Explosively driven impactor grenade

STATEMENT OF GOVERNMENT INTEREST

The invention described herein may be manufactured and used by or for the Government of the United States of America for government purposes without the payment of any royalties therefor.

BACKGROUND OF THE INVENTION

The invention relates in general to grenade type munitions and in particular to a grenade type munition comprising Explosively Driven Impactors (EDIs).

A need exists for a biological and chemical agent defeat warhead. The warhead would enable the attack of chemical and biological agents located within semi-hardened or hardened storage and manufacturing facilities. The warhead would be delivered by a precision air, ship or submarine weapon system, with minimum collateral damage to the surrounding area. To destroy biological and chemical agents, the agents must first be released from their containers. The EDI grenades are designed to rupture containers to release the chemical and/or biological agent contents with minimal collateral damage due to low overpressure from the grenades. Once the agents are released, the Agent Defeat High Temperature Thermal Radiator (HTTR) payload will destroy the agents. The EDI grenade can also be used by individual soldiers as a hand grenade.

The EDI grenades for agent defeat application are thermally fuzed to operate when a pre-determined room temperature is reached. The thermal fuzing is required for agent defeat application because to minimize collateral damage, the room temperature needs to be high enough to create a lethal environment for biological agents before the agent containers are ruptured. The EDI grenades can be alternatively fuzed for other applications such as for anti-personnel. Other fuzing methods for an EDI grenade include time delay, pressure sensing and impact fuzing.

If existing grenades such as the M67, M61 or MK3A2 were used for agent defeat application, the collateral damage would be much higher due to its greater over-pressure characteristic. These hand grenades do not have the penetration capability of an EDI grenade.

The invention will be better understood, and further objects, features, and advantages thereof will become more apparent from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily to scale, like or corresponding parts are denoted by like or corresponding reference numerals.

FIG. 1

is a perspective view of a one embodiment of a grenade body.

FIG. 2

is a perspective view of a second embodiment of a grenade body.

FIG. 3A

schematically shows a fuze and

FIG. 3B

shows a fuze cap.

FIG. 4

is a side view of an explosively driven impactor.

FIG. 4A

is a sectional view of a cup for housing an explosively driven impactor.

FIG. 5

shows a retaining ring.

FIG. 5A

shows a gasket.

FIG. 6

schematically shows a fuze and a booster charge.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The purpose of the Explosively Driven Impactors (EDI) grenade is to cause damage to equipment, storage containers, and personnel. In one scenario, the EDI grenade ruptures containers filled with biological or chemical agents with minimal collateral damage effects due to its low overall overpressure output. The EDI grenade is unique because of the use of EDIs. This application of EDI technology inflicts multi-directional damage, possesses greater penetration capability than existing hand grenades and eliminates the need for a self-righting mechanism.

The EDI grenade includes a grenade body having a substantially spherical shape. For the purposes of this patent, a substantially spherical shape includes spherical, flattened spherical and geodesic shapes. The importance of the substantially spherical shape of the grenade body is that it allows the EDI grenade to be multi-directional no matter how it finally comes to rest. In this regard, a self-righting mechanism is not required. For example, in agent defeat applications, the EDI grenade can affect storage containers regardless if it lands next to or on top of a container and regardless of its landing orientation. The grenade body material may be metallic (steel, aluminum, etc.) or plastic. The diameter of the grenade body may vary from, for example, two inches to thirty-six inches.

FIG. 1

is a perspective view of a one embodiment of a grenade body

10

. Grenade body

10

has a geodesic shape. Grenade body

10

includes a hollow central portion

12

for receiving a fuze. The exterior surface of the body

10

includes a plurality of recesses

14

formed thereon for receiving the EDIs. Each recess

14

includes an opening

16

into the hollow central portion

12

of the grenade body

10

to allow deflagration cord to connect the EDIs with the fuze. The grenade body

10

also includes an opening

18

on the exterior surface for insertion of the fuze. The opening

18

connects with the hollow central portion

12

FIG. 2

is a perspective view of a second embodiment of a grenade body

20

. Grenade body

20

has a flattened spherical shape. Grenade body

20

includes a hollow central portion

22

for receiving a fuze. The exterior surface of the body

20

includes a plurality of recesses

24

formed thereon for receiving the EDIs. Each recess

24

includes an opening

26

into the hollow central portion

22

of the grenade body

20

to allow deflagration cord to connect the EDIs with the fuze. The grenade body

20

also includes an opening

28

on the exterior surface for insertion of the fuze. The opening

28

connects with the hollow central portion

22

.

