GB1605020A - Incendiary projectile - Google Patents

Description

(54) AN INCENDIARY PROJECTILE (71) We MAUSER-WERKE OBERN DORF GmbH a Joint Stock Company organised under the laws of Germany (Fed.

Rep.) of Teckstrasse 11, 7238 Oberndorf/ Neckar, Federal Republic of Germany 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 an armourpiercing incendiary projectile.

According to the present invention there is provided an armour-piercing incendiary projectile comprising a casing, a sub-calibre metal core and an incendiary charge of zirconium metal.

Preferably, the zirconium metal is in the form of solid zirconium or zirconium sponge and is located in the rear of the core and/or in a tip of the bullet and/or constitutes said tip. The tip may be constituted by a ballistic cap made of zirconium or other metal or metal alloy.

The zirconium is preferably in the form of an insert in the cap and/or the core and the shape of the insert conforms to the shape of the recess in which it is located.

The ballistic cap preferably has a spigot portion engaging and or complementary shape to a head of the core. The spigot portion is preferably constructed without threads. The arrangement is preferably such that the ballistic cap may be pressed under pre-tension into a corresponding annular gap formed between the core head and the casing.

Tests have shown that by using zirconium as the incendiary charge in armour-piercing ammunition, above all against targets in air-to-air and air-to-ground use, a good incendiary effect and also a relatively high depth effect due to hard core fragments in conjunction with penetrating zirconium is achieved at fairly low cost and without requiring constructional charges to the core.

The so-called "kill probability" is in this case increased by approximately 15....20%.

When using zirconium tipped ammunition, apart from the effect when penetrating armoured plates, above all the effect against inflammable fluids, such as kerosene, diesel propellant etc., after penetrating aircraft tanks, armoured plates etc. is notably increased. By utilising the lubricating effect inherent in zirconium, penetration of armoured plates for example is facilitated, because in this case a eutectic mixture of iron and zirconium is formed, which considerably hastens the transition of armoured material from the solid to the liquid state.

A known and inasmuch indispensable minimum requirement of a metal with a good incendiary effect is that it should release a relatively large quantity of heat during the formation of the oxide. The incendiary effect is greater, the greater this quantity of heat. Zirconium fulfils this requirement.

In order to initiate the combustion, the surface temperature of the zirconium must be brought to self-ignition temperature. In a zirconium tipped bullet, the quantity of heat necessary for this purpose is supplied by its impact energy on striking the target. Upon impact, the zirconium is broken into small and very small pieces. The fractured surfaces of the resulting particles oxidize very quickly and thus provide an additional quantity of heat. The surface temperature of the zirconium depends on the surface: volume ratio i.e., with respect to the volume, small particles have a large surface.

They are heated to a higher temperature by a certain quantity of heat than particles with a greater volume. They therefore develop a better incendiary effect.

Zirconium has the further advantage that it may be processed relatively easily by conventional methods, is completely non toxic and is chemically compatible with explosive material powder etc. Apart from the fact that zirconium tipped ammunition may be stored for long periods, the cost resulting from additional material for the ballistic caps of zirconium or zirconium sponge as well as the costs resulting from the bodies to be pressed into the caps, are relatively low. These costs are in the order of several pennies.

The invention is illustrated by means of several embodiments in the drawings and is correspondingly described hereafter.

Figure 1 shows a hard core or heavy metal bullet in vertical section with a core consisting of zirconium sponge, pressed into a ballistic cap of conventional material, possibly alloy.

Figure 2 shows a bullet according to Figure 1, but with a solid zirconium core inside the ballistic cap, Figure 3 shows a bullet in vertical section, whose ballistic cap consists of zirconium, Figure 4 shows a bullet according to Figure 3, but in which a body consisting of zirconium sponge also pressed into the inside of the cap consisting of zirconium and finally, Figure 5 shows a bullet in vertical section with a ballistic cap of conventional material, possibly alloy and a zirconium body located at the rear of the core.

Before the construction of individual armour-piercing bullets is described with reference to the drawings, on account of the fact that they are relatively unknown, some chemical, physical and technological data relating to zirconium are given hereafter: Zirconium - this chemical symbol is Zr - is a steel grey to silver white metal with a specific gravity of = 6.5. Zirconium occurs naturally as a mineral (zirconium silicate) and as zirconium oxide or sand (ZrO2). The number in the period system is 40, the atomic weight 91.22. Whereas the structure of a zirconium is hexagonal, ep-zirconium is cubic body centred.The melting point is approximately 1850"C, the boiling point 3577"C. At 20"C, the density amounts to 6.49 g/cm3, the E-modulus 9.5 . loS kp/cm2 and the tensile strength 35 kp/mm2. In its technical configuration, zirconium and its alloys appear as powder, bars, tubes, strips, films and rods and also in the form of sheets.

In pyrotechnics, compressed zirconium sponge of varying strength and with or without magnesium inserts are used in the same way as hydrated zirconium.

The bullets shown in vertical section in Figures 1 to 5 all have the same basic construction, so that the same reference numerals will always be used hereafter for corresponding parts.

