Abstract:
A rocket propelled grenade shield including a flexible net and a frame secured to the flexible net supporting the flexible net. Spaced hard points are attached to the net, the hard points including a base portion with a cavity therein and a plug received in said cavity locking each hard point to the flexible net.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 13/624,287 filed Sep. 21, 2012 which hereby claims the benefit of and priority thereto under 35 U.S.C. §§119, 120, 363, 365, and 37 C.F.R. §1.55 and §1.78, which application is a continuation of U.S. patent application Ser. No. 12/807,532 filed Sep. 8, 2010 which is a continuation-in-part of U.S. patent application Ser. No. 12/386,114 filed on Apr. 14, 2009 which claims the benefit of and priority to Provisional Application No. 61/124,428 filed on Apr. 16, 2008 under 35 U.S.C. §§119, 120, 363, 365, and 37 C.F.R. §1.55 and §1.78, all incorporated herein by this reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The subject invention relates to ordinance shielding. 
       BACKGROUND OF THE INVENTION 
       [0003]    Rocket propelled grenades (RPGs) and other ordinance are used by terrorist groups to target military vehicles and structures. See WO 2006/134407 incorporated herein by this reference. 
         [0004]    Others skilled in the art have designed intercept vehicles which deploy a net or a structure in the path of an RPG in an attempt to change its trajectory. See U.S. Pat. Nos. 7,190,304; 6,957,602; 5,578,784; and 7,328,644 all incorporated herein by this reference. Related prior art discloses the idea of deploying an airbag (U.S. Pat. No. 6,029,558) or a barrier (U.S. Pat. No. 6,279,499) in the trajectory path of a munition to deflect it. These references are also included herein by this reference. 
         [0005]    Many such systems require detection of the RPG and deployment of the intercept vehicle quickly and correctly into the trajectory path of the RPG. 
         [0006]    Static armor such as shown in U.S. Pat. Nos. 5,170,690; 5,191,166; 5,333,532; 4,928,575; and WO 2006/134,407 is often heavy and time consuming to install. When a significant amount of weight is added to a HMMWV, for example, it can become difficult to maneuver and top heavy. Such an armor equipped vehicle also burns an excessive amount of fuel. 
         [0007]    Moreover, known static systems do not prevent detonation of the RPG. One exception is the steel grille armor of WO 2006/134,407 which is said to destroy and interrupt the electrical energy produced by the piezoelectric crystal in the firing head of the RPG. Bar/slat armor is also designed to dud an RPG. But, bar/slat armor is also very heavy. Often, a vehicle designed to be carried by a specific class of aircraft cannot be carried when outfitted with bar/slat armor. Also, if the bar/slat armor is hit with a strike, the RPG still detonates. Bar/slat armor, if damaged, can block doors, windows, and access hatches of a vehicle. 
         [0008]    Chain link fence type shields have also been added to vehicles. The chain link fencing, however, is not sufficiently compliant to prevent detonation of an RPG if it strikes the fencing material. Chain like fencing, although lighter than bar/slat armor, is still fairly heavy. Neither bar/slat armor nor the chain link fence type shield is easy to install and remove. 
         [0009]    Despite the technology described in the above prior art, Rocket Propelled Grenades (RPGs) and other threats used by enemy forces and insurgents remain a serious threat to troops on the battlefield, on city streets, and on country roads. RPG weapons are relatively inexpensive and widely available throughout the world. There are varieties of RPG warhead types, but the most prolific are the PG-7 and PG-7M which employ a focus blast or shaped charge warhead capable of penetrating considerable armor even if the warhead is detonated at standoffs up to 10 meters from a vehicle. A perfect hit with a shaped charge can penetrate a 12 inch thick steel plate. RPGs pose a persistent deadly threat to moving ground vehicles and stationary structures such as security check points. 
