BAR ARMOR SYSTEM FOR PROTECTING AGAINST ROCKET-PROPELLED GRENADES
A bar armor system is provided for reducing damage caused by RPGs launched towards a vehicle. The bar armor system includes at least one bar array, comprised of lateral bars and vertical bars, wherein the lateral bars are set in predetermined positions so as to reduce the possibility of shaped charges being directed towards the target vehicle. Tubular shaft retainers are provided to be positioned in annular openings in the vertical bars. The lateral bars can be of a round or hexagonal cross-section, and when hexagonal lateral bars are employed, the flat surfaces of the cross-section are positioned horizontally by the tubular shaft retainers so as to minimize the area presented to an oncoming RPG, particularly when the RPG strikes at a non-normal incidence. Push washers can be employed at the outside surfaces of the vertical bars so as to hold them in position. A mounting system is provided that is capable of positioning the bar armor system at close distances to the vehicle so that the overall size and weight of the vehicle is not unduly increased by the bar armor system. The mounts can include rotary latches to provide easy installation and removal. The system can also be of an electrically-conductive unified composition so that efficient electrostatic coating techniques can be used to cover the system. The system can also be provided in the form of kits for ready installation and for more economical repair.
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1. Field of the Invention
This invention relates to bar armor. More particularly, this invention relates to bar armor systems for protecting a vehicle from rocket-propelled grenades.
2. Description of Related Art
Shortly after rocket-propelled grenades (“RPGs”) were used to attack vehicles, various forms of standoff armor arose to attempt to reduce the effectiveness of the RPGs. Towards the end of World War II, anti-vehicle infantry weapons came into wider use in response to the increasing use of tanks. To try to protect against these weapons, tank crews utilized a rudimentary form of standoff armor such as field-mounted bedsprings and/or screen doors positioned on the tank. Later, during the Vietnam War, additional forms of rudimentary standoff armor were employed, often comprised of scrap metal, screens, chicken wire, and chain-link fencing.
These rudimentary standoff armor systems were cumbersome and not very successful. The protection they attempted to afford was marginal at best. Generally, these systems merely attempted to cause the RPG to not strike a vehicle directly but to detonate away from the target. No attempt was made in these systems to prevent the RPG from detonating or to cause the RPG to do as little damage as possible upon detonation.
More recently, formal designs have been suggested to attempt to provide greater protection by reducing the chances of normal detonation of an RPG. General Dynamics has installed what it terms a “slat armor” system for a Stryker Armored Personnel Carrier (“APC”). This “slat armor” weighs approximately 5200 pounds and is quite cumbersome. Another system that has been suggested, produced by the company BAE Systems, uses a series of square aluminum bars, termed L-ROD™, for trying to protect vehicles such as the Buffalo and RG-31 in use by the United States military. Still another system has been employed by Canadian forces to retrofit the Leopard 2 tanks with a “slat armor” to help defend against RPGs. The Israeli military also began using a “slat armor” system in 2005 to help protect its heavily-modified Caterpillar D9R Armored Bulldozer against RPG attacks. Several of these later designs have operated by attempting to actually deaden the RPG by causing an electrical short in the RPG on impact.
While these later designs have offered some improvement over the earlier rudimentary systems, they have not been entirely successful, and have even raised additional difficulties. For example, although it is desirable to extend protection away from the vehicle, some of these systems appear to have extended the protection too far, resulting in increased size and weight and decreased maneuverability. The increase to vehicle dimensions also makes the vehicle unnecessarily more visible in the field, thereby causing additional danger to the occupants. These designs also have subjected the vehicle to increased wear and tear, and undue restriction in operations, such as in crowded urban environments, because of the increased size.
In addition, current systems also includes a lack of modularity in assembly and installation. For example, most current bar and slat armor systems are welded together and/or are welded directly to the vehicle, to provide the strength needed to defeat an RPG threat. Such welding is difficult and time-consuming. Additionally, when the welded designs break, a large portion of the bar or slat armor has to be replaced, rather than replacing only the damaged section. This is expensive, time-consuming, and decreases the time that the protected vehicle is available for field use.
While not all previously-designed systems have employed welding, even the non-welded systems have not been satisfactory. For example, some systems use non-conductive parts, such as plastic bushings, to assemble the armor systems. However, use of such parts can prevent a quick and efficient electrostatic coating and can instead require the use of wet paint, which is more expensive, less efficient, and more time-consuming.
