US2983225A

US2983225A - Projectile

Info

Publication number: US2983225A
Application number: US542911A
Authority: US
Inventors: Nelson A Walker
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-06-30
Filing date: 1944-06-30
Publication date: 1961-05-09
Anticipated expiration: 1978-05-09

Description

y 1961 N. A. WALKER 2,983,225

PROJECTILE Filed June 30, 1944 FIG. 2

INVENTOR w WALKER A RNEY PROJECTILE Nelson A. Walker, Santa Fe, N. Mex., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed June 34 1944, Ser. No. 542,911

1 Claim. (Cl. 102-93) This invention relates to subcaliber projectiles of the type which comprises a subcaliber core having full cahber supporting and centering means releasable from the core when the projectile emerges from the gun barrel. More particularly, the invention has reference to a novel projectile of the character described having a generally cup-shaped supporting and centering means releasable from the core by reverse setback in the initial flight of the projectile after it emerges from the gun.

It has been proposed heretofore to fit the rear end portion of a projectile core into a cup-shaped sabot'acted upon by the powder pressure in the gun barrel and designed to release from the core when the projectile leaves the gun muzzle. However, this type of projectile as previously constructed is unsatisfactory for various reasons, among which are its dependence upon both centrifugal force and reverse setback for release of the sabot, the tendency for the core to become wedged in the sabot under setback so that release of the sabot from the core is uncertain, and serious disturbance of the core flight incident to release of the sabot.

One object of the present invention, therefore, resides in the provision of a sabot type projectile comprising a subcaliber core fitted closely at its rear end into a cupshaped sabot which is positively discarded from the core by reverse setback, without seriously disturbing the flight of the core.

Another object of the invention is to provide a projectile of the character described in which the cup-shaped sabot carries a turning band for imparting rotation to the core by action of the gun ri-fling.

A further object is to provide a projectile of the character described in which the cup-shaped sabot has a tapered fit over the rear end portion of the core for centering the core in the sabot and avoiding disturbance of the core flight due to releaseof the sabot.

Still another object of the invention resides in the provision of a projectile of the character described in which the cup-shaped sabot and the core have complementary parts for positively limiting the wedging action of the core in the tapered portion of the sabot under setback when the projectile is fired from a gun.

An additional object is to provide a sabot type projectile-comprising a subcaliber core, a cup-shaped sabot in which the rear end portion of the core is closely fitted, and a sleeve-like bourrelet fitted closely around the core and part of the sabot, the front end of the bourrelet being open whereby the bourrelet and sabot are slidable off the rear end of the core as a unit under reverse setback.

These and other objects of the invention may be better understood by reference to the accompanying drawing, in which:

Fig. 1 is a longitudinal sectional view of a projectile made in accordance with the invention, and

Fig. 2 is a view in side elevation of the cup-shaped sabot shown in Fig. 1.

Referring to the drawing, the projectile there shown comprises a subcaliber core which may be made of Patented May 9, 1961 steel subjected to suitable treatment for hardening. At its front end portion, the core 10 has an ogive 10a, and directly to the rear of the ogive the core is tapered slightly toward the base of the projectile, as shown at 10b, the taper extending over the major portion of the On the rear end portion of the core 10 is a substantially full caliber sabot 13, which may be made of steel, or the like. The front face of the sabot 13 at its central portion is flat, as shown at 14, and fits closely against the flat base of the projectile core, the sabot surface 14 and the adjacent core surface being disposed in a plane normal to the core axis. A hollow boss 15 projects forward-1y from the front faceof sabot 13 into an annular space 13a between the core 1% and bourrelet, and surrounds the fiat surface 14 of the sabot, the boss being preferably integral with the sabot. The inner surface of the boss 15 is tapered toward the flat face 14, as shown at 16, whereby the abruptly tapered portion 11 of the core is closely received in the. boss. However, a slight clearance is provided between thetapered side wall 16 of boss 15 and said abruptly tapered portion 11 of the core, providing an oversize socket for a purpose to be described presently. The sabot 13 extends radially outwardly beyond the boss 15 to provide a shoulder, the front face 17 of which is flat and lies in the same plane as the sabot face 14. At its central portion, the sabot has an opening 18 extending through the sabot for the passage of powder gases from a tracer charge (not shown) in the rear end portion of the core.

A unitary substantially full caliber sleeve-like bourrelet 20 is fitted closely around the intermediate tapered portion 1% of the projectile core, the inner surface of the sleeve being tapered to complement the taper 10b. Near its rear end, the bourrelet 20 has an internal shoulder 21 engaging the front end of the sabot boss 15. To the rear of the shoulder 21, the bourrelet is fitted closely around the external cylindrical surface of boss 15, the rear end of the bourrelet being seated against the front face 17 of the sabot shoulder.

