Technical Field of the Invention

The present invention relates to a system that renders a torpedo ineffective that is caught by a net by means of being used by surface and underwater platforms against a torpedo or a similar threat.

State of the Art

Torpedoes pose a great threat both for surface and underwater vessels. In torpedo systems available in the state of the art, a torpedo is guided to the target by means of sonar homing heads that operate in passive and active modes. Some heavy torpedo systems, on the other hand, are capable of tracking the wake of surface vessels and may be guided to the target by using this wake.

Torpedo countermeasure systems operate based on disrupting the acoustic connection established between the torpedo and the target or deceiving the torpedo by imitating acoustic characteristics thereof because of the fact that torpedoes are guided to a target by means of acoustic methods. Torpedoes have become substantially resistant to acoustic deception due to the developments in torpedo homing heads and guiding technologies as well as the increase of torpedo ranges.

The basic method adopted by modern torpedoes against deceptive countermeasures like decoys and jammers is that they approach a decoy/jammer just like they approach a target. Thus, the torpedo runs past a decoy/jammer as it approaches decoy/jammer. Since the torpedo does not receive the signature of a real target from a decoy/jammer in close range, it determines that its target is a decoy/jammer and continues seeking another target. Even though this particular measure is effective in terms of saving time for the respective platform, meanwhile ensuring that the torpedo depletes its energy, these torpedoes, despite the fact that being deceived for a plurality of times, do not deplete their energy completely because of their increasing ranges and can eventually find the actual target. The patent document numbered “JPH06135382” was examined as a result of the preliminary search conducted in the state of the art. The invention disclosed in said patent application mentions a torpedo protective system in which a torpedo attack is prevented by using a torpedo protective net. Said invention provides the underwater positioning of the net structure by means of weights and floats.

The patent application numbered "GB2172853" was examined as a result of the preliminary search conducted in the state of the art. In the invention disclosed in said patent application, a ship is surrounded by nets to catch or otherwise obstruct a torpedo in order to prevent a ship from being sunk by torpedoes. In the embodiment disclosed in said patent application, a net is launched into the path of the torpedo, thus catching or slowing it sufficiently to render it harmless.

The state of the art revealed no system that allows for unreeling a net from an end thereof with the advance of a moving carrier device in water.

Consequently, the existence of aforementioned disadvantages in the state of the art as well as the inability of available solutions in this regard necessitated making an improvement in the relevant technical field.

Objects of the Invention

The present invention relates to a system that renders a torpedo ineffective that is caught by a net by means of being used by surface and underwater platforms against a torpedo or a similar threat.

The most important object of the present invention is to physically obstruct a torpedo threat thereby rendering it unable to navigate or making it uncontrollable.

Another important object of the present invention, unlike the acoustic decoys and jammers, which render a torpedo threat unguided to an actual target but keep it functional, is to disable a torpedo threat that is guided towards a target and/or decoy/jammer system. Thus, the torpedo is ensured to run past a decoy/jammer, thereby making the countermeasures developed for the respective decoy/jammer class ineffective. Another object of the present invention is to ensure that it may be used against torpedoes independent of the fact that a torpedo is substantially resistant to decoys/jammers. Thus, the present invention does not get affected by the reduction of the reliability of torpedo countermeasure systems due to the increase of decoy/jammer resistance of a torpedo that poses a threat to the reliability of torpedo countermeasure systems.

Yet another object of the present invention is to ensure that the inventive product may function even in the case of a torpedo thread successfully distinguishes the actual target and guided thereto. Thus, the risk, which emerges in case a torpedo is resistant to decoy/jammer systems, is eliminated to a great extent.

Structural and characteristic features of the present invention as well as all advantages thereof will be understood more clearly from the figures disclosed below and from the detailed description provided by making references to said figures. Therefore, the respective evaluation should be conducted by taking said figures and the detailed description into consideration. of the Figures

FIGURE 1 illustrates the moment in which the carrier device is launched into the water.

FIGURE 2 illustrates the side view of the inventive carrier device.

FIGURE 3 illustrates the exploded view of the inventive carrier device.

FIGURE 4 illustrates the isometric view of the inventive underwater net.

Reference Numerals

100. Carrier Device

101. Rear End Retainer

102. Underwater Net

103. Acoustic Transmitter 104. Strip

105. Reflector Unit

200. Platform

300. Torpedo

Description of the Invention

The present invention relates to a system that renders a torpedo ineffective that is caught by a net by means of being used by surface and underwater platforms against a torpedo or a similar threat.

The present invention comprises a carrier device (100), a rear-end retainer (101 ), an underwater net (102), an acoustic transmitter (103), a strip (104), and a reflector unit (105).

