SSRsi Disclaimer & Note on Text:
This text was found on the internet. While it IS a US Patent item, the veracity of the information is unknown - and therefore suspect.

SSRsi does not advocate the home preparation of any form of propellant, explosive, or other pyrotechnics or devices. Attempting to do so without specialized training, equipment and facilities will almost certainly result in serious injury to persons and property.

Explosives, pyrotechnics  and propellants or devices are generally regulated by law and their manufacture is usually frowned upon (if not outright prohibited) by law enforcement.

This text is presented by SSRsi for information purposes only.

Do not attempt to duplicate the processes described herein.

United States Patent 4,493,260
Foster January 15, 1985

Annular shaped charge for breaching masonry walls

Abstract
A shaped charge and method of breaching reinforced masonry walls is disced. The shaped charge includes an 
annular liner located centrally between the ends of a cylindrical container filled with explosive. The device is placed 
in a pilot hole in the wall and is detonated simultaneously at the ends. The charge creates an annular radially
expanding jet of explosive gases and fragments directed into the wall providing a man size opening therein.

Inventors: Foster; John S. (Richmond, VA)
Assignee: The United States of America as represented by the Secretary of the Navy (Washington, DC)
Appl. No.: 549841
Filed: November 8, 1983
Current U.S. Class: 102/307; 102/308; 102/476
Intern'l Class: F42B 001/02
Field of Search: 102/306,307,308,309,310,476

					References Cited [Referenced By]
						U.S. Patent Documents
2839997 	Jun., 1958 	Church et al. 	102/307.
3191533 	Jun., 1955 	Hopson 		102/306.
3244102 	Apr., 1966 	Wofford et al. 	102/307.
3404600 	Oct., 1968 	Bilek 		102/306.
3837279 	Sep., 1974 	Cooke, Jr. 	102/24.
4063509 	Dec., 1977 	Leonard et al. 	102/310.
4184430 	Jan., 1980 	Mock 		102/307.
4348955 	Sep., 1983 	Rowley et al. 	102/317.
4418622 	Dec., 1983 	Foster et al. 	102/307.

						Foreign Patent Documents
113685 	Aug., 1941 	AU 		102/476.
1728461 	Jan., 1973 	DE 		102/476.
2533585 	Feb., 1977 	DE 		102/476.
2287027 	Jun., 1976 	FR 		102/476.
205750 	Feb., 1968 	SU 		102/306.
Primary Examiner: Nelson; Peter A.
Attorney, Agent or Firm: Beers; Robert F., Walden; Kenneth E., Wein; Frederick A.

						Claims
What is claimed is:

	1. A device for breaching masonry walls comprising:

	a symmetrical container for insertion into a pilot hole in the wall having a first cylindrical
	cavity portion disposed at one end, a second cylindrical cavity portion disposed at a
	second end, and a third cavity portion disposed midway between said first and second
	cavity portions the shape of the third cavity portion being defined by an annular concave
	portion of said container extending into said third cavity portion and defining a shaped
	charge liner adapted to collapse, invert, fragment, and create a jet of annular radially
	expandable fragments and explosive gases;

	an explosive filling said cavity portions presenting two exposed surfaces at the first and
	second cavity portions for generating the explosive gases and a force for collapsing,
	inverting, and fragmenting the concave shaped charge liner; and, simultaneous detonation
	means associated with the explosive surfaces for simultaneous initiating detonation of
	said explosive in the first and second cavity portions.

	2. The device as defined in claim 1 wherein the concave shaped charge liner portion is an
	annular hemispherial shape section of the container located midway between the first and
	second cavity portions.

	3. A device for breaching masonry walls comprising: a hollow case for placement in a
	pilot hole in an external structure, an explosive disposed within said case for generating
	explosive gases, said explosive including two opposed portions and means associated
	with said opposed portions for simultaneously initiating detonation of said explosive of
	said portions, and

	means associated with said case for generating an annular radially expanding jet of
	explosive gases and case fragments directed into the external structure, said means
	comprising an annular concave portion disposed midway along the length of the case and
	extending radially inward of the case, the concave portion defining an annular shaped
	charge liner adapted to collapse, invert. fragment and form the annular radially expending
	jet.

	4. The device as defined in claim 3 wherein the concave portion is hemispherical in shape.

						Description

BACKGROUND OF THE INVENTION
This invention relates to shaped charges, and more particularly to a shaped charge and method for breaching 
reinforced masonry construction.

In the demolition of masonry structures, and in particular the breaching of reinforced concrete walls, sufficient for 
persons to pass through, large quantities of bulk explosives have been required. For example, to breach a two foot 
thick reinforced concrete wall, so that a person could pass through the hole created, a minimum of 28 pounds of 
bulk explosive placed next to the wall is required. Such large quantities of explosive in bulk form are dangerous and 
time consuming to handle. Special precautions must be taken to protect personnel and special containers and 
material handling equipment is required to transport such explosives.

Also bulk explosive must be placed next to the wall at the location where it is to be breached, which makes it difficult, 
if not impossible, to penetrate the wall at locations off the ground. When bulk explosives are detonated next to a 
wall, a substantial portion of the explosive force is directed away from the wall and is not utilized to penetrate the
structure. This is dangerous to surrounding structures and personnel and is a highly inefficient use of the explosive.

