US3862603A

US3862603A - Light weight sabot

Info

Publication number: US3862603A
Application number: US308382A
Authority: US
Inventors: Jeffrey S Kornblith; Jerold L Swedlow
Original assignee: US Department of Navy
Current assignee: US Department of Navy
Priority date: 1972-11-21
Filing date: 1972-11-21
Publication date: 1975-01-28
Anticipated expiration: 1992-01-28

Abstract

A sabot having a plurality of substantially hollow, J-shaped petals. Integrally formed support struts extend radially inward from the petal surface to engage positioning grooves in the projectile skin. Driving band sections are swaged into recesses formed in the petals and a pre-notched holding band secures the petals to the projectile. The J-shaped curved portion engages an aft-positioned circumferential groove to transmit driving forces to the projectile.

Description

. a v States Kornblith et a1.

LIGHT WEIGHT SABOT Inventors: Jeffrey S. Kornblith, Oxon Hill.

Md.; Jerold 1L. Swedlow, Pittsburgh, Pa.

The United States of America as represented by the Secretary of the Navy, Washington, DC.

Filed: 1 Nov. 21, 1972 Appl. Nd; 308,382

Assignee:

US. Cl 102/93, 102/56, 102/926 Int. Cl. F42b 13/16, F42b 31/00 Field of Search 102/52, 93, 94, 56, 92.6,

' References Cited FOREIGN PATENTS OR APPLICATIONS 1,231,601 4/1960 France 102/93 1 .lan.28, 1975 1,016,766 9/1952 France 102/93 Primary Examiner-Robert F. Stahl Attorney, Agent, or Firm-R. S. Sciascia; J. A. Cooke [57] ABSTRACT A sabot having a .plurality of substantially hollow, J- shaped petals. integrally formed support struts extend radially inward from the petal surface to engage positioning grooves in the projectile skin. Driving band sections are swaged into recesses formed in the petals and a pre-notched holding band secures the petals to the projectile. The .l-shaped curved portion engages an aft-positioned circumferential groove to transmit driving forces to the projectile.

19 Claims, 4 Drawing Figures FATE FEB MM 2 81975 I LIGHT WEIGHT SABOT BACKGROUND OF THE INVENTION port. With fin stabilized projectiles, a single sabot positioned near the center of gravity is usually employed with the fins designed to ride the bore of the launcher and provide the second support point.

Currently used sabots are generally solid or nearly solid pieces made of material such as steel or aluminum. The petals of these sabots are overly heavy and travel appreciable distances after separation from the projectile. Heavy sabot petals decrease the range of the projectile and present a serious hazard to personnel and property in the launch area as they fall afterseparation. During assembly, each petal must be securely attached, such as with a plurality of fastening keys, necessitating additional steps in assembly and requiring more parts in the sabot.

SUMMARY OF THE INVENTION Accordingly, one object of this invention is to provide a new and improved sabot device for subcaliber projectiles.

Another object of the invention is to provide a new and improved sabot that is light in weight and structurally adequate to sustain the imposed loads.

Another object of the invention is to provide a new and improved light weight sabot having fewer parts than sabot designs heretofore used.

Still another object of the present invention is the provision of a light weight sabot with improved locking mechanism.

Yet still another object of the instant invention is to provide an improved sabot device with petals presenting minimum hazard upon discard.

Briefly, in accordance with one embodiment of this invention, these and other objects are attained by providing a sabot device having a plurality of identical, light weight petals secured to the subcaliber projectile with a pre-notched holding band. Each petal comprises a curved outer surface with an inwardly curved aft portion and having integrally formed struts extending radially inwardly from the surface to engage grooves formed in the projectile. Swagged into recesses formed in the petal outer surfaces are sections of a driving band which engages the barrel of the launch device. When positioned upon the projectile, the sabot device forms a substantially concentric, truncated cylinder with the curved aft portion engaging a circumferential groove formed in the end of the projectile and the struts positioning and supporting the projectile within the launcher barrel.

BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of the invention and many of the attendant advantages thereof will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: I

FIG. 1 is a side view of a projectile embodying the sabot of the present invention; 7

FIG. 2 is a side elevational view of the sabot of FIG. I partly in section and to an enlarged scale;

FIG. 3 is a cross-sectional view of the sabot taken along line 3-3 of FIG. 2 with one sabot petal displaced for greater clarity; and

FIG. 4 shows a perspective view of a petal of the sabot.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, wherein like reference characters designate identical or corresponding parts throughout the several views, and more particularly to FIG. 1 thereof, subcaliber projectile 10 is shown supported in the rifled barrel 12 of a suitable launch device. While projectile 10 is shown to be of the spin-stabilized type, it is understood that the sabot of the present invention may be equally advantageously used with tin-stabilized projectiles and smooth bore launch devices. Projectile 10 is supported approximate the front end by front riders 14 of the type known and used in the art and the aft tail portion of the projectile is positioned and supported by the sabot device of the present invention, generally designated as 18. A triangular wedge ring 16 is positioned on the projectile forward of the sabot to facilitate loading into the barrel, as will be more fully described hereinafter. An obturator 20, also of the type known and used in the art, is positioned aft of sabot 18 and provides a fluid seal for the propellant gas and transmits the driving force to the sabot and projectile.

Referring now to FIGS. 2 and 3., sabot 18 comprises a plurality of identical, substantially hollow segments or petals 24., four such petals being shown only for purposes of illustration. A lesser or larger number of petals may be used, with corresponding changes in the num' ber of receiving grooves formed in the projectile skin. A recess 26 is provided at the forward end of petal 24 to receive a holding band 34 which is described more fully hereinbelow. Recess 28, positioned behind and of greater depth than holding band recess 26, occupies a substantial portion of petal exterior surface 22 and receives driving band section 32, described more fully below. Pyramidal-shaped protrusions 40, integrally formed on the base of driving band recess 28, will penetrate the inner surface of the copper driving band section 32 which is swagged into recess 28 to ensure a tight, non-slipping attachment with petal 24. Obviously, other shapes for protrusions 40 are within the scope of the invention.

The aft end portion 30 of sabot petal 24 terminates in an arcuate fashion, curving inwardly and then extending towards the forward end portion such that, when viewed in the longitudinal side section of FIG. 2, petal 24 has substantially a Lshape. The arcuate portion 30 of the J is thickened to sustain the axial driving forces transmitted to sabot 18 via obturator 20. Curved portion 30 terminates at lip 36 which engages a coupling groove 38 circumferentially formed in the aft end of projectile 10. Lip 36 cooperates with groove 38 to 7 both position the sabot and to transmit to the projectile mate the aft end thereof. The cooperative relationship between

struts

42, 44 and

grooves

46, 48 serves to position the petal 24 circumferentially on projectile l and provides the mechanical linkage between the barrel wall 12'of the launching device and the projectile. Side or positioning struts 42 are integrally formed at the longitudinal edges of petal 24. Struts 42 taper radially inwardly and terminate in half-V-shaped end or foot portions 50 which fit matingly with similarly configured V- shaped grooves 46 to position segments'24 onto the projectile. As shown in FIG. 3, each side struts 42 has a longitudinally extending, flush, flat surface 56 which abut indentical surfaces of adjacently positioned segments and extends radially inward from outer surface 22 to provide unencumbered surfaces of separation of the sabotpetals after projectile launch.

Thecenter strut 44 of each petal 24 also is integrally formed with petal surface 22 and extends radially inwardly, terminating in a squared-off, flat foot portion 52 which matingly engages similarly configured center strut groove 48 formed on the projectile skin. Center strut 44 is inclined relative to the radial direction at an angle determined by the torsional loads imposed upon shown in FIG. 4. In using the sabot of the present invention in non-spin stabilized projectiles, the center strut need not necessarily be inclined since torsional loads are not encountered and may be omitted completely if so desired.

While the preferred embodiment described hereinabove shows each sabot petal to have two side struts and an inclined center strut, it is Within the purview of the invention that the number of struts may be other than as shown. For example, additional center struts may be provided if necessitated by load requirements or similarly the center strut may be eliminated all together. Alternatively, all the struts, i.e., the side as well as the center struts, may be angularly inclined.

As set forth hereinabove, the aft portion of the projectile is provided with a plurality of

longitudinal grooves

46, 48 and circumferential groove 38, preferrably machined into the skin of the projectile. The length of the longitudinal grooves should be at least as long as the sabot but may be longer. Groove 38 extends completely around the aft end of projectile 10.

Sabot petals 24, with integrally formed struts 42, 44 and .l-shape curved end portion 30, may be fabricated by any suitable method, for example, such as casting or machining. Investment casting presents advantages in producting intricate shapes with minimum manual finishing required. Any suitable material may be used in fabricating the sabot, such as aluminum or steel or any alloy capable of withstanding the applied stresses. Aluminum is desirable since it is light in weight and strong.

