US3359905A

US3359905A - Sabot projectile

Info

Publication number: US3359905A
Application number: US537816A
Authority: US
Inventors: Engel Walter
Original assignee: Oerlikon Buehrle Holding AG
Current assignee: OC Oerlikon Corp AG Pfaeffikon
Priority date: 1965-04-01
Filing date: 1966-03-28
Publication date: 1967-12-26
Anticipated expiration: 1984-12-26
Also published as: SE302733B; AT260733B; DE1578185A1; BE678906A; CH435039A; NL6603145A; GB1143967A; NL133127C

Description

Dec. 26, 1967 w. ENGEL SABOT PROJECTILE 2 Sheets-Sheet 1 Filed March 28, 1966' w. ENGEL Dec. 26; 1967 SABOT PROJECT ILE 2 Sheets-Sheet 2 Filed March 28, 1966 Fig. 7

10d

17d 171d 175d 27 22d. 7/0

Fig.6

United States Patent 3,359,905 SABOT PROJECTILE Walter Engel, Zurich, Switzerland, assignor to Oerlikon- Buhrle Holding AG, Zurich, Switzerland Filed Mar. 28, 1966, Ser. No. 537,816 Claims priority, application Switzerland, Apr. 1, 1965, 4,523/ 65 9 Claims. (Cl. 102--93) ABSTRACT OF THE DISCLOSURE A discarding sabot projectile wherein projectile member is held in a sabot under an axial prestress. The projectile member has a groove around the periphery thereof into which is received a lock ring, which projects beyond the periphery of the projectile member and is axially held within the sabot by means of an axially adjustable member. The sabot contains a deformable support which, upon firing of the projectile, is contacted by the rear surface of the projectile member and deformed. The deformation of the support causes the projectile member to rotate with the sabot, which is rotated by the riding of the gun barrel. The resultant centrifugal force causes the lock ring to expand radially whereby the ring releases the projectile member from the sabot.

This invention relates to a sabot projectile adapted to be mounted on a cartridge, and having a sabot member, which engages the cartridge, and a projectile member which is supported by the sabot member. The projectile member is held within the sabot member by locking means which is so designed that it can expand at right angles to the axis of the projectile in response to selected movement thereof, whereby the projectile member is released from the sabot member.

In a projectile of this type known in the prior art, the projectile member is provided witha coaxial projection extending rearwardly through the rear end of the sabot member. However, the diameter of this projection is much smaller than the forward part of the projectile member. The projectile member is disposed in the sabot member with its annular support surfaces urging it toward the rear. That is, the end wall of the sabot acts as a first thrust face. The axial projection has an annular groove in its periphery into which a locking element is received. The locking element protrudes radially beyond the peripheral surface of the axial projection, and bears against the rear surface on the end wall of the sabot member, thereby acting as a second thrust face, which completes the existing device for holding the projectile member in the sabot member.

In guns with a high rate of firing, the projectile is fed axially into the breech and is stopped suddenly in the projectile chamber from a high feed velocity during the loading operation. As a result, the holding unit for a projectile member of the existing type, mentioned above, is exposed to a very substantial amount of inertia when the projectile member stops. The faces which transmit these forces to the sabot, are comparatively small. Thus, they are often unable to withstand such stresses and they are pressed in, or their edges are raised by material forced out of the way, or recesses are formed in the end wall.

The intended expansion of the applicants locking element cannot occur during introduction of his projectile into the breech and the adjacent rifling grooves of the barrel. Thus, the detachment of the projectile member from the sabot member cannot take place under such circumstances,

The above-mentioned drawbacks in existing projectiles are particularly serious where the projectile member is made of a material having a high specific gravity, such as tungsten carbide or a similar material, and the sabot, or

its thrust faces, are made of a material of low specific gravity, such as a light alloy, both of which are basic requirements, above all else, for projectiles of this type. The

'two dangerous disadvantages are thus created. That is,

the holding unit becomes slack and the separation of the projectile member from the sabot fails to take place.

