US 3648613 A
A bomb blanket adapted to be placed over a bomb about to explode so as to minimize the lateral blast effect and to contain the spread of shrapnel, said blanket including upper and lower covers fabricated from moisture-resistant and fire-retarding material, a plurality of layers of ballistic cloth located between the covers to make the blanket shrapnel proof, and a plurality of centrally located apertures extending through the ballistic cloth with the size, number, and orientation of the apertures being parameters selected to permit the gas released by an explosion to vent therethrough and create a vacuum under the central portion of the blanket.
Description (OCR text may contain errors)
United States Patent Cunn [541 BOMB BLANKET 2,326,713 8/1943 Wesseler ..89/36A FOREIGN PATENTS OR APPLICATIONS 262,765 2/1964 Australia 102/22 1,743 1877 Great Britain ..89/36 A 161,425 11/1957 Sweden ..89/36 A Primary Examiner-Samuel W. Engle Attomey-Arthur T. Groeninger Mar. 14, 1972 ABSTRACT A bomb blanket adapted to be placed over a bomb about to explode so as to minimize the lateral blast effect and to contain the spread of shrapnel, said blanket including upper and lower covers fabricated from moisture-resistant and fire-retarding material, a plurality of layers of ballistic cloth located between the covers to make the blanket shrapnel proof, and a plurality of centrally located apertures extending through the ballistic cloth with the size, number, and orientation of the apertures being parameters selected to permit the gas released by an explosion to vent therethrough and create a vacuum under the central portion of the blanket.
The effectiveness of the blanket is due to the downward flexure or puckering of the corners of the blanket about the bomb as the bomb explodes so as to reduce the lateral blast effect and to prevent spread of shrapnel, such puckering being primarily attributable to the partial vacuum or venturi effect created on the underside of the blanket in the central region thereof as the gas released by an explosion vents through the apertures. The effect is enhanced by limiting the number of layers of ballistic cloth which extend the full dimension of the blanket so as to allow the corners of the blanket to more readily flex downwardly to enclose about the bomb. The effect is still further enhanced by tightening an adjustable strap arrangement to initially set the blanket in a puckered state about the bomb prior to explosion.
13 Claims, 6 Drawing Figures Patented "March 14, 1972 ARTHUR ATTORNEY BOMB BLANKET BACKGROUND OF THE INVENTION 1. Field of the Invention The instant invention relates generally to blankets for minimizing the explosive forces of bombs and like explosive devices. More particularly, the invention relates to bomb blankets for reducing the lateral blast effect and for trapping the shrapnellike fragments released by the explosion of a bomb.
2. Description of the Prior Art Blasting mats have been used in the excavation industry for many years for localizing or muffling the explosive forces of dynamite and blasting powder and thus minimizing the hazards attendant upon the dispersion of rock fragments. The mats are substantial in size and possess considerable weight for they are fabricated from a plurality of interconnected vehicle tire casings or elongated tubes, or rigid girders.
Representative blasting mats are depicted in US Pat. No. 2,926,605 granted to Hammel et al., US. Pat. No. 3,331,322 granted to Belander, and US. Pat. No. 3,371,604 granted to Wikner et al.
Such cumbersome blasting mats are not suitable for police or military bomb squads use, as such must be moved by excavating machinery from blast site to blast site. These blasting mats lack the flexibility necessary for one to easily position a mat about a small object, such as a box thought to contain explosive contents of an unknown type contained therein, and furthermore lack of any provision for reducing lateral blast effect and for trapping the shrapnellike fragments therein if an explosion does occur.
Heretofore, no one has devised a readily handled bomb blanket suitable for police work wherein the primary concern is to protect life and property and which is capable of minimizing the lateral blast effect and containing the flying shrapnel of an exploding bomb.
SUMMARY Thus with the deficiencies of the prior art devices enumerated above in mind, the invention contemplates an efficient and easily manipulated lightweight bomb blanket that envelopes a bomb as it explodes thereby trapping shrapnel and preventing lateral blast effect. The invention is particularly suitable for police and military bomb squad use.
The blanket comprises a plurality of layers of ballistic cloth which resists penetration of shrapnel and the like. The layers of cloth are protected by upper and lower imperforate cover members which are fabricated from flame-retardent and waterproof material to prevent water or flame damage to the cloth.
The blanket includes a plurality of apertures extending through its central portion. These apertures allow the gas released by the bomb to vent therethrough at a velocity which causes the blanket to lift from the ground and create a vacuum under the central portion thereof. The vacuum causes the edges of the blanket to collapse about the bomb thereby containing shrapnel and minimizing the lateral blast effect.
The central portion of the blanket includes additional layers of ballistic cloth as it is this portion of the blanket which is placed directly over the bomb and subject to the greatest impact. These extra layers of ballistic cloth do not extend to the edges of the blanket, the reduced number of layers at the edges increasing flexibility and enhancing the bomb enveloping effect.
