Patent Publication Number: US-6220544-B1

Title: Guided missile

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention concerns a guided missile in particular a projectile which can be fired through the intermediary of a propellent charge gas pressure. 
     2. Discussion of the Prior Art 
     A guided missile of that kind or a mounting arrangement for the rudder blade of such a missile, in particular a projectile which can be fired by means of propellent charge pressure and which can be maneuvered by way of an over-calibre crossed-rudder system is known for example from DE 34 41 534 A1. When such a projectile is fired the rudder blades are folded in, that is to say they are mounted in associated guide and mounting slots in the projectile. Due to the usual, slightly irregular combustion of the propellent charge powder differential pressures occur in the propellent charge chamber, which can bend or twist the rudder blades. In order to prevent the rudder blades from being bent or twisted in that way the rudder blades are mounted or guided in guide slots. In the known projectiles the guide slots are open at the front end in order to make it easier for the rudder blades to be pivoted into the open condition after the respective projectile has been launched. Due to the guide slots being open at their front end in the known projectiles of the kind set forth in the opening part of this specification however it is only possible to a limited extent to avoid bending or twisting of the rudder blades due to the differential pressures in the propellent charge chamber. 
     SUMMARY OF THE INVENTION 
     Therefore the object of the present invention is to provide a guided missile of the kind set forth in the opening part of this specification in which such deformations of the rudder blades by bending or twisting as a result of the pressure differences obtaining in the propellent charge chamber are avoided to a further improved extent. 
     The fact that, in the guided missile according to the invention, each guide slot is closed at its front end by an end portion which is formed with a spoiler end face affords the advantage that, when the projectile is launched, a direct and immediate afflux flow in relation to the rudder blades at their distal end face, that is to say their end face which is remote from their pivot axis, is prevented, which affords the result that flexural and twisting deformation phenomena of the rudder blades can be prevented to a further improved degree. The respective spoiler end face advantageously produces an air flow in such a way that a force component radially inwardly in relation to the longitudinal axis of the projectile, which would prevent or slow down deployment of the rudder blades is avoided. 
     It is quite particularly desirable if, in the guided missile according to the invention, the end portion protrudes in a radial direction of the projectile beyond the longitudinal ribs and the associated rudder blade is provided at its distal end portion with narrow guide ribs which project out of the rudder blade profile and which are disposed in laterally mutually opposite relationship. Such a design configuration for which independent patent protection is requested optimally prevents undesired deformation of the rudder blades due to bending or twisting as a result of the inevitable differential pressures in the propellent charge chamber because. in the inwardly folded condition of the rudder blades, said guide ribs are in contact in the guide slot which is of increased height at its front end, thereby providing for suitable support for the respective rudder blade. 
     In the case of longer rudder blades, each rudder blade can be formed in a central portion with additional narrow guide ribs which are disposed in laterally mutually opposite relationship. 
     In order further to improve the pivotal opening movement of the rudder blades after the projectile according to the invention has been launched, it is desirable if a spring element is provided between the root portion of the respective rudder blade and the associated rudder blade holder for deployment of the rudder blade. The respective spring element can be formed by a spiral spring which with its spiral turns extends around the pivot axis about which the rudder blade can be pivoted open in relation to the associated rudder blade holder. 
     A protected and aerodynamically favourable arrangement of the respective spring element is afforded if the root portion of the rudder blade, for receiving the spiral turns of the spiral spring, is formed with a partially open gap or slot space which extends in an annular configuration around the pivot axis. 
     The guided missile according to the invention provides for a comparatively desirable flow therearound. That desirable flow around the missile advantageously results in unimpeded and consequently faster and more uniform, that is to say symmetrical, opening pivotal movement of the rudder blades. In addition, upon launch the mechanical loading on and thus the deformation of the rudder blades are relatively slight, thereby advantageously resulting in the positioning and control accuracy of the rudder blades being maintained. 
     The configuration of the longitudinal ribs which laterally delimit the respective guide slot, with an end portion which is closed at the front end and which projects beyond the longitudinal ribs in the radial direction of the projectile, and the configuration of the respective rudder blade with laterally mutually oppositely disposed guide ribs at the distal end portion of the respective rudder blade, that is to say the improved guidance effect for the respective rudder blade at its distal end portion, afford the further considerable advantage that the torques which take effect on the root portion of the respective rudder blade upon launch of the missile are considerably reduced. That has a correspondingly positive effect on the positional and control accuracy for the rudder blades. as has already been mentioned above. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further details, features and advantages will be apparent from the following description of an embodiment illustrated by way of example in the drawing of the guided missile according to the invention which is in particular a projectile which can be fired by means of propellent charge gas pressure. In the drawing: 