A core 2, possibly of Wolfram or the like is mounted in a centred manner and rotationally symmetrical in the casing or body 1 of the bullet consisting in manner known per se of steel or the like, coaxially with respect to its longitudinal axis. Adjacent its rear, each bullet is provided with a guide band 3 and with an annular recess, groove or the like la. The latter serves for securing the propellant charge case which is not shown and connected by a press fit, which is rolled or clamped in the recess by the mouth of its case.

The body 1 of the bullet is provided with a ballistic cap 4 at the front and in particular at the height of the core body 2a.

For reasons of simpler and cheaper manufacture, any thread between the body 1 of the bullet and cap 4 for purposes of attachment or connection may be omitted. Due to the construction with a cylindrical recess 4a when mounting the bullet, the cap 4 may engage under certain pre-tension in a corresponding recess Ib In the body 1 of the bullet, so that a secure fit of the cap 4 on or in the body 1 of the bullet is ensured. Since the inside of the cap also corresponds to the shape of the core body, due to this, the latter is simultaneously centred and fixed at the front.

To achieve the principle on which the invention is based, in Figure 1, a body 5 consisting of zirconium sponge is pressed into the cavity of the ballistic cap 4. In this case, the cap 4 consists of metal, possibly alloy.

The embodiment according to Figure 2 corresponds essentially to that according to Figure 1. However, in place of a body 5 of zirconium sponge, a body 5a of solid zirconium is pressed in.

According to the embodiment of Figure 3, the cap 4 consists of solid zirconium 5a.

The cap 4 may be hollow on the inside for ballistic reasons as well as for reasons of mass distribution.

If there are special requirements, such as a high incendiary effect, the ballistic cap 4 may be constructed according to Figure 4 such that it consists of solid zirconium and a body 5 of zirconium sponge is pressed inside the cap.

In the embodiment according to Figure 5, the cap 4 once more consists of conventional metal, such as alloy. In contrast to the embodiments according to Figures 1 to 4, the body 5 of zirconium sponge causing the incendiary effect is located coaxially and centrally in the rear 2b of the core 2.

Using the principle of the invention further unillustrated embodiments are conceivable. Thus, for example, in place of the body 5 of zirconium sponge located in the rear 2b of the hard core, a body of solid zirconium may be used. It is also possible to provide the alloy cap with a body of zirconium sponge or of solid zirconium and additionally to provide a body of one of these materials in the rear 2b of the core.

WHAT WE CLAIM IS: 1. An armour-piercing incendiary projectile comprising a casing, a sub-calibre metal core and an incendiary charge of zirconium metal.

2. A projectile as claimed in claim 1, wherein the zirconium metal is in the form of solid zirconium or zirconium sponge and is located in the rear of the core and/or in a tip of the bullet and/or constitutes said tip.

3. A projectile as claimed in claim 2, wherein said tip is constituted by a ballistic cap made of zirconium or other metal or metal alloy.

4. A projectile as claimed in claim 3, wherein the zirconium is in the form of an insert in the cap and/or the core and the shape of the insert conforms to the shape of the recess in which it is located.

5. A projectile as claimed in claim 3 or 4, wherein the ballistic cap has a spigot portion engaging and of complementary shape to a head of the core.

6. A projectile as claimed in claim 5, wherein the spigot portion is constructed without threads.

7. A projectile as claimed in claim 5 or 6, wherein the ballistic cap is pressed under pre-tension into a corresponding annular gap formed between the core head and the casing.

8. An armour-piercing incendiary projectile substantially as herein described with reference to and as illustrated in Figure 1 or Figure 2 or Figure 3 or Figure 4 or Figure 5 of the accompanying drawings.

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

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. additionally to provide a body of one of these materials in the rear 2b of the core. WHAT WE CLAIM IS:

1. An armour-piercing incendiary projectile comprising a casing, a sub-calibre metal core and an incendiary charge of zirconium metal.

2. A projectile as claimed in claim 1, wherein the zirconium metal is in the form of solid zirconium or zirconium sponge and is located in the rear of the core and/or in a tip of the bullet and/or constitutes said tip.

3. A projectile as claimed in claim 2, wherein said tip is constituted by a ballistic cap made of zirconium or other metal or metal alloy.

4. A projectile as claimed in claim 3, wherein the zirconium is in the form of an insert in the cap and/or the core and the shape of the insert conforms to the shape of the recess in which it is located.

5. A projectile as claimed in claim 3 or 4, wherein the ballistic cap has a spigot portion engaging and of complementary shape to a head of the core.

6. A projectile as claimed in claim 5, wherein the spigot portion is constructed without threads.

7. A projectile as claimed in claim 5 or 6, wherein the ballistic cap is pressed under pre-tension into a corresponding annular gap formed between the core head and the casing.

8. An armour-piercing incendiary projectile substantially as herein described with reference to and as illustrated in Figure 1 or Figure 2 or Figure 3 or Figure 4 or Figure 5 of the accompanying drawings.