         [0010]    Heavily armored, lightly armored, and unarmored vehicles have been proven vulnerable to the RPG shaped charge. Pick-up trucks, HMMWV&#39;s, 2½ ton trucks, 5 ton trucks, light armor vehicles, and M118 armored personnel carriers are frequently defeated by a single RPG shot. Even heavily armored vehicles such as the M1 Abrams Tank have been felled by a single RPG shot. The PG-7 and PG-7M are the most prolific class of warheads, accounting for a reported 90% of the engagements. RPG-18s, RPG-69s, and RPG-7Ls have been reported as well, accounting for a significant remainder of the threat encounters. Close engagements 30 meters away occur in less than 0.25 seconds and an impact speed ranging from 120-180 m/s. Engagements at 100 meters will reach a target in approximately 1.0 second and at impact speeds approaching 300 m/s. 
         [0011]    The RPG-7 is in general use in Africa, Asia, and the Middle East and weapon caches are found in random locations making them available to the inexperienced insurgent. Today, the RPG threat in Iraq is present at every turn and caches have been found under bridges, in pickup trucks, buried by the road sides, and even in churches. 
         [0012]    Armor plating on a vehicle does not always protect the occupants in the case of an RPG impact and no known countermeasure has proven effective. Systems designed to intercept and destroy an incoming threat are ineffective and/or expensive, complex, and unreliable. 
         [0013]    Chain link fencing has been used in an attempt to dud RPGs by destroying the RPG nose cone. See, for example, DE 691,067. See also published U.S. Patent Application No. 2008/0164379. Others have proposed using netting to strangulate the RPG nose cone. See published U.S. Application No. 2009/0217811 and WO 2006/135432. 
         [0014]    WO 2006/134407, insofar as it can be understood, discloses a protective grid with tooth shaped members. U.S. Pat. No. 6,311,605 discloses disruptive bodies secured to armor. The disruptive bodies are designed to penetrate into an interior region of a shaped charge to disrupt the formation of the jet. The shaped charge disclosed has a fuse/detonator mechanism in its tail end. 
       BRIEF SUMMARY OF THE INVENTION 
       [0015]    No known prior art, however, discloses a net supporting a spaced array of hard points at a set off distance from a vehicle or a structure wherein the hard points are designed to dig into the nose cone of an RPG and dud it. 
         [0016]    Pending U.S. patent application Ser. No. 11/351,130 filed Feb. 8, 2006, incorporated herein by this reference, discloses a novel vehicle protection system. The following reflects an enhancement to such a system. 
         [0017]    In accordance with one aspect of the subject invention, a new vehicle and structure shield is provided which, in one specific version, is inexpensive, lightweight, easy to install and remove (even in the field), easy to adapt to a variety of platforms, effective, and exhibits a low vehicle signature. Various other embodiments are within the scope of the subject invention. 
         [0018]    The subject invention results from the realization, in part, that a new vehicle and structure shield, in one specific example, features a plurality of spaced rods or hard points held in position via the nodes of a net and used to dud an RPG or other threat allowing the frame for the net to be lightweight and inexpensive and also easily attached to and removed from a vehicle or structure. 
         [0019]    The subject invention features a vehicle and structure shield comprising a flexible net subsystem including an array of rods or hard points supported by the net subsystem and configured to impact a projectile striking the net. A frame including mounting brackets attached thereto positions the frame in a spaced relationship with respect to the vehicle or structure. A first releasable fastener subsystem releasably secures the net subsystem to the frame. A second releasable fastener subsystem releasably secures the mounting brackets of the frame to a vehicle or structure. 
         [0020]    A vehicle and structure shield system in accordance with the invention features a flexible structure with a fabric border including one of a hook and loop type fastener thereon, a frame for the flexible structure including frame members with the other of hook and loop fastener thereon for releasably securing the flexible structure to the frame, and hard points attached to the flexible structure. 
         [0021]    The frame members typically include the other of the hook and loop fastener material thereon in a spiral wrap configuration thereabout. One preferred flexible structure includes a net with nodes and hard points are attached to the nets at the nodes in an array. The frame may further include rearwardly extending members. In one design, the frame includes frame members forming a polygon with spaced sides and an upper and a lower portion. There may be two spaced rearwardly extending members attached to the upper portion and rearwardly extending members on each side extending from the lower portion to the upper portion with a hinged joint therebetween. 
