Title:
PROJECTILE WITH DIFFERENTIAL TANDEM SHAPED CHARGES
United States Patent 3750582


Abstract:
A projectile utilizing tandem shaped charges is produced, said projectile ving superior armor penetration power than previous shape charge projectiles. The invention described herein may be manufactured, used and licensed by or for the Government for govermental purposes without the payment to us of any royalties thereon.



Inventors:
Kintish, Irving L. (Rockaway, NJ)
Marcus, Irwin (Rockaway, NJ)
Application Number:
05/177736
Publication Date:
08/07/1973
Filing Date:
09/03/1971
Assignee:
ARMY,US
Primary Class:
International Classes:
F42B12/18; (IPC1-7): F42B13/10
Field of Search:
102/24HC,56
View Patent Images:
US Patent References:
3416449Tandem effect anti-tank projectile1968-12-17Brothers
3215074Apparatus for well drilling operations with explosives1965-11-02Robinson, Jr. et al.



Foreign References:
CH341743A
Primary Examiner:
Pendegrass, Verlin R.
Claims:
We claim

1. A projectile comprising:

2. The projectile of claim 1 wherein the distance between the disc and the liner of the rear charge is between 1 and 1.5 shape charge diameters.

3. The projectile of claim 1 wherein the disc is a material selected from the group consisting of steel, copper, alloys of steel, alloys of copper and reinforced fiberglass.

4. The projectile of claim 1, wherein the disc is provided with a plurality of openings therethrough in addition to said central aperture.

Description:
DESCRIPTION OF THE INVENTION

In the projectile explosive art it has been found that the armor piercing ability of a given quantity of explosive charge may be optimized by forming the forward portion of the charge with an appropriate configuration. Such charges are generally referred to as shaped charges, and their armor piercing effectiveness results from providing that shape in the front of the charge which affords the greatest directivity and concentration of explosive force in a localized area. A particularly effective configuration for such shaped charges is that obtained by forming a conical cavity or recess in the forward end of the charge and lining the cavity with some material e.g. copper.

When the end of the explosive charge opposite the liner is initiated, the detonation wave passes over the metal liner causing the liner to collapse upon itself. When the collapsing liner material reaches the axis of the system, it divides into two parts. A small part forms an extremely high-velocity jet and the other part forms a slower but more massive slug.

The high velocity jet is responsible for the relatively deep penetration achieved by the shaped charge. The tip of the jet attains a velocity of about 25,000 feet/sec. and the rear portions of the jet attain velocities of nearly 5,000 feet/sec. This velocity difference within the jet is a result of the physical characteristics of most shaped charges. At the apex of the cone, the ratio of the explosive charge to the liner mass is relatively large. However, as the detonation progresses down the liner, the mass of the liner increases while the amount of explosive available to move it decreases. The ratio goes to zero at the base of the liner because there is no explosive at the base. Therefore, the various portions of the liner reach the axis at progressively lower velocities and generate a jet having a velocity gradient along its length.

Because the jet impacts a target at such high velocities, an exceedingly high pressure is generated. Typically, this pressure is about 4 × 106 psi. The high pressure causes both the jet and the target to deform hydrodynamically. The jet moves the target material radially and flows with it. Penetration continues in this manner until the jet is used up or until the jet decreases to some critical value. Until our invention, penetration of armor by a high velocity jet was limited by the above mentioned forces to approximately 10-12 inches.

An important object of this invention is to increase the efficiency of shape charge projectiles by introducing a follow-through charge in the jet hole formed by the initial charge.

A further object of this invention is to increase the area of damage in a target by introducing a secondary explosive force through a jet hole made by the initial shape charge in the projectile.

Many other objects and many of the attendant advantages of this invention will be readily appreciated as the same become better understood by reference to the following detailed description.

The present invention involves the use of two shape charges in one projectile. The first shape charge upon initiation will form the aforementioned jet which proceeds through a small central hole in a perforated disc, said disc separating the two charges. The slower and later formed slug of the initial change will be impeded by the separating disc causing formation of a shock wave sufficient to detonate the second shape charge. The second shape charge is chosen from explosives having explosive velocities greater than those of the first shape charge such that the jet created by the second charge will precede the slower slug of the first charge and enhance the penetration caused by the jet of the first charge.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of such a tandem shape charge system.

FIG. 2 presents a frontal view of the perforated disc used to separate the charges.

DETAILED DESCRIPTION OF THE INVENTION

Referring now more particularly to the drawings, a projectile container 1 is shown in FIG. 1 and therein an initial shape charge 6 having a conical liner 7'. The projectile container may be made of a low carbon steel or other fragmentation metals. The shape charge 6 is preferably conical in shape although it may also be fluted. The metallic liner for the above shape charge may be any material designed to increase the depth of shape charge penetration e.g. copper, aluminum, antimony or alloys of the above and the liner configuration is chosen to conform to the particular shape charge used. A conical shape charge and liner with an angle of 42° is preferable.

The explosive for the shape charge may be any non-initiating high explosive known to the art such as aliphatic, aromatic and heterocyclic nitrates, nitro-compounds and nitramines, binary explosives (mixtures of 2,4,6 trinitrotoluene and a second explosive such as cyclotrimethylene trinitramine), and plastisol explosives such as PBX (90 percent cyclotrimethylene trinitramine, 8.5 percent polystyrene and 1.5 percent dioctylphthelate).

The disc 4 may be made of reinforced fiberglass or various metals such as steel, copper and alloys thereof. The disc is approximately 1/8 - 1/4 inches thick and is perforated as shown in FIG. 2. The free space 8 or aperture in the center of the disc is so calculated in size as to allow the jet, formed by the initial shape charge detonation, to pass through unhampered while retarding any slug formed by the initial shape charge and liner particles.

The initial shape charger 6 is positioned in the projectile such that the distance between 4 and 5 shown in FIG. 1 is about 1-1 1/2 cone diameters. This distance provides a sufficient stand-off between the initial shape charge and the projectile nose such that optimum effectiveness can be attained from the initial shape charge detonation.

Initiation of shape charge 6 is accomplished by initial detonating agents such as lead azide, mercury fulminate and diazodinitrophenol. These detonating agents are in turn initiated by piezoelectric or base fuzing techniques known to the art.

The secondary shape charge 3 and shape charge liner 7 may be conical, fluted or hemispherical (as shown in FIG. 1) in configuration. As in the initial shape charge system the liner material may be copper, aluminum, antimony, or alloys thereof. The shape charge explosive as in the initial shape charge may be an aliphatic, aromatic or heterocyclic nitrate, nitro compound, or nitramine, a binary explosive, or a plastic explosive provided that the explosive chosen must have a greater detonation rate than the explosive chosen for the initial charge and secondly that the explosive is susceptible to shock wave detonation.

The standoff distance between the secondary shape charge and the projectile nose is about 3-4 cone diameters. This distance will allow sufficient time for initiation and jet formation of the secondary charge. Initiation of the secondary charge is accomplished by the shock wave formed when the slug from the initial shape charge impacts with the disc which divides the two charges. The perforations in the disc as shown in FIG. 2 allow for extrusion of the slug such that a near planar shock wave is produced which will not cause excessive breakup of the secondary charge while initiating it.

The second charge when detonated will form a jet that will penetrate and enhance the perforation of the target already accomplished by the jet of the initial charge.

Thusly through the practice of our invention a projectile is produced which has greater perforation power and which is more efficient than previous shape charge projectiles.

We wish it to be understood that we do not desire to be limited to the exact detail of construction shown and described for obvious modification will occur to a person skilled in the art.