In the know projectiles of this type, the projectile member is retained in the sabot with a certain pretension, to improve the anchoring action by the locking element, by means of slotted spring washers which press a two-piece collar, which is provided with an oblique shoulder, in a wedge-like manner into the groove of the extension, the groove being equipped with a suitably designed counter shoulder. This solution however suffers from the disadvantage that under the influence of the above-mentioned substantial axial forces during loading, the oblique shoulders slide off from each other so that the locking element, which expands as a result, releases the projectile member prematurely. Thus, the projectile member can move forwardly in the sabot and, under certain circumstances, can even become separated from the sabot prior to firing so that it may become jammed in the barrel, which is dangerous.

The object of the invention is the provision of a locking mechanism which is capable of providing a reliable anchoring of the projectile member in the sabot member as well as a reliable, correctly timed separation of the two parts, but in such a manner that the above-mentioned disadvantages are avoided.

According to the invention, this problem is primarily solved by placing the locking unit in front of the end wall and providing at least one of the two thrust faces on an axially adjustable part. Also the locking element is gripped so that it can be released by a relative axial movement between the projectile member and sabot during firing, after which the locking element is moved out of its locking position by centrifugal force.

The advantages of this design are as follows: arrangement of the holding unit in front of the first thrust face and placement of the second thrust face outside the maximum diameter of the projectile member offers the possibility to make all the faces, which serve to support the projectile member, much larger or at least capable of absorbing suitable contact pressure. Moreover, the axially adjustable part allows the pretension in the holding unit, which is matched to the deceleration during the loading operation and can be adjusted while the projectile is assembled. As a result, the locking element is completeiy prevented from expanding until the deformation of the first thrust face by the projectile member creates the required axial play as a result of the firing shock, the play allowing the locking element to expand without interference as a result of centrifugal force.

Further details and suitable embodiments of the invention can be seen from the claims, the following description and the associated drawings, in which:

FIGURE 1 shows a central cross section of a sabot projectile embodying the invention;

FIGURE 2 shows an end view of the sabot projectile of similar import shall have reference to the upper and lower ends, respectively, of the projectile and parts thereof as appearing in FIGURE 1. The terms inner and outer" andderivatives thereof shall have reference to the geometric center of said shell and its parts.

In FIGURE 1, the sabot projectile is comprised of the sabot member and the projectile member 11, which are mounted upon a cartridge (not shown). The sabot 10, which is made of light alloy, for example aluminum alloy, is provided with sleeve-

type extensions

102 and 103 extending forwardly and rearwardly, respectively, away from a solid cylindrical center part which includes the bottom or thrust wall 101. The extensions 103 fits into the open end of the cartridge or casing and remains there in a known manner until the sabot projectile is fired. The projectile 11 is preferably made wholly or partially of tungsten carbide and is basically of cylindrical shape, to which is added a point 21 extending forwardly and a rear part 22 which is connected to a holding unit in the sabot 10. Broadly speaking, the sabot 10 is part of the projectile 11 because it moves therewith when fired.

In the region of the bottom 101, the sabot 10 is encircled by the guide ring 12 which is made of steel and which transmits the rotary impulse from the rifiing grooves in the gun barrel (not shown) to the sabot. A further, guide ring 13 is clamped between the flange 141 of the guide sleeve 14 and the face 104 of the extension 102 when the guide sleeve 14 is threaded into the front end of the extension 102 of the sabot. Also, the periphery of the rig 13 is coaxial with the outer surface 142 of the sleeve 14. The radially inner face of sleeve 14 consists of a rear taper 143 diverging toward the rear and a front taper 144 diverging toward the front. The intersection 145 between said tapered surfaces provides the forward guide for the projectile 11 which is embraced by said intersection.

As can be seen from FIGURE 2, the guide surface of the intersection 145 is interrupted by several semicircular grooves 146 which are uniformly spaced from each other and extend parallel with the axis of the sabot, passing through the tapered surfaces 143 and 144.

As is shown in FIGURE 1, the bottom 101 of the sabot 10 is provided with a coaxial, circular recess 105 into which is machined a further circular and coaxial recess 106 having a smaller diameter. The recess 105 is provided for centering the rear part of the projectile 11 which has its support face 113 supported on an annular surface 107 around the recess 105 which acts as a first thrust face.

