Abstract:
A canister that acts as a pressure vessel that contains a payload and that can withstand pressures that may be generated by the payload internal to the canister in order to contain the payload contents. The canister can be launched from a submarine, with the canister being located internal to the pressure hull of the submarine prior to launch and the canister being launchable from the submarine into the surrounding water. After launching, the canister is designed to release or deploy the payload permitting the payload to perform its intended function(s). The payload contained in the canister can be an unmanned underwater vehicle such as an acoustic training target that is powered by one or more lithium batteries.

Description:
FIELD 
       [0001]    This disclosure relates to a canister that acts as a pressure vessel that can contain a payload, such as an underwater vehicle, and which can be launched underwater, for example from a submarine or other subsurface vessel. 
       BACKGROUND 
       [0002]    Acoustic training targets (ATT) are used for anti-submarine (ASW) training. One example of an ATT is the MK39 Expendable Mobile ASW Training Target (EMATT) available from Lockheed Martin Corporation. The MK39 EMATT uses lithium sulfur dioxide high energy density batteries for power. The MK39 EMATT is currently deployed from surface ships or aircraft. Submarines do not typically deploy the MK39 EMATT because of risks involved in bringing lithium sulfur dioxide batteries on board a submarine. Instead, submarines typically utilize an ATT referred to as a Submarine Mobile Acoustic Training Target (or SubMATT). SubMATTs use lower energy density alkaline batteries that occupy more volume than a standard EMATT. This increases the length of the SubMATT while reducing the volume for advanced capabilities. 
       SUMMARY 
       [0003]    A canister is described herein that acts as a pressure vessel that contains a payload and that can withstand pressures that may be generated by the payload internal to the canister in order to contain the payload contents. The canister can be used on a vehicle from which the canister can be launched. In some embodiments, the vehicle can be a submarine, with the canister being located internal to the pressure hull of the submarine prior to launch and the canister being launchable from the submarine into the surrounding water. After launching, the canister is designed to release or deploy the payload permitting the payload to perform its intended function(s). 
         [0004]    In some embodiments, the payload contained in the canister can be an unmanned underwater vehicle having a propulsion mechanism and a steering mechanism that permits the underwater vehicle to be propelled through the water and steered in desired directions. In some embodiments, the underwater vehicle can be an ATT. In some embodiments, the underwater vehicle can be powered by one or more lithium batteries, for example lithium sulfur dioxide batteries or any other lithium-based batteries. 
         [0005]    Methods of containing a payload while onboard a submarine, as well as launching and deploying a payload, such as an unmanned underwater vehicle containing one or more lithium batteries, from a submarine are also described. The payload containing the one or more lithium batteries is held in the pressure vessel canister prior to launch, with the canister designed to be able to withstand the internal pressure generated in the event that one of the lithium batteries fails. The canister can also be launched from the submarine for deployment of the payload or removal of the canister from the interior of the submarine in the event of a failure of the payload prior to launch. In one embodiment, the canister can be launched from the submarine via the submarine&#39;s trash disposal unit. However, the canister can be launched from any means on the submarine capable of discharging the canister from the interior of the submarine and into the water. 
         [0006]    In one embodiment, a system within the interior of a submarine includes a payload, and a pressure vessel canister defining an interior space, where the payload is contained within the interior space. The payload can be an unmanned underwater vehicle having a propulsion mechanism and a steering mechanism. In some embodiments, the payload can include one or more lithium batteries that power the propulsion mechanism and the steering mechanism. In some embodiments, the unmanned underwater vehicle can be an ATT. The pressure vessel canister can be launchable from the submarine, and once launched, the pressure vessel canister is configured to deploy the unmanned underwater vehicle. 
         [0007]    In one embodiment, a method described herein can include storing a payload that includes one or more lithium batteries inside a submarine within an interior space of a pressure vessel canister. The pressure vessel canister is liquid and pressure tight and is capable of withstanding an internal pressure that is larger than ambient pressure of the submarine, the internal pressure generated as a result of venting by failure of at least one of the one or more lithium batteries. The method can also include launching the pressure vessel canister with the payload contained therein from the submarine, for example from a trash disposal unit of the submarine. 
     
    
     
       DRAWINGS 
         [0008]      FIG. 1  illustrates a submarine and a trash disposal unit from which the pressure vessel canister described herein can be launched. 
           [0009]      FIG. 2  is a detailed illustration of the trash disposal unit of the submarine. 
