CA3216829A1 - Anti torpedo system - Google Patents

Abstract

According to an aspect of the invention, there is provided an anti torpedo system, suitable for use on a ship, comprising operably linked; a combat management system comprising a high frequency hull mounted sonar, to determine the current positon and track ( depth and underwater trajectory) of a torpedo, a plurality of (direct fire) munitions, each comprising an ogive portion terminating with a water drag reduction element, an energetic payload and a programmable fuze for initiating said payload, an auto-fuze setting system, for setting the time of initiation of the programmable fuze, and a gun management system for: receiving the current position and track of said torpedo from the combat management system, and aiming and firing of said munitions, based on the received position and track of the torpedo, such as to cause each fired munition to arrive at or proximate to said torpedo and to cause detonation of the payload.

Description

2 PCT/GB2022/050870 ANTI TORPEDO SYSTEM
The present invention relates generally to anti torpedo defeat system, and more particularly to a ship based anti torpedo defeat system as a final close range neutralisation system and method.
BACKGROUND
Munitions are provided in a number of different forms, for a number of different applications.
Typically, a particular munition will be used for a particular application or intention. Incoming torpedoes are typically prevented by barriers, or by anti-torpedo torpedoes.
The use of anti-torpedo torpedoes, for example deck-launched torpedoes launched from the deck of a vessel, or those launched from a nearby submarine, helicopter or airplane. The use of torpedoes might overcome some of the problems discussed above with regard to range, mainly because torpedoes are self-propelled. However, torpedoes may be slow to deploy. Additionally, it may be difficult to engage with the torpedo at close range, ie time to deploy or from simultaneously launched torpedoes.
SUMMARY OF INVENTION
According to a first aspect of the invention, there is provided an anti-torpedo system, suitable for use on a ship, comprising operably linked;
i) a combat management system comprising a high frequency hull mounted sonar, to determine the current position and track ( depth and underwater trajectory) of a torpedo, ii) a plurality of direct fire munitions, each comprising an ogive portion terminating with a water drag reduction element, an energetic payload and a programmable fuze for initiating said payload, iii) an auto-fuze setting system, for setting the time of initiation of the programmable fuze, and iv) a gun management system for:
receiving the current position and track of said torpedo from the combat management system, and aiming and firing of said munitions, based on the received position and track of the torpedo, such as to cause each fired munition to arrive at or proximate to said torpedo and to cause initiation of the payload.
The gun management system may comprises at least one gun barrel, a fire control system to fire the munition from said gun, an aiming system to control the direction of the gun barrel. The gun management system determines the aim of said gun barrel, based on the current position, ie depth and track of the torpedo. The gun management system causes the activation of the fire control system to fire said each direct fire munition to cause each fired munition to arrive at or proximate to said torpedo and to cause initiation (ie detonation) of the payload.
The combat management system comprises the high frequency hull mounted sonar as the primary means of target acquisition and tracking, however further target acquisition systems may be used, especially when trying to determine the nature of the torpedo.
Preferably the combat management is operably linked to a target deconfliction system, to ensure the identified target is said torpedo.
Further secondary sonar systems may be provided.
The use of direct fire munitions allows for the ability of rapid rates of fire, the direct fire munition may have any calibre of munition that comprises a fuse and HE charge, preferably the calibre in the range of 12.7mm to 40mm. Larger calibre systems would work but offer low rates of fire, and systems like 4 or 5inch naval shells, are designed for deployment at multiple km ranges, rather than sub-km. Further, 4 or 5inch naval shells may have explosive outputs that when fired nearby could cause extensive blast damage to the ship or platform.
The medium calibre munitions provide gun systems which can return rapid rates of fire from at least a few hundred rounds per minute, up to thousands at the 12.7mm range.
There may be one or more gun management systems, such that there are one or more gun barrel calibres, the selection of the calibre being dependant on the proximity of the target torpedo to the ship's hull. The munition launch criteria may comprise at least one of launch timings and fuze settings. There may be first and second gun barrels they may be: the same gun barrel, and the first and second munitions are launched at different times; or the first and second gun barrels are different gun barrels, at different locations on the ship. There may be a first gun barrel on a first ship or platform and second gun barrel on second ship or platform. The second ship or platform may be part of a fleet, it may be an autonomous vessel.
The ammunition comprises the water drag reduction element, which may be selected from any means such as an active element or passive element. The passive element may be surface, ie a shape which causes the water to change to a more gaseous state.
Preferably the water drag reduction element may be a supercavitating surface feature, arranged to vaporise the water.
In a further arrangement the water drag reduction element may comprise an active element, such as for example a gas generator, shaped charge, arranged to provide the energetic displacement of the water, for reducing water drag for the projectile into a body of water.
The anti-torpedo system may be operated at the highest rate of fire for the given munition type. Alternatively, the system may be operated to allow an additive blast effect at the target torpedo. In use there may be a first munition and a second munition, co-ordinating the timing of

