GB1591092A - Detonateless fuse - Google Patents

Description

(54) DETONANTLESS FUZE (71) We, COMMONWEALTH OF AUSTRALIA, the address of which is Crown Solicitor's Office, Canberra, Australian Capital Territory, Commonwealth of Australia, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to improvements in fuzes for initiating detonation in explosives, and refers especially to a system of fuzing which does not require the use of conventional detonants or primary explosives, such as fulminate of mercury, lead azide and lead styphnate. The term "detonantless fuze" used in this specification is intended to refer to a fuze of this character, i.e. a fuze containing no detonants.The invention is applicable to the initiation of explosive weapons such as bombs, shells, rocket warheads, mines and demolition charges.

It is an object of this invention to provide a detonantless fuze for initiating detonation in high explosives, which is capable of effectively replacing fuzes containing detonators in a wide range of explosive weapons. It is not claimed that the fuze of this invention will replace fuzes containing detonators in all cases.

According to one form of the invention a detonantless fuze is provided with comprises a body, a recess in the body, high explosive disposed in the recess, a cavity of reduced diameter formed in the high explosive, an aperture of reduced diameter in the body communicating with the cavity, and means for effecting rapid compression of air within the aperture and cavity whereby the high explosive is initiated.

A feature of the invention resides in the fact that the fuze may be initiated by compression ignition, i.e. thermal ignition of the explosive by compression of air in contact therewith. The essential requirement for initiation appears to be to raise above the ignition point the temperature of small quantities of high explosive in or on the surrounding surface of the cavity.

According to a preferred feature of the invention the high explosive immediately surrounding the cavity is substantially non-porous.

A further feature resides in the provision of means for increasing the rate of rise of pressure applied to the air in the cavity, so that a wide range of sensitivities is obtained, enabling the fuze to be used efficiently against various types of targets. This rise of pressure may be obtained by the sudden compression of a plastic medium into a suitably shaped converging cavity.

In the following description of particular forms of the invention reference is made to the accompanying drawings wherein: Figure 1 is a diagrammatic sectional elevational view showing the arrangement of the body of a fuze according to the invention, Figure 2 is a sectional elevational view of a fuze according to one form of the invention, shown in an unarmed condition, Figure 3 is a view similar to Figure 2 showing the fuze in an armed condition, and Figures 4 and 5 are views similar to Figure 2 showing modified constructions of fuzes according to the invention.

In the several Figures the same reference numerals are employed to indicate the same or corresponding parts.

In one application of the invention, we provide a robust cylindrical container 11 having a central longitudinal cylindrical recess which is filled with high explosive 12, such as tetryl, or penta-erythritol tetranitrate or cyclotrimethylene trinitramine, or some or all of these. The recess filled with explosive is preferably long and narrow. One end 13 of the body is closed except for an aperture or passage 14 of small diameter which extends through the closed end 13 of the body 11. The diameter of the passage is of the order of 0.026" to 0.031" and its length is of the order of 0.1" to 0.2".

The aperture 14 communicates at its inner end with a cavity 15 of similar diameter which extends axially into the column 12 for a distance of the order of 0.2" to 0.3". The density and other conditions of the explosive in the immediate vicinity of the cavity are such that the explosive forming the walls of the cavity is substantially non-porous.

The opposite end of the explosive filling may communicate with a second body of explosive which is initiated by the detonation of the first mentioned explosive. The length and diameter of the explosive filling are of im portance in that if they are less than minimal dimensions the explosive will not reach full detonation. The limiting dimensions are governed by the nature of the explosive used.

The means for initiating the explosive may comprise a chamber of substantially larger volume than that of the aperture and cavity, which chamber is disposed externally to and in communication with the cavity, and mechanism (such as a cup or plunger) for compressing the air in said chamber, whereby a manifold increase in air pressure in the cavity is effected at a rate which results in developments of high temperatures.