           [0010]      FIG. 3  is a perspective view of an assembly of the pressure vessel canister and the payload contained therein prior to launch, with portions of the pressure vessel canister illustrated as being transparent to show the payload contained therein. 
           [0011]      FIG. 4  is a rear perspective view of the assembly of the pressure vessel canister and the payload contained therein prior to launch. 
           [0012]      FIG. 5  is a front perspective view of the assembly of the pressure vessel canister and the payload contained therein prior to launch 
           [0013]      FIG. 6  is a perspective view of the forward hull section of the pressure vessel canister. 
           [0014]      FIG. 7  is an aft end view of the pressure vessel canister prior to launch. 
           [0015]      FIG. 8  is a perspective view of the aft hull section of the pressure vessel canister. 
           [0016]      FIG. 9  is a perspective view of the front portion of the assembly showing a stand-off mechanism holding the front end of the payload in place prior to launch. 
           [0017]      FIG. 10  is another perspective view of the front portion of the assembly showing a removable forward pressure plug prior to launch. 
           [0018]      FIGS. 11A and 11B  are perspective views of portions of the assembly showing a removable pressure plug providing access to an electrical connector of the payload. 
           [0019]      FIG. 12  is a perspective view of the assembly after launch with drag fins on the forward hull section deployed. 
           [0020]      FIGS. 13A, 13B and 13C  illustrate a sequence of deployment of the payload from the pressure vessel canister after the assembly has been launched from the submarine. 
           [0021]      FIG. 14  illustrates an embodiment of the pressure vessel canister and the payload contained therein prior to launch, with portions of the pressure vessel canister illustrated as being transparent to show the payload contained therein, and the aft weight disposed within the pressure vessel canister. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]      FIG. 1  illustrates a submarine  10  within which an assembly  12  of a pressure vessel canister  14  and a payload  16  contained within the canister  14  (best seen in  FIG. 3 ) can be stowed in and transported by, as well as be launched from, the submarine  10 . The submarine  10  is of well-known construction and includes a pressure hull  18  that permits the submarine  10  to travel under water  20  at great depths. The pressure hull  18  defines an interior dry space  22  of the submarine  10  that carries personnel, equipment, etc. A trash disposal unit  24  of conventional construction and operation is provided on the submarine  10  and through which trash can be discharged from the interior space  22  of the submarine  10  and into the water  20 . 
         [0023]      FIG. 2  shows the trash disposal unit  24  as including a tube  26  having an openable and closeable breech door  28  at a top end of the tube  26 , and a valve  30  at the bottom end of the tube  26 . The assembly  12  of the pressure vessel canister  14  and the payload  16  is shown loaded into the tube  26  ready for launch from the submarine  10 . The assembly  12  is loaded into the top of the tube  26  by opening the breech door  28 , inserting the assembly  12 , and then closing the breech door  28 . Water can then be flooded into the interior of the tube  26  and the valve opened  30  to allow the assembly  12  to launch from the tube  26  by falling from and out of the tube  26  under its own mass. In other embodiments, supplemental pressure can be used to aid in launching the assembly  12  from the tube  26 . Further information on the construction and operation of the trash disposal unit  24  can be found in U.S. Pat. No. 5,666,900 the entire contents of which are incorporated herein by reference. 
         [0024]    To help explain and understand the positioning of the payload  16  within the canister  14 , and to help explain the construction and operation of certain features internal to the canister  14 , portions of the canister  14  are illustrated in some of the figures herein as being transparent. 
         [0025]    Referring to  FIGS. 3-5 , the assembly  12  is illustrated in a storage, transport or pre-launch mode. The canister  14  forms a closed container or pressure vessel that is designed to hold gases or liquids, that may be part of or generated by the payload  16 , at a pressure that is substantially larger than the ambient pressure surrounding the canister  14 , for example the ambient pressure contained in the interior space  22  of the submarine  10 . The payload  16  is completely housed within the pressure vessel canister  14  to shield the payload  16  from the external environment outside the canister  14 , and to shield the external environment outside the canister  14  from the payload  16 . 