The carrier device (100) is launched from a threatened platform (200) into the water and moves along a specific route. Said carrier device (100) allows for releasing the rear end retainer (101 ), which retains the rear end of the underwater net (102), to begin unreeling the underwater net (102). It is ensured that the underwater net (102) is completely unreeled as the carrier device (100) follows its course. Once the entire underwater net (102) is unreeled upon releasing the rear end retainer (101 ), the carrier device (100) stops, thereby ensuring that a front end of the underwater net (102) remains stable.

The carrier device (100) may be launched either from countermeasure cartridges available for both underwater and surface platforms or from cartridges that are specially designed for the system. Lightweight and heavyweight torpedo shells may also be used for launching the carrier device (100). The case, in which the size limit is the most severe, is the case in which the system is launched from available decoy/jammer cartridges. Therefore, the characteristics of the system are disclosed in compliance with the aforementioned size limits. Thus, it will be automatically proven that the system is usable in case the system needs to be adapted to accommodate wider diameters and dimensions. 130 mm shells are commonly used for standard underwater decoy/jammer effectors. Dimensions of such systems are shorter than 1 .5 meters. These size limits were taken into consideration for the exemplary sizing prepared for the system. The total volume of the system is approximately calculated as 18 dm ³ along with a form factor of 0.9. The necessary volume to accommodate the battery, which provides the energy required for the propulsion system, short cruising range, and the acoustic transmitter (103), and to accommodate all other equipment may be considered as 5 dm ³ . As such, the volume allocated for the underwater net (102) equals 13 dm ³ . In that case, a volume 2.6 times the volume of the underwater net (102) may be allocated for storing the net. This rate is quite reasonable in terms of the modern parachute storing technology.

The rear end retainer (101 ) is positioned at the rear end of the carrier device (100) and allows for restraining the underwater net (102) inside the carrier device (100) by retaining an end of the underwater net. Once the underwater net (102) is unreeled, said rear end retainer (101 ) retains the rear end of the underwater net (102) and ensures that the underwater net maintains a relatively stationary position in the water. The rear end retainer (101 ) comprises a buoyancy control system or a propulsion system for depth stabilization.

The underwater net (102) is in a reeled form inside the carrier device (100). The underwater net (102) comprises an acoustic transmitter (103) located on a desired position thereof. The walls of the section in which the underwater net (102) is located, may be separated from the system with the desired timing. The underwater net (102) is provided a strip (104) with positive buoyancy on the upper edge of the underwater net and with negative buoyancy on the lower edge of the underwater net for unreeling the net. The underwater net (102) is positioned on the course of the torpedo (300) and ensures that the torpedo (300) gets caught in the underwater net (102) as the torpedo passes through the location in which the underwater net is positioned. The underwater net (102) is positioned such that it stays on the line between the platform (200) and the torpedo (300). As the torpedo (300) traces the target, it is forced to pass through the location in which the net is positioned, thereby ensuring that the torpedo is captured by the underwater net (102). The primary objective of the underwater net (102), rather than stopping the torpedo (300), is to ensure that torpedo gets entangled by the underwater net (102) and the other portions of the system attached to the underwater net (102). The unbalanced hydrodynamic load to be generated by the underwater net (102) and the apparatus attached thereto will prevent the torpedo (300) from being controlled. Additionally, the control surfaces or the propeller of the torpedo (300) may get entangled by the underwater net (102) and the apparatuses attached thereto. Thus, the functionality of control surfaces as well as the propeller are either partially or completely restrained. The underwater net (102) is expected to feature high strength since the aim is to ensure that the torpedo (300) moves together with the underwater net (102) rather than stopping the torpedo (300). The geometry of the underwater net (102) will have a structure such that the center of the underwater net (102) is looser after it is laid into the water. Thus, the torpedo (300) arriving at the underwater net (102) will reach the center of the underwater net (102) as the torpedo tries to move inside the underwater net (102). This will stem from the inertia of the underwater net (102) rather than the change in the direction of the torpedo (300). After the torpedo (300) has reached a relatively central point of the underwater net (102), it will begin dragging the underwater net (102) as a whole. In such a structure, it is suitable for the underwater net (102) to have a strength that is higher at the center and that gradually decreases towards the edges, and the underwater net (102) will feature a material distribution pursuant thereto. The center portion of the underwater net (102) will be manufactured from a material like Kevlar featuring high strength and will have a tighter mesh structure, and towards the edges thereof, and materials like nylon featuring lower strength and density will be used towards the edges of the underwater net. The underwater net (102) comprises a number of strips (104) made from a material featuring high strength and said strips extend from the center to the edges of the underwater net. These strips (104) will extend to the apparatuses located at the ends of the underwater net (102) for maintaining the integrity of the underwater net (102). Another strip, to which the torpedo (300), propeller, and control surfaces thereof are expected to get entangled, and that features a suitable structure and strength high enough for decreasing the activity of the torpedo's (300) propeller, will be provided in the area located at a specific distance from the center. Lightweight torpedo and heavyweight torpedo systems are among the potential targets of the system. The diameters of these systems are 324 mm and 533 mm, respectively. The meshes of the underwater net (102) should have a size that is suitable for preventing the passage of a torpedo (300). The meshes of the underwater net (102) may be in the shape of a hexagon, a square, or a triangle based on the material use and durability requirements. A square mesh model was considered as a basis in order to facilitate the calculations made on the conceptual level. Considering that the size of a single mesh is half the diameter of a lightweight torpedo (300), a torpedo will not be able to pass through the underwater mesh (102) even if the underwater mesh (102) gets ripped at one point. Each mesh will be a square having an edge length of 160 mm. Moreover, considering that the area having a 4-meter diameter at the center of the underwater net (102) is manufactured from a Kevlar mesh with a diameter of 3.2 mm, the total length of the mesh for this particular area of the underwater net (102) equals 164 meters, weight of the mesh equals 1 .6 kg and the volume of the mesh equals 1300 cm ³ . The breaking strength of the netting wire used in the section is approximately 9.3 kilonewtons. It is suitable to weave the rest of the underwater net (102) from a material with decreased strength. The load at the center of the underwater net (102), which entangles around the torpedo (300) is distributed to the edges of the underwater net. An underwater net (102) made from Nylon mesh with 1 .3 mm will be used for the off-center portion of the underwater net (102). The breaking load of the respective material equals 600 Newtons. Considering that the underwater net (102) has an edge length of 15 meters and a square-shaped area, then the total length of the material used for the portion of the underwater net (102) made from nylon is calculated as 2150 meters, the weight of the underwater net (102) is approximately 2.2 kg and the volume of the underwater net (102) is calculated a little less than 3 dm ³ . In that case, the individual weight and volume of the underwater net (102) equal 3.8 Kg and 4.3 dm ³ respectively. The total weight of the underwater net (102) is considered as 4.5 kg while the total volume of the underwater net is considered as 5.0 dm ³ for other apparatuses (apparatuses required for buoyancy, connection members, etc.) provided on the underwater net (102).