     FIG. 1 is a partly sectional side view of a tail structure of the projectile, the rudder blades being in the inwardly folded position, 
     FIG. 2 is a view in longitudinal section of a part of the tail structure shown in FIG. 1, with the rudder blades being shown in the steering position of being pivoted open, 
     FIG. 3 is a partly sectional view on a larger scale of a portion of the tail structure shown in FIGS. 1 and 2 in combination with a rudder blade in the inwardly folded position, 
     FIG. 4 is a side view of a rudder blade of the projectile, and 
     FIG. 5 is a view in section taken along line V-V in FIG.  4  through the rudder blade to illustrate the laterally mutually oppositely disposed guide ribs at the distal end portion of the rudder blade. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to FIG. 1, shown in partial section therein as a side view is a tail structure  10  of a guided missile  12  which is in particular a projectile which can be fired by means of propellent charge gas pressure. As can also be seen from FIG. 2, provided on the tail structure  10  are rudder blade holders  14  which are disposed in diametrally mutually opposite relationship in pairs and which are each displaceable about a steering axis  16 . Provided on each rudder blade holder  14  is an associated rudder blade  18  which is pivotable about a pivot axis  20  between the inwardly folded position shown in FIG.  1  and the pivoted-open steering position shown in FIG.  2 . 
     To mount the rudder blades  18  the tail structure  10  of the missile  12  is formed with guide slots  22 . Each guide slot  22  is defined by two lateral longitudinal ribs  24  and is closed at the front end by an end portion  26 . Each end portion  26  is formed with a spoiler end face  28 . Each end portion  26  projects in the radial direction beyond the lateral longitudinal ribs  24 . That projection distance is indicated in FIG. 2 by reference numeral  30 . 
     As can also be seen from FIGS. 3,  4  and  5 , each rudder blade  18  is formed at its distal end portion  32  that is remote from the associated pivot axis  20 . with narrow guide ribs  36  which protrude out of the rudder blade profile  34  and which are disposed in laterally mutually opposite relationship, as can be seen from FIG.  5 . 
     If the rudder blades  18  are of a given length, then each rudder blade  18  for example can also be formed in a central portion between its distal end portion  32  and its proximal root portion  38  with additional narrow guide ribs  26 ′ as shown in FIG. 4, which are disposed in laterally mutually opposite relationship. 
     In order to facilitate or promote the pivoting opening movement of the rudder blades  18  from the position shown in FIG. 1 into the position shown in FIG. 2, a spring element  40  (see FIG. 2) is provided between the root portion  38  of the respective rudder blade  18  and the associated rudder blade holder  14 . The respective spring element  40  can be formed by a spiral spring which extends with its spiral turns around the pivot axis  20 . As can also be seen from FIG. 4, the root portion  38  of the respective rudder blade  18 , for receiving the spiral turns of the spiral spring  40 , can be formed with an annular depression. that is to say with a gap as indicated at  42 , which extends in an annular configuration around the associated pivot axis  20  and which is partially open in order to be able to secure the one end portion  48  of the spring element  40  to the associated rudder blade holder  14 . The second end portion  46  of the spring element  40 , which is remote from the first end portion  44 , is fixed to the rudder blade  18 , that is to say to an annular fixing portion  48  of the root portion  38  of the rudder blade  18  (see FIG.  2 ). 
     
       
         
           
               
             
               
                   
               
               
                 List of references 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                   
                 10 tail structure (of 12) 
               
               
                   
                 12 missile 
               
               
                   
                 14 rudder blade holder 
               
               
                   
                 16 steering axis (of 18) 
               
               
                   
                 18 rudder blade 
               
               
                   
                 20 pivot axis (for 18) 
               
               
                   
                 22 guide slot (in 10) 
               
               
                   
                 24 longitudinal ribs (on 10) 
               
               
                   
                 26 end portion (of 24, 26) 
               
               
                   
                 28 spoiler end face (of 26) 
               
               
                   
                 30 projection distance (of 26) 
               
               
                   
                 32 distal end portion (of 18) 
               
               
                   
                 34 rudder blade profile 
               
               
                   
                 36 guide ribs (on 32) 
               
               
                   
                 38 root portion (of 18) 
               
               
                   
                 40 spring element (for 18) 
               
               
                   
                 42 gap (at 38) 
               
               
                   
                 44 end portion (of 40) 
               
               
                   
                 46 second end portion (of 40) 
               
               
                   
                 48 annular fixing portion (at 38)