Safety system for a projectile fuse

ES 2 222 698 T3

DESCRIPTION

Security system for projectile fuze.

The present invention relates to a security system, in particular to a projectile for a small-caliber weapon.

In our European patent EP-B-0363079 a small-caliber projectile for a smooth-bore weapon is described preferably fired from a cartridge with a built-in propellant charge, in which the projectile comprises a generally cylindrical casing, a warhead assembly, said head being hollow to house an explosive charge and an initiator, the bushing being provided with a firing pin spring that urges it towards a safety position and remains in a locked condition in the safety position at least one safety pin driven by a spring, and in which the safety pin driven by Spring is adapted to be released upon exit of the projectile from the muzzle of the small-caliber weapon.

Therefore, patent EP-B-0363079 refers to a projectile provided with mechanical safety means to retain the firing pin in the safety position. The mechanical safety means comprise at least one spring-loaded safety pin extending normal to the axis of the firing pin and located in a radial bore in the firing pin to prevent axial movement of the firing pin. The safety pin is radially retained by the cartridge.

There is a drawback associated with this arrangement. As the projectile exits the muzzle of the small-caliber weapon, a strong deceleration occurs when it collides with calm air, causing the shell of the projectile to decelerate and a deceleration force to be applied to the firing pin in the direction of the initiator. The shear stress applied to the shear pin by deceleration between the bushing and the firing pin prevents ejection of the shear pin until the shear stress is overcome by the spring force acting on the pin. The firing pin is thus held in its safety position by the safety pin. Only when shear stress has been reduced does the shear pin release the firing pin. Its effect is to delay the firing of the projectile by at least 0.1 seconds (or about 10 meters) or more reliably by 0.2 to 0.3 seconds, which usually equates to about 20 to 30 meters less range. This means that close range targets cannot be hit and even targets 25 to 30 meters away cannot always be reliably hit.

A further drawback with this arrangement is that there is only one safety means to retain the firing pin in the safety position. The possibility exists, therefore, that the explosive charge could be accidentally initiated if the safety pin were to be dislodged from the firing pin due to the cartridge being damaged, for example.

To solve these problems, patent EP-B0363079 suggests the use of a chemical security means in addition to the mechanical security means. The chemical safety means comprises a layer of combustible adhesive material interposed between the striker and an adjacent hollow portion of the socket. The combustible adhesive material is connected to a bore in the back of the shell adjacent to a propellant charge, such that it is activated by the explosion of the propellant charge when the projectile is fired.

In this arrangement, the combustible adhesive material retains the firing pin in its safe position for a predetermined period of time, after the projectile has been fired. This prevents shear forces from being generated between the firing pin and the safety pin, when the projectile decelerates on collision with calm air. In this way, the ejection of the safety pin occurs immediately after the projectile exits the muzzle of the small-caliber weapon. The time elapsed for the combustible adhesive material to release the firing pin, thus arming the projectile, is determined by the characteristics of the combustible adhesive material.

The problem with this arrangement is that the combustible adhesive material can deteriorate and become unstable if stored for a long period of time, particularly if the adhesive is defective in some way. This is a major drawback if a long storage time is required, as is customary for ammunition.

Another problem associated with this arrangement is that manufacturing limitations can render the combustible adhesive material insufficiently reliable to ensure that any delay in arming equates to a distance of 3 meters from the user when the projectile is fired.

It is known, for example, from documents FR-A-0 424 890, US-A-2,537,855 and US-A2,564,797, that fully mechanical devices can be used to effect the safety locking of the firing pins in fuzes. of projectiles and that strikers can be used, while they are thus locked, to keep the initiator in a safe condition, against forces that call it to an armed situation. In particular, document FR-A-0 424 890, which is considered to be the closest prior art, refers to a bushing, which is usually tubular, with a striker that can be moved axially and safety release means for releasably restraining the striker in a safety position, the safety means having first and second mechanical means. The projectile fuze, in this document, has first and second mechanical means of safety. The first medium is a frangible component. The second medium is a component that moves radially outward under the effect of centrifugal forces.