The annular groove 111, machined into the rear part 22 of the projectile 11, receives an annular locking element 15 of rectangular cross section and having a slot 16, the outer surface of the locking element 15 being numbered 151.

In addition to the guide sleeve 14, the forward extension 102 of the sabot 10 contains an axially adjustable sleeve 17, which is threadedly received in said extension 102. This screwed sleeve 17 has a center bore 174 (FIG- URE 3) which acts as a guide for the projectile 11. The rear end face of sleeve 17 forms a second thrust face 171. A set screw 20 extends radially through the wall of the extension 102 and engages the sleeve 17 to prevent relative rotation.

Between this thrust face 171 and the rear groove wall 114, which runs at right angles to the axis of the projectile and acts as a support point on the projectile 11, there is the above-mentioned annular locking element 15 which protrudes radially beyond the rear part 22 of the projectile 11 and which is expandable under the influence of centrifugal force. The actual rear end of the projectile 11 is also provided with four rifling engagement faces 112 which are ground at equal angular distances from each other and which enclose an acute angle with the projectile axis directed toward the rear and whose intersections with the circular support face 113 lying across the axis form chords in this support face 113. The four chords are located in the range of the annular first thrust face 107 of the sabot 10.

The space 18 defined between the surfaces 108 of the bottom 101, the cylindrical inner surface of the sleeve extension 172 and the second thrust face 171 of sleeve 17, is provided for receiving the locking element after it has expanded.

As can be seen from FIGURE 3, the sleeve 17 is additionally provided with two semicircular grooves 173 parallel with the axis of the sabot projectile. These grooves 173 provide the connecting channels between the annular space 19, formed between the inner wall of the extension 102 of the sabot 10 and the outer face of projectile 11, and the above-mentioned reception space 18 for the locking element 15.

The operation of the described sabot, immediately prior to firing and during actual firing, results from its design and is as follows:

When the sabot projectile of which the sabot 10 forms the front part, is suddenly bottomed at the end of the loading operation into the sabot projectile chamber of a gun barrel, the projectile 11, as a result of its forward inertia causes its rear wall 114, acting as a support face, to press against the locking element 15 and which in turn presses against the second thrust face 171 of sleeve 17 (FIGURE 1). However, since these support points were given a suitable pretension during assembly by suitably dimensioned tightening of the threaded sleeve 17, and since all their faces are at right angles to the axis of impact and are sufficiently largely dimensioned, the locking element 15 always remains clamped without change from assembly to the moment of firing.

However, after firing of the propellent charge, the tremendous acceleration of the sabot 10 within the gun barrel causes the rear support face 113 of the projectile 11 to be pressed backward against the first thrust face 107 with such force that the latter becomes deformed either plastically due to upsetting or elastically due to spring action. When this happens, the projectile 11 will thus move backward relative to the sabot 10, thereby releasing the clamping action of the locking element 15 against the face 171.

As a result of the upsetting action mentioned above, rifiing engagement faces 112, which are ground on the rear part of the projectile will simultaneously be pressed into the thrust face 107 according to one variation of this design. They cause the projectile 11 to be positively engaged with the sabot 10, whereby the rifling effect upon the sabot 10 is transmitted to the projectile 11, inasmuch as frictional forces alone are not adequate to effect such transmission.

During the axial acceleration of the projectile 11 by the propellant gases, the locking element 15 is pressed against the rear groove flank 114 and also made to rotate therewith, due to the resultant friction, so that the locking element 15 will expand as a result of the centrifugal force acting on it even before the sabot 10 leaves the gun barrel. Accordingly, the element 15 expands out of the annular groove 111 and moves into the reception space 18 with the outer surface 151 of the element 15 against the inner surface of the sleeve extension 172.

After the sabot 10 has left the gun barrel, the sabot 10 will undergo more severe deceleration, as a result of air resistance, than the projectile 11, due to its annular front face. Thus, the projectile 11 will move forwardly relative to the sabot 10 and will, after a short interval, become completely separated from the sabot.