         [0026]    The pressure vessel canister  14  prevents potentially hazardous materials from the payload  16  from discharging into the interior space  22  of the submarine  10 . The payload  16  can be any device that is configured to perform a mission outside of the submarine  10  after it is launched from the submarine  10 . In the embodiment illustrated in  FIGS. 3-5 , the payload  16  can be an unmanned underwater vehicle having a propulsion mechanism  40 , such as a rotating propeller, and a steering mechanism  42 , such as steerable control fins, at an aft end  44  thereof that permit the underwater vehicle to be propelled through the water  20  and steered in desired directions after launch and deployment. A forward end  46  of the payload  16  can be bullet-shaped or have another hydrodynamic configuration that facilitates travel of the payload  16  through the water  20  once it is deployed. 
         [0027]    In some embodiments, power for powering the underwater vehicle, including the propulsion mechanism  40  and the steering mechanism  42 , can be provided by one or more lithium batteries (not shown), including, but not limited to, lithium sulfur dioxide batteries or any lithium-based battery. In some embodiments, the unmanned underwater vehicle can be an ATT such as the MK39 EMATT or the SubMATT. In embodiments where the payload  16  is powered by one or more lithium batteries, a failure in one or more of the lithium batteries can cause venting of harmful gases, such as sulfur dioxide (SO 2 ) in the case of lithium sulfur dioxide batteries, and volatile organics from the payload  16 . However, the pressure vessel canister  14  is designed to contain such gases and prevent their spread to the interior space  22  of the submarine  10 . In one non-limiting example, the pressure vessel canister  14  can be designed to withstand up to about 330 psi of internal pressure. 
         [0028]    Referring to  FIG. 6  along with  FIGS. 3-5 , the pressure vessel canister  14  includes a forward hull section  50  and an aft hull section  52 . The forward hull section  50  includes a generally cylindrical housing  54  with a forward end  56  and an aft end  58 . The aft end  58  is formed with a radial outward extending flange  60  that is used for securing the forward hull section  50  to the aft hull section  52  as described further below. The housing  54  is generally hollow and defines a space that receives the payload  16  therein. A cap that includes a bumper  62  ( FIGS. 3-5 and 10 ) is fixed to and closes the forward end  56  of the housing  54  in a liquid tight manner. In one embodiment, the bumper  62  can be substantially rigid and can be formed from a polymeric material including, but not limited to, nylon. The bumper  62  is formed with a plurality of stand-offs  64  to protect the trash disposal unit  24  from damage during launch, and a port in the cap is sealingly closed by a removable plug  66 . Removal of the plug  66  permits water to flood into the interior of the canister  14  as described below. 
         [0029]    A plurality of rails  68  are also provided on the outside of the housing  54 . Each rail  68  extends axially along substantially the entire length of the housing  54 , and each rail  68  extends substantially radially from the housing  54 . The rails  68  help center the assembly  12  within the tube  26  of the trash disposal unit  24 , help protect the assembly  12  from damage, and help prevent damage to the trash disposal unit  24 . 
         [0030]    With reference to  FIG. 8  along with  FIGS. 3-5 , the aft hull section  52  includes a generally cylindrical housing  70  with a forward end  72  and an aft end  74 . The forward end  72  is formed with a radial outward extending flange  76  that abuts against the flange  60  of the forward hull section  50  when the hull sections  50 ,  52  are secured to one another. A sealed retention ring  78 , for example a sealed circumferential clamp, encircles the flanges  60 ,  76  and clamps the flanges  60 ,  76  together to detachably secure the hull sections  50 ,  52  to each other. To help maintain a fluid tight seal between the flanges  60 ,  76 , a sealing gasket (not shown) can be provided between the abutting faces of the flanges  60 ,  76  to prevent fluid leakage between the flanges  60 ,  76  when the flanges  60 ,  76  are clamped together by the sealed retention ring  78 . 
         [0031]    The housing  70  is generally hollow and defines a space that receives the payload  16  therein. A cap  80  ( FIGS. 4 and 7 ) is fixed to and closes the aft end  74  of the housing  70  in a liquid tight manner. A port in the cap  80  is sealingly closed by a removable plug  82 . Removal of the plug  82  permits water to flood into the interior of the canister  14  as described further below. 
         [0032]    A weight  84  is fixed near the aft end  74  of the housing  70  for increasing the mass of the aft end  74 . The weight  84  can take any shape and form, and can be located at any position on or in the aft hull section  52 , as long as the weight  84  can perform the function(s) of the weight  84  described herein. In the illustrated example, the weight  84  is shaped as a cylindrical ring that is disposed about the exterior of the housing  70  at the aft end  74 . In another embodiment illustrated in  FIG. 14 , the aft weight  84  is disposed within the housing  70  at the aft end. As described further below, the weight  84  helps create an aft center of gravity to cause the assembly  12  to achieve the correct orientation in the water  20  after launch for properly deploying the payload  16 . 