- 3 -the triggering of the first explosive charge in the first munition and the second explosive charge in the second munition to establish a co-ordinated explosive event at the target torpedo.
The programmable fuze, may preferably be operated using a delay timer to provide initiation of said fuze at a timing to coincide with the munitions expected arrival at the target torpedo. It may also be advantageous for the fuze to be further adapted to trigger the payload in accordance with one or more of:
after a predetermined time period after entering the water;
upon detection of a target sonar signature;
upon detection of a target magnetic signature;
upon detection of a target electric field signature;
at a predetermined pressure under the water surface;
at a predetermined depth under the water surface;
at a predetermined speed-of-sound in water; or upon impact with said torpedo under the water surface.
The use of selected munitions being selectively programmed to respond to different stimuli, may increase the ability of the munition to effectively neutralise the target torpedo. The selection of the trigger stimuli being selected by determination of the target type, depth, position and track.
The neutralisation of the target torpedo is any event which prevents the torpedo from .. reaching its intended target and detonating its payload to cause damage to said intended target.
The neutralisation may be, but not limited to a variety of events, such as, for example, the detonation of the torpedo's payload, the rupture of fuel tanks, neutralising the torpedo's homing sensors to disorientate, masking or obscuring the presence of the ship from the torpedo's sensors, incapacitating the drive, steering or propulsion system to inhibit its manoeuvrability or damaging the buoyancy of the torpedo to cause it to sink.
Co-ordinating the timing of the triggering of the first explosive charge and the second explosive charge to establish a co-ordinated explosive event at the torpedo, may comprise co-ordinating munition launch criteria.
It will be appreciated that one or more features as described in relation to munition-like aspects or arrangements of the present invention may be used in combination with or in place of one or more features of projectile-like aspects or arrangements, and the other way around. More

- 4 -generally, any one or more features described in relation to any one aspect may be used in combination with, or in place of, any one or more features of any one or more other aspects of the invention, unless such replacement or combination would be understood by the skilled person to be mutually exclusive, after reading of the present disclosure.
LIST OF FIGURES
For a better understanding of the invention, and to show how arrangements of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic Figures in which:
Figure 1 schematically depicts a vessel launching a munition (or, generally, a projectile) from a gun barrel;
Figure 2 schematically depicts the munition launched by the vessel of Figure 1;
Figure 3 schematically depicts the munition of Figures 1 and 2 being directed towards a body of water, in accordance with an example arrangement;
Figure 4 schematically depicts how a fuze of the munition of Figures 1 to 3 may be adapted to initiate a main, explosive, charge of a munition, under the water, in accordance with particular criteria, according to example arrangements;
Figure 5 schematically depicts a component for reducing water drag as forming part of the munition or projectile, in accordance with a different arrangement;
Figure 6 schematically depicts a component for reducing water drag as forming part of the munition or projectile, in accordance with a different example arrangement;
and Figure 7 schematically depicts general methodology associated with reducing water drag for a projectile entering water, in accordance with example arrangements.
DESCRIPTION
There are numerous disadvantages associated with existing apparatus and methods for engaging or generally interacting with incoming underwater targets. These range from a limited range of some existing munitions used for such purposes, to the limited accuracy of existing munitions, or the significant expense associated with existing munitions. In general, there exists no relatively inexpensive, rapidly deployable, and yet accurate munition, or related assembly or methodology, for engaging or generally interacting with underwater objects (e.g. targets) in a desirable manner.
According to the present invention, it has been realised that the problems associated with existing approaches can be largely overcome in a subtle but effective and powerful manner. In particular, it has been realised that an anti-torpedo system can be provided.
The munition comprises an explosive charge and a programmable fuze. The munition is adapted to be fired directly into the water at the incoming threat. Significantly, the munition is adapted to be launched from a gun barrel. This means that the munition typically (and practically likely) includes, or is at least used in conjunction with, a propelling explosive, and is capable of being explosively

