Abstract:
A sub-caliber projectile is described for insertion into a projectile receptacle ( 8 ) having a projectile head ( 1 ) and a tail unit ( 2 ) forming guide vanes ( 4 ), which engages in a cavity of the projectile head ( 1 ). To provide advantageous construction conditions, it is suggested that the guide vanes ( 4 ) of the tail unit ( 2 ) extend up into the hollow projectile head ( 1 ) and the projectile head ( 1 ) be folded clamped into the groin area between the guide vanes ( 4 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is the National Stage of PCT/AT2006/000422filed on Oct. 12, 2006, which claims priority under 35 U.S.C. §119 of Austrian Application No. A 1675/2005 filed on Oct. 13 , 2005. The international application under PCT article 21(2) was not published in English. 
     1. Field Of The Invention 
     The invention relates to a sub-caliber projectile for use in a projectile receptacle having a projectile head and a tail unit forming guide vanes, which engages in a cavity of the projectile head. 
     2. Description Of The Prior Art 
     Sub-caliber projectiles require a projectile receptacle for sealing the projectile in relation to the barrel of a shotgun, for example. The projectile receptacle, which may be implemented as a propellant cup, sabot, or propellant collar, is inserted together with the projectile in a cartridge casing, from which it is driven out after the firing of the propellant charge of the cartridge with the aid of the resulting propellant gases together with the projectile in the barrel. After leaving the barrel, the projectile receptacle is separated from the projectile, which flies further. For this purpose, the projectile receptacle may be provided with intended separation points distributed around the circumference, which cause an umbrella-like spreading of the projectile receptacle and thus detachment from the projectile when the projectile receptacle exits from the barrel. To ensure a stable flight path for the projectile, which flies further, the projectile may have a tail unit having guide vanes projecting radially from the projectile body (U.S. Pat. No. 4,434,718 A). Because different uses require different projectiles, different projectile shapes are provided for different intended uses, which require additional adaptation of the projectile receptacle in particular for sub-caliber projectiles. 
     In order that a center-of-gravity location advantageous for the flight stability may be ensured in sub-caliber projectiles, assembling the projectile from a projectile head and a tail unit separate therefrom, which comprises a material lighter than the projectile head, is additionally known (DE 583 098 B). To connect projectile head and tail unit, the tail unit has a connection projection having a widened head, which is anchored in a corresponding undercut receptacle recess in the base of the projectile head. A complex production method results because this connection requires a melting procedure. 
     SUMMARY OF THE INVENTION 
     Proceeding from a sub-caliber projectile of the type described at the beginning, the invention is thus based on the object of providing a simple, less cumbersome production of sub-caliber projectiles for various intended uses, without having to adapt the projectile receptacle in each case. 
     The invention achieves the stated object in that the guide vanes of the tail unit extend up into the hollow projectile head, and the projectile head is folded clamped into the groin area between the guide vanes. 
     Because the projectile head extends into the area of the guide vanes of the tail unit as a result of these measures, the tail unit may be connected in a formfitting and permanent manner to the hollow projectile head by simply folding in a wall section in the groin area between the guide vanes of the tail unit. This clamp connection allows the use of a uniform shape of the tail unit for different projectile heads with the advantage that not only is the production effort reduced, but rather also additional adaptation of the projectile receptacle to the various projectiles may be dispensed with, because in general the tail unit determines the shape of the projectile receptacle, in particular if the tail unit extends up into the projectile head. 
     In addition, the projectile head is centered in relation to the tail unit without additional measures by the clamping folding in of the wall section. 
     Although various embodiments are possible for the tail units, especially favorable flight conditions result if the tail unit has a main body tapering away from the projectile head, from which the wings tapering off toward the projectile head project radially. 
     Because the projectile head has to receive the tail unit, the capability of housing active agents in the projectile head is restricted. To nonetheless be able to use projectiles according to the invention as carriers for a sufficient quantity of such active agents, the tail unit may be implemented as a hollow. This cavity of the tail unit may also be used as the receptacle of an auxiliary compound or as the receptacle chamber for propellant gases, to displace the projectile center of gravity or to support the detachment of the projectile receptacle through the propellant gases flowing out of the cavity of the tail unit after the projectile exits from a barrel, for example. It does not have to be emphasized further here that the tail unit may also be equipped with a tracer unit at the rear end of the main body of the tail unit. 
