Impeller cavitation system

A method and apparatus for stopping an impeller-driven watercraft is includes distributing a plurality of submunitions in advance of a path of the impeller-driven watercraft. Each of the submunitions includes a buoyant member, a first end cap, and a second end cap; the second end cap is heavier than the first end cap. A lanyard connects the first end cap to the second end cap, optionally passing through the buoyant member. At least one of the submunitions enters an intake vent of the impeller-driven watercraft and attaches to a blade of an impeller of the impeller-driven watercraft, causing cavitation and imbalance, thereby slowing the impeller-driven watercraft.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Great Britain provisional application no. GB1416475.0 titled, “Impeller Cavitation System,” filed on Sep. 17, 2014.

FIELD

This invention relates to the field of law enforcement and more particularly to a system for creating floating security barriers against vessels propelled by water jet or impeller drives.

BACKGROUND

There exists a need for law enforcement to be able to stop watercraft for boarding, inspection, and possible arrests and confiscation of contraband. In many jurisdictions, probable cause is not sufficient reason for opening fire on a watercraft and/or an operator of that watercraft. Often, well equipped law enforcement watercrafts are able to go faster than a suspect's watercraft, but without firing of a weapon, it is difficult to force the suspect to slow down and stop for boarding. The issue is further complicated by potential risk to the public should the suspect lose consciousness and the watercraft continues to move as well as the environmental concerns should fluids escape from the watercraft after being shot.

Certain vessels can be stopped by use of prop entanglement systems such as US Coast Guard SNARE as described in U.S. Pat. No. 8,402,894 or US Coast Guard RGES as described in U.S. Pat. No. 7,975,639. Some law enforcement agencies run alongside the suspect's watercraft and shoot the engines of such vessels with specially designed rounds of ammunition that are designed to disable the engine of a vessel. These existing systems and techniques do not work on small personal watercraft such as jet skis with jet drives consisting of an impeller in a tubular housing. Any watercraft lacking an exposed propeller is unaffected by running over existing entanglement systems. Furthermore, in many such watercrafts, the engine is located close to the driver or possibly between the driver's legs making it impossible to shoot at the engine without risking life and limb of the driver or any passengers. There are situations where the operator is unconscious or otherwise incapacitated and the watercraft needs to be stopped without hurting the operator.

With respect to maritime and riverine law enforcement, there exists a problem in not being able to stop certain classes of watercraft such as small personal watercraft, often referred to as jet skis.

What is needed is a system that will stop or slow watercraft that utilize internal impellers for propulsion.

SUMMARY

One aspect of the present invention provides a floating submunition that, after being sucked into the inlet of a jet drive and hit by the impeller, causes the impeller to cavitate. The submunition is hit by the advancing impeller blade, deforms around the leading edge of the impeller blade and creates cavitation as it is swept around the jet drive unit.

In order to be sucked into the inlet of the jet drive, the submunition is designed to float, preferably in a vertically orientation. The submunition includes a buoyant body and a weight at one end to maintain an upright posture.

In some embodiments, multiple submunitions are placed in a cartridge that is fired in advance of the suspect's watercraft, for example, by a pneumatic launcher, a rocket, firearm, or a spigot mortar, sending the multiple submunitions into the water in front of the suspect's watercraft so that one or more of the submunitions are sucked into the inlet of the jet drive of the suspect's watercraft.

In some embodiments, the buoyant portion of the submunitions is made of closed cell foam or other highly buoyant material, or, in some embodiments, the buoyant portion is a sealed container or tube having a gas or air within the container to provide buoyancy.

In some embodiments, multiple submunitions are placed in a grenade or bomb that is detonated in advance of the suspect's watercraft. In some embodiments, the submunitions are deployed using a sabot that opens once the round has left the barrel of the launcher.

In some embodiments, the materials used to produce the submunitions are selected to biodegrade over relatively short time periods.

In one embodiment, the submunition consists of a buoyant float with a weight at one end and a retaining element such a disc at the other end. A cord, line or wire runs through the buoyant float, joining the weight and the retaining element. It is anticipated that the weight be metal or ceramic with a central hole through which the cord/line/wire runs and is attached.

In some embodiments, the submunitions are between 0.25 inches and 1.5 inches in diameter to facilitate passing through input grates of target watercraft. In some embodiments, the submunitions are less than 1.0 inch in diameter to facilitate passing through input grates of target watercraft. In some embodiments, the submunitions are less than 4.0 inches long to facilitate passing through input grates of target watercraft.

In some embodiments, the submunitions are provided with a range or mix of diameters and lengths to facilitate passing through input grates of target watercraft.

In some embodiments, the submunitions have a proportion of their length above the water when floating vertically, and in some such embodiments between one tenth and one third of the submunitions length is above the water when floating vertically, assuming distilled water.

