Cartridge for providing delayed chaff for use as a decoy for RF radars

A delayed chaff cartridge for use as a decoy for RF radars may include a hollow longitudinal cartridge; one or more hollow capsules; and a propelling element configured to dispatch the capsule out from the hollow cartridge, wherein each hollow capsule includes: two longitudinal parts connected at second end via a pivot, and wherein, at least one of the two longitudinal parts is truncated at a first end.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Israeli Patent Application No. 269088, filed on Sep. 3, 2019.

FIELD OF THE INVENTION

The present invention generally relates to a chaff cartridge for use as a decoy for RF radars. More particularly, the present invention relates to a delayed chaff cartridge for use as a decoy for RF radars.

BACKGROUND OF THE INVENTION

Chaff cartridges are elements that are configured to carry and spread decoy material (e.g., chaff) to form a radar countermeasure. The spread decoy material forms a cloud of small, thin pieces of metal, metallized glass fiber and the like, which cloud appears as a cluster of primary targets on radar screens or swamps the screen with multiple returns, for example, in order to distract radar-guided missiles from their targets.

Modern chaff cartridge includes a hollow longitudinal container, a chaff payload (e.g., chaff fibers) and a propelling unit, also known as, a squib/impulse cartridge/propellant/pyrotechnic charger, for ejecting the chaff payload out from the hollow cartridge. The chaff fibers are packed and cut into dipoles ranging in length from 3 mm to over 60 mm. The chaff payload is ejected from the chaff cartridge, and thus from the aircraft/marine-vessel, immediately.

In order to increase the efficiency of the radar's decoy and to prevent aircraft contamination from chaff fibers, it is required to delay the spreading of the chaff fibers from the chaff cartridge. Therefore, a chaff cartridge with a delayed ejection/dispatching mechanism was developed.

SUMMARY OF THE INVENTION

Some aspects of the invention may be directed to a delayed chaff cartridge for use as a decoy for RF radars. In some embodiments, the delayed chaff cartridge may include: a hollow longitudinal cartridge; one or more hollow capsules; and a propelling element configured to dispatch the capsule out from the hollow cartridge. In some embodiments, each hollow capsule may include two longitudinal parts connected at second end via a pivot, and at least one of the two longitudinal parts may be truncated at a first end.

In some embodiments, both longitudinal parts may be truncated at the first end. In some embodiments, the hollow longitudinal cartridge may be made from a polymer. In some embodiments, the two longitudinal parts may be made from a polymer. In some embodiments, the at least one longitudinal part may be truncated at an angle of between 10-80°. In some embodiments, the delayed chaff cartridge may further include chaff fibers held inside the one or more hollow capsules.

In some embodiments, the delayed chaff cartridge may further include a cover that covers the first end of the two longitudinal parts. In some embodiments, the propelling element may include at least one of: a squib and a piston. In some embodiments, one hollow capsule from the one or more hollow capsules may further include a piston. In some embodiments, the truncated first ends of the one or more hollow capsules may be facing the propelling element. In some embodiments, the second ends, comprising the pivots, of the one or more hollow capsules may be facing the propelling element.

Some other aspects of the invention may be directed to a delayed chaff cartridge for use as a decoy for RF radars. In some embodiments, the delayed chaff cartridge may include: a hollow longitudinal cartridge; one or more hollow capsules; and a propelling element facing a first end of one hollow capsule and configured to dispatch the capsule out from the hollow cartridge. In some embodiments, each hollow capsule may include two or more longitudinal elements connected via weak bonds configured to disassemble the hollow capsule after dispatching.

In some embodiments, the hollow longitudinal cartridge may be made from a polymer. In some embodiments, the two or more longitudinal elements are made from a polymer. In some embodiments, the delayed chaff cartridge may further include chaff fibers held inside the one or more hollow capsules. In some embodiments, the propelling element comprises at least one of: squib and piston. In some embodiments, one hollow capsule from the one or more hollow capsules may further include a piston.

DETAILED DESCRIPTION OF THE INVENTION

Aspects of the invention may be directed to a delayed chaff cartridge for dispatching and spreading chaff fibers in the air. A delayed chaff cartridge according to some embodiments of the invention may be configured to spread the chaff fibers a predefined time after dispatching from the cartridge or at a predefined distance from the aircraft/marine-vessel due to a delaying mechanism. The delaying mechanism may include adding one or more capsules to hold the chaff fibers and be dispatched from the cartridge. The capsule may be designed to open in the air a predefined time from the dispatching or at predefined distance from the aircraft/marine-vessel.