None of these prior patent specifications, however, considers the provision of greater safety in handling and use, by means of a plurality of several independently active mechanical safety bolts, which are designed and configured to fire in response. to different situations in the shooting process.

An object of the present invention is to provide a small caliber projectile having a safety means for retaining a firing pin in a safe position prior to firing and releasing the firing pin upon application of acceleration forces as a result of firing.

Another object of the present invention is to provide a small caliber projectile that has at least two mechanical safety means.

They are 2 222 698 T3 independent, to retain a firing pin in a safety position before firing.

Another object of the present invention is to provide a small-caliber weapon projectile having a safety means for retaining a firing pin in a safety position prior to firing, which acts to delay the arming of the projectile when firing, in a further manner. reliable than with the previously known medium.

According to one aspect of the present invention, there is provided a small-caliber projectile for small-caliber weapons, the projectile including:

a bushing, which is usually tubular, provided with a striker that can move axially;

a compression spring that provides an elastic force;

an explosive warhead that has an explosive charge and an initiator that has safe and armed conditions and is capable of, when in its armed position and when struck with sufficient force by said firing pin, to detonate the explosive charge from said head;

wherein the sleeve further contains safety release means for releasably restraining the striker against said elastic force, which tends to move the striker away from the initiator, into a safety position, such that said initiator is maintained, by coupling with the firing pin, in its safety condition, against an armed force that tends to request the initiator towards the armed condition;

wherein the safety release means comprises first and second mechanical means;

wherein said first mechanical means comprise at least one component constructed to be frangible in response to the forces experienced when the projectile is fired, the mechanical strength of the frangible element being sufficient to withstand acceleration forces of up to 500 g; ^Y wherein said second mechanical means comprise at least one component provided and configured in such a way that it is ejected from the casing under the influence of said elastic force, when the projectile leaves the weapon, thus allowing said elastic force to displace the striker moving away from the initiator to an extent that allows said initiator to be called into his armed condition.

It should be understood that the abbreviation "g" used herein represents acceleration due to gravity. Typically, a small-caliber projectile will experience an acceleration between 10,000g and 15,000g when fired into the chamber of a small-caliber weapon. The safety release means retains the firing pin in the safe position upon application of acceleration forces less than 500 g to prevent accidental arming of the projectile prior to firing. In this way, the releasable safety means will protect the user if the projectile is accidentally dropped during handling, since the acceleration forces applied to the projectile will generally be less than 500 g.

Furthermore, the firing pin is forced to release itself from said safety position only when the projectile has been fired and only when both the first and second mechanical means were rendered ineffective in a predetermined sequence. In this way, if one of the mechanical means fails, the other prevents the movement of the firing pin from the safety position. Since the latch release means has releasable means that are mechanical, striker restriction is improved and problems associated with chemical degradation are avoided. Furthermore, this can prevent the firing pin from moving towards the initiator when the projectile has been fired and is still in the chamber or bore of the small-caliber weapon.

Preferably, said striker comprises a separate and axially movable base part.

Conveniently, said frangible component comprises a shear safety pin positioned to support said base portion before firing the projectile.

In this way, the first mechanical means is released from the striker by the initial axial movement of the base portion in a direction away from the initiator. The acceleration forces applied to the base part, at the moment of firing, can therefore be used to release the firing pin from the first mechanical means.

In another embodiment, said frangible component comprises a disk element provided between said base part and the sleeve to support said base part before firing the projectile.

In this way, the first mechanical means is released from the striker by the initial axial movement of the base part in a direction away from the initiator. The acceleration forces applied to the base part, upon firing, can therefore be used to release the firing pin from the first mechanical means.

Consequently, the frangible component prevents release of the firing pin from the initiator until significant acceleration forces are applied to the base portion when the projectile is fired. The acceleration forces applied to the firing pin and the base part when firing are considerable and in this way the frangible component can be made strong enough to withstand shock loads due to tampering prior to firing.

