Abstract:
A line storage device prevents a line from becoming entangled. A channel formed in a piece of material defines a non-overlapping zigzag pattern. The line is laid in the channel and extends from opposing ends of the piece of material. The material supports the line in the channel until the line attains a threshold tension at which point the piece ruptures sequentially along the zigzag pattern from each opposing end. The channel can be formed in or on one or more surfaces of the piece of material.

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 anti-entanglement of lines, and more particularly to a device that prevents a line from becoming entangled during storage and during the payout thereof under tension. 
     BACKGROUND OF THE INVENTION 
     Systems requiring the payout of feed line during deployment typically present a potential feed line entanglement problem. An example of one such system is the U.S. Navy&#39;s anti-personnel obstacle breaching system (APOBS) disclosed in “Reliable and Effective Line Charge System,” U.S. patent application Ser. No. 09/12,932, filed on Jan. 24, 1998. Briefly, the APOBS is a portable explosive line charge system used for mine and obstacle neutralization. The system includes a rocket tethered by a line to a series of charges distributed in a spaced-apart fashion along a detonation cord. 
     As witnessed during developmental testing, the line experiences standing wave motion as the rocket propels itself down range. The distributed line charge moves through the standing wave similar to the way a wave travels down a rope that has been whipped up and down. However, rather than the wave moving through the distributed line charge, the distributed line charge moves through the wave as it flies down range. This gives the appearance that the wave is stationary above the ground and along the flight path. The standing wave causes the line to whip the distributed line charge and create acceleration loads that act in multiple directions which tend to cause line charge fuze failure, charge rupture and general entanglement of both the line and distributed line charge. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a device that prevents a system&#39;s feed line from becoming entangled prior to and during deployment. 
     Another object of the present invention is to provide a device that prevents entanglement of a tensioned line that is attached on a first end thereof to a propulsion unit and attached on a second end thereof to a distributed mass. 
     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 line storage device prevents a line from becoming entangled. At least one piece of material is formed with a channel that receives a line therein. The channel defines a non-overlapping zigzag pattern such that the line extends from opposing ends of the piece of material. The material supports the line in the channel until the line extending from the opposing ends attains a threshold tension at which point the piece ruptures sequentially along the zigzag pattern from each opposing end. The channel can be formed in or on one or more surfaces of the piece of material. 
    
    
     BRIEF DESCRIPTION OF THE INVENTION 
     FIG. 1 is a plan view of one embodiment of the line storage device of the present invention used to store line that is to be paid out between a rocket propulsion unit and distributed line charges; 
     FIG. 2A is a top plan view of another embodiment of the line storage device; and 
     FIG. 2B is a bottom plan view of the embodiment shown in FIG.  2 A. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, and more particularly to FIG. 1, one embodiment of the line storage device in accordance with the present invention is shown and referenced generally by numeral  10 . By way of example, line storage device  10  will be described for its use with a rocket-deployed line charge system, the basic elements of which are illustrated in FIG.  1 . However, it is to be understood that line storage device  10  can be used with any similar line charge or other deployment system having a propulsion unit tethered to a distributed and tethered set of individual masses. More generally, the present invention will also be of use in any system requiring the storage of excess line and tangle-free payout of the line as is the case with a parachute system. 
     In terms of the illustrated line charge system, a rocket  100  has a line  102  coupled on one end thereof to an aft end of rocket  100 . The other end of line  102  is coupled to the forward end of distributed line charge  104 . Briefly, line charge  104  includes a fuze or detonator  106  coupled to a plurality of distributed explosive charges  108  by means a detonating cord  110 . A substantial amount of line  102  (e.g., eight feet or more) extends between rocket  100  and fuze  106 . For proper operation of line charge  104 , rocket  100  must travel down range with line  102  being paid out thereafter. Payout of line  102  must be tangle-free in order to assure proper placement of line charge  104  and activation of fuze  106 . That is, if line  102  becomes entangled with itself during payout, line charge  104  may not be placed in its anticipated location. If line  102  becomes entangled with line charge  104 , failure of fuze  106  as well as inaccurate placement of line charge  104  can result. Accordingly, it is necessary to store line  102  in a tangle-free fashion as well as provide for its payout in a tangle-free fashion. 
