Ejectable aerodynamic cap for guided munition and guided munition comprising such a cap

Abstract

An ejectable protective cap for controlled munition comprises a munition body of cylindrical form, having a front end comprising a central part directed toward a target. The cap comprises n portions distributed around a longitudinal axis, to cover the front end, n being an integer≧2, a cap portion having an edge in contact with an edge of a contiguous cap portion with it in a respective plane of assembly of two contiguous cap portions passing through the longitudinal axis, a pyrotechnic initiator for each cap portion comprising a pyrotechnic initiator body securely attached to the respective cap portion, a piston plunger that can slide in a seal-tight manner by one of its ends, the free other end in contact with the contiguous cap portion to separate, upon simultaneous activation of n pyrotechnic initiators, edges of the contiguous cap portions and release the front end of the munition body.

1 . An ejectable protective cap for controlled munition comprising a munition body of cylindrical form of longitudinal axis ZZ′, having a front end of the munition body comprising a central part intended to be directed toward a target, comprising:
 n cap portions C 1 , C 2 , . . . Ci, . . . Cn of the same forms, distributed around said longitudinal axis ZZ′, intended to cover the front end of the munition body, n being an integer number equal to or greater than 2, i being the rank of the cap portion, a cap portion Ci having at least one edge in contact with an edge of a cap portion which is contiguous with it in a respective plane of assembly of two contiguous cap portions passing through the longitudinal axis ZZ′, a pyrotechnic initiator for each cap portion, each of the pyrotechnic initiators comprising, along a longitudinal axis AA′, a pyrotechnic initiator body securely attached to the respective cap portion Ci, a piston plunger being able to slide in a seal-tight manner by one of its ends, along said longitudinal axis AA′, the free other end of the piston plunger being in contact with the contiguous cap portion to separate, upon the simultaneous activation of the n pyrotechnic initiators, the edges in contact of the contiguous cap portions, from their respective planes of assembly and release the front end of the munition body. 
 
     
     
         2 . The ejectable protective cap as claimed in  claim 1 , wherein each pyrotechnic initiator comprises an igniter between the pyrotechnic initiator body and the piston plunger to separate, upon its activation, the piston plunger from the body of the pyrotechnic initiator and exert a separation force F between the two contiguous cap portions. 
     
     
         3 . The ejectable protective cap as claimed in  claim 1 , wherein, n being equal to 2, it comprises two cap portions of symmetrical forms relative to a plane of assembly passing through the longitudinal axis ZZ′, the two cap portions being a bottom half-cap and a top half-cap. 
     
     
         4 . The ejectable protective cap as claimed in  claim 3 , wherein the two assembled half-caps intended to closely encompass the front end of the munition body, each comprise an outer surface wall in half-ovoid form of axis of revolution ZZ′ forming the external surface of the front of the munition. 
     
     
         5 . The ejectable protective cap as claimed in  claim 4 , wherein the two assembled half-caps comprise an internal surface of ovoid form covering the central part of the munition body connected to another internal surface of circular cylindrical form comprising a threading ( 44 ) intended to produce a threaded link with the munition body, a circular edge to abut on a shoulder of the munition body when screwed onto the munition body. 
     
     
         6 . The ejectable protective cap as claimed in  claim 5 , wherein the two half-caps comprise, in the thickness of their wall, at the level of the other internal surface of circular cylindrical form, cells on either side of a plane Py at right angles to a plane P 1  of assembly passing through the axis ZZ′ for the insertion of the pyrotechnic initiators. 
     
     
         7 . The ejectable protective cap as claimed in  claim 2 , wherein the pyrotechnic initiator body comprises, in addition, an electrical connection pin intended to receive at least two electrical wires for the activation of the igniter. 
     
     
         8 . The ejectable protective cap as claimed in  claim 3 , wherein the pyrotechnic initiators are mounted head-to-tail on either side of a plane Py at right angles to the plane of assembly of the two half-caps and passing through the axis ZZ′. 
     
     
         9 . The ejectable protective cap as claimed in  claim 3 , wherein the bottom and top half-caps each comprise a respective edge in contact with one another in the plane of assembly. 
     
     
         10 . The ejectable protective cap as claimed in  claim 9 , wherein the bottom half-cap comprises, on its edge situated in the plane of assembly, a longitudinal groove that extends on either side of the axis ZZ′, the top half-cap comprising, symmetrically relative to said plane of assembly, on its edge situated in said plane of assembly a longitudinal tenon extending on either side of the axis ZZ′ of the same external dimensions as those of the longitudinal groove ( 110 ) to form a fitting between the two half-caps of tenon/mortice type. 
     
     
         11 . The ejectable protective cap as claimed in  claim 3 , wherein the two half-caps are held together by a securing belt of circular cylindrical form of axis ZZ′, in a circular groove around two half-caps. 
     
     
         12 . The ejectable protective cap as claimed in  claim 11 , wherein the securing belt comprises, in the plane of assembly, on either side of the plane Py, embrittlement zones to provoke the rupture of said securing belt upon the separation of the half-caps by the action of the pyrotechnic initiators. 
     
     
         13 . A guided munition, further comprising an ejectable protective cap as claimed in  claim 1 . 
     
     
         14 . The guided munition as claimed in  claim 13 , wherein the central part of the munition body of cylindrical form on the axis ZZ′ is connected to the munition body by a circular cylindrical body of the same axis ZZ′ comprising a body threading intended for the screw-fastening of the cap onto the munition body and a rear part of the munition body comprising a shoulder in ring form of axis ZZ′ of tapered cone surface inscribed in a cone of generatrix Pe close to a perpendicular to the external surface of the munition body, at the level of said shoulder, the cap comprising an internal surface  40  of ovoid form covering the central part of the munition body connected to another internal surface of circular cylindrical form comprising another threading of the same diameter as the body threading intended to produce a threaded link between the cap and the munition body, a circular edge of the same form as the shoulder of the munition body abutting on this shoulder when the cap is screwed onto the munition body. 
     
     
         15 . The guided munition as claimed in  claim 14 , wherein the shoulder comprises a groove in ring form of axis ZZ′, open on its tapered cone surface, containing an electrically insulating material, comprising, on said tapered cone surface, two annular tracks, of electrically conductive material, with axes of revolution that are the same as the axis ZZ′ for the electrical connection of the pyrotechnic initiators. 
     
     
         16 . The guided munition as claimed in  claim 15 , wherein the pyrotechnic initiator body also comprises an electrical connection pin intended to receive at least two electrical wires each equipped with a flexible contact in contact with a respective annular track in the shoulder of the munition body.