Patent Description:
Conventional launcher-fired <NUM> projectiles or grenades are designed with fragmenting bodies. For engagement in urban environment, low-velocity variants of these grenades are fired at shorter distances to breach doors, shutters, windows, gates, barricades and so on; desirably, these door-breaching projectiles are non-fragmenting, ie. generates little hazardous fragments or shrapnel upon explosion (both to the launcher and any occupants behind the door, shutter, window, etc.).

<CIT>, describes a <NUM> door breaching projectile, as shown in <FIG>. This projectile uses a forward extending stand-off device, which detonates an explosive charge before the nose of the projectile actually strikes the door. Thus, early detonation produces pressure waves against the door exterior which force the door to open inwardly. Shrapnel produced by the detonation of the projectile remains outside the door.

In another approach, <CIT>, describes another <NUM> door breaching projectile. This projectile is made of a composite housing, filled with an insensitive explosive and designed for point detonating (PD). In addition, <CIT> describes a <NUM> grenade round to breach doors without throwing a significant amount of shrapnel into a building's interior or back to the shooter. The grenade has a thrust column that forms a forward extension and is supported directly by the ogive. The thrust column bears on a set of hammer weights and a striker includes such hammer weights. Upon impact, an impact load is transmitted from the thrust column to the striker, which is located on a fuse assembly.

Despite development of the above projectiles, there is a need to provide a new type of <NUM> projectile for breaching doors and barricades in urban military or law enforcement.

The following presents a simplified summary to provide a basic understanding of the present invention. This summary is not an extensive overview of the invention, and is not intended to identify key features of the invention. Rather, it is to present some of the inventive concepts of this invention in a generalised form as a prelude to the detailed description that is to follow.

The present invention seeks to provide a new type of <NUM> projectile or grenade for breaching doors or barricades during urban law enforcement.

The invention provides a door breaching projectile according to claim <NUM>. The door breaching projectile comprising: a shell containing an explosive charge; a mouth at an open end of the shell being connected to a rear edge of a body member; a mouth of a hollow ogive being connected to a forward edge of the body member; a safe-and-arm mechanism disposed in the body member, which safe-and-arm mechanism delays alignment of a detonator pin with a detonator charge only after the door breaching projectile has been propelled over a safe distance from the launcher and has spin rotated through predetermined numbers of spin; and a plunger slidable in a seat member, which assembly is mounted on a forward face associated with the forward edge of the body member; so that, upon the door breaching projectile impacting on a door or barricade, the plunger is forced into the seat member to impinge onto the detonator pin, which then sets off the detonator charge and explosive charge, such that explosive shock waves cause the door/barricade to cave in but the projectile remains substantially outside the door/barricade.

Preferably, the door breaching projectile further comprises a sleeve. The sleeve is being received in the seat member so that the plunger is slidable inside the sleeve under influence of an impacting force.

Preferably, a leading end of the plunger contacts an inside surface of the ogive near a forward tip. It is also possible that the leading end of the plunger sits in a collar formed on the inside surface of the ogive. It is also possible that the leading end of the plunger sits inside a hollow guide member which is integrally formed to extend from an inside tip surface of the ogive. It is possible that the hollow guide member is dimensioned with outside and inside diameters that are substantially similar to respective outside and inside diameters of the sleeve, with the hollow guide member and sleeve being longitudinally aligned but dispenses with the plunger. In another possibility, the leading end of the plunger is formed with a mushroom head.

Preferably, the shell, body member, ogive, plunger and seat member are made from a polymer or polymers.

In another embodiment, the present invention provides a door breaching grenade. The door breaching grenade comprises the above projectile being coupled to a propulsion cartridge.

In yet another embodiment, the present invention provides a method for breaching a door/barricade from a distance. The method comprising: launching a projectile from a grenade launcher to impact on the door/barricade; after the projectile is armed, delay rotating a safe-and-arm mechanism so that a detonator charge is aligned with a detonator pin fitted in a seat member, which seat member is mounted on a forward face of a body member; and upon the projectile impacting on the door/barricade, causing impact force on the door/barricade to impinge on the detonator pin to set off both the detonator charge and an explosive charge disposed aft of the body member, so that explosive shock waves cause the door/barricade to cave in whilst the projectile remains substantially outside the door/barricade.

This invention will be described by way of non-limiting embodiments of the present invention, with reference to the accompanying drawings, in which:.

One or more specific and alternative embodiments of the present invention will now be described with reference to the attached drawings. It shall be apparent to one skilled in the art, however, that this invention may be practised without such specific details. Some of the details may not be described at length so as not to obscure the invention. For ease of reference, common reference numerals or series of numerals will be used throughout the figures when referring to the same or similar features common to the figures.