Reference is now made toFIGS. 1A-1C, which are illustrations of a delayed chaff cartridge for providing a delayed chaff as various dispatching stages according to some embodiments of the invention. A delayed chaff cartridge100may include a hollow longitudinal cartridge20, and one or more hollow capsules10for holding chaff fibers40, as illustrated inFIGS. 1B and 1C. In some embodiments, during assembly of delayed chaff cartridge100, one or more hollow capsules10may be packed with chaff fibers40and may be inserted into longitudinal cartridge20, as illustrated inFIG. 1C. In some embodiments, delayed chaff cartridge100may further include a propelling element30facing a first end of one hollow capsule10and configured to dispatch capsule10out from hollow cartridge20. In some embodiments, each hollow longitudinal capsule10may include two longitudinal parts11and12connected at a second end via a pivot13. In some embodiments, longitudinal parts11and12may be similar or different from each other.

In some embodiments, at least one of the two longitudinal parts11and12may be truncated at the first end (e.g., ends11aand/or12a, illustrated inFIG. 2A) facing propelling element30. Detailed view of hollow capsule10is given inFIGS. 2A-2Cdiscussed herein below.

In some embodiments, hollow longitudinal cartridge20may be made from any suitable material, for example, aluminum or a polymer, such as, Acrylonitrile butadiene styrene (ABS), nylon, polypropylene, polyethylene, epoxy resin and the like. In some embodiments, hollow longitudinal cartridge20may have any cross-section geometry, for example, a circle, a square, a rectangle, a hexagon and the like, and the invention, as a whole, is not limited to the illustrated square cross-section.

In some embodiments, propelling element30may include one of: a squib34and a piston32. Squib34may include any propellant material/pyrotechnic charging material configured to explode or expands and push and dispatch capsule10out from hollow cartridge20. Squib34may explode or expands in the vicinity of piston32, thus pushing piston32to eject or dispatch one or more capsules10. In some embodiments, squib34may be located between capsule10and piston32. In some embodiments, piston32may be a separate standalone part or may be integrated part of capsule10.

In some embodiments, cartridge100may include chaff fibers40held inside one or more hollow capsules10. Chaff fibers40may be any suitable conductive fibers, for example, metal fibers, glass fibers coated by metallic coating (e.g., aluminum), carbon fibers and the like. Chaff fibers40may be packed/wrapped inside and cut into dipoles ranging in length from 3 mm to over 60 mm. In some embodiments, several different cuts having different lengths and dipoles may be held in a single hollow capsule10. The selection of chaff cuts and dipoles may be conducted based on the radar the chaff should decoy.

In some embodiments, upon dispatching from longitudinal hollow cartridge20, one or more capsules10may be delayed before opening, and thus the spreading of chaff fibers40held inside one or more capsules10may also be delayed. In some embodiments, the truncated structure of one or more capsules10may cause the delay in opening, as discussed herein below.

Reference is now made toFIGS. 2A-2C, which are illustrations of hollow capsules10for a delayed chaff cartridge100according to some embodiments of the invention. In some embodiments, each capsule10may include two longitudinal parts11and12connected at second end via a pivot13. Pivot13may be any pivot, for example, a metal rod, a metal sheet and the like, connecting two longitudinal parts11and12. Pivot13may be a structure included in two longitudinal parts11and12, for example, when two longitudinal parts11and12are extruded, injection molded, or cast. Such a pivot may include two elements, wherein at least one of the elements is configured to be at least partially pivotally inserted into the other.

In some embodiments, at least one of the two longitudinal parts11and/or12may be truncated at first end11a,11b,11c. In some embodiments, when capsule10may be configured to be launched from the back side of a moving platform (e.g., an airplane) against the progression direction of the moving platform, the truncated first end may be facing propelling element30(as illustrated and discussed with respect toFIG. 5A). In some embodiments, when capsule10may be configured to be launched from the front side of the platform in the progression direction, the second end that includes pivot13may be facing propelling element30(as illustrated and discussed with respect toFIG. 5B). In some embodiments, the truncation may force a delay in the opening of capsule10, due to the wind acting on capsule10during the dispatching. The wind may push longitudinal parts11and12against each other. In some embodiments, both longitudinal parts11and12may be truncated at first ends11a,11b,11c,12a,12b,12c. In some embodiments, elements11and/or12may be truncated at various different angles between 10°-80° (with respect to a longitudinal axis of cartridge100), for example, 45° (as illustrated inFIGS. 2A and 2C), 60° (as illustrated inFIG. 2B), 30°, 20°, 50°, 70° and the like. In some embodiments, the higher the angle is, the higher are the forces acting on elements11and12, and, therefore, the longer may be the delay in the opening of capsule10.

In some embodiments, two longitudinal parts11and12may be made from any suitable material, for example, from a polymer, such as, Acrylonitrile butadiene styrene (ABS), nylon, polypropylene, polyethylene, epoxy resin and the like.

In some embodiments, a cover14, illustrated inFIG. 2C, may cover the first end of the two longitudinal parts11and12, for example, truncated ends11cand12c. In some embodiments, cover14may add an additional delay to the opening of capsule10and/or may help to keep chaff fibers40inside capsule10after dispatching. In some embodiments, cover14may be attached to the end of the two longitudinal parts11and12without any additional connecting elements. In some embodiments, cover14may be connected to the end of the two longitudinal parts11and12by a connecting element, such as, a pin or a snap.

