US2939395A - Sabot for high velocity projectile - Google Patents

Description

June 7, 1960 l. R. BARR 2,939,395

SABOT FOR HIGH VELOCITY PROJECTILE Filed July 22, 1954 IN VEN TOR.

IRWIN R. BARR BY qwym SABOT FOR HIGH VELOCITY PROJECTILE Irwin R. Barr, Kingsville, Md., assignor to Aircraft Armaments, Inc., Baltimore, Md., a corporation of Maryland Filed July 22, 1954, Ser. No. 445,053

6 Claims. (Cl. 102-93) This invention relates to sabots used for producing high muzzle velocities in projectiles, and more particularly to a sabot adapted to grip the projectile during the travel through the gun barrel so that it is not necessary to provide means to fasten the sabot to the projectile, thus providing a clean aerodynamic surface when the sabot is removed after the projectile leaves the gun barrel.

It is well known that the velocity imparted to a projectile in a gun barrel may be increased by providing an annular collar, usually known as a sabot, to increase the area on which the propelling pressure acts in order to increase the total propelling force.

Since it is desirable to make the diameter of a projectile small with relation to its mass in order to increase its penetrating characteristics, the total propelling force acting on the rear of such a projectile may be quite small. To increase the total propelling force without a corresponding increase in total mass, it is well known to add a relatively light weight sabot to the projectile to increase the area on which the propelling force acts. To fasten the sabot to the projectile it has previously been found necessary to provide means such as threads, annular grooves, lugs, or other devices on the projectile and on the sabot. Such fastening means, however, constitute discontinuities in the aerodynamic surface of the projectile and may, especially where fins are utilized to stabilize or rotate the projectile in flight, cause difliculties of an aerodynamic nature. In addition, especially in large size projectiles, threads, slots, lugs, and like add to the cost of manufacture,

The present invention} contemplates a sabot which will utilize the pressure in the gun barrel to develop a force tending to constrict the sabot around the projectile so that the frictional force between the sabot and the surface of the projectile is suflicient to prevent relative motion between the sabot and the projectile while in the gun barrel, such force disappearing after the projectile has left the gun, so that the sabot is effective in imparting added velocity to the projectile and may be easily removed by suitable means once the projectile has left the gun barrel. Such a sabot is easy to manufacture, simple to install on the projectile, inexpensive, and effective in producing high projectile velocities. In addition, it allows the use of light materials such as plastics and other non-metals, greatly decreasing the total mass of the projectile and sabot, and hence increasing the acceleration imparted to the missile by the propelling charge.

It is the object of this invention, therefore, to provide a sabot for a high velocity projectile which requires no means carried by the projectile for fastening the sabot to the projectile.

'It is another object of this invention to provide a simple and economical sabot especially adapted for use with projectiles having a large mass and small diameter.

It is a further object of this invention to provide a sabot which utilizes the propelling pressure in the gun 2,939,395 Patented June 7, 1960 ice barrel to develop frictional forces for holding the sabot and projectile together while in the gun barrel.

These and further objects of this invention will become apparent from the following description and the accompanying drawings.

In the drawing: 7 v

Fig. 1 is a cross sectional view showing a missile and a sabot of the type contemplated by this invention contained within a gun barrel. 7

Fig. 2 is a perspective view of one embodiment of the sabot contemplated by this invention.

Fig. 3 is a perspective view of a second embodiment of a sabot of the type contemplated by this invention.

In Fig. 1 there is shown a typical combination of a high velocity projectile and a sabot of the type contemplated by this invention. The projectile 2 is of the type which is made long with respect to its cross sectional area to increase its mass and give it increased penetrating characteristics for any given velocity. Although the sabot herein disclosed is especially adaptable for use with this type of projectile, it is to be understood that the sabot may be used with any other type of projectile in order to increase its velocity and range.

As is shown in Figs. land 2, the sabot 1 includes an opening 8 extending longitudinally therethrough for receiving the projectile Z. Projectile 2 is of uniform crosssection and has its longitudinal axis coincidentwith the axis of the bore of gun 3. A front cylindrical portion 4 of the sabot is adapted to fit the bore of the gun 3 so as to prevent leakage of the propelling gases past the sabot when the gun is fired, and serves to keep the projectile 2 axially aligned with the bore of the gun during the travel of the projectile therethrough. The rearward portion of the sabot, in the form shown in Figs. 1 and 2, is tapered from the cylindrical portion 4 rearwardly to the end thereof to form a conical pressure surface 5 on which the propelling gases act. ing, conical pressure surface 5 is a surface of revolution.

erated is coincident with the axis of the bore of gun 3.

The total force acting on the pressure surface 5 may be considered to have two components, one acting parallel to the longitudinal axis of the gun barrel and serving to propel the sabot 1 through the gun barrel, and a second component acting normal to the longitudinal axis aforementioned and circumferentially around the pressure surface 5, thereby tending to constrict the after portion of the sabot and causing it to grip tightly the projectile 2, developing a frictional force between the sabot and the projectile suflicient to prevent relative motion therebetween while each is being propelled through the gun barrel by the propelling gases.