FIG. 3A

schematically shows a fuze

30

. Fuze

30

is disposed in the hollow central portion

12

of the grenade body

10

or the hollow central portion

22

of the grenade body

20

. The EDI grenade contains a single fuze

30

. Fuzing methods include thermal, time delay, pressure sensing and impact, depending upon the application. The EDIs (

FIG. 4

) are all connected to this common fuze

30

so that the EDIs will all initiate at the same time.

FIG. 3B

shows a fuze cap

32

for closing the openings

18

,

28

on the exterior surface that connects with the hollow central portions

12

,

22

. The fuze cap

32

may include threads

34

that mate with threads on the interior of openings

18

,

28

.

FIG. 4

is a side view of an explosively driven impactor (EDI)

40

. EDI

40

includes a circular metal disk

42

, a backing layer

44

, high explosive

46

, an ignition device

48

and deflagration cord

50

. The EDI

40

fits in the recesses

14

,

24

in the grenade bodies

10

,

20

with the circular metal disk

42

facing outward. The deflagration cord

50

is fed through the openings

16

,

26

in the recesses

14

,

24

. All the cords

50

are joined together and then attached to fuze

30

so that all the EDIs will actuate at the same time.

Circular metal plate

42

is preferably concave on its side

52

, that is, the side that faces away from the grenade body. The internal side of plate

42

is preferably convex. A preferred metal for plate

42

is copper. The thickness of plate

42

is, for example, from about 0.07 inches to about 0.125 inches. The plate thickness depends on the plate diameter and the target thickness desired to be penetrated. The plate

42

is pressed formed into its curved shape. Copper is easily formed into different shapes. The recesses

14

,

24

are deep enough so that the EDIs

40

do not extend further outward than the adjacent exterior surface of the body

10

,

20

.

Behind plate

42

is a backing layer

44

comprising an elastomer such as solid rubber (i.e., not foam rubber). The backing layer

44

is attached to plate

42

with adhesive. The high explosive

46

may be molded into shape or pressed into recesses

14

,

24

. If the explosive

46

is molded, it is adhered into the recesses

14

,

24

with an adhesive compatible with the explosive

46

. The explosive

46

is preferably a Class 1.1 High explosive such as C4 or HMX. The plates

42

with backing layer

44

attached are dropped into the recesses

14

,

24

on top of the explosive

46

. Plate

42

is secured with a retaining ring

60

(See FIG.

5

). There is a groove

62

along the circumference of each recess

24

(See

FIG. 2

) to accept the retaining ring

60

. The backing layer

44

is slightly compressed during the retaining ring installation to take up any volume between the backing layer

44

and the explosive

46

.

Prior to installing the explosive

46

and plate

42

, an ignition device

48

is installed into each recess

14

,

24

. The ignition device

48

has a small amount of energetic material, such as Boron Potassium Nitrate, in a metallic housing to initiate the explosive

46

. Deflagration cords

50

are attached to each ignition device

48

. After the ignition devices

48

are all installed and the deflagrating cords

50

are fed out of each recess

14

,

24

and into the fuze hole

12

,

22

, the explosives

46

and plates

42

are installed. After the explosives and plates are installed the deflagrating cords

50

are connected together and joined to a single fuze

30

. The fuze is then installed into by way of opening

18

,

28

into the hollow central portion or fuze hole

12

,

22

. A fuze cap

32

is preferably threaded to cover the opening

18

,

28

. If a time delay fuze is used (such as those used in hand grenades) there will be a pull pin through the cap

32

. When the pull pin is pulled, the fuze is activated.