The blanket may optionally further include an adjustable strap on one cover which functions as a handle and can further function to flex downwardly the corners of the blanket so that the blanket assumes a puckered condition as it is placed over the bomb. This initial puckered consition of the blanket functions in a positive manner to assure that the released gas will be directed to the centrally located apertures.
Other objects, advantages and desirable features of the instant invention will become apparent in light of the following description of the invention when construed in connection with the accompanying sheet of drawings.
DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of the bomb blanket constructed in accordance with the principles of the present invention.
FIG. 2 is a cross section taken on lines IIII of FIG. 1.
FIG. 3 is a diagrammatic view illustrating various contours of the blanket and it's positions relative to ground as a bomb explodes.
FIG. 4 is a perspective view illustrating the working face of a bomb blanket which includes straps to allow handling and to allow initial puckering.
FIGS. 5 and 6 illustrate manners in which the blanket can be handled.
DETAILED DESCRIPTION Referring now in greater detail to the drawings in which similar reference numerals refer to similar parts, FIG. 1 depicts a bomb blanket indicated generally by reference numeral 10. The blanket 10 is adapted to be placed over a bomb as shown at 12, the bomb being shown packaged as is conventionally the case encountered by bomb squads.
Referring to FIG. 2, bomb blanket 10 includes a lower cover 14 and an upper cover 16 with a plurality of layers of ballistic cloth generally designated 18 disposed between the covers. The ballistic cloth is conventionally available ballistic cloth such as that shown and described in US Pat. No. 2,8l6,578 or as described in US. military specifications MIL-C78I2C Mar. 31, 1959), MIL-F-43539 Aug. 23, I967), or MlL-C-l 2369B (July 25, 1968) available through Naval Supply Depot, 5801 Tabor Avenue, Philadelphia, Pa. l9l20, and by this reference incorporated herein.
The covers 14 and 16 which are rectangular in shape, are sewn or otherwise secured together along their edges (not shown). Covers 14 and 16 are imperforate and fabricated from a fire-retarding material, i.e., not capable of supporting a flame, and moisture-resistant material to protect the ballistic against water and fire damage. The moisture resistance is required to protect ballistic cloth 18 as water acts as a lubricant and reduces the resistance of ballistic cloth. Fire-retarding material is required so as to protect the ballistic cloth from a burning fuse or smolding Molotov cocktail and it enhances the smothering effect to extinguish a burning fuse prior to explosion.
As shown in FIG. 2, the layers of ballistic cloth 18 comprise a plurality of upper layers 18A which only cover the central portion of the blanket, generally less than three-fourths the dimension of the blanket, and a plurality of lower layers 188 which extend the full dimension of the blanket. The purpose for this arrangement is to provide maximum strength in the central impact area while increasing the flexibility of the outer edges of the blanket so that the blanket more readily encloses about a bomb as it explodes, as hereinafter more particularly described.
The greater the number of layers of ballistic cloth 18, the greater the strength of the blanket. The exact number will de pend on the thickness and resistance character of the particular ballistic cloth used and number of layers used in lower layers 18A should not be so great as to prevent flexing. While not shown in FIG. 2, when using commercially available ballistic cloth as described by the aforenoted MIL Spec., the lower layers 188 should comprise between five and I5 layers and the central portion comprising both lower and upper layer groups 18A and 188 should comprise at least 15 layers.
Layers 18 may be secured together by sewing in any convenient pattern and the assembly of layers snugly contained between the covers 14 and 16.
In order to allow gas to vent through the central portion of the blanket, a first series of spaced apertures 20 are situated near themiddle of ballistic cloth l8 and a second series of spaced apertures 22 are located radially outwardly therefrom. The cover members 14 and 16 are not perforated so as to protect the ballistic cloth as hereinbefore described. However, upon explosion, portions of the covers overlying and underlying the apertures are blasted through thereby allowing gas to escape through the apertures.
The size, number and location of apertures 20 and 22 are parameters selected to permit the gas released by an explosion to properly vent therethrough. Gas flow from the explosion must be directed upward to minimize the deathly and destructive lateral blast effect and to cause a vacuum beneath the center of the blanket so as to cause the same to envelope about the bomb. In order to accomplish the above results, each aperture should be no less than 84 inch in diameter, nor greater than one inch and preferably between $6 inch and :inch. When less than A inch in diameter. the gas cannot vent rapidly enough through the apertures and as a result, the gas spreads laterally preventing the blanket from collapsing about the bomb. When greater than 1 inch, shrapnel goes through the blanket and the blanket does not lift as the gas vents too rapidly.
The number of apertures will vary with the size of the blanket. The arrangement of FIG. 1 containing 14 apertures is designed for a blanket 4 feet square and in this size range, the number of apertures can vary from between five and 30 but preferably between l and 20. As with the size of the apertures, the number of apertures should not be too few so as to prevent sufficiently rapid venting nor to numerous to cause to rapid venting.