In one embodiment, a submunition is disclosed including a buoyant member, a first end cap and a second end cap. A lanyard (or other connecting member) connects the first end cap to the second end cap, in some examples, passing through the buoyant member. The second end cap is heavier than the first end cap promoting an upright orientation when suspended in a fluid such as water.

In another embodiment, a method of stopping an impeller-driven watercraft is disclosed including distributing a plurality of submunitions in advance of a path of the impeller-driven watercraft, each of the submunitions includes a buoyant member, a first end cap, and a second end cap; the second end cap is heavier than the first end cap. A lanyard (or other connecting member) connects the first end cap to the second end cap. At least one of the submunitions enters an intake vent of the impeller-driven watercraft and attaches to a blade of an impeller of the impeller-driven watercraft, causing cavitation and imbalance, thereby slowing the impeller-driven watercraft.

In another embodiment, a submunition is disclosed including a buoyant member made of low-density polyethylene foam, a first end cap made of steel and a second end cap also made of steel, the second end cap being heavier than the first end cap. A lanyard (or other connecting member) connects the first end cap to the second end cap, passing through the buoyant member.

DETAILED DESCRIPTION

Referring toFIGS. 1-5, cross sectional views and end views of a submunition10are described. The submunition10is an impeller jamming system. As shown inFIGS. 7-9, one or more of the submunitions10is launched into the water in front of a watercraft20(any impeller-propelled watercraft20such as a jet ski, etc.). The intent is for one or more of the submunitions10to clamp onto a blade27of the impeller26(seeFIG. 8) of the watercraft20. Once one or more submunitions10clamp onto the blade27of the impeller26, the submunition(s)10move with the blade27of the impeller26as it rotates, causing cavitation within the impeller cavity30, reducing the thrust28/28′ and slowing the watercraft20for boarding by, for example, a law enforcement personnel.

It is desired that the submunition10float on the water in front of the watercraft20so that the submunition10submerges slightly when hit by the bow of the watercraft20, then by way of the buoyancy of the submunition10, the submunition10quickly recovers and is sucked into the intake21(seeFIGS. 8 and 9) of the watercraft20. The submunition10is then hit by the impeller26and bends around the leading edge of a blade of the impeller26and remains on the blade27of the impeller26by way of memory of the lanyard4and/or by way of an optional adhesive applied to the submunition10. In some embodiments, once the engine of the watercraft20is stopped, the submunition10falls off of the blade27of the impeller26, allowing future use of the watercraft20with no or minimal damage to the watercraft20and the impeller26.

The submunition10comprises a buoyant body7with two endcaps3/5at each end. The endcaps3/5are connected to each other by a lanyard4(or other connecting member) that in some embodiments passes through the buoyant body7. Each endcap3/5is affixed to respective ends of the lanyard4by any way known for affixing, including, but not limited to welding, soldering, adhesive, a knot, crimping, etc. For example, inFIGS. 4 and 5, the lanyard4is shown affixed to the endcaps3/5by a weld9.

So that the submunition10floats in an upright fashion, the upper endcap3is of less mass than the lower endcap5and, therefore, when placed in water, the upper endcap3remains at or above the surface of the water and the lower endcap5sinks below the surface of the water. By providing this upright orientation, the probability of being sucked into the intake21of the watercraft20is greatly enhanced.

The buoyant body7is made of a material or has a structure that makes the buoyant body7lighter than water (e.g., sea water, river water, lake water), providing sufficient buoyancy as to keep the submunition10and endcaps3/5afloat until external forces are applied (e.g., until hit by the leading edge of a hull of the watercraft20). In the example shown inFIG. 2, the buoyant body7is made of a material1that has a specific gravity relative to water that is less than 1.0. It is further desired that the overall specific gravity relative to water of the entire submunition10is less than 1.0, allowing the submunition10to partially float with the upper endcap3at or above the surface of the water. It is understood that the specific gravity with respect to water depends upon the type of water (e.g., salt water or fresh water) as well as the temperature and air pressure. To this, the submunition10is designed to operate in one or more types of target water (e.g. a submunition10designed for fresh water or a submunition10designed for salt water, etc.).

In some embodiments, the buoyant body7is made of a material1that is a foam material such as low-density polyethylene foam that is often used in packing materials. In some embodiments, the buoyant body7is made of a buoyant material1that is starch-based or starch-based foam that biodegrades relatively quickly when exposed to water. In some embodiments, the buoyant body7is made of a buoyant material1that is edible by marine life. In this embodiment, it is anticipated that when the blade27of the impeller26hits the submunition10, the buoyant body7deforms or exits the submunition10.

