50 on to a plane perpendicular to the projectile axis. The relations are such that the acceleration which can be imparted to the light jacket 25 by this gas power is at least equal to the acceleration sustained by the projectile relieved of the weight of the jacket 25 and the hood 40. The danger of any displacement of the jacket 25 with respect to the rear part 4 is countered by the anchoring of the jacket in the rear part. The securing is ensured by the fact that the rearmost portion of the jacket 25 is designed as a forward-closing key ring which is clamped between the surface 31 or between the lands 28 and the groove bottoms 29 on the one side and the surface 21 of the rear part 4. A gas force acting on the surface 50 of the jacket forces the ring 47 with sealing effect against the surface 23 of the rear part 4. This arrangement prevents the gas from penetrating between ring 47 and surface 23 and thus unduly enlarging the gas hit area of the jacket and, accordingly, the gas force acting on the jacket in axial direction.

Under the pressure acting on the cover 44 of the hood 40 inside the gun bore 27 at firing, the cover 44 is separated from the hood 40 at the placed of intended rupture 45 and thrown rearwards, so that the pressure now also acts on the inside of the hood. With increasing spinning speed, the hood 40 is ripped apart by the centrifugal force acting on it, and the fragments settling against the gun bore 27 are pushed out of it forwards by the jacket 25.

Once the projectile has left the barrel, the centrifugal force causes the jacket 25 to disintegrate into segments moving radially outwards, and this is aided by places of intended rupture formed by the webs 51 bounded by the bottoms of the grooves 36 and the surface of the jacket 25. The said segments detach themselves from the rearmost portion of the jacket 25 anchored in the rear part 4 substantially along a plane perpendicular to the projectile axis and containing the ring groove 37. Under the action of the centrifugal force also, the segments of the extension 5 of the rear part 4 which are bounded by the slots 18 and which are additionally subjected to the centrifugal forces acting on the segments of the sleeve 15 and the locking element 14 are torn from the rear part 4 and hurled from the core 1. The said core is then completely free and, as it presents less resistance to the air than does the rear part 4, moves forward independently of the latter.

In a further example as shown in FIG. 6, the foremost portion of the extension 5 of the rear part 4 is curled inwardly (53) and rests against the flange 16 of the sleeve 15. With this arrangement, the inertia force acting on the core 1 when the cartridge is fed into the cartridge chamber is transmitted not to the jacket 25, but direct to the extension 5, i.e. to the rear part 4, thus dispensing with the need for ridges 17 on the extension 5. This also applies in the third example as shown in FIG. '7, wherein the sleeve 54 is screwed up with the extension 5 bearing the thread 56. From the end face, slots 55 are cut into the sleeve 54 at regular angular intervals. These slots form the boundaries of segments into which the sleeve 54 disintegrates at firing under the action of the centrifugal force.

The

elements

14 and 15 in FIGS. 1 and 6 for the support of the core .1 can also be united to form a single securing body. Such a body has substantially the same cross-section as the two

elements

14 and 15 together and is also split into several segments of equal size.

I claim:

1. Sabot projectile comprising a projectile core (1) which extends along an axis, a sabot (3), (4, 25) with an approximately cylindrical rear part (4) having on its circumference a groove (21, 23, 24), said groove defined by two spaced substantially parallel side walls (21, 24) and a flat bottom surface (23) connecting said side walls (21, 24), said side walls being annular portions of imaginary cones having apices pointing rearwards in relation to the direction of flight, said sabot (3), (4, 25) having a jacket (25) encompassing the projectile core (1) and fitting into said groove (21, 23, 24) to form a gas tight connection between said jacket (25) and said rear part (4) and a driving band (26) integral with said jacket (25) located in the area of said groove (21, 23, 24) in the rear part (4) to improve the tightness between said jacket (25 and said rear part 4).

2. Sabot projectile comprising a projectile core (1) extending along an axis, a sabot (3, 4, 25) with an approximately cylindrical rear part (4) having a groove (21, 23, 24) on its circumference, said groove defined by two spaced substantially parallel side walls (21, 24) and a flat bottom surface (23) connecting said side walls (21, 24) said side walls being annular portions of imaginary cones having apices pointing rearwards in relation to the direction of flight, said sabot (3), (4, 25) having a jacket (25) encompassing the projectile core (1) said jacket (25) having on its rear part pointing in the flight direction of the projectile two spaced substantially parallel surfaces being annular portions of imaginary cones having apices pointing rearwards, both of said surfaces contacting the side walls (21, 24) of the groove (21, 23, 24) of the rear part (4), said jacket (25) having a driving band (26) located in the area of the groove (21, 23, 24) of the rear part (4) to improve the tightness between said jacket (25) and the rear part (4).

3. Sabot projectile according to claim 1 for a rifted gun bore (27) wherein the outer diameter of said driving band (26) is greater than the greatest interior diameter of the gun bore (27) 4. Sabot projectile according to claim 2 comprising a locking ring (14) an annular groove (12) in the projectile core (1) Where the locking ring (14) fits in, a frnt surface (52) on said locking ring (14) whereby said front surface (52) serves as a first resting surface, and with a second surface (34) on said jacket (25) which is parallel to said first resting surface (52) of the locking ring (14) and set at a distance from said first resting surface (52), a sleeve (15) resting on one hand on said first resting surface (52) of said locking ring (14) and on the other hand on said second resting surface (34) of said jacket (25) to prevent the axially displacement of the projectile core (1) in relation to the jacket (25) in one direction.

5. Sabot projectile according to claim 4, wherein said jacket (25) of the sabot (3) has a bore step (34), which forms said second resting surface of the jacket (25) and a flange (16) on said sleeve (15) which rests against said second resting surface (34) of the sabot (25).

6. Sabot projectile according to claim 4 wherein said rear part (4) of the sabot has an extension (5) and said extension has a shoulder (53) which constitutes said second resting surface of the sabot (3, 4, 25).

7. Sabot projectile according to claim 6 wherein said extension (5) of the rear part (4) has annular ridges (17) of saw-tooth shaped cross-section, whereby the annular ridges (17) form an additional connection between the rear part.( 4) and said jacket (25).

References Cited UNITED STATES PATENTS 2,669,930 2/1954 Darby et al. 10293 3,096,715 7/1963 Dufour 10293 X 3,349,712 10/ 1967 Schwager et al. 102-93 FOREIGN PATENTS 1,298,756 6/ 1962 France.

573,914 12/1945 Great Britain.

586,174 3/ 1947 Great Britain.

752,448 7/1956 Great Britain.

150,557 6/1955 Sweden.

351,522 2/1961 Switzerland.

ROBERT S. STAHL, Primary Examiner