The acoustic transmitter (103) may be fixed on the underwater net (102) and used for attracting the torpedo (300) towards the underwater net (102) by being carried by means of the carrier device (100). Furthermore, said carrier device (100) and the rear end retainer (101 ) may also have acoustic capabilities. When the acoustic transmitter commences transmission, the torpedo (300) will be guided to the acoustic transmitter (103) just like a decoy is guided to the system and eventually will be caught by the underwater net (102).

The reflector unit (105) is positioned on the underwater net (102) and enables being classified as a target by the torpedo (300) which is seeking in the active mode. When the reflector unit (105) is spread to the entirety of the underwater net (102), the possibility of being classified as a target by the acoustic homing head of the torpedo (300) is much higher than decoys performing pointwise transmission. Thus, the effect of the torpedo's (300) decoy/jammer resistance on the success of the system is even further reduced. The torpedo (300) is attracted towards the underwater net (102) once the echoes generated by the reflector units (105) on the underwater net (102) are classified as a target. Other decoy/jammer systems of the target platform may also be utilized in order to attract the torpedo (300) towards the underwater net (102). After the torpedo (300) reaches the underwater net (102), the torpedo (300) will get entangled by the underwater net (102) due to the torpedo's (300) velocity relative to water, the drag force that is generated by water and that affects the underwater net, and the inertia of the underwater net (102). Accordingly, the torpedo (300) will become uncontrollable and therefore dysfunctional. This effect is even further improved in case the propulsion and control system of the torpedo (300) is entangled by the underwater net (102).