Furthermore, the frangible component can be easily manufactured and its resistance to breakage reliably controlled during manufacture.

It is preferred that the initiator is requested to move from its safe condition to its armed condition by rotating, about an axis perpendicular, to the axis of the sleeve.

Consequently, the initiator can only rotate to the cocked position under spring impulse once the firing pin has disengaged.

In another embodiment, the elastic force applied to the firing pin is provided by the compression spring which has sufficient stiffness to prevent the firing pin from moving towards the initiator, due to the deceleration experienced by the projectile, when it leaves the muzzle of a small firearm. caliber.

Since the firing pin is propelled in an axial direction away from the initiator, this can prevent movement of the firing pin toward the initiator immediately after the projectile exits the muzzle of the small-caliber weapon. In this case, the firing pin hits the initiator only when the projectile hits the target.

Conveniently, the component that can ex

ES 2 222 698 T3 being pressed from said second mechanical means comprises at least one spring-driven safety pin.

In this way, the safety pin can be radially restrained in a cartridge from which the projectile is fired. For example, the safety pin can be restricted, in its radial movement, by the internal surface of the bore of the weapon from which the shot occurs and is released on exit from the muzzle. The projectile is thus armed immediately upon exit or within a short distance after exiting the muzzle of the weapon.

In preferred embodiments, two spring loaded safety pins are provided for release in opposite radial directions.

In this way, any imbalance of the projectile is avoided once it has been fired.

Preferably, said sleeve supports a plurality of stabilizing fins limited to abutting against the sleeve before firing the projectile, but capable of deployment when the projectile leaves the weapon, and in which at least one of said fins prevents the expulsion of the component that it can be ejected from said second mechanical means until said deployment occurs, the deployment being assisted by the movement of said firing pin under the elastic force.

In a particular embodiment, the firing pin is provided with a stabilizing disk that has a frusto-conical lateral part arranged in contact with the component that can be ejected from the second mechanical means.

Conveniently, said initiator is constructed to generate, when in its armed position, an initiating explosive charge in response to the impact received from the firing pin and comprises means for causing the initiating explosive charge to conform to a predetermined shape around the axis of the initiator. , and wherein said initiator axis is misaligned with the axis of movement of said firing pin when held in its safe position.

In a particular case, when the axis of said initiator is misaligned with the axis of movement of the firing pin, an armor means is interposed between the initiation charge and that of said explosive head.

In a particular embodiment, the initiation explosive charge is contained in a cupped structure and the armor comprises a part of said structure.

The invention will now be described, by way of illustration only, with reference to the accompanying drawings, in which:

Figure 1 is a vertical cross-sectional view of the arrangement of a projectile withdrawn from a 3 "(7.56 cm) 12 gauge cartridge, with no such projectile arrangement being made in the present invention.

Figure 2 is a cross-sectional view similar to Figure 1 and illustrates another projectile arrangement not embodying the present invention;

Figure 3 is a cross-sectional view similar to Figure 1 and illustrates another projectile arrangement not embodying the present invention ;

Figure 4 is a cross-sectional view simulating Figure 1 and illustrates a projectile according to a first embodiment of the present invention;

Figures 5 (a) and 5 (b) are partial cross-sectional views illustrating a relationship between the initiator and the components of the warhead alternative to that illustrated in Figure 4 safely (but accidentally fired) and weapons, respectively, and Figure 6 is a cross-sectional view illustrating another relationship between the initiator and the components of the warhead alternative to that illustrated in Figure 4.

In all figures, similar components of small-caliber projectiles have the same reference numerals.

With reference to Figure 1, the projectile (1) is constituted by a hollow explosive head (2) and a hollow casing (3). The projectile has a generally cylindrical configuration around a central axis and is made, in this case, of aluminum castings. The explosive head (2) and the cap (3) are cast parts, formed separately, provided with interlocking means in the form of an externally threaded part (4) on the cap and an internally threaded part (5) on the head. explosive. The warhead and shell are attached immediately prior to mounting with a 12-gauge cartridge.