It can be appreciated that bulk explosives are inefficient means for breaching concrete structures and there is a 
need for a small, lightweight, relatively safe and powerful device for breaching such structures. Ideally the device 
would be capable of providing man size openings in the structure.

SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide for an explosive device capable of breaching reinforced 
masonry construction.

Another object of the invention is to provide for an explosive device for breaching reinforced concrete walls that 
expends substantially all of its explosive energy in breaching the wall.

A further object of the invention is to provide for an explosive device for breaching reinforced concrete walls that 
does not require the use of bulk explosives.

Another object of the invention is to provide for an explosive device that is capable of making man size openings in 
reinforced concrete walls.

A still further object of the invention is to provide for an explosive device for breaching concrete structures that is 
easily handled by personnel.

And, another object of the invention is to provide for an explosive device for breaching concrete walls that reduces 
the risk of injury to personnel and surrounding structures. The objects of the invention are achieved and the 
shortcomings of the prior art are overcome by utilizing the principles of shaped charges by providing for a shaped 
charge device having a hemispherical annular shaped liner centrally located between the ends of the device. The 
device is filled with an explosive. The device is positioned within a pilot hole in the wall to be breached and the 
opposing ends are simultaneously detonated causing the annular liner to collapse creating an annular jet directed 
Radially outward into the wall.

BRIEF DESCRIPTION OF THE DRAWINGS
	FIG. 1 is a pictorial representation of the preferred embodiment of the invention.
	FIG. 2 is a vertical longitudinal cross-sectional view of the preferred embodiment
	showing details of construction.
	FIG. 3 is a front pictorial view showing graphically the preferred embodiment in use
	breaching a wall.
	FIG. 4 is a horizontal longitudinal cross-sectional view of the wall of FIG. 3 showing
	graphically the preferred embodiment in use.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Shown in FIG. 1 is an hourglass shaped charged 10. The shaped charge includes an outer case 12 having a first 
cavity portion 14 on one end and a second cavity portion 16 on an opposing second end. Cavities 14, 16 are 
interconnected by a third cavity portion 18 located coaxial there between. Third cavity 18 has a reduced radial 
dimension 19 centrally located there along, see FIG. 2, and a shape defined by an annular concave section of case
12 located equidistance from each end. The concave section defines a shaped charge liner 20. Liner 20 has a 
reduced cross-sectional thickness from the portions of case 12 that surround cavities 14, 16. Liner 20 is designed 
to collapse, invert, and form an expanding annular jet 22, see FIG. 4, when the device is detonated. Case 12 and 
liner 20 are preferably machined from a single piece of material capable of forming reactive jets, such as aluminum 
or zirconium; however, other acceptable liner and case materials include castable zinc aluminum alloys. Changing 
the liner shape and material changes the effect of the charge. For example, the hemispherical liner gives large 
mass-fraction in the jet, and an aluminum liner gives an increased energetic jet. Other acceptable shapes include V 
and parabolic shapes. Those skilled in shaped charges can readily adapt other shapes and materials having the 
benefit of the disclosure herein, e.g., truncated conical shaped cavities 14, 16, or a combination of cylindrical and 
conical.

Cavities 14, 16, 18 are filled with any well known explosive 17 used in shaped charges, e.g., those generally known 
as Composition B, HMX, Octol, RDX, or other cast loaded or press loaded explosives.

In use, the device is initiated simultaneously at the opposite ends by initiation means, not shown, and included 
preferably on the surfaces of the charge on each end. Shown in FIGS. 3 and 4 is a portion of a reinforced masonry 
wall 24 that is to be breached. In use, a pilot hole 26, is slightly larger than the diameter of charge 10 for providing 
enough clearance for jet formation. Pilot hole 26 is made in the wall at the location to be breached. The pilot hole is 
made by conventional means, such as an impacting shape charge or projectile. To breach an 8" thick double 
reinforced concrete wall providing a man sized hole, on the order of 2 square feet, the shaped charge of this 
invention only need be 8 inches in length, 3.5 inches in diameter at cavities 14, 16, provided with a hemispherical 
liner having a 2 inch diameter, and filled with approximately 2-3/4 pounds of one of the above mentioned explosives.
A 3-1/2 inch pilot hole is within the capabilities of present devices.

Charge 10 is placed within the pilot hole and the charge in cavity portions 14, 16, are simultaneously detonated with
the detonation waves travelling toward reduced section 19 into cavity portion 18 thus causing liner 20 to collapse, 
invert, and form an annular, radially expanding jet of liner material and further causing explosive gases 22 directed
into the wall interior, as shown in FIG. 4, to breach the wall.

Having described the preferred embodiment and its operation, those skilled in the field will readily be able to devise 
other embodiments and modifications having the benefit of said description in conjunction with the accompanying 
drawings Therefore said embodiments and modifications are to be considered within the scope of the appended
claims.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 

End of Text

Return to Self-Reliance>>Weapons>>Explosives page.

Please Read The Website Disclaimer!
Copyright 1986-2009, The Survival & Self-Reliance Studies Institute (SSRsi), All Rights Reserved
Site conceptualized, designed, created & maintained by MEG Raven
Snail Mail: SSRsi, PO Box 2572 Dillon, CO. 80435-2572