As soon as the rear end 22 of the projectile 11 has moved out of the recess 105 in the bottom 101, air can move through the grooves 146 of the guide sleeve 14 into the annular space 19, and thence through the two groves 173 in sleeve 17 so that it can exert additional braking action on the bottom 101 of the base 10. The air resistance acting on the base is thereby abruptly and very substantially increased, which accelerates the separation of the projectile 11 from the sabot 10.

In the following further examples, the modified components retain their numbering, except where their shape is changed, in which case the sufiix a is added to FIG- URE 4, and the suffix b is added to FIGURE 5, etc. Additional parts are given new numbers.

The second example shown in FIGURE 4 is distinguished from the design described above (according to FIGURE 1) by the fact that a threaded part 23 is screwed into the suitably matched sabot 10a from the rear end thereof. The sleeve 17 is omitted and, to make up for this, the interior of the forward sabot extension 102a has the same shape as that previously shown for sleeve 17, including a corresponding, second thrust face 171a. The bottom 101 of the sabot 10 is provided by the end wall of the threaded part 23 so that the latter has a cup-shaped appearance. It is also fitted with a first thrust face 107a.

In the example shown in FIGURE 4 the operation is basically the same as that described with reference to the first example. However, it should be noted that the locking element 15 finds its second thrust face at the recessforming surface 171a of the sabot 10a. The deformation of the other thrust face 107a, however, takes place here upon the threaded part 23.

The variation shown in FIGURE 5 for supporting the rear part of the projectile 11 is formed by a special upsetting element 25 which can be plastically deformed and is inserted into a center bore 24 of bottom 101b of sabot b. The upsetting element 25 is provided with an extension 26 protruding beyond the bottom surface 107]; and lying opposite to the support face 113 of rear part 22 to act as first thrust face 26b for the same purpose as in the preceding examples.

In the example shown in FIGURE 5 the support face 113 of rear part 22 comes to rest on the surface 26b on the extension 26 of the upsetting element 25. The cross section of the surface 26b on the upsetting element 25 is so dimensioned that, when the propellant charge is fired, the reaction pressure of projectile 11 deforms the extension 26 until the support face 113 of rear part 22 finally comes to rest on the bottom surface 107b. At that point the friction is generated which transmits the rotary movement from the sabot 10b to the projectile 11.

In the example shown in FIGURE 6, the sabot 100 for supporting the same projectile 11 has an elastically deformable first thrust face 260 which is provided by the upper surface of a disk spring 25c which is located in a recess 1050 in the base bottom 1010, which is slightly deeper than the recess 105 (FIGURE 1). During the acceleration phase of the sabot 10c the rear part 22 of the projectile 11 presses the spring 250 against the base bottom 101c as a result of the inertia acting on the projectile 11. This causes spring 250 to undergo elastic deformation so that the rear part 22 will approach the bottom surface 107c, of recess 105c, thereby releasing the clamping action upon the locking element 15. However, as soon as the acceleration of the projectile 11 diminishes, the spring force of spring 250 will overcome the inertia of the projectile 11 so that the latter, after having been released from the locking element 15 as a result of centrifugal force, is pressed forwardly with respect to the sabot 10c. Thus, the spring 25c constitutes not only a means for transmitting torque from the sabot 10c to the projectile, but also a driving element which additionally helps the separation of the projectile 11 from the sabot 100.

FIGURE 7 shows a holding device for a projectile 11d with a modified rear part 22d. The forward part of projectile 11d may take exactly the same form as described before with respect to FIGURE 1. The rear part 22d is tapered rearwardly in steps to form several, successive truncated cones while retaining an annular groove 111d which terminates at its rear end in a support face 114d for the locking element 15d. In this example, the element 15d is designed in the form of a thin-walled sleeve having lengthwise and rearwardly opening slots 27 uniformly spaced around said sleeve. The rear part of the sleeve 15d, which contains said slots 27, is bent inwardly to form lugs 28 substantially parallel with and near to the tapered wall 119, which is inclined relative to the axis of the shell, adjacent the wall114d.