The bushing (3) is provided with an axial bore (6) that houses an axially movable cylindrical firing pin (7). The firing pin (7) is provided, at its operating end closest to the explosive head (2), with a conical needle part (8) to come into contact with the charging initiator (23), which is located in the head explosive. The striker (7) also comprises a stabilizer disc part (9), adjacent to the needle part, a reduced diameter shaft part (10) adjacent to the stabilizer disc and a base part (11). The stabilizer disc (9) and the base part (11) have an outer diameter that is practically the same as the inner diameter of the axial bore (6). The base part (11) comprises an annular recess (12) on its side adjacent to the part of the reduced shaft (10).

In the drawing, the striker (7) is illustrated in its safety position. The striker (7) is retained in this position by a safety release means, comprising a mechanical releasable restraint means in the form of two opposing elastic safety pins (13) and a mechanically releasable restraint means in the form of a hollow frangible disc element (15).

The safety pins (13) are each located in a stepped through hole (16) in the bushing (3). The through holes (16) have an axis that is perpendicular to the axis of the bushing (3). The safety pins (13) comprise a pin cap portion (17) and a shank portion (18) that is located in the reduced diameter portion of the through hole (16). The shank portion (18) of the safety pin has an outer diameter that is essentially the same as the inner diameter of the reduced diameter portion of the through hole. A compression spring (19) is provided in the larger diameter portion of the stepped through hole (16) and rests on the cap portion of the pin (17) to urge the locking pin (13) radially outward. The safety pins (13) are held in the through hole by engagement with the firing pin (7). At their distal ends, each of the safety pins comprises a reduced diameter portion (20) adjacent the stem portion (18) and an outwardly flared conical portion (21) defining a retainer. Part diameter

The reduced ES 2 222 698 T3 (20) extends from the stepped through hole and engages the front axial face (22) of the base portion (11). The outwardly flared conical portion (21) is partially located in the annular recess (12) and prevents axial movement of the firing pin (7) in the direction of the initiator (23).

Due to the fact that the safety pins (13) are retained by firing pin (7), assembly is considerably simplified since it is no longer necessary to manually retain the safety pins (13) in their pre-expanded condition before placing them in a cartridge. for your use.

The hollow frangible disc element (15) is located between the base part (11) of the firing pin (7) and an annular back plate (24) that is coupled to the bushing (3). The mechanical strength of the frangible element is such that it prevents axial movement of the firing pin, in a direction opposite to the initiator before firing, and is crushed by displacement of the firing pin in said axial direction upon firing. In this regard, the frangible element can withstand acceleration forces applied to the firing pin of up to 500 g.

A compression spring (25) is provided around the conical part (8) of the firing pin (7). The compression spring is retained by engagement with the stabilizer disc portion (9) and an annular retaining plate (26) which is attached to the inner surface of the bushing (3). The annular retaining plate (26) has a central opening (30) to house the conical part (8). In the illustrated safety position, the compression spring does not apply a significant load to the safety pin.

Located at the distal end of the sleeve (3), and around its outer periphery, are four fins (27) which, in use, extend radially outward from the body of the sleeve (3). The fins (27) are of a precise configuration such that, in their folded down position within the cartridge or barrel, for example, they will rest on the outer periphery of the casing. For this purpose, the fins (27) are coupled by means of a hinge at (28), the axis of the hinge being slightly at an angle with the longitudinal axis of the projectile, in such a way that the air pressure will cause the fins (27) to open and spin the projectile as it exits the muzzle of the weapon. The fins (27) can be formed from an elastic material, such as copper, or can be molded to their final shape from plastic or a malleable metal, such as aluminum.