The driving band sections 32, of any suitable material, such as copper, are swaged onto each petal prior to assembly of sabot 18 onto the projectile. The swagg ing process forces the band sections 32 into the driving band recess 28, causing portrusions 40 to penetrate the inner surface of sections 32 and to become embedded therein, resulting in a tight, non-slipping attachment of band section 32. In the preferred embodiment the outer surface of section 32 is smooth, i.e., the surface is not pre-engraved with grooves which engage the barrel riflings. This permits ready use of sabot 18 in both smooth and rifled barrels. The smooth surface of section 32, upon loading of the projectile, engages the barrel riflings and becomes engraved during launch. However, section 32 may be pre-engraved with rifling grooves. During launch, the driving band engages the rifling of barrel l2, imparting rotation to projectile 10 as the projectile proceeds within the barrel.

The holding band 34, which may be made of any suitable material, such as brass, is adapted to be positioned within recess 26, the free ends thereof being suitably secured, as by spot welding. Band 34 may be provided with a plurality of notches, spaced along its length, to permit the band to fracture at these notch points.

Wedge ring 16, of substantially triangular cross section and made of any suitable material, such as plastic, in an annular device which is positioned upon projectile 10 forward of

grooves

46, 48 before petals 24 are attached'The inner diameter of ring 16 is sized to achieve this position. Forward surface 62 of ring 16 is inclined relative to the surface of the projectile with aft surface 64 flat to abut the forward edge surface of sabot 18. The primary objective of ring 16 is to facilitate loading of projectile 10. Subsequent to launch, ring 16 slides off the tapered aft portion of the projectile after petals 24 have separated. Alternatively, ring 16 may be provided with a plurality of notches or otherwise structurally weakened to cause structural failure of the ring, permitting ring 16 to separate in pieces under centrifugal spinning forces.

Fitted obturator 20, fabricated of any suitable material, such as plastic, is positioned aft of sabot I8 behind projectile 10. The aft surface 58 of obturator 20 is sub- I stantially flat, presenting a flat surface against which the propellant gas expands, while the forward surface 60 is contoured to conform to the curvature of the aft end of sabot 18. As shown in FIG. 2, obturator 20 may be flared outwardly, form the forward surface 60 toward the aft surface 58 to ensure a tight gas seal between the obturator and barrel 12.

Prior to loading the projectile into the launch device, sabot 18 and front riders 14 are assembled onto projectile 10. The front riders are positioned and attached to projectile 10 by suitable, well-known means, such as fitting grooves, securing bands or straps, or separate stabilize it. After exiting from the barrel. the obturator present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

l. A sabot comprising a plurality of separable seg-' ments and rupturable means to secure said segments in assembled condition, each of said segments having arcuate, longitudinally extending inner and outer surfaces, one longitudinal end terminating in a portion curved toward said inner surface to form a substantially J-shape when viewed in longitudinal section, said arcuate surfaces being curved in the direction transverse to the longitudinal direction, and a plurality of longitudinal support struts integrally formed with and extending the longitudinal length of said inner surface.

2. The sabot of claim 1 wherein a first set of select ones of said longitudinal struts are angularly inclined with respect to perpendiculars to said curved surfaces.

3. The sabot of claim 2 wherein a second set of select ones of said struts comprise planar surfaces of separation permitting said arcuate surface to separate into a plurality of segments.

4. The sabot of claim 3 wherein said rupturable securing means comprises a band receivable in a recess in said surface.

5. The sabot of claim 4 further comprising force transmission means positioned on said surface.

6. The sabot of claim 5 wherein said force transmission means comprise driving band sections positioned in a second recess in said surface.

7. A sabot device for projectiles comprising:

a plurality of separable petal segments, each of said segments having:

arcuate, longitudinally extending inner and outer surfaces, said surfaces being curved in the direction transverse to the longitudinal direction, one longitudinal end portion curved toward said inner surface to form a J-shape to be received within the aft end portion of the projectile, and a plurality of longitudinal support struts integrally formed with and extending the longitudinal length of said inner surface to support said petal segment on the projectile;

rupturable securing means positioned on said petal segments to hold said segments in assembled condition on the projectile; and

force-transmitting drive means positioned on said petal segments to transmit the driving force to the projectile.