- 5 -propelled and withstanding such explosive propulsion. This is in contrast with, for example, an anti-torpedo torpedo.
The munition is adapted to be launched and then enter a body of water, typically within which body of water a torpedo target to be engaged with is located. The fuze of the munition is adapted to trigger the explosive charge of the munition underwater, for example in accordance with pre-set criteria. The use of a gun barrel also ensures high degree of accuracy of ranging and general targeting.
The invention is subtle but powerful. The invention is subtle because it perhaps takes advantage of some existing technologies, in the form of firing a munition from a gun barrel. At the same time, the munition will typically be a projectile, therefore including no form of self-propulsion.
This means that the munition is relatively simple and inexpensive. Altogether then, this means that the munition according to example arrangements can be used to accurately, cheaply, effectively, and generally efficiently engage with the torpedo. Also, the use of a munition that is capable of being launched from a gun barrel means that multiple munitions can be launched very quickly in succession from the same gun barrel, or in succession and/or in parallel from multiple gun barrels, optionally from different ships or platforms, or optionally being targeted onto or into the same location or vicinity at or proximate to the target torpedo.
There may be one target torpedo engagement or a synchronous multiple target torpedo engagements, either performed form one or more platforms.
While munitions or in general projectiles launched from a gun barrel will, of course, be adapted for launch from such a gun barrel (e.g. and therefore able to survive that launch with little or no damage), there may nevertheless be a need to facilitate safe or effective entry of the munition into a body of water. This is because the munition may impact that body of water with considerable speed and impact. For a medium calibre direct fire munition it is not desirable to consider soft entry, ie to slow the munition prior to entry into the water.
Clearly hard entry causes impact with the water which may cause damage to, or destruction of, the munition, or initiation of the payload, which is undesirable. This risk needs to be balanced with the need to maintain a ballistic, or as close to ballistic, or as close to a predictable, trajectory as possible, so that any targeting of the target torpedo, or co-ordination of targeting of a target torpedo with one or multiple munitions, can be implemented in a practical, reliable and consistent manner.
One way of overcoming one or more of these problems, if not all of these problems, is to reduce water drag for the munition or projectile, for example, by interacting with an area or region of water into which the munition is to be targeted. This means that slowing or arresting of the munition is reduced, while at the same time minimising or avoiding the risk of damage of the munition as it enters the water. And also preventing or limiting significant changes in trajectory of the munition as it enters the water.