The warhead assembly (2) consists of an aluminum casting with a generally cylindrical configuration and comprises a dome-shaped front end. This front end joins the cylindrical part that extends downwards towards the bushing (3). The hollow part of the warhead (2) is provided with an explosive (29), for example A5. The explosive block (29) is, in this particular arrangement, provided with a central bore (31) for housing an initiator (23) which, in this particular example, defines part of a bait-holder mechanism. The initiator (23) is rotatably mounted on an axis perpendicular to the axis of the warhead (2) for displacement between the illustrated angular position and an elastic skew position, spaced 90 degrees apart. The initiator (23) is provided with a wedge-shaped slot (41) which engages the tip of the conical portion (8) when the firing pin is in the safety position. In this way, the firing pin (7) retains the initiator (23) in the illustrated non-cocked angular position. Resilient means (not illustrated) are provided to rotate the initiator (23) through a 90 degree angle to a cocked position when the firing pin is moved relatively rearward. The initiator (23) is further provided with openings (32) to accommodate the tip of the conical portion (8) when rotated to the cocked position.

Pre-molded fragmentation parts (not illustrated) can also be formed on the internal or external faces of the warhead (2). Alternatively, the warhead (2) can be formed from a hard epoxy resin in which a plurality of ball bearings have been exposed. The advantage of the latter construction is that the weight of the warhead (2) can be carefully adjusted by using the correct weight and number of ball bearings. Furthermore, of course, the balance point of the projectile assembly can be altered by placing the ball bearings in various positions in varying numbers within the body of the material that forms the warhead (2).

In use conditions, the explosive charge that is molded into a predetermined shape is coupled between the warhead (2) and the initiator (23). The bushing (3) is assembled by placing the frangible disk element (15) at the base of the bore (6) of the bush (3) once the firing pin (4) is inserted into the bore (6). The safety pins (13) are then inserted into the bore (6) and pressed into position. With the part of the cap (17) of the safety pins (13), in retention conditions in its pressure state, the firing pin (7) is then retained in its safety position and the cap (3) and the explosive head (2) can be screwed together. If, in this position, the projectile is accidentally dropped even with the cartridge case removed, the concussion will not release the firing pin (7) because the safety pins (13) are engaged with each other and the frangible disk element (15) is strong enough not to break. The fins (27) are then placed into their radially inward positions and the device is slid into a standard 12 gauge cartridge such that they fit on top of the cleat felt immediately above the propellant charge.

The cartridge can then be placed in a standard weapon with a cylindrical barrel and in the normal firing shape. Upon firing, the projectile (1) leaves the cartridge (not illustrated) and travels along the smoothbore barrel. The acceleration force applied to the projectile in the barrel is usually in the order of magnitude of 10,000 g to 15,000 g. The acceleration force of the firing pin (7) causes the firing pin (7) to crush the frangible disc element (15). This allows the firing pin to travel in an axial direction away from the initiator (23). The initiator (23) is thus released from its unarmed position and rotates about its axis at a 90 degree angle to its armed position. As the firing pin moves rearward from the initiator (23), the safety pins (13) disengage from the annular recess (12). At the exit of the barrel, the restriction from the inner wall of the bore is removed and the safety pins (13) are immediately ejected radially outward.

Upon exiting the barrel, the projectile decelerates as

ES 2 222 698 T3 because the pressure of the propellant gases in the barrel no longer acts. The deceleration of the projectile urges the firing pin (7) towards the initiator (23). Contact between the firing pin (7) and the initiator (23) is avoided, in this phase, by the forward movement of the firing pin which is antagonistic to the restraining force applied by the compression spring (25). When the projectile (1) hits the target, the deceleration forces applied to it are much greater and the associated force acting on the firing pin (7) exceeds the restraining force of the compression spring (25) and the tip of the firing pin (7) penetrates through the initiator opening (32), causing the charge to explode.