         [0022]    The preferred hard points each include a post portion and a base portion with a cavity receiving the post portion therein. In one specific design, each hard point includes a front face, sidewalls extending rearward from the front face including slots therethrough for the cords of a net, a cavity surrounded by the sidewalls, and a plug sized to be frictionally received in the cavity locking the cords of the net in the cavity. 
         [0023]    The plug may include an outer wall with a knurled surface. The front face may have six sides then there are six two opposing sidewalls which may have slots therethrough in the middle of the opposing sidewalls and there may be a slot between adjacent sidewalls on each side of the two opposing sidewalls. 
         [0024]    In one embodiment, the hard points include steel, weigh between 10 and 80 grams, the front face has an area of between 0.1 and 0.8 in. 2 , the sidewalls each have an area of between 0.1 and 0.8 in. 2 , the cavity is round, and the plug is cylindrical in shape. Typically, the slots each terminate in a rounded portion. 
         [0025]    The subject invention, however, in other embodiments, need not achieve all these objectives and the claims hereof should not be limited to structures or methods capable of achieving these objectives. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0026]    Other objects, features and advantages will occur to those skilled in the art from the following description of a preferred embodiment and the accompanying drawings, in which: 
           [0027]      FIG. 1  is a highly schematic three-dimensional exploded view showing an example of one shield protection system in accordance with the subject invention; 
           [0028]      FIG. 2  is a schematic side view of a HMMWV vehicle equipped with hook and loop patches for installation of the shield system shown in  FIG. 1 ; 
           [0029]      FIG. 3  is a schematic partial side view showing a shield subsystem in accordance with an example of the subject invention now installed on a portion of a vehicle; 
           [0030]      FIG. 4  is a schematic three-dimensional front view showing one example of a hard point rod attached to adjacent nodes of two spaced nets in accordance with the subject invention; 
           [0031]      FIG. 5  is a schematic three-dimensional exploded view showing another example of a hard point rod in accordance with the subject invention; 
           [0032]      FIGS. 6A-6D  are schematic views of other hard point designs in accordance with examples of the subject invention; 
           [0033]      FIG. 7A-7B  are schematic views of a plug for the hard point shown in  FIGS. 6A-6D . 
           [0034]      FIG. 8  is a schematic three-dimensional front view showing a number of net shields removeably attached to a military vehicle in accordance with the subject invention; 
           [0035]      FIG. 9  is a schematic three-dimensional side view showing a number of net shields attached to the side of a military vehicle; 
           [0036]      FIG. 10  is a highly schematic three-dimensional top view showing a RPG nose duded by the shield subsystem in accordance with the subject invention; 
           [0037]      FIG. 11  is a schematic three-dimensional exploded front view showing telescoping frame members in accordance with the subject invention; 
           [0038]      FIG. 12A  is a front view of a frame structure in accordance with an example of the invention; 
           [0039]      FIG. 12B  is a view of one portion of the frame structure shown in  FIG. 12A ; 
           [0040]      FIG. 12C  is a front view of one frame member of the frame structure shown in  FIG. 12A  showing a spiral wrap of Velcro material thereabout; 
           [0041]      FIG. 13  is a partial schematic view showing a frame structure attached to the front of a vehicle in accordance with an example of the subject invention; and 
           [0042]      FIG. 14  is a flow chart depicting the primary steps associated with a method of protecting a vehicle or structure in one example of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0043]    Aside from the preferred embodiment or embodiments disclosed below, this invention is capable of other embodiments and of being practiced or being carried out in various ways. Thus, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. If only one embodiment is described herein, the claims hereof are not to be limited to that embodiment. Moreover, the claims hereof are not to be read restrictively unless there is clear and convincing evidence manifesting a certain exclusion, restriction, or disclaimer. 