Among the additional deficiencies in later designs is that they have not addressed the specific weapons sought to be defeated. As a result, these designs do not adequately address the detonation details and capabilities of current weaponry and the dynamics of RPG impact. It appears that, in the past, more attention has been given to the economy of using commercially available materials, such as reinforcing bars used in construction, than to considerations for increasing effectiveness to prevent the formation of the most damaging explosions by the RPG. Nor does it appear that earlier designs have given consideration to the dynamics and geometry of the bar armor systems themselves, and their components, to most effectively prevent formation of the most damaging explosions by RPGs.
Accordingly, it is an object of the present invention to provide a bar armor system that can reduce the damage caused by RPGs targeting a vehicle. It is another object of the invention to minimize the formation of the most damaging explosions caused by RPGs launched at a vehicle. It is a further object of the invention to maintain effective protection against RPGs without unduly extending the size or increasing the weight of the vehicle. It is another object of the invention to provide a bar armor system that can position lateral bars so they can offer better protection against an oncoming RPG. It is a further object of the invention to provide a bar armor design that can be readily installed and repaired. It is still another object of the invention to provide a bar armor system that can be produced in kits, which can facilitate efficient installation and repair. Additionally, it is an object of the invention to provide a bar armor system that can be made of electroconductive materials that can be electrostatically coated when fully assembled. These and other objects of the invention will become apparent from the following brief summary of the invention, drawing figures, detailed description, and claims.
BRIEF SUMMARY OF THE INVENTIONThe present invention provides a bar armor for protecting a vehicle from rocket-propelled grenades. The bar armor comprises at least one bar array and mounts for mounting the bar arrays to the vehicle. The bar arrays are comprised of a plurality of lateral bars, which can be either round or hexagonal in cross-section; at least two vertical bars, each having a plurality of annular openings; and a plurality of tubular shaft retainers disposed in the annular openings of the vertical bars for receiving the lateral bars and for holding the lateral bars in a predetermined position.
The lateral bars are approximately 5/16″ in diameter (which, for hexagonal cross-section lateral bars, is measured across the flats) and can be spaced apart at a distance less than about 57 mm for particular RPG threats. The hexagonal lateral bars are oriented having two flat faces oriented substantially vertically so as to provide a better geometry for reducing RPG shaped charge detonation. The bar arrays can further comprise at least two push washers disposed on at least one of the lateral bars abutting at least one of the vertical bars to prevent translation of the vertical bars. The mounts can comprise a bracket, which can further comprise a rotary latch, adapted to work in conjunction with particular lateral bars. The mounts can position the lateral bars at a distance of less than about 9 inches from the vehicle. The invention also provides bar armor that can be installed in kits, for easy installation, repair, and replacement. The system is also adapted to be electrostatically coated, including with a chemical agent resistant coating (“CARC”) to promote further efficiencies.
The bar armor system of the present invention is adapted to minimize damage caused by rocket-propelled grenades (“RPGs”) by reducing the incidence of shaped charges forming upon contact or near-contact with a vehicle sought to be protected. Shaped charges are directionally-oriented explosive detonations (i.e., combustions that propagate via self-sustaining supersonic shock waves) that have the particular effect and highest incidence in causing damage. Shaped charges can be very damaging. Depending on the particular RPG, a shaped charge can penetrate at least 30 cm into armored steel or more. It is unacceptable to attempt to combat shaped charges by simply increasing the thickness of the vehicle armor. The increased thickness would make the vehicle so massive and cumbersome that it could effectively render the vehicle immobile.
The present invention reduces the need for increased armor thicknesses by substantially reducing the risk of shaped charges causing damage to a targeted vehicle. Among the ways this is achieved is by causing the RPG to deflagrate (i.e., combust via subsonic thermal conductivity) rather than form a shaped charge upon detonation. When the RPG deflagrates, it may still travel at a significant velocity and can still explode into fragments. However because deflagration is subsonic and largely non-directional, it causes much less damage than does shaped charge detonation.
Referring to
The present invention protects against a wide array of RPGs. Among the most widely-used RPGs are the RPG-7 and the RPG-7m. Referring to
It has previously been suggested that an effective way of preventing an RPG 090 from forming a shaped charge is by bringing outer ogive 092 and inner ogive 093 into sustained electrical contact, thereby creating an electrical short circuit that prevents a voltage differential from traveling to and triggering detonator 094. For an RPG launched towards a target, short-circuiting can be accomplished by crushing outer ogive 092 until it physically contacts and deforms inner ogive 093 before piezoelectric fuse 091 compresses upon hitting a target, as shown in
The present invention greatly increases the ability of the bar armor to reduce damage caused by RPG shaped charges by increasing the likelihood of short-circuiting. This is accomplished with a dynamically structured design that minimizes the points of contact upon which a RPG hit will result in the formation of a shaped charge, and maximizes the possible points of contact in which a RPG hit will result in crushing the ogives, thereby short-circuiting the RPG and stopping detonation.