Referring now to Figure 2, the projectile (1) is substantially the same as the projectile of Figure 1. The projectile of Figure 1 differs from that of Figure 2 in the sense that the firing pin (7) comprises two components separated. The conical tip part (8), the stabilizer disc (9) and the reduced diameter shaft part (10) constitute a single component and the base part (11) is formed as a separate component. The base part (11) is provided with a central blind bore (60) and an annular flange (61) at its outer radial periphery on its axial front face (22). The reduced diameter shaft portion (10) is located in the blind bore (60) at its end furthest from the tip portion (8). The reduced diameter part has an outside diameter that is practically the same as the inside diameter of the blind bore (60) and comprises a shoulder (62), located along its entire length, which is stressed when engaging a stepped annular recess (63) in the opening of the blind bore (61) by the compression spring (25). The safety pins (13) have a constant diameter shaft portion (18) that has a slot (64). The groove (64) provides a retainer for the annular flange (61) that prevents axial displacement of the firing pin (7) in the direction of the initiator (23). In this regard, it is to be understood that the groove (64) and annular flange (61) replace the reduced diameter portion (20) and the outwardly deployed conical portion (21) of the shear pins (13) and recess annular (12) of the projectile of Figure 1.

The projectile in Figure 2 is fired in the same way as the projectile in Figure 1. Upon firing, the acceleration force applied to the base part (11) causes the base part (11) to crush the disk element. frangible (15). This allows the base part (11) to move in the axial direction away from the initiator (23) relative to the stem part (10). As the base portion (11) moves rearward away from the initiator (23), the safety pins (13) disengage from the annular flange (61). The axial displacement of the shaft part (10) in the opposite direction to the initiator is prevented by the engagement of the safety pins (13) with the disk part (9). The initiator (23) is thus held in the disassembled position by engagement of the tip portion (8) and the V-groove (41). At the exit of the barrel, the safety pins protrude radially outwards and the driving force of the compression spring (25) urges the shaft part (10) towards the base part (11) in the axial direction away from the initiator (23 ). This causes the initiator (23) to be released from its unarmed position. The initiator (23) is then rotated through a 90 degree angle to its armed position to thereby arm the projectile.

Referring now to Figure 3, the projectile (1) is substantially the same as that of Figure 1. The projectile of Figure 3 is different from that of Figure 1 in that the safety pins (13) have a shaft portion (42) of constant diameter extending from the cap portion (17). In Figure 3, the safety pins (13) are restricted in their radial movement in the through holes (16) by the interposer cartridge. In the illustrated safety position, the safety pins (13) can be inserted into the forward-facing axial side (22) of the base part (11) to prevent axial displacement of the firing pin (7) in the direction of the initiator ( 23) and can also engage the opposite axial side of the stabilizer disc (9) to prevent axial movement of the firing pin (7) in the opposite direction of the initiator.

The secondary mechanical releasable restraint means are provided with a plurality of circumferentially spaced radially movable elements. (43). The elements (43) usually have an "L" shaped cross section and are inter-coupled in an annular groove (44) formed in a reduced diameter portion (45) of the firing pin (7) adjacent to the base portion (11). The elements (43) are urged radially inward in the annular groove (44) by elastic means (46) between the elements (43) and the bushing (3). The elements (43) are housed in an annular recess (47) formed in the bore (6) at the end of the cap remote from the explosive head (2). Annular recess (47) defines a stepped axial surface (49) in bore (6). The radial dimension of the elements (43) is such that, in the illustrated skewed position, the elements (43) extend radially out of the annular recess (44) and part along the axial surface (48) in the recess annular (47). In this position, the elements (43) define a radial gap (50) between the bushing and its radially outer ends. Furthermore, in this position the elements (43) prevent axial movement of the firing pin (7) in the direction towards the initiator (23) by engaging the stepped axial surface (49). The radial dimension of the gap (50) is marginally greater than that of the annular recess (45). The striker (7) is axially aligned in the bore (6) by locating its end furthest from the conical portion (8) in an opening (51) provided in the end plate (24).

The initiator (23) is retained, in a non-mobile manner, in the explosive (29) by the annular plate (26).