         [0044]      FIG. 1  shows an example of flexible structures, e.g., net subsystem  10  and including an array of rods  12  configured to impact a projectile (e.g., the nose of an RPG) striking net  14 . Frame  16  includes mounting brackets  18   a - 18   d  attached to rearwardly extending members  19   a  and  19   b . The function of frame  16  and net  14  is to position rods  12  in a spaced relationship with respect to a vehicle or structure and to space the rods  12  apart from each other in an array. When an RPG impacts net  14 , rods  12  may angle inwardly towards the nose of the RPG tearing into it and duding the electronics and/or electrical or electronic signals associated with the arming or detonation mechanisms of the RPG. By flexible, we generally mean a net which does not retain its shape unless supported in some fashion. When not attached to frame  16 , net  14  can be rolled and then folded and/or net  14  can be bunched up. 
         [0045]    Preferably, net subsystem  10  is removeably secured to frame  16  and frame  16  is removeably secured to vehicle  20 ,  FIG. 2  (e.g., a HMMWV vehicle). In one particular example, frame members  22   a - 22   d  include hook type fasteners secured to the outside thereof and the net periphery includes loop type fasteners on the inside thereof. Loop type fasteners are also secured to the rear of frame  16  mounting brackets  18   a - 18   d  and corresponding pads or patches  28   a - 28   d ,  FIG. 2 , adhered to vehicle  20 , include outer faces with hook type fasteners. The hook and loop fastening mechanisms, however, maybe reversed and other flexible fastener subsystems may also be used. The hook and loop fastening subsystems of U.S. Pat. Nos. 4,928,575; 5,170,690; 5,191,166; and 5,333,532 are preferred. 
         [0046]      FIG. 3  shows frame members  22   a  and  22   b  including hook type fastener strips  30   a  and  30   b , respectively, and net periphery fabric border  24  including loop type fastener strips  32   a  and  32   b . Mounting bracket  18   c ′ is attached to rearwardly extending frame member  19   a ′ and includes a rearward face with loop type fasteners.  FIG. 3  also shows optional strap  34  extending from ear  36  on frame member  22   a  to attachment  38  on vehicle  20  which may also be secured to vehicle  20  using hook and loop fasteners. Additional straps may also be included.  FIG. 3  also shows first (outer) net  40   a  and second (inner) net  40   b  with their nodes interconnected via rods  12 ′. 
         [0047]    As shown in  FIG. 4 , rod  12 ′ includes base portion  50  and post portion  52  extending from base portion  50 . Post  52  includes castellations  54   a - 54   d  for the chord lines  56   a  and  56   b  of net  40   a  defining node  58 . Similarly, base  50  includes castellations (e.g, castellations  60   a  and  60   b ) for lines  62   a  and  62   b  of net  40   b  also defining a node (not shown). The lines of the nets may be glued or otherwise secured in the castellations. 
         [0048]      FIG. 5  shows a single net design where net lines  66   a  and  66   b  defining node  68  are secured between post portions  68  frictionally received in cavity  70  of base portion  72  of rod  12 ″. The preferred rod is made of steel, has a one inch post, and weighs between 15 and 30 grams. 
         [0049]      FIGS. 6A-6B  shows hard point  12 ′″ with forward facing base portion  72 ′ with cavity  70 ′ receiving post or plug  68 ′,  FIG. 7  therein in a friction fit manner. This hard point is designed for nets including horizontal cords intersecting vertical cords. See  FIGS. 1 and 5 . In this preferred design, the net cords are received through slots  73   a - d  in wall  74  of hard point  72 ′. The slots, as shown for slot  73   a , terminate in rounded portion  77  preventing wear of the net chords. Wall  74  in this embodiment defines a six-sided structure with six sharp corners  75   a - 75   f  which dig into the skin of an RPG ogive. Top surface  76  may be flat as shown or concave. Slots  73   a  and  73   c  receive vertically extending cord  66   b ,  FIG. 5  while slots  73   d  and  73   b ,  FIG. 6A  receive horizontally extending cord  66   a ,  FIG. 5 . In one specific design, the hard point and the plug were made of steel, hard point  72 ′ was 0.625 inches from one edge to an opposite edge, and 0.72 inches tall. Cavity  70 ′ was 0.499 inches in diameter and 0.34 inches deep. Five gram cylindrical plug  68 ′,  FIGS. 7A-7B  was 0.35 inches tall, 0.500 inches in diameter, and includes knurling as shown at  78  on the outer wall surface thereof. 
