Patent Application
20250137763
This disclosure relates to explosive charges for underwater targets, and more particular to a tandem charge configuration to form larger holes inside those underwater targets. The tandem charge may, for example, be used to penetrate double-hulled ships and submarines or in commercial applications such as fracking to remove oil from the ground.
Shape-forming charges are explosive charges shaped to focus the effect of the explosive's energy in specific direction and are purely kinetic in nature. A shape-forming charge is composed of two major components: an explosive charge and a metal liner on a forward surface of the explosive charge. The angle formed by the metal liner is referred to as the “apex angle”. Shape-forming charges may be used to penetrator armor, punch holes in naval vessels such as surface ships or submarines or to perforate wells in the oil and gas industry.
One type of shape-forming charge is referred to as an explosively formed penetrator (EFP). Detonation of the explosive charge causes the metal liner to fold, forward or backward, into a single coherent penetrator that is accelerated to extremely high velocities. Formation of the penetrator is approximately 100% mass efficient (at least 90%). The apex angle is typically 150°-170°. The EFP can be configured to form the single coherent penetrator as a slug or as an annular ring. The annular ring may have a larger diameter than the slug and thus cut a larger hole in the target but will have less penetration depth.
Another type of shape-forming charge is referred to as a shaped charge. The shaped charge liner has an apex angle of typically 60° or less. Upon detonation, the liner material collapses toward the centerline and is projected forward as both a slug and a metal jet. The slug makes up approximately 75% of the liner mass and has minimal penetration. The slug travels slower than the EFP but the metal jet tip travels much faster (approximately 3×) and thus has much greater penetration capabilities than the EFP. The tradeoff is that the metal jet has a much smaller diameter than either the EFP slug or annular ring and a lesser stand-off distance than either.
To prosecute hardened targets such as tanks, armored personnel carriers or bunkers, a missile/rocket/guided munition may be provided with a tandem charge. A shaped charge is positioned in front of a penetrator or blast warhead. The shaped charge forms the axial metal jet to punch a small hole in the hardened target. The penetrator/blast warhead have sufficient kinetic energy provided by the missile/rocket/guided munition to follow the axial metal jet to penetrate and destroy the hardened target. Without the lead hole formed by the jet, neither the penetrator nor blast warhead could sufficiently penetrate the hardened target to destroy the target.
To prosecute underwater targets such as a surface ship hull or a submarine, the shape-forming charge may have to penetrate a single or double hull and target a critical system with double-hulls being the norm. A shaped charge that forms a high velocity axial metal jet will punch a very small hole, one having a diameter approximately 10% of the diameter of the shaped charge itself, through both hulls with sufficient residual velocity to degrade the critical system assuming proper targeting. However, the small size of the hole is readily plugged and will not produce a flow rate of water inside the hull sufficient to disrupt operations. The effectiveness of the shaped charge is dependent on the proper aiming of the jet to impact critical systems within the target. This represents the current state-of-the-art in torpedo (“self-propelled underwater vehicle”) design.
Another approach is a tandem shape-forming charge in which an on-axis shaped charge is configured to form a very high velocity axial metal jet and an annular explosive charge and liner are configured to form a high velocity annular EFP. The axial metal jet penetrates and forms a hole in both the outer and inner hulls with sufficient residual velocity to target an on-board system. The annular EFP penetrates and forms a larger hole in the outer hull only. The larger hole may be between 100% and 140% of the diameter of the annular charge. The hole formed in the inner hull by the axial metal jet is about 10% of the diameter of the annular charge.
The following is a summary that provides a basic understanding of some aspects of the disclosure. This summary is not intended to identify key or critical elements of the disclosure or to delineate the scope of the disclosure. Its sole purpose is to present some concepts of the disclosure in a simplified form as a prelude to the more detailed description and the defining claims that are presented later.
The present disclosure provides a tandem charge for prosecution of underwater targets such as double-hulled sea going vessels including surface ships and submarines or in fracking operations to remove oil and gas from the Earth. The tandem charge may be specifically configured to open larger holes in the inner surface of the target than a standard shape-charge jet to increase the flow rate of water through those holes to for example, disrupt operations within the double-hulled vessel or to better remove oil or gas from the ground. Alternately, the tandem charge may be configured to disrupt operations on the other side of the outer surface of the target.
In an embodiment, a tandem charge includes both a precursor charge (PC) and a follow through charge (FTC) oriented within and along an axis of a charge casing with the FTC positioned in front of the precursor charge. The precursor charge includes an explosive charge and a liner configured such that upon detonation of the first explosive material the liner forms an annular explosively formed penetrator (EFP) that is projected along the axis and passes around the FTC to cut a first hole in an outer surface of the target. The FTC is configured to pass through the first hole in the outer surface of the target for detonation on the other side of the outer surface of the target. The flow of water carries the FTC through the first hole in the outer surface without the need for additional propulsion. In an embodiment, detonation of the FTC forms a second hole in an inner surface of the target e.g., the inner hull of a surface vessel or submarine. The diameter of the second hole being at least 30% of the diameter of the undetonated precursor charge.
In an embodiment, the FTC may be a blast charge that upon detonation expands both longitudinally along the axis and radially from the axis. The blast charge may or may not be a fragmentation charge. This may be referred to as an “omnidirectional” detonation. Omnidirectional detonation has the advantage of not requiring the FTC to maintain a precise orientation with respect to the inner surface of the target. The blast charge should open a second hole in the inner surface that is approximately 40-60% of the diameter of the undetonated precursor charger.