Upon firing, the projectile (1) exits the cartridge (not illustrated) and travels along the smoothbore barrel. Upon exiting the barrel, the restriction of the internal walls of the bore is removed and the safety pins (13) are immediately ejected. Then, the movement of the firing pin (7) towards the initiator (23) is prevented by the engagement of the elements (43) and the axial surface (49) only. As the projectile exits the barrel, the fins (27) unfold and cause the projectile to rotate around its axis. At a predetermined point, the rotation of the projectile generates sufficient centrifugal force on the elements (43) to force them radially outward against the force of the spring biased drive means (46). When the elements (43) engage with the annular recess (47), they disengage from the annular recess (45) and thus release the firing pin

ES 2 222 698 T3 (7). This typically occurs 0.3 seconds after the barrel exits, resulting in a delay in projectile arming, which equates to about 30 yards (27.4 meters) of range reduction, which is sufficient to ensure firing. user safety. Once the projectile is armed, the tip of the firing pin (7) can penetrate the initiator on impact with the target.

Referring now to the invention, Figure 4 illustrates a projectile (1) according to a first embodiment of the present invention. The projectile (1) of Figure 4 is formed similarly to the arrangements of the projectiles of Figures 1 to 3 in that it has a hollow warhead (2) and a hollow casing (3). In the drawing of Figure 4, the detail of the warhead (2) has been omitted for the sake of clarity. The explosive head (2) and the cap (3) are separately formed castings with interlocking means in the form of an externally threaded part (70) on the explosive head (2) and an internally threaded part (71) on the bushing (3).

The projectile of Figure 4 is provided with a two-piece firing pin (7). The firing pin (7) of the projectile of Figure 4 is similar to the firing pin (7) of the projectile of Figure 2 in the sense that the conical tip portion (8), the stabilizing disc (9) and the shaft (10) They are formed as a single component and the base part (11) as a separate component. The stem part (10) is located in a central through hole (72) in the base part (11). The stabilizer disc comprises a flat base (73) and a frusto-conical side portion (74) which together provide a recess (75) on the initiator side of the stabilizer disc. A cylindrical sleeve (76) is located in the bore (6) of the sleeve (3), adjacent to the firing pin (7). An annular shoulder (77) is provided at the end of the sleeve (76) closest to the tip of the firing pin (8) to receive one end of a compression spring (25). The other end of the compression spring is located in the recess (75) to engage the flat base (73) of the stabilizer disc for engagement with the base (11).

The striker (7) is retained in the illustrated safety position by a primary mechanical releasable restraint means, comprising at least one spring-loaded safety pin (78) and a secondary releasable mechanical restraint means in the form of a frangible disc element (79). In this embodiment, the safety release means further comprises a tertiary mechanical releasable restraint means, in the form of at least one shear pin (80) provided in a recess (83) in the base (11).

The safety pin (78) is located in an inclined through hole (81) in the side of the bushing (3). At one end, the safety pin (78) engages the frusto-conical side portion (74) of the stabilizer disc (9). The safety pin (78) is urged in a radially outward direction by the compression spring (25) acting on the disc (9) and is constrained within its through hole (81) by a fin (27) when it is in its folded-down condition, as illustrated.

The shear pin (80) is located in a through hole (82) in the side of the bushing (3) and extends into a recess (83) provided in the base (11). The shear pin (80) is provided with a reduced diameter frangible portion (84), which is positioned to correspond with the position between the recess (83) and the through hole (82).

The spring-driven initiator (23) is located within the bore (6) of the bushing. The initiator (23) is provided with a stepped outer surface (85) that engages the tip of the conical portion (8) when the firing pin is in the safety position. The initiator (23) is spring biased to its cocked position corresponding to the opening (32) that is aligned with the axis of the firing pin.

The projectile of Figure 4 is fired in an identical manner to the projectiles of Figures 1 to 3. Upon firing, the acceleration force applied to the base part (11) causes the base part (11) to crush the element of frangible disc (79) and shear pin (80) for shear. This allows the base part (11) to move in the axial direction away from the initiator (23), relative to the stem part (10). Axial movement of the stem portion (10) in the direction away from the initiator is prevented by engagement of the safety pin (78) with the frusto-conical portion (74). The initiator (23) is thus held in its disassembled position by engagement of the tip portion (8) with the stepped outer surface (85) when in the smooth-bore gun barrel. At the exit of the barrel, the fins (27) unfold and the safety pin (78) is expelled radially outward and the driving force (25) urges the shaft part (10) towards the base part (11) in the axial direction away from the initiator (23). This causes the initiator (23) to be released from its disarmed position. The initiator (23) is then rotated about 30 degrees to its armed position to arm the projectile.