         [0050]    Side walls  74   a - 74   f  extend rearward from front face  76  defining cavity  70 ′ surrounded by the side walls. Opposing sidewalls  74   a  and  74   d  have slots ( 73   a ,  73   c ) in the middle of each side wall. Slots  73   d , and  73   b , in turn, are between adjacent sidewalls  74   b  and  74   e  and  74   f  and  74   e , respectively. Sidewall  74   b  and  74   c  are between opposing sidewalls  74   a  and  74   b  on one side of member  72 ′ while sidewall  74   f  and  74   e  are between opposing sidewalls  74   a  and  74   d  on the opposite side of member  72 ′. 
         [0051]    In this specific design, the base portion  72 ′ and plug  68 ′ ( FIG. 7 ) were made of hardened steel (e.g., ASTM A108 alloy 12L14) and combined weighed between 10 and 80 grams. A base portion with more or less sides is also possible. For a six sided design, the area of face  76 ,  FIG. 6B , is typically about 0.5 in. 2 , e.g. between 0.1 and 0.8 in. 2 . Sidewalls  74   a - f  typically have an area of 0.37 in. 2 , e.g., between 0.1 and 0.8 in. 2 . Slots  73   a - d  may be 0.05-0.15 inches wide and between 0.2 and 0.8 inches long. 
         [0052]    Manufacturing of a net with hard points in accordance with the subject invention is thus simplified. A net node is placed in cavity  70 ′,  FIG. 6A  with the net chords exciting through slots  73   a - 73   d  and plug  68 ′,  FIG. 7A  is then driven in to cavity  70 ′,  FIG. 6A  to lock the node of the net in the hard point. The hard points are typically made of conductive material and may include a protective rust resistant non-reflective, conductive coating (zinc plating, flat olive in color). In one example shown in  FIGS. 6C-6D , base portion  72 ″ weighed 30 grams and was machined from 0.625 hex bar stock. Walls  74   a - 74   f  were 0.72″ tall. Slots  73   a - 73   d  were 0.080 inches across and 0.350″ in length. These dimensions will vary, however, depending on the design of the net. 
         [0053]    There are trade offs in the design of the hard points and also the net. The aspect ratio of the hard points, their size, center of gravity, mass, and the like all play an important role. Hard points which are too large, for example, and a net mesh size which is too small, results in too much surface area to be stricken by an RPG, possibly detonating the RPG. Hard points which are too small may not sufficiently damage the RPG ogive and dud the RPG. Steel is a good material choice for the hard points because steel is less expensive. Tungsten, on the other hand, may be used because it is heavier and denser, but tungsten is more expensive. Other materials are possible. The hard points may be 0.5 inch to 0.75 inches across and between 0.5 inches and 1 inch tall. 
         [0054]    It is preferred that the net node is placed at the center of gravity at the hard point. The length of the hard point is preferably chosen so that when an RPG strikes the net, the hard point tumbles 90 degrees and digs into the RPG ogive. The moment of inertia of the hard point is designed accordingly. In still other designs, the hard point may have more or less than six sides. The hard points may weigh between 10 to 80 grams although in testing 60 grams was found to be optimal, e.g., a 30 gram base portion and a 30 gram plug. Hard points between 10 and 40 grams are typical. 
         [0055]    The net material may be polyester which provides resistance to stretching, ultraviolet radiation resistance, and durability in the field. Kevlar or other engineered materials can be used. A knotted, knotless, braided, or ultracross net may be used. The chord diameter may be 1.7 to 1.9 mm. Larger net cords or multiple cords are possible, however, the cord(s) design should be constrained to beneath threshold force to dynamic break loads typical of RPG impact and engagements. The typical net mesh size may be 176 mm (e.g., a square opening 88 mm by 88 mm) for a PG-7V RPG and 122 mm for a PG-7 VM model RPG. But, depending on the design, the net mesh size may range from between 110 and 190 mm. 