In an embodiment, the FTC may be configured upon detonation to form either a slug or annular EFP. The slug and annular EFPs should open second holes in the inner surface that are approximately 30-40% and 60-80%, respectively, of the diameter of the undetonated precursor charge. The slug EFP opens a smaller hole but has greater penetration capability than the annular EFP. Both must maintain a relatively precise orientation to the inner surface, e.g., +/−25 degrees to orthogonal to the surface to remain effective.
In an embodiment, a sensor e.g., an impact, magnetic or proximity sensor, transmits a fire signal via cabling to both the precursor charge and FTC. The precursor charge is detonated to form the annular EFP that cuts the cabling to release the FTC. The fire signal is delayed at the FTC prior to initiating detonation of the FTC to allow for passage of the FTC through the hole formed by the precursor charge. Alternately, a separate impact, magnetic or proximity sensor could be positioned on the FTC itself.
These and other features and advantages of the disclosure will be apparent to those skilled in the art from the following detailed description of preferred embodiments, taken together with the accompanying drawings, in which:
The present disclosure provides a tandem charge for prosecution of underwater targets such as double-hulled sea going vessels including surface ships and submarines or in fracking operations to remove oil and gas from the Earth. The tandem charge may be specifically configured to open larger holes in the inner surface of the target than a standard shape-charge jet to increase the flow rate of water through those holes to for example, disrupt operations within the double-hulled vessel or to better remove oil or gas from the ground. Alternately, the tandem charge may be configured to disrupt operations on the other side of the outer surface of the target.
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Tandem charge 18 a follow through charge (FTC) 20 positioned in front of a precursor charge (PC) 22 along a longitudinal axis 24 of charge casing 25. PC 22 includes an explosive charge 26 and a metal liner 28. Metal liner 28 is positioned on a forward surface of explosive charge 26 and configured with an apex angle 29, typically 150°-170°, such that upon detonation of explosive charge 26 the detonation wave propagates forward along axis 24 causing liner 28 to fold, forwards or backwards, to form a coherent annular EFP 30 that is projected along longitudinal axis 24 and passes around FTC 20 to cut a first hole 32 in an outer surface 34 of a target 36 such as a surface vessel or submarine. FTC 20 is configured to pass through the first hole 32 in the outer surface 34 of the target 36 for detonation 38 on the other side of the outer surface of the target. The formation of the first hole 32 in the outer surface 34 causes water to flow rapidly through the first hole 32 and carrier FTC 20 through the first hole 32 to the other side. Detonation 38 of the FTC may form a second hole in an inner surface of the target or may be used to degrade critical systems behind the outer surface. Annular EFP 30 is effectively exhausted by cutting first hole 32 and retains little capability to penetrate and form a second hole in another surface.
To effectively prosecute underwater targets, and specifically to form large holes in multiple surfaces of the targets such as is found in double-hulled ships and submarines, the positioning of FTC 20 in front of the PC 22 is critical. Upon detonation of PC 22, FTC 20 is released and allowed to be carried by the flow of water through the hole in the outer surface. In underwater applications, the FTC 20 does not have sufficient kinetic energy to force its way through or to expand first hole 32 in outer surface 34 of the target. FTC 20 needs to flow cleanly through first hole 32 with the onrushing water. Positioning FTC 20 in front of the PC 22 far forward in casing 25 accomplishes this.
A sensor and electronics package 40 is suitably positioned in the nose of the torpedo. The package may include an impact, magnetic or proximity sensor that triggers a fire signal to initiate detonation. In this example, the fire signal is carried via cabling 42 to the aft end of PC 22 and to FTC 20. The fire signal initiates detonation of PC 22 to form annular EFP 30 that cuts the cabling 42 to release FTC 20. The fire signal is delayed at the FTC prior to initiating detonation of the FTC to allow for passage of the FTC through the first hole 32 formed by the precursor charge. Alternately, a separate impact, magnetic or proximity sensor could be positioned on the FTC 20 itself.
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With FTC 214 configured as a blast charge, the second hole 216 in the inner hull has a diameter that is at least 50% of the diameter of the precursor charge 210. This compares to the shaped charged jets that represent the current state-of-the-art (SOA) in torpedo designs that produce a hole in the inner hull that is approximately 10% of the precursor charge. Assuming a depth of 100 m, this produces a 2,200% increase in flow rate of water through the inner hull into the surface ship or torpedo as compared to the shaped charge jet.
If the FTC 214 where configured to produce a slug EFP with a hole diameter in the inner hull of 30% of the diameter of the precursor charge, the flow rate would increase approximately 900% as compared to the shaped charge jet. If the FTC 214 were configured to produce an annular EFP with a hole diameter in the inner hull of at least 70% of the diameter of the precursor charge, the flow rate would increase approximately 4,900% as compared to the shaped charge jet.
Bottomline, a tandem charge that combines an annular EFP to open a hole in an outer hull to allow a FTC to be carried through the hole by onrushing water to the inner hull where its detonation forms a larger hole in the hull than the SOA shaped charge jet greatly enhances the capabilities of a torpedo to degrade the double-hulled structure of a surface ship or submarine and system operations therein.
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While several illustrative embodiments of the disclosure have been shown and described, numerous variations and alternate embodiments will occur to those skilled in the art. Such variations and alternate embodiments are contemplated, and can be made without departing from the spirit and scope of the disclosure as defined in the appended claims.