The present invention, while adapted to be effective to defeat multiple types of RPGs, is dynamically and structurally designed so as to be most effective at defeating the detonation of particular RPGs or a particular family of RPGs. The bar armor of the invention takes into consideration the size and geometry of the particular RPG warhead 090; the speed or range of speeds over which the RPG is most likely to strike a target; the size, sensitivity, and location of the piezoelectric fuse 091; the size, thickness, material composition, and material strength of the outer ogive 092 and the inner ogive 093; and the dimensions and durability of the vehicle 001 that the bar armor protects.
Referring again to
Each bar array 100 provides a modular, standard-sized bar armor segment readily adaptable to protect multiple types and configurations of vehicles 001. A typical bar array 100 can be approximately 6 feet high and 3 feet wide depending on the number of bar arrays to be employed in protecting a particular vehicle. It will be understood that to protect other vehicles or portions of vehicles, and/or against other threats, bar array panels of various sizes and in various numbers can be used.
Referring to
The vertical bars can also vary in number. For a bar array having approximately 30 lateral bars, the bar array can use two vertical bars. As will be discussed in more detail below, the bar arrays can be provided in the form of a kit so that the bar armor can be readily transported and installed on the vehicles at the most convenient location for installation. In addition, it is contemplated that providing the bar armor in the form of discrete bar arrays permits removal, repair, and reinstallation of a particular bar array without removing the entire bar armor from the vehicle.
Referring to
As shown in
As shown in
Referring to
Vertical bars 300 are of dimensions appropriate to protect a vehicle 001 such that each vertical bar 300 covers all or a portion of the height of vehicle 001, as shown in
Vertical bars 300 can be made of materials strong enough so that the bar armor can withstand a RPG hit on lateral bars 200 without vertical bars 300 undergoing undue plastic deformation. Thus, vertical bars 300 can be made from a wide variety of materials such as steel, aluminum, titanium, or others with the necessary strength, weight, and material characteristics. Preferably, vertical bars 300 can be made of a wrought aluminum alloy. More preferably, vertical bars 300 can be made of an age-hardenable grade of wrought aluminum alloy with high strength and ductility, such as 7075-T651 drawn, cold-finished, and stress-relieved aluminum bar stock with an ultimate tensile strength of 80 ksi and 8% elongation to failure.
Vertical bars 300 have, at predetermined intervals, annular openings 310 which are of such geometry as to be in registering relationship with outer geometry 421 of shaft retainers 400. As shown in
The vertical bars are positioned relative to the lateral bars so as to provide sufficient restraining force to keep the lateral bars at distance spacing 220 in the event of an RPG hit. This, in turn, requires that vertical bars 300, as well, maintain their position. To implement this, push washers 500 can be placed on vertical bars 300 to provide a restraining force to assist keeping vertical bars 300 in their predetermined position and orientation. This can further prevent vertical bars 300 from spreading apart horizontally when the lateral bars 200 are hit by an RPG 090. As shown in
Preferably, as shown in
Advantageously, the lateral bars in each bar array, are positioned and kept in positions so as to maximize protection from RPGs. If allowed to unduly translate from those positions, the lateral bars would be less effective because the lateral bars would no longer be at the predetermined spacing, areal profile, and position best suited to prevent a particular RPG from forming a shaped charge. Also, allowing undue rotation of the lateral bars reduces the effectiveness of the lateral bars in preventing shaped charge formation. Preferably, the shaft retainers' inner geometry operates to prevent undue rotation of the lateral bars. Preferably, the shaft retainers have a tubular outer dimension 421 and can have an inner geometry 422 adapted to fit in registering relation with lateral bars 200. The use of shaft retainers allows each bar array 100 to be quickly assembled by inserting lateral bar 200 into shaft retainer 400 located in annular opening 310 of vertical bar 300 without need for undue welding, bolting, screwing, or chemical lubricants, although some alternative uses of such means is also contemplated.
It is desirable to prevent the vertical bars from becoming unduly plastically deformed if the lateral bars are struck by an RPG. Among the advantages that the bar armor system 010 of the invention can provide is that the lateral bars are designed to deform and/or fracture upon being struck by an RPG, such that the vertical bars can remain substantially undamaged. In this event, prompt repair can be facilitated because the vertical bars (which attach to the mounts) can remain in place and only the damaged shaft retainers and damaged lateral bars would need to be replaced and/or repaired.