The metal plates

42

undergo a controlled acceleration when the explosive

46

is initiated. The EDI performance characteristics are tailored to meet the required flight distance and target strength. The EDIs

40

are substantially evenly patterned on the grenade body surface. The EDIs

40

are simultaneously initiated when the fuze

30

senses a specific environmental temperature (if the fuze is a thermal fuze). In the agent defeat application, the EDIs are initiated by a thermal fuze when the HTTR reaction drives the temperature in the target area to 250-500° F. Dependent upon the target penetration requirement, the weight ratio of plate

42

to high explosive

46

can be less or greater than one to two.

The grenade disperses the EDIs

40

in multiple directions at a variety of target configurations and at a large velocity range. During dispersal, the grenade can interact with a variety of stationary objects. The body structure is designed to withstand high acceleration loads and high velocity impacts. The orientation of the grenade can vary depending on launch/dispersal velocities and impact angles. Therefore, the grenade body contour is designed with a self-righting shape. At rest, the grenade will position itself in a predefined orientation. This orientation will aim a predefined number of EDIs

40

in a repeatable direction with respect to the ground surface.

Upon detonation, the plates

42

are dispersed at velocities great enough to create holes in metal targets such as steel containers. The penetration ability of even a small EDI is substantial. For example, a 2-inch diameter EDI can create a hole in 1-inch thick armor plate. The size of the EDI grenade will depend upon the size of the EDI utilized. The EDIs employed in the grenade have greater penetration capability against armored targets than existing hand thrown grenades such as the anti-personnel M67 and M61 hand grenades. Depending upon the size of the individual EDI, the EDI can penetrate several inches of metal armor.

Some advantages of the EDI grenade include:

1) Incorporating a number of EDIs into a single grenade to effect a much greater level of damage against equipment and personnel than a single EDI.

2) Minimal collateral damage effects to the surrounding area due to the low-overpressure characteristic of the EDI grenade. For example, if the target were a container filled with weaponized Anthrax spores, the lower-overpressure generated by the EDI grenade would minimize dispersal of the Anthrax spores. This is due to the smaller amount of high explosives required for the EDI operation than that required for hand grenades of comparable size.

3) The EDI grenade is multi-directional. A self-righting mechanism is not required. For example, in agent defeat applications, the EDI grenade can affect storage containers regardless if it lands next to or on top of a container and regardless of its landing orientation.

In an alternative embodiment of the invention, each explosively driven impactor comprises a metal plate

42

, a backing layer

44

and an explosive

46

. The explosive

46

, backing layer

44

and metal plate

42

are contained in a metal housing

68

in the shape of a cup (FIG.

4

A). The metal housing

68

is open at the top so that the metal plate

42

is free to launch. The metal housing

68

is made of, for example, aluminum having a thickness of about 0.02 inches. The ignition devices

48

are not used in this embodiment.

The explosive

46

, backing layer

44

and metal plate

42

are placed in housings

68

. Housings

68

are then placed in recesses

14

,

24

. An elastomeric gasket

64

(

FIG. 5A

) is placed atop the housing

62

. The retaining ring

60

is then placed in groove

62

. The elastomeric gasket

64

between the top of housing

68

and retaining ring

60

takes up any assembly gaps and compensates for thermal dimensional changes.

In this alternative embodiment, a booster charge

66

(

FIG. 6

) is placed in the hollow central portions

12

,

22

of the body

10

,

20

, along with fuze

30

. Fuze

30

initiates booster charge

66

which initiates the explosive

46

in the individual EDIs. A physical connection (deflagration cord) between the booster charge

66

and the explosive

46

is not needed, but may be used if desired. The booster charge

66

is near enough to explosive

46

to initiate explosive

46

without deflagration cord. Booster charge

66

comprises, for example, a high explosive.

While the invention has been described with reference to certain preferred embodiments, numerous changes, alterations and modifications to the described embodiments are possible without departing from the spirit and scope of the invention as defined in the appended claims, and equivalents thereof.