         [0033]    A plurality of rails  86  can also be provided on the outside of the housing  70 . Each rail  86  extends axially along substantially the entire length of the housing  70 , and each rail  86  extends substantially radially from the housing  70 . The rails  86  function similarly to the rails  68  in that they help to center the assembly  12  within the tube  26  of the trash disposal unit  24 , help protect the assembly  12  from damage, and help prevent damage to the trash disposal unit  24 . 
         [0034]    The rails  86  are not illustrated in  FIGS. 8 and 13A -C for sake of convenience. When the canister  14  is assembled, the rails  68  on the forward hull section  50  are aligned with the rails  86  on the aft hull section  52 . However, alignment of the rails  68 ,  86  is not required. 
         [0035]    With reference to  FIGS. 4 and 7 , an exterior pressure gauge  88  is provided for measuring and indicating internal pressure within the interior of the canister  14 . The pressure gauge  88  provides a means for personnel to determine whether or not a failure has occurred in the payload  16 , for example in one of the lithium batteries, and whether or not it is safe to open the canister  14  for subsequent deployment of the payload  16 . The pressure gauge  88  can be provided at any location on the canister  14 . In the example illustrated in  FIGS. 4 and 7 , the pressure gauge  88  is provided on the cap  80  at the aft end  74  of the housing  70  of the aft hull section  52  although other locations are possible. 
         [0036]    In some embodiments, the interior of the aft hull section  52  can include an alignment mechanism  90  that interacts with the payload  16  for correctly aligning the payload in the canister  14 . For example, with reference to  FIGS. 3 and 8 , when the payload  16  is an underwater vehicle having steerable control fins, the alignment mechanism  90  can comprise a slot  92  that is defined within the interior of the aft hull section  52  adjacent to the aft end  74 . The slot  92  receives one of the control fins of the payload  16  to hold the payload  16  in place so that the payload cannot rotate within the canister  14 . 
         [0037]    In some embodiments, the interior of the forward hull section  50  can include a stand-off mechanism  94  that holds the front end of the payload  16  in axial position while allowing water to flow past the stand-off mechanism  94  when flooding the canister  14  with water as discussed further below. For example, with reference to  FIGS. 3 and 9 , the stand-off mechanism  94  can comprise a cylindrical ring with a plurality of circumferentially spaced apertures  96  and circumferentially spaced ribs  98 . One end  100  of the stand-off mechanism  94  abuts against the interior surface of the cap of the forward hull section  50 , while the opposite end containing the ribs  98  partially receives the forward end  46  of the payload  16 . 
         [0038]    In some embodiments, a corrosive scuttle plug  102  can be provided in the canister  14 . The scuttle plug  102  fills a through hole through some portion of the canister  14 , but the scuttle plug  102  is made of a material that corrodes relatively quickly when exposed to water, such as sea water, to permit water to flood into the canister  14 . For example, with reference to  FIG. 10 , the scuttle plug  102  is illustrated as filling a through hole that is formed in the bumper  62 . The scuttle plug  102  can be made from magnesium or alloys thereof that are known to react spontaneously and at a controlled rate with sea water. When the scuttle plug  102  corrodes, water can flood into the interior of the canister  14  through the hole previously filled by the scuttle plug  102 . 
         [0039]    In some embodiments, a manual latching relief valve can be provided on the canister  14  to allow interior pressure in the canister  14  to be relieved manually. 
         [0040]    In some embodiments, for example where the payload  16  is programmable, access to the payload  16  can be provided through the canister  14 . For example, when the payload  16  is an underwater vehicle that can be programmed, access can be provided through the canister  14  to an electrical connector  110  on the payload  16  through which the payload  16  can be programmed. For example, with reference to  FIGS. 11A-B , a removable pressure plug  112  can be provided that fills an access port  114  formed in some portion of the canister  14 , for example the housing  70  of the aft hull section  52 . The access port  114  is positioned over the electrical connector  110  of the payload  16  such that when the pressure plug  112  is removed from the access port  114  as shown in  FIG. 11B , the payload  16  can be programmed by plugging into the electrical connector  110  through the canister  14 . 