     To achieve tangle-free storage and payout of line  102 , line storage device  10  is provided. In the embodiment illustrated in FIG. 1, line storage device  10  is a piece or block  12  of material having a channel  14  formed in a surface  16  thereof. Channel  14  is laid out in a non-overlapping zigzag pattern over the length of block  12 . Laid into channel  14  is the excess amount of line  102  between rocket  100  and fuze  106 . The width W of channel  14  can be formed so that line  102  and channel  14  are in press-fit engagement. Alteratively or additionally, line  102  can be secured in channel  14  by, for example, a light tacking glue (not shown) or by tape covering channel  14  and adhered to surface  16 . Such tape can be wrapped about block  12 . The optional tape feature is illustrated in FIG. 1 by dashed lines  18  which indicate the edges of the wrapped tape. 
     Channel  14  is accessed from either end of block  12  so that line  102  can extend from either end of block  12 . The zigzag pattern presented by channel  14  can be any nonoverlapping zigzag pattern into which line  102  can be nondestructively formed. 
     Block  12  is made from a material that supports line  102  prior to the deployment of line charge  104  and that fails or ruptures during the deployment of line charge  104 . By doing so, the present invention provides a means to absorb and release launch energy that produces a standing wave in line  102  as discussed above in the Background of the Invention. More specifically, when rocket  100  begins to travel down range, line  102  between rocket  100  and line storage device  10  is placed in tension by the forward momentum of rocket  100  and the resting weight of line charge  104 . As line  102  is pulled taut at block  12  by rocket  100  at one end and by line charge  104  at the other end, line  102  exerts force on each successive “loop” formed by channel  14  in block  12 . Due to the extreme tensile force, block  12  ruptures sequentially from both ends thereof at each successive loop of channel  14  effectively paying out line  102  while insuring against entanglement and absorbing/releasing launch energy to reduce the loading imparted by the standing wave. The energy is released during the sequential rupturing of block  12 . 
     To support line  102  prior to deployment and failure at time of deployment as described above, block  12  is made from a solid material that will rupture as line  102  achieves a threshold tension. One suitable material is polystyrene which is lightweight, inexpensive, easily formed in terms of both overall shape and channel  14 , and is readily ruptured when line  102  achieves its threshold tension. Other suitable materials include plaster and low density frangible plastics such as polypropylene, acrylic, vinyl, polyvinyl chloride and cellulose acetate just to name a few. Block  12  can be formed from a piece of the selected stock material or could be molded into its specific shape and size. Block  12  could also be formed or molded about a pre-shaped zigzag pattern of line  102  to thereby fully encase line  102  in block  12 . 
     If there is a substantial amount of line  102  that must be stored or if the overall size of block  12  is of concern, the present invention can be extended to store parallel layers of line  102 . For example, line storage device  20  shown in top and bottom plan view in FIGS. 2A and 2B, respectively, creates two layers of channels for storing line  102 . However, as will be appreciated by one of ordinary skill in the art, the following two-layer description can easily be extended to three or more layers. 
     Referring simultaneously to FIGS. 2A and 2B, block  22  has zigzag channel  24  formed in top surface  26  as illustrated in FIG.  2 A. Channel  24  terminates at a feed through hole  28  that passes through to bottom surface  27  into which zigzag channel  25  is formed as illustrated in FIG.  2 B. Since line  102  must still extend from opposing ends of block  20 , line  102  is led across block  20  by a straight channel  29  in bottom surface  27 . By using feed through hole  28  to carry line  102  to its next layer of channel, all of line  102  is kept within and protected by block  102 . Alternatively, line  102  can be led outside of block  102  to the next layer. 
     The advantages of the present invention are numerous. As purely a line storage device, the present invention provides for ease of handling excess line. As a line payout control device, the present invention ensures that no slack develops during payout of the line by holding the line in a frangible package that ruptures in accordance with the sequential storing/payout of the line. Thus, line snags or entanglement during deployment of a line charge system are eliminated thereby providing a high degree of confidence in terms of line charge placement and detonation. 
     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. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described.