The diameters of the support surface 113d and of the first thrust face 107d are slightly smaller than in the preceding examples, as a result of the tapered shape of the rear part 22d. The thrust face for the locking element 15d is formed by an internal shoulder 171d in the threaded element 17d, a cylindrical centering surface 172d adjoining the internal shoulder 171d and encircling the sleeve 15d. The centering surface 172d is connected to the wall surface 176d of a larger bore 18d by means of a shoulder 175d.

During assembly of the sabot 10d designed in accordance with FIGURE 7, the locking element or sleeve 15d is subjected to pressure by means of the threaded sleeve 17d so that it is pretensioned. The internal shoulder 171d of this sleeve 17d thus comes to rest on the cylindrical face at the front end of the locking element 15d, which makes contact with the wall of the bore 172d. The lugs 28 of the element 15d therefore press against the rear groove wall 114d, lying at right angles to the axis of the sabot 10d, and thus locate the projectile 11d with its support face 113d on the thrust face 107d of the base bottom 101d.

As in the examples described above, the locking element 15d is released only during firing when it is made to rotate. As a result of centrifugal force created by such rotation, the lugs 28 bend outwardly around the inner edge of shoulder 175d, acting as fulcrum, as far as the wall of bore 176d of the threaded sleeve 17d. Such bending is permitted by the acceleration of the sabot 10d which presses the projectile against the wall 107d and thereby releases the clamping pressure upon the element 15d. Thus, thereafter, there is nothing to stop the projectile 11d from becoming separated from the sabot 10d in substantially the same manner as discussed above with respect to FIGURE 1.

The five-described examples embodying the invention can be combined with each other as far as the retaining device of the projectile is concerned. For example, the upsetting element 25, the plate spring 250 or the locking element 15d with its lugs 28 bent inward can be combined in a sabot with a threaded part 23 inserted from the rear. These combinations in turn can be extended to sabots with a threaded sleeve 17 inserted from the front and a threaded element 23 inserted at the same time from the rear. Moreover, all the methods of supporting the projectile described above can without difliculty be applied to the projectile 11d (according to FIG- URE 7).

In all these combinations according to FIGURES 1 and 4 to 6 the action of the retaining device follows logically from their design.

Accordingly, although particular preferred embodiments of the invention have been disclosed above in detail for illustrative purposes, it will be recognized that variations or modifications of such disclosures, which lie within the scope of the appended claims, are fully contemplated.

The embodiments of the invention in which an excluflVe property or privilege is claimed are defined as folows:

1. A sabot projectile adapted to be fired from the barrel of a gun having means for imparting rotation to said sabot projectile around a longitudinal axis parallel to its direction of movement, said sabot projectile comprising:

a projectile body extending along the longitudinal axis and having a supporting surface on the rear end thereof and a ring groove in the peripheral surface thereof, said groove having a wall normal to said longitudinal axis; sabot means having a coaxial recess therein adapted to receive said projectile body, said sabot means having means on the periphery thereof adapted to engage said rotation imparting means, said sabot means having front and rear opposed and longitudinally spaced stop faces within said recess normal to said longitudinal axis, said rear stop face acting as a support for the supporting surface on said projectile body and adapted to be deformed by said projectile body, said front stop face being ring shaped and surrounding the projectile body; adjustment means for adjusting the relative axial positions of said front and rear stop faces; and

ringshaped safety means positioned within said ring groove and having a first axial surface supported on said groove wall and a second axial surface in engagement with said front stop face, the engagement force therebetween being controlled by said adjustment means, said safety means being adapted to hold said projectile body within said sabot means until said sabot means attains a minimum rotational speed.

2. A sabot projectile as defined in claim 1, wherein said rear stop face is provided on a plastic deformable portion of said sabot means, and said axial adjustment means prevents said safety means from moving out of engagement with said groove wall until after the deformation of said rear stop face by said projectile body.

3. A sabot projectile as defined in claim 1, wherein said rear stop face is provided on an elastically deformable portion of said sabot means.

4. A sabot projectile as defined in claim 2, wherein said sabot means includes a cylindrical housing having said recess therein, said adjustment means including a sleeve threadedly received within the recess of said housing with said sleeve having a rear axial surface defining said front stop face.