Reference is now made toFIG. 3, which is an illustration of a delayed chaff cartridge according to some embodiments of the invention. A delayed chaff cartridge300may include hollow longitudinal cartridge20, substantially similar to hollow longitudinal cartridge20of delayed chaff cartridge100and a plurality (e.g., two or more) of hollow capsules, for example, the illustrated two hollow capsules10aand10b. The two hollow capsules are a non-limiting example, and any other number of hollow capsules is within the scope of the invention. In some embodiments, each of hollow capsules10a, and10bmay include two longitudinal parts connected at the second end via pivots13aand13brespectively and may further be truncated at the first. In some embodiments, delayed chaff cartridge300may further include one propelling element30located adjacent to the first or the second end of a first longitudinal cartridge10a. In some embodiments, when cartridge300is configured to be launched from the back side of a moving platform (e.g., an airplane), against the progression direction, the truncated first ends of hollow capsules10aand10bmay be facing propelling element30(as illustrated inFIG. 3). In some embodiments, when cartridge300is configured to be launched from the front of the moving platform, in the progression direction, second ends that includes pivots13aand13bmay be facing propelling element30(not illustrated). In some embodiments, each one of hollow capsules10a, and10bmay hold chaff fibers40, as disclosed herein above.

Reference is now made toFIGS. 4A and 4B, which are illustrations of a front and isometric views of a hollow capsule110to be included in a delayed chaff cartridge according to any embodiment of the invention, for example, delayed chaff cartridge100and/or300. In some embodiments, one or more hollow capsules110included in the delayed chaff cartridge may be inserted (alone or in addition to hollow capsule10) to hollow cartridge20. In some embodiments, the delaying mechanism of hollow capsule110may include weak bonds115between at least two longitudinal elements111and112included in hollow capsule110. In some embodiments, hollow capsule110may include four longitudinal elements111and112(as illustrated) bonded to form a rectangular hollow capsule via four weak bonds115. Weak bonds115may be, for example, thinner joins, perforated joins, and the like In some embodiments, capsule110may have any cross-section geometry, for example, a circle, a square, a rectangle, a hexagon and the like and may be divided to any number of longitudinal elements, for example, two, three, four, five, six, or more.

In some embodiments, weak bonds115may be disassembled after the dispatching of capsule110from hollow cartridge20, and thus may open capsule110, thereby allowing chaff fibers40held inside capsule110to be spread in the air.

Reference is now made toFIGS. 5A and 5B, which are illustrations of two optional ejections of a hollow capsule from the chaff cartridges when carried by an airplane according to some embodiments of the invention. In some embodiments, the capsule (e.g., capsule10) may be ejected from a moving platform5(e.g., an airplane) and dispatched from the hollow longitudinal cartridge (e.g., hollow longitudinal cartridge20) against the progression direction of the moving platform5, from the back of moving platform5as illustrated inFIG. 5A. The wind vector acting on the capsule has a direction opposite to the progression direction of the moving platform5. Therefore, for the wind vector to delay the opening of capsule10by acting on truncated ends of longitudinal parts11and/or12, capsule10may be ejected from hollow longitudinal cartridge20, such that the truncated ends are the last part of capsule10to be dispatched, as illustrated. Therefore, capsule10may be inserted in hollow longitudinal cartridge20such that truncated first end11and/or12may be facing propelling element30.

In some embodiments, the capsule (e.g., capsule10) is ejected from a moving platform5(e.g., an airplane) and dispatched from the hollow longitudinal cartridge (e.g., hollow longitudinal cartridge20) in the progression direction of the moving platform5, from the front of moving platform5as illustrated inFIG. 5B. Therefore, for the wind vector to delay the opening of capsule10by acting on truncated ends of longitudinal parts11and/or12, capsule10may be ejected from hollow longitudinal cartridge20such that the truncated ends are the first part of capsule10to be dispatched/ejected, as illustrated. Therefore, capsule10may be inserted in hollow longitudinal cartridge20such that second ends, comprising pivots13, of the one or more hollow capsules10are facing propelling element30.

In some embodiments, for the wind vector to apply closing force on the truncated ends of longitudinal parts11and/or12, longitudinal parts11and/or12may be positioned in cartridge20as illustrated inFIGS. 5A and 5B. In some embodiments, capsule10may be located inside hollow longitudinal cartridge20such that, when capsule10is ejected from cartridge20(in all the disclosed configuration), the wider walls of two longitudinal parts11and12may face the ground. For example, when capsule10is still closed (after dispatching), the edges of longitudinal parts11and12, attached to each other, may be located on the walls of two longitudinal parts11and12that are substantially perpendicular to the ground. In such configuration, a component of the wind vector, perpendicular to at least one truncated surface, may act to delay the opening of capsule10.