A practice projectile

Abstract: A practice projectile free of any explosive or bursting charge, adapted for shooting from aircraft against ground targets or for other kinds of practice shooting and comprising a hollow shell (1), a projectile base (2) and a nose portion (3) which engages the shell along a circumferential partition (7) therebetween, wherein the base (2) is a separate part relatively to the shell (1), whereby a circumferential partition (6) between the base and the shell is formed. The base (2) is fastened to or made integral with a rod or a tube (11) which extends centrally and axially through the shell and is fastened to or made integrally with the nose portion (3), whereby the rod or tube keeps the projectile together as a unit, and the rod or tube, or a fastening member thereof situated on the nose portion, has a weakened portion which axially is situated approximately at the level of the partition (7) between the shell (1) and the nose portion (3).

Description: The invention relates to a practice projectile adapted for shooting from aircraft against ground targets or for other kinds of practice shooting, comprising a hollow shell; a projectile base; and a nose portion which engages the shell along a circumferential partition therebetween; wherein the base is a part separate from the shell whereby a circumferential partition is formed between the base and the shell; and wherein the base is fastened to or made integral with a rod or a tube which extends centrally and axially through the shell and is fastened to or made integral with the nose portion, whereby the rod or tube keeps the projectile together as a unit; and wherein the rod or tube, or a fastening member thereof situated on the nose portion has a weakened portion which is situated in axial direction approximately at the level of the partition between the shell and the nose portion. Practice shooting from aircraft against ground targets is partly performed from a relatively small height. The shooting partly takes place against targets in such a small distance ahead of the aircraft that the aircraft cannot avoid passing over the target area. In order to reduce the costs of the practice shooting projectiles without any explosive or blasting charge are normally used, which means that the projectile is not necessarily broken up into small fragments in the target. Consequently, there is a great danger that ricochets of a relatively large size can be returned upwardly from the target area, and this will happen just in the period when the aircraft having shot the projectile or projectiles passes over the target area. The aircraft, therefore, is in danger of being hit by the ricochets. The ricochets can comprise complete projectiles or large fragments thereof, and the aircraft hull can be seriously damaged and the crew can be in great danger. This problem may be avoided by not flying below a certain minimum height which is larger than the height which the ricochets can reach, but this involves that the practice shooting will not be very realistic, because the shooting must cease in such a great distance from the target that the shooting does not correspond to shooting by use of live ammunition. When live ammunition is used, the projectiles will be broken into small fragments in the target area, and the fragments can only return to a small height, without causing any danger to the aircraft. Also by other kinds of practice shooting it may be desirable or necessary to ensure that the range or height of ricochets is limited, for instance in order that they do not spread beyond the boundary of a shooting field. Different solutions of the problem of ricochetting practice projectiles have been proposed. Projectiles have been made from pressed iron shavings, in order to pulverize upon impact in a target. This solution involves the problem that the projectiles may pulverize during firing from a weapon, due to the large acceleration forces to which the projectiles are subjected. On the other hand, if the projectiles are manufactured with a large or reasonable safety against pulverizing during firing, the projectiles may not even pulverize upon impact in the target. Another attempt consists of making practice projectiles partly or entirely of plastics. This solution leads to a problem with respect to the mass of the projectiles relatively to live projectiles. It is desirable that the practice projectiles should have approximately the same mass as corresponding live projectiles, taking into account the ballistic properties. Moreover, the plastics may be overheated or melt in hot gun barrels. This is a safety problem. It must be taken into consideration that the shooting may take place with a very high firing rate (automatic weapons) and consequently with a high generation of heat. NO Patent No. 146036 describes a subcaliber projectile having a mainly massive projectile body with weakening portions which cause splitting up of the projectile body. The projectile does not comprise any hollow shell or a separate nose portion. A projectile of the type as set forth above is known, for example, from the document DE-A-4 038 371 which disclosure is taken as a basis for the preamble of independent claim 1, wherein a practice projectile is disclosed which is designed in such a manner that it is adapted to burst when pyrotechnical charges inside the projectile are ignited with a predetermined delay after the launching of the projectile when the separating elements have been ignited. In that conventional device, a rod inside the projectile has a weakening groove which will burst under tension when the charges have been ignited and act rearwardly against the base. In this respect, it is explained in detail in DE-A-4 038 371 that it is the gas pressures generated by the charges which cause the break of the weakening groove and the displacement of the bottom part in the direction indicated by an arrow away from the body of the projectile. Moreover, in the construction according to DE-A-4 038 371, the rod is closely surrounded by the shoulders of