         [0056]    The preferred spacing or standoff from the net to the vehicle is between 4 and 24 inches, (e.g., 6-12 inches) but may be between 4 and 60 centimeters. Larger standoffs may extend the footprint of the vehicle and thus be undesirable. Too close a spacing may not insure closing of the electrical circuitry of the RPG ogive by the hard points. The frame and mounting brackets are designed to result in the desired spacing. 
         [0057]    It is desirable that the net material and mesh size be chosen and the net designed such that an RPG ogive, upon striking a net chord, does not detonate. RPGs are designed to detonate at a certain impact force. Preferably, the breaking strength of the net chord material is around 240 lbs so that an RPG, upon striking a net chord or chords, does not detonate. The net is thus designed to be compliant enough so that it does not cause detonation of the RPG. Instead, the hard points dig into the RPG ogive and dud the RPG before it strikes the vehicle or structure. 
         [0058]    This design is in sharp contrast to a much more rigid chain link fence style shield which causes detonation of the RPG if the RPG strikes a wire of the fence. The overall result of the subject invention is a design with more available surface area where dulling occurs as opposed to detonation. 
         [0059]      FIG. 8  shows shields  80   a - 80   f  and the like in accordance with the subject invention protecting all of the exposed surfaces of vehicle  20 .  FIG. 9  shows shields  82   a - 82   d  in accordance with the subject invention protecting the driver&#39;s side of vehicle  20 . Only a few hard points  12 ′″ are shown for clarity. Typically, there is a hard point at each node of the net. 
         [0060]    When an RPG nose or ogive  90 ,  FIG. 10  strikes a shield, the rods or hard points at the nodes of the net(s) angle inwardly toward nose  90  and tear into the skin thereof as shown at  92   a  and  92   b . The hard points can bridge the inner and outer ogive serving as short to dud the RPG. Or, the hard points tear into the ogive and the torn material acts as a short duding the round. If the net and/or frame is destroyed, another shield is easily installed. The net thus serves to position the hard points in an array at a set off distance from the vehicle or structure to be protected. An effectiveness of 60-70% is possible. Chain link fencing exhibited an effectiveness of about 50%. Netting without hard points likely exhibited an effectiveness of less than 50%. Slat/bar armor reportedly had and effectiveness of around 50%. 
         [0061]      FIG. 9  shows how frame members  22   a ′ can comprise adjustable length telescoping sections for ease of assembly and for tailoring a particular frame to the vehicle or structured portion to be protected. 
         [0062]    In one embodiment, the frame members are made of light weight aluminum. One complete shield with the net attached weighed 1.8 lbs. The shield is thus lightweight and easy to assemble, attach, and remove. If a given shield is damaged, it can be easily replaced in the field. The rods connected to the net cell nodes are configured to angle inwardly when an RPG strikes the net. This action defeats the RPG by duding it since the electronics associated with the explosives of the RPG are shorted as the rods impact or tear through the outer skin of the RPG ogive. 
         [0063]    The result, in one preferred embodiment is an inexpensive and light weight shielding system which is easy to install and remove. The shields can be adapted to a variety of platforms and provide an effective way to prevent the occupants of the vehicle or the structure from injury or death resulting from RPGs or other ordinances. When used in connection with vehicles, the shield of the subject invention exhibits a low vehicle signature since it extends only a few inches from the vehicle. 
         [0064]    The system of the subject invention is expected to meet or exceed the effectiveness of bar/slat armor and yet the flexible net style shield of the subject invention is much lighter, lower in cost, and easier to install and remove. The system of the subject invention is also expected to meet or exceed the effectiveness of chain link fence style shields and yet the net/hard point design of the subject invention is lower in cost, lighter and easier to install and remove. 
         [0065]    One design of a frame  16 ,  FIGS. 12A-12B  includes tubular upper frame member  100   a , lower frame member  100   b , and side frame members  100   c  and  100   d  all interconnected via corner members  102   a - d . The result is a polygon with spaced sides and an upper and lower portion. 