     If the tail unit has a section which is setback by the wall thickness of the hollow projectile head and receives the projectile head, a continuous transition from the projectile head to the tail unit may be ensured easily, which improves the flight properties of the projectile. To further improve the flight properties, the vanes of the tail unit may form a control surface inclined in relation to an axial plane in the area of its rear end, which ensures a torque around the projectile axis because of the flow conditions against it, so that the flight stability is increased as a result of the rotation of the projectile around its axis connected thereto. 
     The projectile head may have a setback annular shoulder, which is not only used for the axial support of the projectile receptacle in relation to the projectile, but rather also may provide a contribution to the flight stabilization of the projectile. If the annular shoulder is shaped into an axial annular web having radial notches or slots distributed around the circumference, the effect of the projectile upon incidence on the target may additionally be lastingly influenced, because this annular web tears apart axially as a result of the notches and/or slots and is bent radially outward. A similar effect may be achieved by other implementations of the projectile head, for example, in that the projectile head has an annular bead formed by a centric or annular recess on the front face, which is provided with radial notches or slots distributed around the circumference, which in turn result in an expansion of the annular bead upon incidence of the projectile on a target. To support the mushrooming expansion of the projectile head, the centric recess in the projectile head may extend up to the cavity of the tail unit, a spreading core projecting into the cavity of the tail unit being inserted into the recess, which engages with an annular shoulder in an expansion of the recess provided adjoining the tail unit in the projectile head. Upon incidence of the projectile on the target, the annular bead is additionally expanded with the aid of the annular shoulder of the spreading core by the kinetic energy of the spreading core, by which the effect of the projectile is improved. 
     To improve the penetrating power of the projectile, the projectile head may have an insert made of a heavier material, whose greater kinetic energy may be used for specific intended purposes. If a softer insert is selected, the plastic deformation of the insert may be used for a special projectile effect upon incidence on a harder target. The projectile head may also be molded from a granular material, however, which disintegrates upon incidence on a target. 
     To increase the penetrative force of a projectile, an opening which lengthens the cavity of the tail unit may also be provided in the projectile head to receive a hard projectile core extending into the cavity of the tail unit, which, upon joining of projectile head and tail unit, is held between these design parts without additional measures. Because of its kinetic energy, the projectile core penetrates the front face of the projectile head upon incidence of the projectile on the target and penetrates into the target object. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The subject matter of the invention is illustrated as an example in the drawing. 
         FIG. 1  shows a projectile according to the invention in a simplified side view, 
         FIG. 2  shows the projectile from  FIG. 1  in a base view, 
         FIG. 3  shows a section along line III-III of  FIG. 2 , 
         FIG. 4  shows a section along line IV-IV of  FIG. 3 , and 
         FIGS. 5 through 10  each show different embodiments of a projectile according to the invention in a partially cutaway side view. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The projectile according to the exemplary embodiment from  FIGS. 1 through 4  has a projectile head  1  and a tail unit  2  having guide vanes  4  projecting radially from a main body  3 . The configuration is selected in such a manner that the main body  3  tapers away from the projectile head  1  toward the projectile base, while the guide vanes  4  taper off toward the projectile head  1 . The projectile head  1  is implemented as hollow and has a pot shape, whose wall is identified by  5 . An axial section  6  of the tail unit  2  engages in this pot shape of the projectile head  1 , as may be inferred from  FIGS. 3 and 4  in particular. The guide vanes  4  extend up into the area of the projectile head  1 , whose wall  5  is folded into the groin area between the guide vanes  4 , which is obvious above all from  FIGS. 3 and 4 . This folding in of the wall  5  in accordance with the course of the guide vanes  4  provides a formfitting, self-centering clamped seat between the projectile head  1  and the tail unit  2 . Because the axial section  6  of the tail unit  2  is set back by the thickness of the wall  5  of the projectile head  1 , a continuous transition between the projectile head  1  and the tail unit  2  in the area of the external surface results for the projectile, so that advantageous flow conditions may be maintained for the projectile. 
