Abstract:
A sabot system is defined by a tubular arrangement of curvilinear segments with the tubular arrangement being closed on a first end thereof and open on a second end thereof. The tubular arrangement defines a first outer diameter at its first end and a second and larger outer diameter at its second end. Each segment is made from an elastic material such that when the tubular arrangement is compressed radially at its second end, each of the segments stores a spring force.

Description:
ORIGIN OF THE INVENTION 
     The invention described herein was made in the performance of official duties by employees of the Department of the Navy and may be manufactured, used, licensed by or for the Government for any governmental purpose without payment of any royalties thereon. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to sabots, and more particularly to a sabot system using curvilinear sabot segments for efficient discard at projectile launch. 
     BACKGROUND OF THE INVENTION 
     A sabot supports a subcaliber projectile/round in a larger caliber launch barrel. After launch, a sabot should release or fall away from the projectile/round. Ideally, this situation occurs very quickly after the launch barrel is exited. Typically, sabot petals or segments are straight along their length and depend entirely on aerodynamic forces to bring about their separation from a projectile after exiting a launch barrel. Some sabot systems utilize retaining systems that must fail before aerodynamic forces can act on the petals/segments. Thus, current sabot systems designs have some inherent inefficiencies that can cause sabot petals/segments to remain with the projectile segments longer than necessary. These inefficiencies may cause unwanted drag and/or destabilizing forces on the projectile/round that ultimately affect its trajectory and/or range. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a sabot system that is discarded from a launched projectile/round in an efficient fashion. 
     Another object of the present invention is to provide a sabot system that is simple and reliable. 
     Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings. 
     In accordance with the present invention, a sabot system is defined by a tubular arrangement of curvilinear segments adapted to receive a subcaliber projectile therein. The tubular arrangement is closed on a first end thereof and open on a second end thereof. The tubular arrangement defines a first outer diameter at its first end and a second outer diameter at its second end. The first outer diameter is less than the second outer diameter. Each segment is made from an elastic material such that when the tubular arrangement is compressed radially at its second end, each of the segments stores a spring force. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects, features and advantages of the present invention will become apparent upon reference to the following description of the exemplary embodiments and to the drawings, wherein corresponding reference characters indicate corresponding parts throughout the several views of the drawings and wherein: 
         FIG. 1  is a side cross-sectional view of a sabot system prior to its placement in a launch barrel in accordance with an embodiment of the present invention; 
         FIG. 2  is a head on view of the sabot system taken along line  2 - 2  in  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of the sabot system positioned in a launch barrel; 
         FIG. 4  is a cross-sectional view of the sabot system as it begins to exit the launch barrel; 
         FIG. 5  is a cross-sectional view of an aft end of a sabot system in accordance with another embodiment of the present invention; and 
         FIG. 6  is a cross-sectional view of an aft end of a sabot system in accordance with yet another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, simultaneous reference will be made to  FIGS. 1 and 2  where a sabot system in accordance with the present invention is referenced generally by numeral  10 . Sabot system  10  is illustrated as it would appear prior to its positioning in a launch barrel. As would be understood in the art, sabot system  10  is designed to hold or support a projectile  100  (illustrated by dashed lines to indicate that it is not part of the present invention) which is a subcaliber projectile or round in terms of the barrel (not shown) that it is to be launched from. Further, while projectile  100  is completely contained within sabot system  100 , the present invention is not so limited as projectile  100  could partially protrude from sabot system  10 . 
     Sabot system  10  includes multiple elements that can be fabricated as an assembly or as an integrated, one-piece structure without departing from the scope of the present invention. Accordingly, it is to be understood that the particular construction/fabrication details used to make sabot system  10  are not limitations of the present invention, and that words such as “coupled,” “attached,” etc., used herein apply equally as well to mechanically linked elements and integrated elements. 
     Sabot system  10  includes a base plate  12  (i.e., also referred to in the art as a “pusher plate”) and a number of petals or segments  14  coupled to and extending away from plate  12  to form an open tube-like structure. Segments  14  extend along projectile  100  and are distributed about radial surfaces of projectile  100  as illustrated. In the illustrated embodiment, four segments  14  are shown. However, more or fewer segments could be used in the present invention without departing from the scope of thereof. 
     Base plate  12  is generally a circular plate of diameter “D 1 ” that will allow it to form a sliding fit with the internal diameter of a launch barrel. The outer face  12 A of base plate  12  will receive launch impulse when sabot system  10  and projectile  100  are to be expelled from a launch barrel. Accordingly, base plate  12  will generally be solid as illustrated. 
     Each of segments  14  will generally be the same so that a description of one segment  14  will provide an understanding of the present invention. However, as will be appreciated by one of ordinary skill in the art, segments  14  need not be identical to accomplish the goals of efficient discard in accordance with the present invention. 
     Each segment  14  extends from its constrained end  14 A (i.e., where coupled to base plate  12  such that ends  14 A lie within the confines of diameter D 1 ) along all (or a portion) of projectile  100  to an unconstrained end  14 B. Between ends  14 A and  14 B, segment  14  traverses a curvilinear path (e.g., a simple arc as shown) such that end  14 B lies outside an imaginary right circular cylinder (indicated by dashed line  16 ) formed by an axial extension of base plate  12 . For example, ends  14 B could reside on the perimeter of circle (as best seen in  FIG. 2 ) having a diameter “D 2 ” that is larger than diameter D 1 . 
     In addition to their curvilinear structure described above, each of segments  14  is made from a flexible and elastic material. That is and as will be explained further below, when segments  14  are compressed radially towards projectile  10 , each of segments  14  develops and stores a spring force in opposition to the radial compression force. Suitable materials for segments  14  (and base plate  12 ) include a variety of plastics and metals, the choice of which is not a limitation of the present invention. 
     In operation, sabot system  10  and projectile  100  are positioned in a barrel  300  of a launcher as illustrated in  FIG. 3 . The inner surface of barrel  300  causes ends  14 B of segments  14  to be compressed radially against projectile  100  such that segments  14  develop and store a spring force F s . During launch, base plate  12  receives an impulse force F I  that propels sabot system  10  and projectile  100  down barrel  300 . When ends  14 B exit barrel  300  as illustrated in  FIG. 4 , spring force F s  acts to initiate the spreading of segments  14  from projectile  100 . That is, the discard operation of sabot system  10  is initiated before it fully exits barrel  300 . This pre-spreading of segments  14  allows sabot system  10  to make more efficient use of aerodynamic forces since segments more readily catch air as sabot system  10  exits barrel  300 . Furthermore, the initiation of segment spreading does not require the failure of a retaining system for its operation. Therefore, sabot system  10  achieves its discard operation in an efficient and reliable fashion. 
     Although the invention has been described relative to a specific embodiment thereof, there are numerous variations and modifications that will be readily apparent to those skilled in the art in light of the above teachings. For example, unconstrained ends  14 B can be tapered as shown to direct air flow into the tube-like region defined by segments  14  thereby hastening the spreading of segments  14  as they exit barrel  300 . In addition and as mentioned above, ends  14 A can be coupled to base plate  12  in a variety of ways. Two other exemplary embodiments are illustrated in  FIGS. 5 and 6 . In  FIG. 5 , ends  14 A are coupled to the outside edge face of base plate  12  such that diameter D 1  is defined by the outside edges of base plate  12 . In  FIG. 6 , ends  14 A are fitted in base plate  12  with the outer edges of base plate  12  forming an annular ring that forms a sliding fit with a launch barrel. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described. 
     Finally, any numerical parameters set forth in the specification and attached claims are approximations (for example, by using the term “about”) that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of significant digits and by applying ordinary rounding.