Shaft retainers 400 are strong enough to keep lateral bars 200 from translating or rotating during the use of the bar armor system. Shaft retainers can be made of any composition and dimensions capable of achieving the aforementioned results. Preferably, shaft retainers are made of metal, such as spring steel, or aluminum, titanium, or other steels sufficiently protected to resist corrosion. Most preferably, shaft retainers are composed of zinc-coated steel alloy, containing between about 0.3% and about 0.8% carbon by weight, sufficient to increase both yield and ultimate tensile strength substantially to a “spring steel quality” from the cold-working (i.e., plastic deformation) of the material in forming the shaft retainer.
Referring to
Lateral bars 200 in shaft retainers 400 in vertical bars 300 are separated by spacing 220. Spacing 220 is selected to be most effective in preventing particular RPG threats forming shaped charges. This spacing provides a low areal percent for direct contact by a RPG, especially when the RPG is travelling at an off-angle (i.e., not normal to the plane of the bar array). For the RPG-7 and RPG-7m, the spacing 220 between lateral bars 200 is less than about 57 mm, and is preferably approximately 53 mm. Preferably, lateral bars are approximately 5/16″ in diameter. The diameter of a cross-section of hexagonal lateral bar 205 is measured from flat 206 to the opposite flat 206 across the narrowest part of the cross-section. More preferably, lateral bars 200 are either round in cross-section 201 with a yield strength of at least about 100 ksi, or hexagonal in cross-section 205 with a yield strength of at least about 93 ksi.
Many cross-sectional geometries of lateral bars 200 can be effectively used to combat a particular RPG threat. Round cross-sections are rotation invariant, i.e., they present the same profile to an RPG threat upon any axial rotation of any degree. As such, directional orientation is not necessary for a round lateral bar 201.
As will be explained below with reference to a hexagonal cross-section 205, lateral bars of non-round cross-sectional geometries used against each RPG threat should be placed at the proper orientation most effective in combating that threat. Proper orientation will present the smallest amount of surface area towards an oncoming RPG threat.
As shown in
Referring again to
However, large standoffs are not without their problems. A large standoff will place more weight further away from the vehicle's center of mass, thereby increasing its moment of inertia and decreasing the handling ability of the vehicle. A larger standoff will also increase the size and weight of the mounts. Additionally, a larger standoff will increase the profile and effective size of the vehicle. This will decrease the vehicle's mobility, prevent it from entering constricted environments, and make it easier to spot and target with hostile fire.
According to the present invention, the standoff to defeat the RPG-7 and RPG-7m is set at only about 7-7.5 inches from the exterior of the vehicle. This standoff minimizes the negative effect on handling, maneuverability, and vehicle profile while still allowing the lateral bars to form a contact between outer ogive 092 and inner ogive 093. While a distance of 7-7.5 inches is preferred, it will be understood that other standoff distances can be employed based on the configuration of the particular RPG threat sought to be defeated and the specific configuration parameters of the bar array used.
Mounts 600 operate to affix bar array 100 to a vehicle 001 at standoff distance 620, and are of sufficient strength and in sufficient quantity to support and retain the bar arrays 100 under a variety of conditions, including impact from an RPG. The mounts can be as lightweight and inexpensive as possible. Preferably, the mounts are also easy to use and operable for rapid installation and removal of a bar armor system pursuant to this invention. Most preferably, the mounts attach magnetically to the vehicle sought to be protected, which greatly enhances ease of use in the field.
Preferably, the present invention comprises at least two sets of mounts per bar array, a set of upper mounts and a set of lower mounts. The upper mounts can operate without a positive locking feature for simplicity and ease of installation. The lower mounts can operate in conjunction with a rotary latch to provide a quick and easily-obtained positive lock for an installed bar array 100.
As shown in
The bar array 100 of this invention can come assembled or semi-assembled in a kit ready for mounting on vehicle 001. The kit can comprise at least two vertical bars each having a plurality of annular openings, a plurality of lateral bars being either round or hexagonal in cross-section, a plurality of shaft retainers, and mounts for mounting said bar array. The kits can also comprise push washers and latches such as rotary latches. The kit can also include vertical bars wherein the shaft retainers are already positioned in the annular openings.
The bar array of this invention can be entirely electroconductive. This can enable the use of electrostatic coating techniques which are quicker and more efficient than wet paint methods. Preferably, the electrostatic coating comprises a chemical agent resistant coating.
As seen from the above, a bar armor system has been described which is effective in defeating or substantially defeating RPGs. The bar armor system of the invention does not unduly extend the size and weight of the vehicle. Advantageously, the system positions lateral bars to be most effective against RPGs and provides an arrangement wherein damaged parts can be replaced with a minimum of difficulty. The invention also facilitates installation and repair with minimum effort and enables electrostatic coating with maximum efficiency.