     The projectile head  1  is provided with a setback annular shoulder  7 , which on one hand improves the flight stability of the projectile and on the other hand is used for an axial support of a projectile receptacle  8 , indicated by dot-dash lines in  FIG. 3 . This projectile receptacle  8 , which is implemented as a propellant cup according to the exemplary embodiment, causes a seal of the sub-caliber projectile in the barrel from which the projectile is fired. The projectile is therefore also inserted together with the projectile receptacle  8  in a cartridge casing, which receives the propellant charge between the cartridge base and the propellant cup. 
     Because of the division of the projectile into a projectile head  1  and a tail unit  2  manufactured separately from the projectile head  1 , which is permanently connected to the projectile head by folding in the wall  5  of the projectile head in the groin area between the guide vanes  4  of the tail unit, advantageous conditions are provided for the production of various projectiles, without having to tailor the projectile receptacle  8  to the particular projectile, because the tail unit  2 , which extends over a significant length of the projectile, may be used for various projectiles without a shape change. To be able to take different embodiments of the projectile into consideration, the tail unit  2  may additionally be implemented as hollow, so that if needed the cavity  9  may be used for receiving an active agent or an additional compound. 
     Although the sub-caliber projectile already provides good flight properties because of the tail unit  2 , the flight stability may be improved further if the guide vanes  4  form a control surface  10  inclined in relation to an axial plane in the area of its rear end, as indicated in  FIGS. 1 and 2 . These control surfaces  10  cause a torque on the projectile because of the air flowing against them, which sets the projectile into rotation around its longitudinal axis, so that the flight stability of the projectile may be improved by the twist thus achieved. 
     Various embodiment variants are illustrated in  FIGS. 5 through 10 , which may be produced easily because of the design of the projectile according to the invention. However, this selection is only exemplary and does not preclude other embodiments. According to the exemplary embodiment from  FIG. 5 , which shows a tail unit  2  corresponding to the exemplary embodiment from  FIGS. 1 through 4 , the annular shoulder  7  is implemented as an axial annular web  11 , which has radial notches  12  distributed around the circumference, so that because of the notch effect, the annular web  11  tears open upon incidence on a target and the sectors of the annular web  11  formed by the tearing are bent radially outward. In addition, the cavity  9  of the tail unit  2  is filled up with an auxiliary compound  13  to increase the projectile weight and achieve a center of gravity displacement. 
     According to  FIG. 6 , the projectile head  1  is provided on its front face with an annular recess  14  coaxial to the projectile longitudinal axis, which separates an external annular bead  15  from the remaining projectile head  1 . This annular bead  15  again has notches  16  distributed around the circumference to achieve tearing open of the annular bead  15  upon impact, and thus improve the effect of the projectile. According to  FIG. 7 , the projectile head  1  forms a centric recess  17  coaxial to the projectile axis, so that an annular bead  15  again results, which is provided with radial notches or slots  18  for tearing open, to ensure spreading open of the projectile head  1  along these slots  18 . 
     A projectile head  1  which has an insert  19  made of a heavier or softer material than the remaining projectile head  1  is illustrated in  FIG. 8 . With a heavier insert  19 , the penetrative force of the projectile is increased. If the insert  19  is softer, the plastic deformation of the insert  19  upon incidence of the projectile on a target may be used for a special projectile effect. 
     According to  FIG. 9 , the projectile head  1  forms an opening  20  lengthening the cavity  9  of the tail unit  2  for receiving a hard projectile core  21  extending into the cavity  9  of the tail unit  2 , which is axially secured when the projectile head  1  is clamped on the tail unit  2  by folding in the projectile wall  5  between the projectile head  1  and the tail unit  2 . This projectile core  21 , which is manufactured from steel, for example, penetrates the front wall  22  of the projectile head  1  upon incidence of the projectile on a target, to penetrate deeper into the target. 
     The projectile according to  FIG. 10  is provided with a spreading core  23 , which is inserted into a centric recess  17  of the projectile head  1  extending up to the cavity  9  of the tail unit  2  and projects into the cavity  9 . This spreading core  23  has an annular shoulder  24 , which engages in an expansion  25  of the recess  17  of the projectile head  1  adjoining the tail unit  2 . Upon incidence of the projectile on a target, the kinetic energy of the spreading core  23  causes the annular bead  15 , which is formed by the recess  17  and provided with notches  16 , to be additionally expanded via the annular shoulder  24  after tearing open, which increases the effect of such a projectile.