The torpedo (300) threat detection range for surface and underwater platforms is considered to be between 1000-2000 meters. Despite the fact that a torpedo (300) does not cruise at its maximum speed until it comes really close to a target (since it will lose the target due to its noise), the speed of the torpedo posing a threat may be considered 50 knots in order not to go out of the safe zone. This speed value is the maximum speed for many heavyweight and lightweight torpedoes (the maximum speed of many systems is less than 50 knots). The time required for the torpedo (300) to reach a target is 39 seconds if the torpedo (300) is detected at 1000 meters and 78 seconds if the torpedo is detected at 2000 meters in a case in which the velocity of retreat of the target platform (200) is not taken into consideration. In an embodiment of the present invention, the system is launched to water with the available countermeasure or torpedo (300) shells by the underwater or surface platform that is under a torpedo (300) threat. Determining the launch time and direction of the system by considering the direction and distance of the torpedo (300) threat is further increases the effectiveness of the system. The system is not required to move away from the target contrary to other moving decoys/jammers. Therefore, having the required range and speed is enough for the system in order to ensure secure separation from the launching platform (200) and to be able to lay the underwater net (102) in the desired direction. It will be enough to standoff at a maximum of approximately 50-100 meters from the launching location of the system. If the speed of the system is adjusted to be 15 knots (a typical speed for many moving decoy systems), the system will need approximately 13 seconds to travel 100 meters. In case a torpedo (300) threat is detected, the automated decision system of the submarine/vessel can decide to deploy countermeasures within 5 seconds and launch the system to water. There is a time window of 39 seconds for functionally using the system (for laying the net completely) in the worst-case scenario pursuant to a preloaded engagement scenario. Time periods remaining for detecting a torpedo (300) threat and for launching the system to water is 5 seconds, 13 seconds for the system to complete its course, and 39 - (13 + 5) = 21 seconds for laying open the underwater net (102). Even though the deployment of the underwater net (102) begins while the system is on the way, in order to stay within the safe zone, the deployment of the underwater net (102) is considered to begin once the system has reached its location.

After reaching the predetermined location, the carrier device (100) begins laying the underwater net (102). The width and the depth of said underwater net (102) will be approximately 10-20 meters (however, these values apply to systems launched from submarine countermeasure cartridges and it is possible to lay much bigger underwater nets (102) by means of larger carrier systems). The rear end retainer (101 ) of the carrier device (100) is separated from the carrier device (100) for immobilizing one corner of the underwater net (102). This separation occurs around the first edge of the line on which the underwater net (102) is desired to be laid. This separated unit, due to the hydrodynamic drag force effecting thereon, ensures that the underwater net (102) is unreeled from the carrier device (100). The respective unit may comprise components like fins or a parachute which may be activated upon the unit's separation from the carrier device (100). When this part is being separated, the portion comprising the propulsion system of the carrier continues its own movement. The portion comprising the underwater net (102) is deployed during the moment of separation of said part. Thus, the underwater net (102), which is suspended in water between the unit that is trying to maintain its position by means of hydrodynamic dragging and the unit that continues its own movement by means of the propulsion motor, begins being laid upon the increase in the distance between said two units in the line remaining between the units. The underwater net (102), depending on the density of the material used therein, comprises strips (104) with densities varying on the upper and the lower edges thereof to ensure that the underwater net can be laid in water. Thus, it is laid after being released to the water and becomes ready to use.

Laying the underwater net (102) requires at least 21 seconds. In the case of using an underwater net (102) with a depth of 20 meters, it will be enough to lay open the net with a speed of 1 m/s. The underwater net (102) will have a weight and buoyancy distribution suitable to be laid open with at least this speed. It is also possible for the threatened platform to move away during said period. In case the speed of the threatened platform is 20 knots, then it will be able to move 216 meters during a 21 - second period.

The propulsion system of the carrier device (100) may be located at the fore or the aft portion thereof. If the propulsion system is positioned at the fore, then the system is pulled by means of the propeller located at the fore. The propulsion system may also be positioned at the aft. In that case, the system reaches the location in which the underwater net (102) will begin being laid open. After leaving the unit that will retain one end of the underwater net (102) at this location, it begins moving in the opposite direction and navigates to the other corner of the line in which the underwater net (102) will be laid open. In this configuration, laying the underwater net (102) takes more time.

The acoustic transmitter (103), which will deceive the torpedo (300) by transmission, will be positioned at approximately a central portion of the underwater net (102). It is also possible for this apparatus to perform only acoustic transmission just like the decoys/jammers available in the state of the art or to generate echoes by listening to the sonar transmission relayed by the torpedo (300) sonar and deceiving the torpedo (300). The equipment used for such purposes is not so different from the ones commonly used in decoy/jammer systems available in the state of the art. In addition, since the other parts of the carrier device (100) stay attached to the underwater net (102), they will generate echoes in the active sonar transmission. The torpedo (300) may think that these echoes are emitted by a target. Thus, guiding the torpedo (300) to the underwater net (102) is facilitated even more. Certain underwater net (102) meshes on the underwater net (102) may be covered with surfaces that will serve as reflectors in terms of acoustics. Accordingly, this will help the underwater net (102) to generate echoes imitating an actual target and to deceive a torpedo (300).

It is also possible to use the underwater net (102) without an acoustic transmitter (103). In that case, a different moving/stationary decoy/jammer may be used for guiding the torpedo (300) to the underwater net (102). It is also possible to use the underwater net (102) without any acoustic assistance and such that it will be positioned on the potential course of the torpedo (300). A curtain may be created between the torpedo (300) and the target platform (200) by using a plurality of net components simultaneously.