In one arrangement, a cylindrical cup may be mounted on the body adjacent to the apertured end thereof so as to be slidable thereover, a cylindrical air space or chamber being formed between the closed end of the cup and the outer end of the aperture. When the cup is moved towards the body, as by striking a target, the air in the chamber is compressed, and the pressure increase in the narrow cavity in the explosive filling is such as to raise the temperature of the air sufficiently to ignite the explosive.

In lieu of employing a cup, we may utilise a plunger operating in a cylinder, or a resilient or compressible member which may be deformed so as to effect a required pressure increase in a chamber to which the plunger or compressible member is connected or in or on which it is mounted.

Figures 2 and 3 of the drawings illustrate one form of detonantless fuze constructed according to the invention and suitable for bombs or like weapons, comprising a cylindrical body 11 having a central cylindrical recess filled with high explosive 12. The forward end 13 of the body 11 is closed and a narrow aperture 14 extends therethrough and communicates with a cavity 15 of similar diameter formed in the forward end of the filling 12. An outer body section 16 is screwed to the body and is provided with a cylindrical cup 17 of enlarged diameter which extends forwardly of the body 11. A plunger 18 is slidably mounted in the cup 17 and is formed with a cylindrical skirt 19 which fits slidably over the forward end of the body 11, an air space 20 being thereby formed within said plunger and forwardly of the body.A compression spring 21 surrounds the plunger skirt and bears at one end against the plunger and at the other end against an abutment on the outer body section 16. It will be understood that the body 11 and the outer body section 16 may be formed in one piece if so desired.

An arming cap 22 of standard design is screwed to the outer body section 16 as shown in Figure 2 and is provided with vanes 23 whereby the cap will revolve and detach itself from the fuze when the weapon is in flight.

When the fuze is in its unarmed condition as shown in Figure 2 the plunger 18 is held in its inner or restricted position by a projection 24 formed on the arming cap 22, which engages the outer face of the plunger. When the arming cap detaches itself from the fuze then as indicated by Figure 3 the plunger 18 is moved forwardly by the action of the spring 21, air being admitted to the space 20 between the plunger and the forward end of the body through apertures 25 formed in the outer body section 16, and the fuze is then in its armed condition. On approaching or striking the target the plunger 18 is forced rearwardly against the action of the spring 21 and the air within the space 20 is compressed.Thus the air pressure in the cavity 15 within the explosive 12 is raised to a considerable extent causing a corresponding rise in the temperature of the air to the ignition point of the explosive surrounding the cavity 15. Detonation of the explosive 12 in the fuze body 11 causes initiation of the explosive 26 contained in a magazine 27 secured to the rear end of the body, or may be caused to initiate detonation in other explosives.

Figure 4 shows another construction according to the invention wherein a detonantless percussion fuze is provided having a metal body 11 formed with a central recess containing explosive filling 12 and an enlarged chamber 28 communicating with said recess by a narrow aperture 14 of substantially smaller diameter than that of the recess. The said aperture 14 communicates with a cavity 15 of similar diameter and length formed in the filling 12. A nose plug or plunger 29 is mounted in the forward end of the chamber 28 and is held in position by a rib or collar 30 which projects into a recess in the wall of the chamber 28, the said rib being sheared when the plunger 29 strikes an object. The rearward movement of the nose plug or plunger 29 compresses and heats the air in the chamber 28 and cause ignition of the explosive filling.

In a further arrangement which is illustrated in Figure 5 we provide a form of detonantless fuze which comprises a body 11 and an outer body 16, the body 11 having a central narrow cylindrical recess filled with compressed high explosive 12. The rear end of the recess is closed by a cover 31, and the body 11 is formed to extend across and close the forward end of the recess except for a narrow aperture or passage 14 which communicates with said recess and with a cavity 15 of the same diameter formed in the filling 12, as in previous arrangements. A conical recess or cavity 32 is formed in the body 11 adjacent to and communicating with the aperture or passage 14, and a plug 33 of rubber or other plastic material of approximately hemispherical shape is disposed across the forward and larger end of the conical recess 32 and is held in position by a thin metal cup 34, the skirt 35 of which is attached to the body 11 by pressing into a groove 36 therein.