- 6 -Figure 1 schematically depicts a system 1 in accordance with an example arrangement. In this example, the assembly comprises a vessel 2 located on a body of water 4.
The vessel comprises a gun 6 having a gun barrel 8. the vessel comprises a high frequency hull mounted sonar 7, optionally other detectors may be used, to detect the presence of the target torpedo.
A munition 10 is shown as being explosively launched from the barrel 8 directly into the water 4 towards the target torpedo 5 Figure 2 shows the munition 10 of Figure 1 in more detail.
The munition 10 comprises a fuze system 20, in this example located in a nose or head of the munition 10. The munition 10 also comprises an explosive charge 22. The fuze system 20 is arranged to trigger the explosives charge 22, when the munition 10 is in the water, and at a suitable target location (e.g. at a target object, or target region of water), or for example meeting certain triggering criteria.
Prior to being fired, the munition 10 (or more particularly its fuze system 20) is programmed.
The programming might take place within the gun, within the barrel, or even within a particular range after launch of the munition 10, for example by wireless transmission or similar. The programming might be undertaken to implement or change particular fuze criteria, for example to trigger the explosives charge 22 within the munition 10 in accordance with particular criteria.
Typically, in order to achieve this programming, the munition 10 will comprise a fuze system 20 that is programmable in nature. In other words, the fuze system 20 is able to be programmed or configured as desired.
The criteria for triggering the charge 22 can take one or more of a number of different forms, for example: after a predetermined time period after the munition has entered the water; upon detection of a target sonar signature; upon detection of a target magnetic signature; upon detection of a target electric field signature; at a predetermined pressure under the water surface;
at a predetermined depth under the water surface; at a predetermined salinity of water; at a predetermined temperature of water; at a predetermined speed-of-sound in the water; or upon impact with a target under the water surface. All of these are environmental conditions.
As will be discussed in more detail below, the triggering, or timing of that triggering, might also relate to the reception of a co-ordinating data signal, for example received from another munition, or an object different to (i.e. not including) another munition, for example to co-ordinate the triggering of the explosive charges of multiple munitions and establish a co-ordinated explosive event.
As is typical for munitions fired from a gun barrel, the munition may be arranged to be launched from a rifled gun barrel. Alternatively the munition may be fin-stabilised. The exact configuration would be dependent on the required application.
The munition may be fired from the barrel by a mechanical firing pin, electric or thermal ignition.
Of course, care will need to be undertaken to ensure that the combination of munition properties (e.g. size, weight, shape, component parts, and so on) and firing specifications (e.g.

- 7 -explosive propulsion, launch angle) is such that the munition 10 does not explode on launch.
Further as the torpedo may be heading towards the vessel, there may need to be care as to ensure that at very acute angles that the gun does not fire munitions at the deck of the vessel.
There may be an electronic virtual mask or actual barrier to prevent such occurrence.
Turning to Figure 3, shows an overview of the system, which is split into 3 interconnected levels; the ship level systems 200, the gun level systems 210 and the projectile level systems 220.
The centre of the ship level systems is the combat management system 230. This takes information from the high frequency desk mounted sonar and any other target acquisition systems to identify and locate the incoming torpedo. Information is then exchanged with the target deconfliction system 240 to minimise the chance of friendly fire from occurring.
Once the target has been identified, is in range and no friendly units are in the line of fire then the information is passed to the gun level systems 210. The key information will be the torpedo location, depth and velocity. The gun management system will then aim the weapon in the correct direction (taking into account any deflection of the projectile's path due to striking to water's surface) and will calculate an appropriate fuze timer delay. The combat management system may be linked to one or more gun level systems, either on the ship or one on or more further platforms.
The fuze may be configured to detonate at the same depth as the torpedo using the following information:
The depth of the torpedo from the combat management system.
The angle of incidence of the projectile onto the water from the aiming subsystem/gun management system.
Either the firing from the gun or the impact on the water as a zero time to start the delay timer.
A model (either theoretical or empirical) of how the projectile will decelerate in the water.
The time delay required will be constantly changing as the torpedo progresses and the angle of the gun fire changes. Therefore so the system will be configured to individually set the fuze of every projectile just prior to/at the point of firing/at the point of exit from the barrel. Once the fuze is set and gun is pointing in the correct direction the fire control system will fire the round.
Figure 4 shows the munition 10 after it has impacted upon and entered into the body of water 4, and is descending down through the water 4. Figure 4 shows that the fuze system of the munition 10 may be adapted to trigger 40 an explosive charge within the munition 10 to successfully and effectively engage with the torpedo target 42.