In some embodiments, as shown inFIG. 3, the buoyant body7is made as an enclosed tube12having seals13at each end, providing buoyancy due to air, gas, or, even by being evacuated within the cavity contained by the tube12and seals13. In this embodiment, it is anticipated that when the blade27of the impeller26hits the submunition10, the tube12fractures. In some embodiments, the enclosed tube12is the connecting member, connecting the end caps3/5.

In some embodiments, as shown inFIG. 1, the buoyant body7is coated with an outer layer15. In some such embodiments, the outer layer is made of paper or a water-soluble film that slows water ingress into the buoyant material1, thereby slowing the decomposition of the buoyant material1. In some embodiments, the outer layer15includes an adhesive that, when struck by a blade27of the impeller26of a watercraft20, the adhesive of the outer layer15aids in adherence of the submunition10to the blade27of the impeller26. In some embodiments, the adhesive is water activated or micro encapsulated to prevent the submunitions10from bonding to each other in the launch cartridge but then the submunitions10become sticky when exposed to water or when the submunitions10are hit by the impeller blade27.

Although there is no limitation on size, it is preferred that the submunition be longer (the distance between the endcaps3/5) than wider. In some embodiments, the submunitions are between 0.25 inches and 1.5 inches in diameter to facilitate passing through intake grates of target watercraft20. In some embodiments, the submunitions10are less than 1.0 inch in diameter to facilitate passing through intake grates of target watercraft20. In some embodiments, the submunitions10are less than 4.0 inches long (the distance between the endcaps3/5) to facilitate passing through intake grates of target watercraft20.

It is fully anticipated that the submunitions10are provided with a range or mix of shapes, diameters, and lengths to facilitate passing through intake grates of a variety of target watercrafts20.

In some embodiments, the submunitions10have a proportion of their length above the water when floating vertically (endcap5submerged and endcap3at or above the surface), and in some such embodiments between one tenth and one third of the submunitions length is above the water when floating vertically, assuming a specific type of water such as fresh water, salt water, etc.

The lanyard4is made of a material that is sufficiently strong as to not break under the initial force of a hit by the blade27of the impeller26. Suitable materials are fishing line, braided fishing line, annealed wire (e.g., baling wire), etc. Although not required, it is preferred to use a material that has plastic properties, in that, when bent, the material remains bent. For example, annealed wire will remain bent after the submunition10bends around the leading edge of the blade27of the impeller26.

It is anticipated that in some embodiments the endcaps3/5are made of metal or ceramic with a central hole through which the lanyard4runs and is attached. To achieve an upright posture when in the water, the upper endcap3has less mass than the lower endcap5. For example, the upper endcap3is a 24 gauge steel washer and the lower endcap5is a 12 gauge steel washer. In some embodiments, the endcaps3/5are made from a material that is not harmful to the environment and will eventually biodegrade such as steel or iron. In some embodiments, the lower endcap5is made from a formed piece of metal, shaped so as to create cavitation bubbles when the submunition10is situated on the leading edge of a rotating blade27of an impeller26.

Referring toFIG. 6illustrates multiple submunitions10in a pack50ready for deployment. In this example, the pack50is launched from a weapon by way of pneumatic pressure or an explosive charge, sending the multiple submunitions10into the air and, eventually, into the water preceding the path of the watercraft20.

Referring toFIG. 7illustrates the deployment of one or more submunitions10in advance of a watercraft20. One or more of the submunitions10is launched into the water in front of a watercraft20(any impeller-propelled watercraft20such as a Jet Ski, etc.) by a propulsion mechanism32from, for example, a law enforcement vehicle (e.g. boat30, helicopter, airplane, from land, etc.).

Referring toFIGS. 8 and 9, one of the submunitions10entering the intake21of a watercraft20(inFIG. 8) then adhering to a blade27of an impeller26of a watercraft (inFIG. 9) is shown. The intent is for one or more of the submunitions10to clamp onto the blade27of the impeller26(seeFIG. 9) of the watercraft20. Once one or more submunitions10clamps onto the blade27of the impeller26; the submunition(s)10move with the blade27of the impeller26as it rotates, causing imbalance and cavitation within the impeller cavity30. InFIG. 8, the watercraft20driven by a person25(perhaps a criminal or a person with a medical condition) is moving at a high rate of speed and the submunition10is floating in the path of the watercraft20, then the submunition10is hit by the hull of the watercraft20and submerges, recovering to enter the intake21of the watercraft20within the propulsion shroud30where, as inFIG. 9, the submunition after being hit by the blade27of the impeller26holds onto the blade27of the impeller26causing cavitation within the propulsion shroud30. The cavitation and imbalance reduces the output thrust28/28′ from a high output thrust28(seeFIG. 8) to a low output thrust28′ (seeFIG. 9). The low output thrust28′ allows a small amount of maneuverability and low speed so that the watercraft20has difficulty escaping the law enforcement vehicle (e.g. boat32).