The outer body extends forwardly of the plug 33 and is provided with a nose 37. A disc shaped diaphragm 38 is attached to the nose 37 by a frangible annulus 39 with its inner surface spaced by a short distance from the forward or outer curved end of the deformable plug 33. The nose 37 is designed so that when the device strikes a target the diaphragm 38 is forced inwardly against the deformable plug 33, causing said plug to be compressed into the conical recess 32 in the body 11. The air in said recess is thus forced through the narrow passage 14 into the cavity 15 in the explosive filling. By this means we obtain an increase of the air pressure in the cavity 15, and the increase in pressure so effected is sufficient to raise the temperature of the air and thus of the surrounding particles of explosive to ignition point, so that initiation of the explosive is effected.The manner of the deformation of the deformable plug 33 can be varied by surrounding it, in the space behind the diaphragm 38, with a liquid or plastic material instead of air.

The term "plastic material" is intended to mean any material which like rubber is capable of flowing in a plastic manner under impact.

In one example of a fuze of the latter type the cylindrical recess in the body is filled with 0.15 grams of priming secondary explosive pressed at 162 lbs dead load, in three increments, having a density of 1.5 gms/cc, the priming being located at the forward end of the recess. The remainder of the recess is filled with stemming comprising 1 gram of high explosive pressed at 62 lbs dead load, in eight increments, having a density of 1.35 gms/cc. It will be understood that this invention is in no way limited to the type of filling employed or to the compression or density thereof or to other specific details of this or a similar nature.

WHAT WE CLAIM IS: 1. A detonantless fuze which comprises a body, a recess in the body, high explosive disposed in the recess, a cavity of reduced diameter formed in the high explosive, an aperture of reduced diameter in the body communicating with the cavity, and means for effecting rapid compression of air within the aperture and cavity whereby the high explosive is initiated.

2. A detonantless fuze according to claim 1 wherein the high explosive immediately surrounding the cavity is substantially nonporous.

3. A detonantless fuze according to claim 1 or claim 2 having means for increasing the rate of rise of pressure applied to the air in the cavity.

4. A detonantless fuze according to any preceding claim having a converging cavity communicating with the said aperture, and a plastic medium adapted to be suddenly compressed into the said converging cavity.

5. A detonantless fuze comprising a body having an elongated recess formed therein and an aperture of reduced diameter opening through one end of the body into the said recess, high explosive filling said recess except for a cavity of substantially the same diameter as the aperture and communicating therewith, said high explosive being of such a density at least in the vicinity of the cavity to render the walls of said cavity substantially non-porous, and a plunger slidable relative to said body and forming in association with said body an air space communicating with the aperture in said body.

6. A detonantless fuze according to claim 5 wherein the said plunger has a sleeve slidable over said body and a spring so disposed between the plunger and a portion of said body so as to urge said plunger into an armed condition in which the air space is a maximum.

7. A detonantless fuze according to claim 5 wherein the plunger is a nose plug slidable in a recess in the body and shearable means are provided for retaining the nose plug in position.

8. A detonantless fuze comprising a body shaped to provide an elongated recess therein opening to one end of said body and a second recess opening to the other end of said body and converging therefrom with an aperture of reduced diameter connecting said recesses, high explosive filling said elongated recess except for a cavity of substantially the same diameter as the aperture and communicating therewith, said high explosive being of such a density at least in the vicinity of the cavity to render the walls of said cavity substantially non-porous, a plug of rubber or other plastic material disposed so as to block the opening into said converging recess, and means for retaining said plug in position.

9. A detonantless fuze according to any preceding claim wherein the diameter of the said cavity is of the order of 0.026" to 0.031" and the length of said cavity is of the order of 0.2" to 0.3'.