the shell segments at the front portion close to the nose. In the longitudinal direction of the projectile, the rod is further closely surrounded by the drum portion and an axial bore in the bottom portion. Hence, the rod is held and guided along its entire axial length in the interior of the projectile. The result is that the weakening grove in the conventional projectile will never burst due to any bending because the rod is mechanically supported radially along its entire length and cannot bend at all. The document EP-A-0 407 288 discloses a practice projectile which has a completely different construction wherein no central rod is used in order to connect the nose, the shell and the base of a projectile. Hence, the object underlying the present invention is to provide a practice projectile which is simple and non-expensive in its construction, which avoids any ricochetting up to a height which brings an aircraft firing such a projectile into any danger, and which at the same time secures the necessary strength of the projectile during firing. The object is solved in an advantageous manner by a practice projectile as set forth above which is characterized in that the shell is a unit constituted by an open tube which is clamped between the base and the nose and which is free of any explosive or bursting charge, in that the rod or tube extends freely through the inner space of the shell without being mechanically supported radially between its two ends, and in that the rod or tube is dimensioned to burst upon a mechanical impact of the projectile against a target under an acute angle. A further development of the projectile according to the invention is characterized in that the hollow space between the shell and the rod or tube is filled with a granular material, such as metal shavings or sand. According to a specific embodiment of the projectile according to the invention, the abutment faces between the base and the shell, and between the nose and the shell are inclined and diverge from the axis of the shell to the outside in opposite directions. With the practice projectile according to the invention, the object is solved in an advantageous and satisfying manner. Contrary to prior-art devices, no explosive or bursting charges are used or required in the practice projectile according to the invention. Rather, it is adapted to burst merely by an impact against the respective target. Thus, the practice projectile according to the invention comprises two partitions, and prior to and during firing the projectile is kept together as a unit by means of the rod or tube. Upon impact against a target, and in particular an inclined impact, the weakened portion of the rod or tube or its fastening member will burst. Thereby, the projectile is divided into units, each of which having of course a smaller mass than the complete projectile, and each of which having substantially poorer ballistic properties than the complete projectile. The air resistance or drag acting against each of the units will to a large degree limit the height to which the units can be brought by ricochetting from a target area. During practice shooting from aircraft the firing can take place similarly as during shooting of live ammunition, i.e. that the aircraft can shoot against ground targets also from small heights and distances and shortly after the firing pass over the target area, without danger of being hit by ricochetting projectiles. By other kinds of practice shooting the invention makes it possible to limit the spreading of ricochets. A projectile according to the invention can be given the same shape, mass and mass distribution as live ammunition, and without any problems the projectile can be made with such a mechanical strength that it can withstand firing from a gun or firing as a selfpropelled missile. The invention will hereinafter be explained more detailed, with reference to the accompanying drawing, which shows non-limiting examples of embodiments of a practice projectile according to the invention. Fig. 1 shows a longitudinal section through a first embodiment of a projectile according to the invention. Fig. 2 shows a longitudinal section through a second embodiment of the projectile. Fig. 3 shows a longitudinal section through a third embodiment of the projectile. Each of the Figs. shows a practice projectile comprising a shell 1, a nose portion 3 and a base 2, whereby a rod or tube 11 connects the nose portion 3 and the base 2. The base 2 constitutes a separate part relatively to the shell 1. The base 2 and the shell 1 abut each other along a partition 6. Also the shell 1 and the nose portion 3 are separate parts which abut each other along a partition 7. Thus, the rod or tube 11 keeps the projectile together as a unit prior to and during firing and also in the flight towards a target. In the embodiment of Fig. 1 a rod 11 is made integrally with the base 2, and the rod has a threaded end portion 15 which has been screwed into a threaded bore 12 in the nose portion 3. In order to ensure proper engagement in the partitions 6 and 7 the bore 12 may be somewhat longer than the end portion 15 screwed into it. In the embodiment of Fig. 2 a tube 11 is made integrally with the base 2, and the nose portion 3 comprises a threaded stud 14 which has been screwed into a threaded end portion 16 of the tube 11. The embodiment of Fig. 3 is similar to the embodiment of Fig. 1 with respect tc the connection between the base 2 and the nose portion, in that a rod 11 has been screwed into a threaded bore 12 in the nose portion 3. In this embodiment the base 2 comprises a rearwardly open recess which contains a tracer charge 10, and the recess is partly closed by means of a disc 9 which retains the charge 10 in the recess and has a central aperture. In all of the embodiments shown the shell 1 is in a conventional manner equipped with a guiding band 4, and moreover the shell has a circumferential groove 13 for fastening of a cartridge case by clamping or deforming the case into the groove. All of the projectiles shown are cartridge