Figure 4 has been described as comprising a single safety pin (78) and a shear pin (80) also unique. In another embodiment, these pins are complemented by a second shear pin (78) and shear pin (80) located diametrically opposite in their respective positions.

The embodiment of the invention illustrated in Figure 4 provides a very significant improvement in the safety of projectiles of this class, based on the important fact that, until the initiator (23) is allowed to move to its armed position, there is no direct line of impact of the firing pin (7) on the initiator, nor a direct line of communication between the initiator and the explosive (29). This is used to further advantage in the second and third embodiments of the invention, illustrated, in part, in Figures 5 (a), 5 (b) and 6.

Referring now to Figure 5 (a), it can be seen that the initiator (23) is contained within a cupped construction (90), made of aluminum, and preferably surrounded by a sheet of titanium (91) or coated, of another mode, or incorporating a layer of titanium, with a thickness of the order of magnitude of 0.001 inches. The explosive charge of the head (29) is contained behind a shield (92), which takes a cap shape towards the initiator (23) with a thin central part (93). The cup structure (90, 91) is formed with a flange portion (94), which faces the armor (92), such that, in general, when the projectile is secure, the flange portion (94) is rests in front and parallel with the thin part (93) of the shield (92) when the initiator (23) is not in line with the main load. By this means, a load shaping is arranged

ES 2 222 698 T3 of the initiator and a shield of the main charge (29), in such a way that, in the event of an accidental firing of the initiator charge by some external agent, as indicated by the fracture of the flange part (94), the energy of the charge does not impact directly on the main charge (29), as it deviates from the direct "line of sight" and furthermore, the flange portion (94) of the cupped structure (90, 91) tends to be open, as illustrated in (94a), and thus provides a reinforced shield between the initiating charge and the main explosive charge (29) of the projectile.

Figure 5 (b) is identical to Figure 5 (a), except that it illustrates the assembled condition, in which the cup-frame (90, 91) has been allowed to rotate in such a way as to align the load (23) with the thin area (93) of the shield (92). In this condition, when ignition of the initiator charge occurs, as illustrated, the open portions of the flange portion (94) no longer overlap the thin area (93) of the shield (92) and, in effect , helps to concentrate the initiator charge on the main explosive charge (29) of the warhead, that is, they provide a "channel of fire" that directs the energy of the initiator to the main charge.

In the embodiment of Figure 6, the main difference from Figure 5 is that it is provided with a shield plug (95) that is integral and rotates with the initiator (23), thus obviating the need for the flange portion (94) for the cup-frame (90, 91) which is otherwise as described in connection with Figure 5. The plug (95) is shaped, dimensioned and manufactured of a suitable material to resist or at least lessen the impact on the main explosive charge (29) of an accidental discharge of the initiator charge. In this regard, it can be relatively bulky since, of course, it automatically moves out of the line of action between the initiator (23) and the main explosive charge (29) of the projectile when the initiator rotates to its armed position.

The combination, as illustrated in Figures 5 and 6, of shaping, at least to some extent, the initiator charge, biasing the shaped charge, with respect to the direct path to the main explosive charge, in a "unarmed" condition and providing additional armor along the direct path in the "unarmed" condition, provides a significant degree of additional security against unwanted detonation of the main charge, while it does not compromise the sensitivity of the warhead to detonation in the "armed" condition, when the initiator charge is rotated to align with the direct path to the main explosive charge.

It should be understood that Figures 4 to 6 illustrate only particular embodiments of the invention. In this regard, although the present invention is described with reference to fins, it should be appreciated that the invention also relates to projectiles that do not comprise fins.