- 8 -As discussed above, the triggering 40 might be achieved by triggering the explosives charge after a particular time 44, for example from one or more of a combination of launch from the gun barrel as described above, and/or a predetermined time period after entering the water 4 (e.g. an environmental condition). This latter time period will typically equate to a particular depth 46 within the water 4 (e.g. based on expected or calculated rate of descent).
Alternatively, the triggering 40 may occur at the particular depth 46 in combination with or irrespective of the timing 44. For example, an alternative or additional approach might involve the direct detection of depth (via one or more sensors or similar). Depth may detected based on time, as above, or perhaps based on water pressure under the surface, the salinity of the water, the temperature of the water or even the predetermined speed-of-sound in the water. All of these may be indicative of depth within the water, for example which had been known in advance from mapping of the area, from physics principles, and/or sensed by the munition 10 via one or more sensors when descending through the water 4.
Of course, the fuze may also be adapted to trigger the explosives charge upon impact with the torpedo target 42. However, it may be safer to employ some form of depth-activation, so that the munition 10 explodes at/near the depth of the torpedo target 42, avoiding possible unintentional explosions at or near objects that are not torpedo targets 42.
As above, the fuze may be programme with such criteria, or related criteria necessary for the fuze to trigger 40 the explosive as and when intended. Also discussed above, the triggering of the fuze 10 will almost certainly be based on an environmental condition of some kind, for example one or more of the conditions described above, including a period of time for which the munition 10 has been in the water. Again, and simply to be clear, all the conditions above will equate to environmental conditions, including such as, for example, detection of a target sonar signature, detection of a target magnetic signature, detection of a target electric field signature, and so on. In other words, the triggering of the explosives charge might advantageously require an environmental trigger of some kind. This means that while a degree of programming or hard wiring of triggering criteria might be provided, for example in the fuze system of the ignition, or programmed into the munition, an element of environmental sensing or triggering is required..
Additionally, this might assist in the co-ordination of the triggering of explosives charges of multiple munitions when located underwater, to establish a co-ordinated explosive event at a target location, for example a particular pattern of explosions relative to that target location, and/or where the munitions explode at the same time, or in a particular sequence, and so on.
. For instance, the use of munitions allows for multiple munitions to be launched in rapid succession, in combination, in parallel, from a single gun barrel, from different gun barrels, or from gun barrels of the same platform (e.g. vessel), or from different gun barrels of different platforms (e.g. different vessels). This flexibility brings about a subtle yet powerful further advantage. This is the co-ordination of the triggering of explosive of multiple munitions, launched from one or more guns.

- 9 -Figure 5 schematically depicts a projectile 140 according to an example arrangement. The projectile might comprise a fuze system and related explosive charge as discussed above. In this example, the component for reducing water drag is located in a nose or head of the projectile 140. The component comprises a gas generator 144 arranged to eject gas from an outlet 146, typically at a location of the projectile 140 that is to come into first contact with the water at a location 148 of water entry.
The gas generator 144 might take any one of a number of different forms, and could advantageously comprise a rocket motor which is a relatively simply, straightforward and effective element for generating bubbles in water. The gas generator 144 might be initiated during flight of the projectile 140, for example just before impact with the region 148 of water 4. Bubbles generated by the generator 144 will adhere to or generally move along an outer surface of the projectile 140, meaning that the projectile 140 enters the water 4 at the target location 148 more readily, and more smoothly, thus ensuring that an expected or predicted trajectory is maintained, or better maintained than if the gas generator 144 was not used. Bubbles might also simply be provided ahead of the projectile 140, for much the same benefit.
Figure 6 shows an alternative example of projectile 150 in which a nose or head 152 of the projectile comprises a component for interacting with the water 4 in the form of a charge, and typically a shaped charge 154. The charge 154 may be triggered to detonate or explode just before impact with target location 148 of the body of water 4, to at least partially vaporise the water or more generally introduce bubbles in the location 148, to soften water entry for the projectile.
Figure 7 shows a yet further example of a projectile 160. In this example, a head or nose 162 of the projectile 160 is provided with a supercavitating surface feature 164, arranged to vaporise the water at the target location when the projectile and its surface feature 164 comes into contact with that target location 148. Typically, the supercavitating surface feature 164 might comprise one or more supercavitating grooves, which are simplistic surface features useful for introducing the required vaporisation of the water, and associated reduction in water drag for the projectile 160 as a whole.
Although a few preferred arrangements have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims.