         [0041]    In some embodiments, to help the forward hull section  50  separate from the aft hull section  52  after launch, means can be provided for increasing drag on the forward hull section  50  compared to the aft hull section  52 . For example, with reference to  FIGS. 4-5 and 12 , drag fins  120  can be provided on the forward hull section  50 . The drag fins  120  can be pivotally attached at leading edges  122  thereof to the housing  54  between the rails  68 . The drag fins  120  can pivot from a closed position shown in  FIGS. 4 and 5 , where the drag fins  120  are substantially flush with the outer surface of the housing  54 , to an open position shown in  FIG. 12 , where the drag fins  120  project outwardly from the forward hull section  50 . 
         [0042]    In some embodiments, for example where one or more lithium batteries are within the canister  14 , a gas absorbent pack can be included within the canister  14  to absorb gases that may be emitted in the event of a failure of one or more of the lithium batteries. In one embodiment, the absorbent pack can be mounted internally in the forward hull section  50  just behind and outside the perimeter of the port containing the removable plug  66 . 
         [0043]    An example operation of the pressure vessel canister  14  and the payload  16  will now be described. In this example, it will be assumed that the payload  16  is an unmanned underwater vehicle that is powered by one or more lithium batteries. It will also be assumed that the assembly  12  has been loaded into the submarine  10 , that the submarine  10  is traveling submerged in the water  20 , and that the canister  14  is launched from the trash disposal unit  24  of the submarine  10 . However, other variations are possible. The canister  14  is designed to withstand the pressure of multiple ones of the batteries venting as a result of battery failure, for example with up to about a 10× safety factor. In addition, the canister  14  containing the unmanned underwater vehicle and the failing battery(s) can be immediately flushed out of the submarines trash disposal unit  24  in the event of a “severe” battery failure. 
         [0044]    For normal operation, the end user would monitor the pressure gauge  88 . With the canister  14  in a normal low pressure range, the pressure plug  112  can be removed to access the underwater vehicle and the mission of the underwater vehicles can be programmed. The pressure plug  112  can be replaced if the user is not ready to launch and to maintain safety. 
         [0045]    To prepare for launch under normal circumstances, the end plugs  66 ,  82  (and optionally the pressure plug  112 ) and the retaining ring  78  of the canister  14  are removed and the canister  14  with the underwater vehicle still encased therein is placed in the trash disposal unit  24 . The canister  14  is loaded into the tube  26  of the trash disposal unit  24  with the forward end down and the aft end up. The canister  14  is then launched from the trash disposal unit  24 . Because the plugs  66 ,  82  and the plug  112  have been removed, water that is introduced into the tube  26  of the trash disposal unit  24  during launch can flow into the canister  14 . The weight  84  attached to the aft section of the canister  14  pushes the canister  14  out of the trash disposal unit  24  as the sea water flows around and into the canister  14 . 
         [0046]      FIG. 13A  depicts the canister  14  shortly after exiting the trash disposal unit  24 . The canister  14  is oriented with the forward end down and the aft end up. The weight  84  at the aft end creates an aft center of gravity, thereby causing the canister  14  to rotate as shown in  FIG. 13B . As the canister  14  rotates, sea water can flow under the drag fins  120 , causing the drag fins  120  to automatically open to the position shown in  FIG. 12  (the drag fins are not illustrated in  FIGS. 13A-C  for convenience). The increased drag created by the drag fins  120  helps the forward hull section  50  separate from the aft hull section  52  as shown in  FIG. 13B . The aft hull section  52  also falls away from the underwater vehicle whereby the underwater vehicle is now deployed and clear of the hull sections  50 ,  52  to begin its intended mission. 
         [0047]    In the event of an emergency, for example one or more lithium batteries fails as indicated by the pressure gauge  88 , the canister  14  may need to be launched from the submarine  10  without subsequent deployment of the underwater vehicle in order to remove the canister  14  from the submarine  10 . In such an event, the canister  14  can be loaded into the trash disposal unit  24  with the end plugs  66 ,  82 , the pressure plug  112 , and the retaining ring  78  still in place to maintain the pressure integrity of the canister  14 . The canister  14  can then be launched from the trash disposal unit  24  into the water  20 . The corrosive scuttle plug  102  reacts with the water, ultimately opening its associated through hole to allow water to flood into the canister  14  as the canister  14  sinks to the bottom. 
         [0048]    The examples disclosed in this application are to be considered in all respects as illustrative and not limitative. The scope of the invention is indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.