SE442445B - OPENING PROJECTIL WITH LONG-TERM PERODYNAMIC SURFACES - Google Patents

Description

8100385-7 2 properties such as the combat ammunition it must replace in order for the exercise shooting to be as realistic as possible.

This requirement has then meant that, for example, the maximum firing range for the exercise ammunition has had to correspond to the maximum firing range for the combat ammunition in question. This in turn has meant that for the practice shooting, reference has been made to a few large firing ranges and that relatively large areas have had to be canceled to allow the practice shooting.

As a result, a type of projectile projectile has recently been proposed which, up to a certain firing distance, exhibits substantially the same ballistic properties as the munitions in question, but which has a maximum firing range which is substantially reduced relative to conventional munitions.

The advantage of such exercise ammunition is that realistic shooting exercises can be carried out on much smaller practice fields than has previously been the case.

An example of an exercise projectile of the above-mentioned type is described in German patent 1 678 197. This exercise projectile comprises in its front part a number of channels which are designed in such a way that an air flow is formed in the channels and gives the projectile an impulse in the opposite direction of the projectile's direction of rotation. In an alternative embodiment, these channels can be replaced by a number of vanes 7, but even in this case it is the axial air flow that is used to give the projectile an impulse, which is opposite in relation to the direction of rotation of the projectile.

By thus designing the projectile with means which deflect the axial air flow, the rotation of the projectile can be slowed down so much that it finally reaches a critical value where the projectile is no longer stable in its trajectory but tips or "overturns".

Thereby, the air resistance increases very sharply with the result that the firing width is limited.

A disadvantage of the described projectile is that both the deflection channels and the vanes make the projectile relatively complicated and thus expensive to manufacture. It is also difficult to adapt the projectile to different shooting distances. Through the interventions in the front part of the projectile, there is also a risk that the ballistic properties of the projectile will also change up to the firing distance. The object of the present invention is therefore to provide a simpler exercise projectile from a manufacturing point of view which can also be easily adapted to different firing distances. What can then mainly be considered to characterize the invention is that the aerodynamic surfaces are formed directly on the cylindrical intermediate part of the projectile. The aerodynamic surfaces can then either be designed as fins, which is suitable for a sub-caliber projectile, or formed by grooves or recesses taken up directly in the cylindrical surface, for example with a full-caliber projectile. What the two types have in common is that the air resistance increases in the projectile's rotation rotation and causes the projectile's rotation to slow down after firing. At a certain rotational speed, the projectile becomes unstable and "overturns". By adjusting the positions of the surfaces, fi xmhá <and / or number, this critical speed can be made to occur at a desired distance, usually immediately after the target distance during practice shooting.

In the following, the invention will be described in more detail in connection with the accompanying drawings, which in Figure 1 show three different configurations in the case that the aerodynamic surfaces consist of fins on the cylindrical intermediate part and in Figure 2 an alternative embodiment where the aerodynamic surfaces are formed by receiving grooves in the cylindrical surface.

The projectile body shown in the figures is an example of a suitable projectile shape and is in its basic form identical in all cases and comprises a conical tip 1, a cylindrical intermediate part (body) 2 and a tail portion 3. The projectile has in this case been designed for launching by means of a drive mirror (not shown) and has therefore been fitted with a tail section with grooves for carrying. In the case of a full-caliber version, however, the tail section may have a different design.

On the cylindrical web 2, four fins 4 are symmetrically placed around the periphery of the projectile but axially in three different places: at the front (figure a), in the middle (figure b) and at the rear (figure c) on the cylindrical web 2. The fins are axial oriented, i.e. parallel to the projectile axis of the projectile 5, and extends substantially radially from the cylindrical web 2. In the axial direction the fins occupy about one third of the length of the cylindrical web and in the radial direction about one fifth of the radius of the cylindrical 8100385 -7 4 life 2. For aerodynamic reasons, the front transverse surface 6 of the fins is chamfered so that it forms 450 with the projectile axis of symmetry 5 and further the edges are ground approximately 450 so that the fin forms a point forward.

As the projectile rotates after exiting the fire tube of the piece, the side surfaces of the fins will, due to the air resistance, slow down the rotational movement of the projectile. When this movement is slowed down so much that the speed is below a certain critical value, the projectile is no longer stable but tilts or "overturns", which means that the projectile's air resistance increases sharply so that its forward movement is also slowed down. By choosing the size of the fins, ie their extent in the radial and axial direction and their positions in the axial direction in an appropriate manner, the said instability can occur immediately after the actual target distance.

Compared with previously proposed ducts or surfaces for deflecting the air flow in the axial direction, the described projectile means a significant simplification from a manufacturing point of view. No intervention in the basic shape of the projectile body needs to be made. The fins can be mounted separately on the cylindrical web 2 but can also alternatively be mounted on a replaceable ring which is threaded on the cylindrical web 2. The latter is an advantage because then a number of replaceable rings can be used with different fin configurations adapted for different shooting distance. In figure 1a such a ring 7 has been indicated which in this case is immersed in a corresponding recess in the cylindrical surface of the web 2.

Figure 2 shows an example of an alternative embodiment where the aerodynamic surfaces for braking the rotation of the projectile are formed by grooves 8 in the cylindrical intermediate part 2 of the projectile.

Like the fins, the grooves 8 are symmetrically arranged around the periphery of the projectile and the position, depth and extent of the grooves in the axial direction can be easily adapted for the braking effect one wishes to achieve. If the grooves 8 do not occupy the entire cylindrical life in the axial direction, the groove is suitably terminated with a chamfer 9 of 450 for aerodynamic reasons.

The embodiment according to Figure 2 can be used for both sub-caliber projectiles and full-caliber projectiles, while the variant according to Figure 1 with fins is used for sub-caliber projectiles. In the case of sub-caliber projectiles, the projectile is provided with a propulsion mirror, in which case the fins and grooves in the intermediate part can advantageously be used as support for this propulsion mirror.

The invention is not limited to the embodiments shown above as examples, but can be modified within the scope of the following claims. In the embodiments shown above, for example, four symmetrically placed fins and grooves have been indicated. It will be appreciated that another number may be chosen. Furthermore, of course, the fins or grooves can have the same extent in the axial direction as the cylindrical: life 2.

Claims (7)

1. 00385-7 XTENTKRAV. 2. A rotationally stabilized exercise projectile of the type which, up to a certain firing range, exhibits substantially the same ballistic properties as the munitions in question, but which has a maximum e to the conventional range which is substantially reduced relative to the ionic munitions, including a leading cylindrical member. intermediate part and a compared with the pointed part ch intermediate part short, cut-off tail portion, and provided with an 8) mainly radially directed and characterized snakes directly on ntal aerodynamic surfaces (4, arallella with the projectile symmetry axis (5) (4, 8) is the cylindrical intermediate part of the projectile (2). (2). Projectile according to Claim 2, characterized in that the aerodynamic surfaces consist of fins (4) arranged directly on the cylindrical surface of the intermediate part (2). A projectile according to claim 3, characterized in that the fins (4) in the radial direction have an extension of approximately one fifth of the radius of the cylindrical intermediate part (2). 5. A projectile according to claim 2, characterized in that the aerodynamic surfaces consist of grooves (8) received directly in the cylindrical surface of the intermediate part (2). Projectile according to Claims 3 or 5, characterized in that the fins (4) or the grooves (8) are arranged symmetrically around the periphery of the intermediate part (2). A projectile according to claim 3, characterized in that the fins (4) are arranged on a replaceable ring (7) which in turn is mounted on the cylindrical intermediate part (2).