Claims (11)

- 1 0 -

1. An anti torpedo system, suitable for use on a ship, comprising operably linked;
v) a combat management system comprising a high frequency hull mounted sonar(?)õ to determine the current positon and track ( depth and underwater trajectory) of a torpedo, vi) a plurality of (direct fire) munitions, each comprising an ogive portion terminating with a water drag reduction element, an energetic payload and a programmable fuze for initiating said payload, vii) an auto-fuze setting system, for setting the time of initiation of the programmable fuze, and viii) a gun management system for:
receiving the current position and track of said torpedo from the combat management system, and aiming and firing of said munitions, based on the received position and track of the torpedo, such as to cause each fired munition to arrive at or proximate to said torpedo and to cause initiation of the payload.

2. The system according to claim 1, wherein the gun management system comprises at least one gun barrel, a fire control system to fire the munition from said gun, an aiming system to control the direction of the gun barrel, (said gun management system causing the aim of said gun barrel, based on the location, depth and track of the torpedo, activation of the fire control system to fire said munition to cause each fired munition to arrive at or proximate to said torpedo and to cause detonation of the payload)

3. The system according to any one of the preceding claims wherein the combat management system comprises a further target acquisition system.

4. The system according to any one of the preceding claims, wherein the water drag reduction element which causes the water to change to a more gaseous state.

5. The system according to claim 4, wherein the water drag reduction element is a supercavitating surface feature, arranged to vaporise the water

6. The system according to claim 4, where the water drag reduction element comprises a gas generator, shaped charge, arranged to provide energetic displacement of the water, for reducing water drag for the projectile.

7. The system according to any one of claims wherein there is a first munition and a second munition, co-ordinating the timing of the triggering of the first explosive charge in the first munition and the second explosive charge in the second munition to establish a co-ordinated explosive event at the torpedo.

8. The munition assembly according to any preceding claim, wherein the fuze is further adapted to trigger the payload in accordance with one or more of:
after a predetermined time period after entering the water;
upon detection of a target sonar signature;
upon detection of a target magnetic signature;
upon detection of a target electric field signature;
at a predetermined pressure under the water surface;
at a predetermined depth under the water surface;
at a predetermined speed-of-sound in water; or upon impact with said torpedo under the water surface.

9. A system according to any one of the preceding claims wherein the combat management is operably linked to a target deconfliction system, to ensure the identified target is said torpedo.

10 A system according to any one of the preceding claims, wherein the direct fire munition has a calibre in the range of 12.7mm to 40mm.

11. A method of triggering an explosive charge for each of a plurality of munitions, the method comprising:
firing a first munition from a first gun barrel into water to engage with a torpedo, the first munition comprising a first explosive charge and a first fuze system, adapted to trigger the first explosive charge proximate to the torpedo;
.. firing a second munition from a second gun barrel into water to engage with the torpedo, the second munition comprising an second explosive charge and a second fuze system, adapted to trigger the second explosive charge proximate to the torpedo and/or first munition; and co-ordinating the timing of the triggering of the first explosive charge and the second explosive charge to establish a co-ordinated explosive event at the torpedo.