<FIG> shows a known <NUM> door breaching projectile <NUM>. This door breaching projectile <NUM> employs a forward extending contactor <NUM>, such that a detonator <NUM> is activated before the ogive <NUM> strikes a door or barricade <NUM>. As a result, an explosive charge <NUM> inside the door breaching projectile <NUM> is activated on an exterior of the door or barricade. Thus, the door <NUM> bears a substantial portion of the explosive forces, and any shrapnel created by the exploding breaching projectile remains substantially outside the door or barricade and any potential injury to occupants behind the door is limited.

<FIG> shows a breaching projectile 10a being propelled at an oblique angle at a door or barricade <NUM>, which is often the case in real life. In this non-point detonating impact, any forward extending contactor like the one described above would negate the purpose of providing the shaped ogive; hence, there is a need to provide another type of door breaching projectile and grenade.

<FIG> shows a door breaching grenade <NUM> according to an embodiment of the present invention. In the following description, the door breaching grenade <NUM> is made up of a projectile <NUM> coupled to a propulsion cartridge <NUM>. This door breaching grenade <NUM> differs from a conventional grenade in that: (<NUM>) the ogive portion is relatively longer or the head of the projectile is relatively longer; (<NUM>) the safe-and-arm mechanism is located forward of the booster or explosive charge in the projectile; (<NUM>) the projectile is substantially made from a polymer, which does not fragmentate into shrapnel; and (<NUM>) the safe-and-arm mechanism is tuned for relatively short fuzing.

As shown in <FIG>, the door breaching projectile <NUM> is made up of a shell <NUM>, a body member <NUM> and a hollow ogive <NUM>. An open end of the shell <NUM> is connected to a rear edge <NUM> of the body member <NUM>, whilst the hollow ogive <NUM> is connected to a forward edge <NUM> of the body member <NUM>. Housed inside the body member <NUM> is a safe-and-arm mechanism <NUM>, which allows the door breaching projectile <NUM> to be armed only after the projectile <NUM> has been propelled to a safe distance away from the launcher and has spin rotated a predetermined number of turns. A seat member <NUM> is mounted on a forward face 142a that is associated with the forward edge <NUM>. The seat member <NUM> has a centre hole <NUM>, which is coaxial with a longitudinal axis of the door breaching projectile <NUM>. The seat member <NUM> is shaped like a stool with a wide base seated in contact with the forward face 142a, as seen in <FIG>. Disposed coaxially in the centre hole <NUM> of the seat member <NUM> is a cylindrical sleeve <NUM>. A closed end of the sleeve <NUM> has a through-aperture <NUM>, through which is fitted a detonator pin <NUM>. The detonator pin <NUM> has a shoulder <NUM> and the shoulder <NUM> is located below the sleeve <NUM> such that the detonator pin <NUM> is slidable in a rearward direction with respect to the forward propulsion of the door breaching projectile <NUM>. One end of a plunger <NUM> is fitted inside the sleeve <NUM> such that there is an air gap between the plunger <NUM> and the detonator pin <NUM>, whilst the opposite end of the plunger <NUM> is in contact with an inside surface of the ogive <NUM> near the forward tip. The fit between the plunger <NUM> and the sleeve <NUM> allows sliding of the plunger <NUM>; to fix this non-activated position of the plunger <NUM> inside the sleeve <NUM>, a shoulder <NUM> is provided on the plunger <NUM>.

Now, referring again to <FIG>, a booster charge <NUM> is disposed at a rear face 141a associated with the rear edge <NUM> of the body member <NUM>, such that when the door breaching projectile <NUM> is armed, the detonator pin <NUM> is aligned with a detonator charge <NUM> mounted on the safe-and-arm mechanism <NUM>, and the detonator charge <NUM> is also aligned with the booster charge <NUM>. An inside cavity of the shell <NUM> rearward of the safe-and-arm mechanism <NUM> is filled and compacted with a predetermined amount of explosive charge <NUM>. In use, when the booster charge <NUM> is ignited by the detonator charge <NUM> as the door breaching projectile <NUM> impacts on an exterior of a door/barricade <NUM>, the explosive charge <NUM> is set off and shock waves from explosion of the explosive charge <NUM> force the door/barricade <NUM> to cave in, whilst the projectile <NUM> is still substantially outside the door/barricade. Further, as the shell <NUM>, body member <NUM>, ogive <NUM>, seat member <NUM>, sleeve <NUM> and plunger <NUM> are made from an engineering polymer or various types of polymers, this/these polymer(s) does/do not disintegrate into small pieces and there is substantially little shrapnel created by explosion of the explosive charge <NUM>. Further, as the safe-and-arm mechanism <NUM> is located forward of the explosive charge <NUM>, limited amounts of disintegrated parts, if any, from the safe-and-arm mechanism are thrown back in the direction of the launcher.