         [0066]    Spaced rearwardly extending members  104   a  and  104   b  are attached to the upper portion of the members  100   d  and  100   c , respectively, just below the corner members  102   a  and  102   b . Rearwardly extending members  106   a  and  106   b  are on each side of the frame and each include a hinged joint  108   a  and  108   b , respectively. Each of these members extends between a side member at the bottom of the frame and a rearwardly extending member at the top of the frame where they are hingely attached thereto. All of the hinged joints may be pin and clevis type joints as shown. As shown in  FIG. 12C , each frame member  100   a - 100   d  includes a spiral wrap  110  of a hook type fastener material secured thereto to releasably receive the loop type fastener material ( 32   a ,  32   b ,  FIG. 3 ) of the net fabric border. In this way, the net is easily attached and removed from the frame. 
         [0067]    Typically, the frame is attached to the vehicle or structure using metal plates with an ear extending outwardly therefrom, such as plate  120 ,  FIG. 12   b  with ear  122 . 
         [0068]    In other instances, however, features already associated with the vehicle or structure to be protected can be used to secured the frame with respect to the vehicle or structure. 
         [0069]    For example,  FIG. 13  shows frame  16 ″ attached to a vehicle. Frame  16 ″ includes frame members  130   a - 130   g , rearwardly extending member  132   a  and  132   b  hingely connected to plates  134   a  and  134   b , respectively, bolted to the vehicle. Features  136   a  and  136   b  of vehicle  20 ′ are connected to the joints between frame members  130   b ,  130   g  and  130   f . Thus, the frame, the mounting brackets, and the like may vary in construction depending on the configuration of the vehicle or structure to be protected, the location on the vehicle to protected and the like. Typically, the frame members are tubular aluminum components and in one example they were 1-2 inches outer diameter, 0.75-1.75 inches inner diameter, and between 3 and 10 feet long. 
         [0070]    Assembly of a vehicle or structure shield, in accordance with the invention, typically begins with cutting the bulk netting, step  200 ,  FIG. 14  into square or rectangular shapes. Next a fabric border is sewed to the net edges, step  202  and includes loop type fastener material on at least one side thereof. 
         [0071]    The hard points are they secured to the net nodes, step  204 . For example, the net may be laid on a table and hard point female members  72 ′,  FIG. 6A-6B  are positioned under each node with the net cords extending through slot  73   a - 73   d . Plugs  68 ′,  FIG. 7 , are then driven partly into each cavity of the female base portions using finger pressure and/or a hammer. Then, the plugs are seated in their respective cavities using a pneumatic driver. 
         [0072]    The appropriate frame is then designed and assembled step  206 ,  FIG. 14 , and the hook fastener material is taped or glued to the frame members (see  FIG. 12C ), step  208 . In the field, the frame is secured to the vehicle or structure, step  210 , and the net is attached to the frame, step  212 , using the loop type fastener material of the net periphery border and the hook fastener material on the frame members. 
         [0073]    Assembly of the frame to the vehicle or structure and releasably attaching the net to the frame is thus simple and can be accomplished quickly. 
         [0074]    Although specific features of the invention are shown in some drawings and not in others, however, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention. The words “including”, “comprising”, “having”, and “with” as used herein are to be interpreted broadly and comprehensively and are not limited to any physical interconnection. Moreover, any embodiments disclosed in the subject application are not to be taken as the only possible embodiments. 
         [0075]    In addition, any amendment presented during the prosecution of the patent application for this patent is not a disclaimer of any claim element presented in the application as filed: those skilled in the art cannot reasonably be expected to draft a claim that would literally encompass all possible equivalents, many equivalents will be unforeseeable at the time of the amendment and are beyond a fair interpretation of what is to be surrendered (if anything), the rationale underlying the amendment may bear no more than a tangential relation to many equivalents, and/or there are many other reasons the applicant can not be expected to describe certain insubstantial substitutes for any claim element amended. 
         [0076]    Other embodiments will occur to those skilled in the art and are within the following claims.