8. The sabot device of claim 7 wherein at least one of said longitudinal struts is inclined with respect to said arcuate outer surface.

9. The sabot device to claim 7 wherein at least two of said longitudinal struts are integrally formed along the lateral edges of said petal segment forming a flat surface whereby the flat surfaces of abutting petal segments form planes of separation.

10. The sabot device of claim 9 further comprising an additional longitudinal strut positioned between said lateral edge struts and inclined with respect to a perpendicular to said arcuate outer surface.

11. The sabot device of claim 10 wherein said drive means comprise a plurality of driving band sections positioned within a recess in said petal segments.

12. The sabot device of claim 11 wherein said securing means comprise a holding band positioned in a second recess in said petal segments adapted to rupture under centrifugal force.

13. The sabot device of claim 12 further comprising an annular wedge ring positioned on the projectile forwardly of said petal segments and a contoured obturator abutting said inwardly curved end portion of said petal segments.

14. In combination, a projectile having a plurality of longitudinally extending grooves circumferentially spaced on the exterior, aft surface and a sabot device comprising:

a plurality of separable petal segments, each segment having arcuate, longitudinally extending inner and outer surfaces with an inwardly-curved, J-shape'd, longitudinal end portion, and

a plurality of longitudinal support struts integrally formed with and extending the longitudinal length of said inner surface to engage said longitudinal grooves;

projectile drive means positioned on said petal seg ments; and

rupturable securing means receivable on said petal segments to hold said segments in assembled condition on said projectile.

15. The combination of claim 14 further comprising a circumferential groove formed in the aft end portion of said projectile to receive said inwardly curved, J- shaped end portion of said petal segments.

16. The combination of claim 15 wherein at least one of said longitudinal struts is inclined with respect to the radial direction of said arcuate surfaces.

17. The combination of claim 16 wherein said projec' tile drive means comprise sections of a driving band positioned within a recess in said petal segments and said rupturable securing means comprise a notched holding band.

18. The combination of claim 17 further comprising:

an annular wedge ring positioned on said projectile forwardly of said petal segments and an obturator positioned aft of said projectile abutting said petal segments.

19. The combination of claim 14 further comprising:

Claims

1. A sabot comprising a plurality of separable segments and rupturable means to secure said segments in assembled cOndition, each of said segments having arcuate, longitudinally extending inner and outer surfaces, one longitudinal end terminating in a portion curved toward said inner surface to form a substantially J-shape when viewed in longitudinal section, said arcuate surfaces being curved in the direction transverse to the longitudinal direction, and a plurality of longitudinal support struts integrally formed with and extending the longitudinal length of said inner surface.

7. A sabot device for projectiles comprising: a plurality of separable petal segments, each of said segments having: arcuate, longitudinally extending inner and outer surfaces, said surfaces being curved in the direction transverse to the longitudinal direction, one longitudinal end portion curved toward said inner surface to form a J-shape to be received within the aft end portion of the projectile, and a plurality of longitudinal support struts integrally formed with and extending the longitudinal length of said inner surface to support said petal segment on the projectile; rupturable securing means positioned on said petal segments to hold said segments in assembled condition on the projectile; and force-transmitting drive means positioned on said petal segments to transmit the driving force to the projectile.

14. In combination, a projectile having a plurality of longitudinally extending grooves circumferentially spaced on the exterior, aft surface and a sabot device comprising: a plurality of separable petal segments, each segment having arcuate, longitudinally extending inner and outer surfaces with an inwardly-curved, J-shaped, longitudinal end portion, and a plurality of longitudinal support struts integrally formed with and extending the longitudinal length of said inner surface to engage said longitudinal grooves; projectile drive means positioned on said petal segments; and rupturable securing means receivable on said petal segments to hold said segments in assembled condition on said projectile.

15. The combination of claim 14 further comprising a circuMferential groove formed in the aft end portion of said projectile to receive said inwardly curved, J-shaped end portion of said petal segments.

17. The combination of claim 16 wherein said projectile drive means comprise sections of a driving band positioned within a recess in said petal segments and said rupturable securing means comprise a notched holding band.

18. The combination of claim 17 further comprising: an annular wedge ring positioned on said projectile forwardly of said petal segments and an obturator positioned aft of said projectile abutting said petal segments.

19. The combination of claim 14 further comprising: an annular wedge ring positioned on said projectile forwardly of said petal segments and an obturator positioned aft of said projectile abutting said petal segments.