2B shows a door breaching grenade 100a according to another embodiment of the present invention. The door breaching grenade 100a shown in FIG. 2B is similar to that shown in <FIG> except that the sleeve is now integrally formed with the seat member <NUM> and the leading end of the plunger 166a is located in a collar <NUM> formed on the inside surface of the ogive <NUM>. The collar <NUM> is provided so that when the door breaching projectile 101a impacts onto a door/barricade <NUM> at an oblique angle, a component of the impact force at the ogive is transferred effectively to the plunger 166a and urges the plunger 166a to slide into the seat member <NUM>, thereby, to actuate the detonator pin <NUM> and to set off the detonator, booster and explosive charges.

<FIG> shows a door breaching grenade 100b according to another embodiment. An ogive <NUM> of the door breaching grenade 100b has a hollow guide member <NUM> which is integrally formed to extend from an inside tip surface of the ogive <NUM>; the hollow guide member <NUM> has a longitudinal axis that is co-axial with the longitudinal axis of the projectile 101b. Disposed inside the hollow guide member <NUM> is a plunger 166b; as in the above embodiment, a proximal end of the plunger 166b is disposed to slide in a sleeve <NUM>, with the sleeve <NUM> being located in a seat member <NUM>. As seen from <FIG>, an air gap is provided between the end of the plunger 166b and the detonator pin <NUM> for safe mechanical handling of the grenade 100b. The hollow guide member <NUM> allows a component of an oblique impact force at the ogive to transfer effectively along the plunger 166b to actuate the detonator pin <NUM>.

<FIG> shows a door breaching grenade 100c according to another embodiment of the present invention. The door breaching grenade 100c shown in <FIG> is a variation of the embodiment shown in <FIG>. As seen in <FIG>, the hollow guide member <NUM> is integrally molded to extend from an inside surface of the ogive <NUM> at the forward tip, with both outside and inside diameters substantially similar to those of the sleeve <NUM>. When assembled, the hollow guide member <NUM> is longitudinally aligned with the sleeve <NUM>, preferably with a small air gap in between. In another embodiment, there is no substantial air gap between the hollow guide member <NUM> and the sleeve <NUM>. It is possible that in another embodiment, a plunger is disposed inside the hollow guide member <NUM> and the sleeve <NUM>, with the plunger to assist transfer of impact force on the ogive to the detonator pin <NUM>.

<FIG> shows a door breaching grenade 100d according to yet another embodiment of the present invention. The door breaching grenade 100d shown in <FIG> is similar to that shown in <FIG> except that a leading end of the plunger 166d is now shaped with a mushroom head. This mushroom-head plunger 166d is provided to transfer effectively a component of an oblique impact force at the ogive <NUM> along the plunger 166d to actuate the detonator pin <NUM> when the projectile 101d is put to such a use.

<FIG> shows the above door breaching projectile <NUM> impacting at an oblique angle on a door/barricade <NUM>. Upon impact, the ogive <NUM> fractures along a thickness transition between the shaped ogive portion and the cylindrical portion. The fractured ogive becomes deformed in shape but the impact forces have a component that acts along the plunger <NUM>. As a result, the plunger <NUM> is forced to slide into the seat member <NUM> and plunges or impinges onto the detonator pin <NUM>. By this instant, the projectile <NUM> is already in the armed position and the detonator pin <NUM> is aligned with the detonator <NUM>, which detonator <NUM> is also aligned with the booster charge <NUM>. Actuation of the detonator pin <NUM> then sets off the detonator <NUM>, booster <NUM> and explosive <NUM> charges, so that shock waves from the explosion force the door/barricade <NUM> to cave in, whilst the projectile <NUM> remains substantially outside the door/barricade. In this manner, injury to any occupant or destruction of property behind the door/barricade is limited. A complementary method of using the above projectile or grenade is thus provided.

Claim 1:
A door breaching projectile (<NUM>,100a-100d) comprising:
a shell (<NUM>) containing an explosive charge (<NUM>);
an open end of the shell (<NUM>) with a mouth being connected to a rear edge (<NUM>) of a body member (<NUM>);
a hollow ogive (<NUM>) with a mouth being connected to a forward edge (<NUM>) of the body member (<NUM>); and
a safe-and-arm mechanism (<NUM>) disposed in the body member (<NUM>), which safe-and-arm mechanism delays alignment of a detonator pin (<NUM>) with a detonator charge (<NUM>) only after the door breaching projectile (<NUM>,100a-100d) has been propelled over a safe distance from the launcher and has spin rotated through predetermined numbers of spin;
characterised in that: a plunger (<NUM>) is slidable in a seat member (<NUM>), with the seat member (<NUM>) being mounted on a forward face associated with the forward edge (<NUM>) of the body member (<NUM>);
wherein, upon the door breaching projectile (<NUM>,100a-100d) impacting on a door or barricade (<NUM>), the plunger (<NUM>) is forced into the seat member (<NUM>) to impinge onto the detonator pin (<NUM>), which then sets off the detonator charge (<NUM>) and explosive charge, such that explosive shock waves cause the door/barricade (<NUM>) to cave in but the projectile (<NUM>,100a-100d) remains substantially outside the door/barricade.