case ammunition, but it will be understood that the invention is not limited to this type of ammunition. In the embodiment of Fig. 2 the tube 11 extends in the entire distance between the nose portion 3 and the base 2. However, more or less of the tube length may be in the form of a massive rod, for instance in order to increase the mass of the projectile towards one of the ends thereof. The partitions 6 and 7 may be conical, in order to cause mutual alignment of the components of the projectile. If the projectiles, having an annular hollow space between the shell 1 and the rod or tube 11, have a smaller mass than live projectiles, the hollow space can be filled for instance with a granular material, such as for instance metal shavings or sand, in order to adjust the mass. In a projectile according to the invention the rod or tube 11 or the stud 14 shown in Fig. 2 is dimensioned to burst when the projectile hits a target under an acute angle after having been fired from an aircraft in a relatively small height, in a downwardly inclined direction, or after having been fired under other kinds of practice shooting. For instance the threads of the rod 11 shown in Fig. 1 or 3 or the threads of the stud 14 shown in Fig. 2 may constitute a weakened area which will burst when the projectile hits a target. Of course the rod or tube 11 or the stud 14 may comprise another kind of weakening means, such as one or more circumferential grooves. Tests will have to be carried out in order to determine whether the weakened area actually bursts under the shooting conditions which the projectiles are to be used. When the weakened area bursts the projectile will no longer be kept together as a single unit. In the embodiment of Fig. 1 the nose portion 3, possibly together with a portion of the rod 11, will constitute a first unit, the shell 1 will constitute a second unit and the base 2 and the rod 11 or a remainder of the rod will constitute a third unit. In the embodiment of Fig. 2, provided that the stud 14 is the part which bursts, the nose portion 3 will constitute a first unit, the shell 1 will constitute a second unit and the base 2, the tube 11 and the stud 14 (or the major portion of the stud) will constitute a third unit. In this embodiment the weakened area may also be situated on the tube 11, near or around the stud 14. In the embodiment of Fig. 3 the same units as in the embodiment of Fig. 1 will be constituted, the only difference being that the base 2 in the embodiment of Fig. 3 comprises the recess for the tracer charge 10. The charge 10 will of course have combusted partly or completely during the flight of the projectile. Each of the above mentioned units will have poor ballistic properties, compared with a complete projectile. Each unit has a mass which is substantially smaller than that of the complete projectile. The unit constituted by the shell 1 is an open tube, and when the velocity of this unit decreases the unit will at a certain velocity be unstable and not be able to move in a ballistic path, and the unit will then fall relatively steeply to the ground. Thus, upon an impact against a target the projectile will be divided into units which are not able to ricochet in a path of the same height or in the same range as a complete projectile. The invention is not limited to full caliber ammunition. The projectile can be a sub-caliber projectile on which a sabot is mounted for the firing, whereby the sabot is discarded immediately when free of the gun barrel. The invention can also be used for self-propelled missiles, such as rocket propelled practice grenades. In the latter case the base 2 may have a tail portion equipped with fins. All the components of a projectile according to the invention except from a tracer charge or a propulsion charge may be made of steel or metal. As a non-limiting example the shell, the rod or tube and the base may be made of steel and the nose portion may be made of a light alloy, for instance an aluminium alloy.

Claims: A practice projectile adapted for shooting from aircraft against ground targets or for other kinds of practice shooting, comprising a hollow shell (1), a projectile base (2), and a nose portion (3) which engages the shell along a circumferential partition (7) therebetween, wherein the base (2) is a part separate from the shell (1), whereby a circumferential partition (6) is formed between the base (2) and the shell (1), and wherein the base (2) is fastened to or made integral with a rod or a tube (11) which extends centrally and axially through the shell (1) and is fastened to or made integral with the nose portion (3), whereby the rod or tube (11) keeps the projectile together as a unit, and wherein the rod or tube (11), or a fastening member (14, 15) thereof situated on the nose portion (3) has a weakened portion which is situated in axial direction approximately at the level of the partition (7) between the shell (1) and the nose portion (3), characterized in that the shell (1) is a unit constituted by an open tube which is clamped between the base (2) and the nose (3) and which is free of any explosive or bursting charge, in that the rod or tube (11) extends freely through the inner space of the shell (1) without being mechanically supported radially between its two ends, and in that the rod or tube (11) is dimensioned to burst upon a mechanical impact of the projectile against a target under an acute angle. The projectile according to claim 1, characterized in that the hollow space between the shell (1) and the rod or tube (11) is filled with a granular material, such as metal shavings or sand. The projectile according to claim 1 or 2, characterized in that the abutment faces (6, 7) between the base (2) and the shell (1) and between the nose (3) and the shell (1) are inclined and diverge from the axis of the shell (1) to the outside in opposite directions.

Inventors: ANGARD INGE M, STRANDLI KARE R, ANGARD, INGE M., STRANDLI, KARE R.
Applicants: RAUFOSS AS, RAUFOSS A/S
Application year: 1992
Main classification: F42B8
IPC codes: F42B8