This invention generally relates to protection of vehicles and structures from Rocket Propelled Grenades. More particularly, it relates to reducing the weight and improving the effectiveness of bar armor by inhibiting bar separation by means of low density frangible connections between the bars.
Rocket Propelled Grenades (RPGs) have been employed since World War II against armored vehicles and fortifications. They are cheap, effective, and difficult to counter. Currently, millions of these weapons are used by insurgent and guerilla forces, as well as regular forces in many countries. RPGs can penetrate as much as a foot of steel armor, so it is not practical to use steel for RPG protection on most vehicles because of the weight. To provide at least partial protection against these weapons, bar or slat armor has been developed, and is in use on a number of military vehicles. Bar armor works by exploiting a design feature in the RPG, namely that causing the inner and outer ogives (the hollow conical forward members of the RPG warhead) to become electrically connected causes the piezoelectric nose element to become short circuited, thus denying electrical power to the initiating element at the rear of the RPG. When an RPG passes between the bars of bar armor at high speed without the forward nose element hitting a bar, the outer ogive is crushed into the inner ogive, a short circuit is established, and the RPG is dudded. Bar and slat armor is much lighter than steel would be, but is still relatively heavy when applied to large areas of an armored vehicle, adding hundreds or even thousands of pounds. For many applications, lighter solutions are desired, as well as improved effectiveness and visibility through the bars.
Currently, bar armor is typically composed of aluminum bars 30 to 40 inches long, each separated by about 3 inches, with a square cross section about ½ inch on a side. Slat armor is similar but with a cross section more typically ¼ inch across by 1 or 2 inches in depth. With low cost materials, these dimensions cannot easily be reduced because the resultant low lateral strength allows the bars or slats to be pushed apart by the RPG ogive without inflicting sufficient damage. However, it would be possible to reduce these dimensions if the bars could be constrained laterally without introducing structural members that could themselves provide sufficient impact to the piezoelectric element to set off the RPG.
It is therefore an object of the present invention to provide an improved bar armor solution for protection against RPGs by inhibiting lateral spreading of the bars through the use of low density frangible cross-attachment members between the bars that provide sufficient strength to prevent bar spreading and are also of low enough aereal density and of sufficient frangibility to avoid detonation of the RPG if the cross-attachment members are struck by the nosepiece of the RPG, thus allowing thinner bars to be used than would otherwise be possible.
It is a further object of the present invention to provide a means of reducing the weight of bar armor.
It is a further object of the present invention to provide a means of increasing the effectiveness of bar armor.
It is a further object of the present invention to provide a means of improving the visibility through bar armor.
It is a further object of the present invention to reduce the cost of bar armor systems.
This foregoing and other features and advantages of this invention will be apparent from the following detailed description of the invention as illustrated in the accompanying drawings, in which:
The present invention improves the performance of bar armor against RPGs by inhibiting the spreading of the bars, thus allowing smaller cross section bars to be used. This can result in lighter weight, improved performance, improved visibility through the bars, and lower cost.
To understand how this works, it is first necessary to understand the operation of an RPG and of bar armor.
RPG and Bar Armor Operation
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The invention consists of various means of providing cross-attachments between the bars of a bar armor system for the purpose of minimizing lateral bar spreading of the type shown in
The overall length of the system C is typically between 3 feet and 4 feet and the height D is typically 3 feet to 4 feet. The cords are attached to each bar by wrapping them around each bar as is shown in
The cross-attachment cords can be made of a variety of high strength materials such as Mason® Braided nylon string, Kevlar®, Spectra®, or other high strength fibers or polymers including high test fishing line such as 100 pound ANDE® Monster Monofilament Line. Acceptable cord diameters will depend on the strength and density of the cord material, but will generally be in the vicinity of 0.5 mm-2 mm. Thin flexible steel or high strength copper wires of roughly 0.1 mm-0.5 mm or steel braids such as Hillman® picture wire may also be used. Alternatively, tapes such as ¼″ Scotch® reinforced mailing tapes may be used. This has the advantage of being self-adhesive. Cloths or ribbons of high strength material such as nylon or polyester can also be used. All these materials can also be made into bands 18 or loops 19 of the appropriate size that can be slipped over two adjacent bars and glued into place, as shown in
Appropriate glues include nearly any high-quality waterproof glue such as Gorilla Glue®, Liquid Nails®, or Duro® rubber sealant.
Cross section shapes can include rectangles, trapezoids, triangles, ovals, and Vs. Tapering the bar at the rear to form a trapezoid or triangle would save additional weight and aid the visibility at non-horizontal angles. Various bar materials may be used including high strength metals such as McMaster Carr 7075 aluminum bar stock, spring steel, or titanium alloy; composites such as carbon-fiber/epoxy; ceramic elements such as Coors® alumina; or combinations of these.
Another embodiment consists of closer spacing of the cross-attachments. This would potentially allow thinner cords to be used and could further reduce bar separation in the event that one of the cords is broken by the RPG. Spacings as close as one inch might be advantageous.
In another embodiment, fasteners or clamps 20 with nubs on the ends attached to each bar at 1″-3″ spacings may be used as depicted in
Yet another embodiment includes holes in the bars such that a cord or wire can be threaded through the bars and tied or welded into place.
In yet another embodiment, the cross-attachments may be attached non-perpendicularly. A criss-cross attachment pattern such as shown in
There are many possible embodiments of this invention. Nothing in the above examples is intended to limit the invention more narrowly than the appended claims. The examples are intended to be illustrative rather than exclusive.
This patent application claims priority over Provisional Patent Application Ser. No. 61/573,449 filed on 6 Sep. 2011, incorporated herein by reference.
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