The sabot 13 is externally grooved on its cylindrical surface, as shown at 23. A turning band 24, which may be made of annealed copper, is press-fitted on the grooved portion 23 and bears against the rear end of bourrelet 20. The band 24 has an external diameter somewhat greater than that of the cylindrical sleeve 20, so that the band is adapted to be engraved by the usual rifling in the gun barrel to impart rotation to the projectile. The turning band may be screwed instead of press-fitted on the sabot, in which case it will be understood that the thread is in such a directionthat rotation of the turning band 24 by the rifling acts to tighten the band on the sabot. The components 13, 2t and the turning band 24 comprise what .is conveniently termed a sabot assembly which, as later appears, is adapted to he slid from the core in one piece.

The operation of the projectile is as follows:

When the projectile is fired from a gun, the pressure of the powder propellant acts upon the relatively large area of the sabot 13 and turning band 24. As the projectile moves along the gun barrel, the force of setback on the upon it by the sabot 13 and bourrelet 20.

An important feature of the present invention is the relatively sharp taper 11 at the extreme rear end portion of the core and in the sabot boss 15. In this conneotion, it has been found that in prior projectiles having a conventional cup-type sabot, the latter cannot be made to release from the core without seriously disturbing the flight of the core, this disturbance being manifested by the core tumbling in flight. The P ecise reason for such disturbance is not clear. However, I have found that by abruptly tapering the extreme rear end portion of the core where it fits into the oversize socket of the sabot boss, a clean break occurs between the core and sabot assembly whereby this disturbance at release may be avoided. The release is further facilitated by the slight taper betweenthe core and bourrelet. As soon as the sabot and bourrelet start to slide back, the core is pletely free of the surrounding structures.

With the tapered fit between the core and the sabot boss, it is essential that the core be prevented from wedging into the tapered portion of the boss under setback incident to acceleration of the projectile, because any such wedging action would interfere with the release of the sabot and bourrelet from the core when the projectile emerges from the gun muzzle. In the new projectile, wedging of the core in the sabot boss is prevented because of the clearance maintained between the core and the tapered portion of the boss by engagement of the flat base of the bore with the surface 14 of the sabot. Thus, the bearing surface during setback is on the base of the core and not on its tapered portion 11.

It will be understood that the torque incident to rotation of the turning band 24 by the gun rifling is transmitted to the core principally through the sabot 13 but to some extent through the bourrelet also. In this connection, the force of setback of the core against the sabot face 14 due to acceleration of the projectile increases the pressure and therefore the friction between the sabot and core, whereby the torque transmission is facilitated. Also, the setback force of the bourrelet 20 on the sabot increases the pressure and friction between these parts so that the bourrelet is better adapted to transmit torque from the turning band and sabot to the core comwithout lost motion. It will be noted that the sabot and bourrelet are released as one piece. This piece follows the same trajectory as the core at first, but due to unfavorable aerodynamic shape the range is less. In many subcaliber constructions the disoardable portions are released centrifugally, the fragments causing a hazard to personnel in front of the gun. Since the discardable portion in the present invention is in one piece which goes in the same direction as the core, this hazard is reduced to a minimum.

I claim:'

A subcaliber projectile comprising, a subcaliber core having an ogive at one end thereof and being inwardly tapered slightly from said ogive towards the other end thereof, said other end of said core having an abruptly tapered terminal portion and a base normal to the axis of said core, a sabot assembly mounted on the core, said assembly comprising a full caliber, open-ended, internally tapered bourrelet fitted closely around the core with its forward end terminating adjacent the rear of said ogive, the rearward end of said bourrelet terminating approximately in the plane of the base of said core and having an internal annular recess, the axial length of said recess being substantially the same as the axial length of said abruptly tapered terminal portion, and a sabot having a boss fitted tightly in said recess and having surfaces firm- 1y abutting the end of the bourrelet and the base of the core, said boss having a tapered socket receiving said abruptly tapered terminal portion of said core, said tapered socket having cross-sectional dimensions larger than the cross-sectional dimensions of said abruptly tapered terminal portion of said core, thereby providing a clearance between said socket and said terminal portion; whereby the core is prevented from wedging into the tapered portions of the sabot assembly under setback incident to acceleration of the projectile, and a clean break between the sabot assembly and the core of the projectile is assured upon firing of the projectileunder reverse setback incident to aerodynamic drag on the sabot assembly.

References Cited in the file of this patent UNITED STATES PATENTS 29,272 Hotchkiss July 24, 1860 1,973,604 Brandt Sept. 11, 1934 2,306,140 Reed Dec. 22, 1942 FOREIGN PATENTS 496,879 France Aug. 20, 1919 131,034 Great Britain Aug. 21, 1919 812,680 France Feb. 8, 1937