It should be understood that while the invention has been described with reference to preferred embodiments, other alternatives within the scope of the invention are contemplated, and the scope of the invention is to be limited only by the claims presented below.
Claims
1. Bar armor system for protecting a vehicle from rocket-propelled grenades, comprising:
- at least one bar array;
- said bar array being comprised of: a plurality of lateral bars, said lateral bars being either round or hexagonal in cross-section; at least two vertical bars, each having a plurality of annular openings; and a plurality of tubular shaft retainers disposed in said annular openings of said vertical bars for receiving said lateral bars and for locating said lateral bars in a predetermined position; and
- mounts for mounting said bar array to said vehicle.
2. The bar armor system of claim 1, wherein said tubular shaft retainers are comprised of a spring steel alloy containing, by weight, between about 0.3% and about 0.8% carbon.
3. The bar armor system of claim 1, wherein said lateral bars are round in cross-section and have a yield strength of at least about 100 ksi.
4. The bar armor system of claim 1, wherein said lateral bars are hexagonal in cross-section and have a yield strength of at least about 93 ksi.
5. The bar armor system of claim 1, wherein said lateral bars are approximately 5/16ths of an inch in diameter.
6. The bar armor system of claim 1, wherein said lateral bars are hexagonal in cross-section, wherein two flat faces of the cross-section are oriented substantially horizontally.
7. The bar armor system of claim 1, wherein said lateral bars are each spaced apart at a distance less than about 57 mm.
8. The bar armor system of claim 1, wherein said lateral bars are each spaced apart at a distance of approximately 53 mm.
9. The bar armor system of claim 1, wherein said lateral bars are comprised of a steel alloy with greater than 2% uniform plastic deformation up to ultimate tensile strength and a total elongation to failure of not less than 5%.
10. The bar armor system of claim 9, wherein said steel alloy is selected from the group consisting of: AISI 1144 steel and AISI 41L40 steel.
11. The bar armor system of claim 1, wherein said bar array further comprises at least two push washers disposed on at least one of said lateral bars abutting at least one of said vertical bars.
12. The bar armor system of claim 11, wherein said bar array has a top and a bottom, and said push washers are disposed on the lateral bars second from top and second from bottom of said bar array.
13. The bar armor system of claim 1, wherein each of said mounts comprises a bracket.
14. The bar armor system of claim 13, wherein at least one of said brackets further comprises a rotary latch.
15. The bar armor system of claim 1, wherein said mounts position said lateral bars at a standoff distance of less than about 9 inches from the vehicle.
16. The bar armor system of claim 1, wherein said mounts position said lateral bars at a standoff distance of approximately 7.5 inches from the vehicle.
17. The bar armor system of claim 1, wherein said mounts attach to the vehicle magnetically.
18. The bar armor system of claim 1, wherein said bar array is approximately 3 feet wide.
19. The bar armor system of claim 1, wherein said vertical bars are substantially rectangular in cross-section.
20. The bar armor system of claim 1, wherein said vertical bars are approximately six feet in length, about one-half inch in width, and about one inch in depth.
21. The bar armor system of claim 1, wherein said vertical bars are comprised of a wrought aluminum alloy.
22. The bar armor system of claim 21, wherein said wrought aluminum alloy is 7075-T651 aluminum.
23. The bar armor system of claim 1, wherein each bar array is electrostatically coated.
24. The bar armor system of claim 23, wherein the electrostatic coating comprises a chemical agent resistant coating.
25. A kit for preparing a bar armor system comprising:
- at least two vertical bars, said vertical bars having a plurality of annular openings;
- a plurality of lateral bars, said lateral bars being either round or hexagonal in cross-section;
- a plurality of shaft retainers with an outer geometry adapted to be in registering relationship to said annular openings of said vertical bars and an inner geometry adapted to be in registering relationship to said lateral bars;
- said vertical bars, lateral bars, and shaft retainers operative to assemble into a bar array;
- and mounts for mounting said bar array to a vehicle.
26. The kit of claim 25, further comprising a plurality of push washers.
27. The kit of claim 25, wherein said mounts further comprise rotary latches.
28. The kit of claim 25, wherein said shaft retainers are already placed and oriented in said annular openings of said vertical bars.
Type: Application
Filed: Mar 25, 2010
Publication Date: Sep 29, 2011
Applicant: GENERAL ATOMICS (San Diego, CA)
Inventors: William R. KELLNER, JR. (Lovettsville, VA), Paul C. DICKSON (San Diego, CA), Paul W. TRESTER (Encinitas, CA)
Application Number: 12/731,200
International Classification: F41H 7/00 (20060101);