10. A detonantless fuze substantially as hereinbefore described with reference to Figure 1 or Figures 2 and 3 or Figure 4 or Figure 5 of the accompany drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. shaped diaphragm 38 is attached to the nose 37 by a frangible annulus 39 with its inner surface spaced by a short distance from the forward or outer curved end of the deformable plug 33. The nose 37 is designed so that when the device strikes a target the diaphragm 38 is forced inwardly against the deformable plug 33, causing said plug to be compressed into the conical recess 32 in the body 11. The air in said recess is thus forced through the narrow passage 14 into the cavity 15 in the explosive filling. By this means we obtain an increase of the air pressure in the cavity 15, and the increase in pressure so effected is sufficient to raise the temperature of the air and thus of the surrounding particles of explosive to ignition point, so that initiation of the explosive is effected.The manner of the deformation of the deformable plug 33 can be varied by surrounding it, in the space behind the diaphragm 38, with a liquid or plastic material instead of air. The term "plastic material" is intended to mean any material which like rubber is capable of flowing in a plastic manner under impact. In one example of a fuze of the latter type the cylindrical recess in the body is filled with 0.15 grams of priming secondary explosive pressed at 162 lbs dead load, in three increments, having a density of 1.5 gms/cc, the priming being located at the forward end of the recess. The remainder of the recess is filled with stemming comprising 1 gram of high explosive pressed at 62 lbs dead load, in eight increments, having a density of 1.35 gms/cc. It will be understood that this invention is in no way limited to the type of filling employed or to the compression or density thereof or to other specific details of this or a similar nature. WHAT WE CLAIM IS:

1. A detonantless fuze which comprises a body, a recess in the body, high explosive disposed in the recess, a cavity of reduced diameter formed in the high explosive, an aperture of reduced diameter in the body communicating with the cavity, and means for effecting rapid compression of air within the aperture and cavity whereby the high explosive is initiated.

2. A detonantless fuze according to claim 1 wherein the high explosive immediately surrounding the cavity is substantially nonporous.

3. A detonantless fuze according to claim 1 or claim 2 having means for increasing the rate of rise of pressure applied to the air in the cavity.

4. A detonantless fuze according to any preceding claim having a converging cavity communicating with the said aperture, and a plastic medium adapted to be suddenly compressed into the said converging cavity.

5. A detonantless fuze comprising a body having an elongated recess formed therein and an aperture of reduced diameter opening through one end of the body into the said recess, high explosive filling said recess except for a cavity of substantially the same diameter as the aperture and communicating therewith, said high explosive being of such a density at least in the vicinity of the cavity to render the walls of said cavity substantially non-porous, and a plunger slidable relative to said body and forming in association with said body an air space communicating with the aperture in said body.

6. A detonantless fuze according to claim 5 wherein the said plunger has a sleeve slidable over said body and a spring so disposed between the plunger and a portion of said body so as to urge said plunger into an armed condition in which the air space is a maximum.

7. A detonantless fuze according to claim 5 wherein the plunger is a nose plug slidable in a recess in the body and shearable means are provided for retaining the nose plug in position.

8. A detonantless fuze comprising a body shaped to provide an elongated recess therein opening to one end of said body and a second recess opening to the other end of said body and converging therefrom with an aperture of reduced diameter connecting said recesses, high explosive filling said elongated recess except for a cavity of substantially the same diameter as the aperture and communicating therewith, said high explosive being of such a density at least in the vicinity of the cavity to render the walls of said cavity substantially non-porous, a plug of rubber or other plastic material disposed so as to block the opening into said converging recess, and means for retaining said plug in position.

9. A detonantless fuze according to any preceding claim wherein the diameter of the said cavity is of the order of 0.026" to 0.031" and the length of said cavity is of the order of 0.2" to 0.3'.

10. A detonantless fuze substantially as hereinbefore described with reference to Figure 1 or Figures 2 and 3 or Figure 4 or Figure 5 of the accompany drawings.