While not critical, it is preferred that the apertures 20 and 22 be disposed in circular paths as the bomb blasts out in all directions and the circular path arrangement assures a more uniform collapse about the bomb. It is also preferred that each of the apertures be circular in cross section to eliminate corner portions which have a greater tendency to tear. The number of aperture paths can be greater than the two illustrated providing venting is not to rapid. In addition, the apertures should be contained within the reenforced area which includes extra ballistic layers 18A so as not to interfere with the flexing at the periphery of layers 18B.
Referring to FIG. 3, the blanket is shown in a series of positions from the time a bomb explodes. In position A, the blanket l0 rests over the bomb prior to explosion. in position B, the bomb has exploded, covers 14 and 16 have to be blasted put at 14A and 16A to expose the apertures and the blankets and bomb fragments rise as gas vents through apertures causing a vacuum under the central portion. In position C, the blanket and fragments continue to rise, and, due to the gas escaping through the apertures. the vacuum is set up, and the blanket completely collapses about the exploding bomb fragments. The blanket with it's contents will rise to considerable height but the lateral effect is minimal. The central portion reenforced by extra layers of ballistic cloth 18A withstand the major blast effect. The relatively flexible peripheries of layers l8B readily collapse to the position shown.
The enveloping action can be improved if the blanket is initially flexed at the time of the explosion. For this purpose, and as shown in FIG. 4, cover 14, the working face of the blanket in contact with the bomb (the blanket shown upside down in FIG. 4) may optionally have sewn thereto a series of four straps 24, 26, 28 and 30. The straps have a loop portion at their inner most end and extend outwardly at 90 intervals about the cover. A web 32 passes through the loop portion of all the straps. The web and straps are preferably constructed of a material having a tensile strength greater than 2,000 lbs. per square inch.
Buckle 34 is placed upon web 32 so as to adjust the length thereof. Buckle 34 may be of any conventional type whereby the web may be adjusted in length and may be of the type conventionally used in auto or aircraft safety belts. By foreshortening web 32, a pulling force is exerted upon straps 24, 26, 28 and 30 and the corners of the blanket tend to flex inwardly or pucker. The dotted lines in FIG. 4 indicate such puckering.
Web 32 may be used as a handle as illustrated in FIG. 5 in approaching a bomb to be covered. The blanket provides protection for the police officer as he approaches the bomb.
Straps 24, 26, 28 and 30 also include loop portions as shown at 36, 38, 40 and 42.
A bomb may have to be removed from a particular location,
and in this instance, loops 36, 38, 40 and 42 may be conveniently utilized to receive a pole 44 which when slipped through the loops as indicated in FIG. 6 serves as a handle so that the blanket and the bomb contained therein can be manipulated and carried to a safe area.
The foregoing is a description of a preferred embodiment of the invention which is exemplary in nature. Manifestly, the invention is not limited in scope to the specific configuration detailed above, but includes all such variations as falls within the spirit and scope of the inventive concepts by the instant invention.
What is claimed is:
I. A blanket comprising a. a first plurality of layers of ballistic cloth,
b. a second plurality of layers of ballistic cloth superimposed on a central portion of said first plurality of layers of ballistic cloth,
c. the periphery of said second plurality of layers of ballistic cloth terminating short of the periphery of said first plurality of layers of ballistic cloth whereby the periphery of said blanket is flexible and light in relation to the central portion of said blanket,
d. a plurality of aperture means extending through said first and second plurality of layers of ballistic cloth for allowing passage of sufficient gas therethrough to create a partial vacuum under said central portion when a bomb explodes beneath said blanket.
2. The blanket of claim 1, means for flexing the comers of said blanket.
3. The blanket of claim 2, wherein the means for flexing the corners of said blanket includes a plurality of spaced straps secured to the top of said blanket, each of said straps having a loop at its inner end, and means passing through all of said straps, means for adjusting the length of said last mentioned means to exert a pulling force upon said straps.
4. The blanket of claim 1, including upper and lower imperforate cover members covering said ballistic cloth to protect the same from fire and moisture.
S. The blanket of claim 4, said cover member being constructed from material which is waterproof and flameproof.
6. The blanket of claim 1, means for releasably securing a pole to said blanket.
7. The blanket of claim I, wherein said first plurality of layers comprise between five and fifteen layers of ballistic cloth.
8. The blanket of claim I, the dimension of said first plurality of layers is less than three-fourths the dimension of said second plurality of layers.
9. The blanket of claim 1, said plurality of apertures each having a diameter less than 1 inch and greater than 54 of an inch.
10. The blanket of claim 9, said plurality of apertures ranging in number between five and 25 for each 4 square foot area of blanket.
T1. The blanket of claim 1, said plurality of apertures arranged in circular paths.
12. The blanket of claim 1, each of said apertures being circular in cross section.
I3. The blanket of claim I, wherein said plurality of apertures are situated in two concentric rows.