5. A sabot projectile as defined in claim 2, wherein the sabot means includes a cylindrical housing and said adjustment means comprises a screw member threadedly received within said housing, said screw member having a front face thereon defining the rear stop face of said sabot means.

6. A sabot projectile as defined in claim 2, wherein said projectile body is provided with a plurality of engagement surfaces thereon extending from said rear supporting surface, said engagement surfaces enclosing an acute angle with respect to said longitudinal axis and intersecting rear supporting surface so as to form chords there- 7. A sabot projectile as defined in claim 2, wherein said sabot means is provided with a plastic, deformable, cylindrical projection thereon extending into said recess adjacent the rear supporting surface of said projectile body, the front axial face of said projection defining said rear stop face.

8. A sabot projectile as defined in claim 3, wherein a spring plate is positioned within the recess of said sabot means with the front surface of said spring plate defining said rear stop face.

9. A sabot projectile as defined in claim 6, wherein said safety means is formed as a thin-walled sleeve having a plurality of longitudinally extending lugs secured thereto with the rear ends of said lugs being bent radially inwardly so as to be supported on said groove wall.

References Cited UNITED STATES PATENTS 1,209,611 12/1916 Mustin et al. 10293 1,973,604 9/1934 Brandt 10292.5 2,389,846 11/ 1945 Ericson 102-92.5 2,669,930 2/1954 Darby et a1. 102--93 FOREIGN PATENTS 301,298 1/1920 Germany.

BENJAMIN A. BORCHELT, Primary Examiner.

W. KUJAWA, Assistant Examiner.

Claims

1. A SABOT PROJECTILE ADAPTED TO BE FIRED FROM THE BARREL OF A GUN HAVING MEANS FOR IMPARTING ROTATION TO SAID SABOT PROJECTILE AROUNG A LONGITUDINAL AXIS PARALLEL TO ITS DIRECTION OF MOVEMENT, SAID SABOT PROJECTILE COMPRISING: A PROJECTILE BODY EXTENDING ALONG THE LONGITUDINAL AXIS AND HAVING A SUPPORTING SURFACE ON THE REAR END THEREOF AND A RING GROOVE IN THE PERIPHERAL SURFACE THEREOF, SAID GROOVE HAVING A WALL NORMAL TO SAID LONGITUDINAL AXIS; SABOT MEANS HAVING A COAXIAL RECESS THEREIN ADAPTED TO RECEIVE SAID PROJECTILE BODY, SAID SABOT MEANS HAVING MEANS ON THE PERIPHERY THEREOF ADAPTED TO ENGAGE SAID ROTATION IMPARTING MEANS, SAID SABOT MEANS HAVING FRONT AND REAR OPPOSED AND LONGITUDINALLY SPACED STOP FACES WITHIN SAID RECESS NORMAL TO SAID LONGITUDINAL AXIS, SAID REAR STOP FACE ACTING AS A SUPPORT FOR THE SUPPORTING SURFACE ON SAID PROJECTILE BODY AND ADPATED TO BE DEFORMED BY SAID PROJECTILE BODY, SAID FRONT STOP FACE BEING RING SHAPED AND SURROUNDING THE PROJECTILE BODY; ADJUSTMENT MEANS FOR ADJUSTING THE RELATIVE AXIAL POSITIONS OF SAID FRONT AND REAR STOP FACES; AND RING-SHAPED SAFETY MEANS POSITIONED WITHIN SAID RING GROOVE AND HAVING A FIRST AXIAL SURFACE SUPPORTED ON SAID GROOVE WALL AND A SECOND AXIAL SURFACE IN ENGAGEMENT WITH SAID FRONT STOP FACE, THE ENGAGEMENT FORCE THEREBETWEEN BEING CONTROLLED BY SAID ADJUSTMENT MEANS, SAID SAFETY MEANS BEING ADAPTED TO HOLD SAID PROJECTILE BODY WITHIN SAID SABOT MEANS UNTIL SAID SABOT MEANS ATTAINS A MINIMUM ROTATIONAL SPEED.