The after portionof the sabot may be made as long as necessary to increase the total frictional force developed. In practice it has been found that the form shown in Figs. 1 and 2 is most suitable for use with sabots fabricated from non-metallic materials such as the various plastics, fiberglass, and the like. It should be noted that the exact configuration of the pressure surface 5 is not controlling, and any shape which will provide the necessary constricting force may be used. For some applications, sabots made of metallic material may be desirable, and the form shown in Fig. 3 has been found to be more suitable for this purpose. Because of the increased stiffness of metal over plastics, in order to develop the required frictional forces between the sabot'and the projectile, longitudinal slits 6, as shown in Fig. 3, are formed in the after portion 5 of the sabot. To prevent escape. of the propelling gases through the slits and along the projectile, the slits may be filled with a suitable resilient non-metallic material 7 which can be compressed to allow the gas pressure As can be seen from the drawtion, a large diameter light weight sabot may be combined with a small diameter aerodynamically smooth: high mass projectile, providing a method for the produc tion of high velocities in such missiles by use of an inexpensive, lightand simple sabot, withoutthe necessity for modifying the projectile to provide'means to fasten the sabot and the projectile together. The sabot contemplated by this invention is adaptable for use with projectiles of all sizes, being particularly suitable for use with armor piercing projectiles and with high velocity, low caliber anti-personnel projectiles.

It is to be understood that this invention is not limited to the particular arrangements shown and described, and that many modifications may be made without departing from the scope of the invention as set forth in the appended claims.

I claim: a V

1. In combination, a sabot of constrictable material adapted to be propelled along the axis of a gun bore, said sabot having a cylindrical front portion adapted to slideab ly engage the bore to prevent leakage of propellent gases past the sabot when the gun is fired, said sabot having a rear portion tapered from the cylindrical front portion rearwardly to the rear end thereof, said rear end being of a diameter smaller than the diameter of the cylindrical front portion, said rear portion forming a generally conical pressure surface upon which the propellent gases are adapted to act to propel the sabot along the axis of the bore, said sabot having a cylindrical aperture therein extending axially through at least said rear portion, and a cylindrical projectile of substantially the same diameter as the aperture engaged therein, said rear portion adapted to be constricted by the action of the propellent gases on the conical pressure surface and caused by such action to tightly grip said projectile and develop a frictional force between the sabot and projectile suflicient to prevent inertial forces from causing relative axial motion therebetween while the sabot and projectile are propelled in the bore by said gases.

2. The combination of claim 1 wherein said projectile has a tail portion which projects rearwardly beyond the rear end of the rear portion of the-sabot, and said tail portion has stabilizing fins attached thereto.

. 3. The combination of claim 1 wherein the rear portion of said sabot has a plurality of axially extending slits which connect the conical pressure surface to said cylindrical aperture.

"4. Ammunition of the type'described comprising an elongated projectile of substantially uniform cross-section, the longitudinal axis of said projectile being aligned with the axis of a gun bore through which the projectile is adapted to be propelled, and a sabot for pulling the I projectile through the bore, said sabot having a cylindrical front portion adapted to slideably engage the walls of the bore, said sabot having a constrictable rear portion engaged around the projectile, said rear portion being tapered from the cylindrical front portion to the rear end of said rear portion with said rear end being of a diameter smaller than that of the cylindrical front portion thus forming a generally conical pressure surface on said sabot adapted to be acted upon by propellent gases, said rear portion adapted to be constricted around the projectile by the action of the propellent gases on said pressure surface for tightly gripping the projectile and developing a frictional force between the rear portion and the projectile sufficient to prevent relative axial motion there between as the sabot and projectile are propelled through the bore by the propellent gases.

rected which cause the sabot to be propelled through the bore and radial components directed toward said internal surface which cause the internal surface to be radially constricted, and a projectile having an outer surface engaged with the internal surface of said rear portion, the action of the propellent gases upon the external surface of the rear portion causing its internal surface to be radially constricted upon the outer surface of the projectile sufficiently to develop therebetween, a frictional force large enough to prevent inertial forces from causing relative axial movement between the sabot and projectile as the propellent gases act upon the sabot and projectile in the bore, whereby the sabot and projectile are propelled as a unit in the bore.

6. Ammunition of the type described comprising an elongated projectile of substantially uniform cross-section, the longitudinal axis of said projectile being aligned with the axis of a gun bore through which the projectile is adapted to be propelled, and a sabot for pulling the projectile through the bore, said sabot having a cylindrical- References Cited in the file of this patent UNITED STATES PATENTS 37,979 Roberts Mar. 24, 1863 39,180 Stafford July 7, 1863 104,884 Reinshagen June 28, 1870 110,590- Reinshagen Dec. 27, 1870 2,480,927 Hopkins Sept. 6, 1949 2,820,412 Beeuwkes Jan. 21, 1958 FOREIGN PATENTS 66,446 Denmark Mar. 15, 1948

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