Patent Publication Number: US-6655313-B1

Title: Collapsible wet or dry submersible vehicle

Description:
ORIGIN OF THE INVENTION 
     The invention described herein was made in the performance of official duties by employees of the Department of the Navy and may be manufactured, used, licensed by or for the Government for any governmental purpose without payment of any royalties thereon. 
     Field of the Invention 
     The invention relates generally to submersible vehicles, and more particularly to a submersible vehicle having a hull that is substantially or completely collapsible and that can be used as a wet or dry submersible vehicle. 
     Background of the Invention 
     Manned submersible vehicles are used in a variety of naval and civilian activities. “Dry” submersible vehicles are constructed to keep water out of the various operator compartments whereas “wet” submersible vehicles must be piloted by scuba-equipped operators as the vehicle is allowed to fill with water during the submerging thereof. Dry submersible vehicles are generally large and are designed for long underwater missions. Wet submersible vehicles provide a number of advantages when compared to dry submersible vehicles. For example, wet submersibles are neutrally buoyant and, therefore, require less power than a comparably-sized dry submersible which needs a greater amount of propulsion power to overcome the vehicle&#39;s inherent buoyancy. Thus, wet submersible vehicles can be smaller thereby making them more maneuverable in shallow and/or obstacle-laden water environments. Further, wet submersibles are ideal for search and rescue missions since the operators thereof are already outfitted with scuba gear and can quickly exit the vehicle when needed. Currently, submersible vehicles are designed to be either “wet ” or “dry”. However, there is no submersible. vehicle designed to be operated in both wet and/or dry modes. 
     The problems associated with existing wet and dry submersible vehicle designs include: i) substantial weight requiring larger propulsion and steering systems, ii) a rigid constant shape that prevents their stowage in a smaller, logistically desirable volume for transportation and storage, and iii) their inability to adapt to either a wet or dry submersible stat us. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide an improved submersible vehicle. 
     Another object of the present invention is to provide a submersible vehicle design that will be of loser weight when compared to comparably-sized existing submersible vehicles. 
     Still another object of the present invention is to provide a submersible vehicle that can be collapsed to a smaller volume for transportation and storage. 
     Yet another object of t he present invention is to provide a submersible vehicle that can be used as either a wet or dry submersible vehicle. 
     A still further object of the present invention is to provide a submersible vehicle having both wet and dry submersible portions. 
     Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings. 
     In accordance with the present invention, a submersible vehicle has a hull having a forward end and an aft end. The hull has an outer wall that is at least partially constructed of a multi-wall fabric having a sealed space between at least two walls thereof. The sealed space is controllably filled with one of air, water, and a combination of air and water in order to control the buoyancy of the hull formed from the multi-wall fabric. Means are provided for propelling and steering the hull in the water. The interior volume of the hull can remain dry or can be filled with water for a wet mode of operation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects, features and advantages of the present invention will become apparent upon reference to the following description of the preferred embodiments and to the drawings, wherein corresponding reference characters indicate corresponding parts throughout the several views of the drawings and wherein: 
     FIG. 1 is an exploded schematic view of a collapsible submersible vehicle in accordance with an embodiment of the present invention; 
     FIG. 2 is a cross-sectional view of one of the hull assembly&#39;s inflatable sections taken along line  2 — 2  of FIG. 1; 
     FIG. 3 is a side view of the submersible vehicle in its deflated state with the collapsed hull assembly folded and captured between joined nose and tail assemblies; 
     FIG. 4 is a side view of the submersible vehicle in its inflated state having a boom coupling the nose and tail assemblies; 
     FIG. 5 is a side view of the submersible vehicle in its inflated state with an extendable boom being used to couple the nose and tail assemblies; 
     FIG. 6 is a side view of the submersible vehicle in its inflated state with a shock absorbing boom being used to couple the nose and tail assemblies; 
     FIG. 7 depicts an operation scenario for the in-air deployment of the submersible vehicle in its deflated state; and 
     FIG. 8 is a schematic view of a wing kit used for the in-air deployment of the submersible vehicle. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, and more particularly to FIG. 1, an embodiment of the collapsible submersible vehicle of the present invention is shown in exploded form and is referenced generally by numeral  10 . In the illustrated embodiment, submersible vehicle  10  has the following three main assemblies: a collapsible hull assembly  12 , a nose assembly  14 , and a tail assembly  16 . However, it is to be understood that the present invention is not limited to this construction. Accordingly, the scope of the present invention should be considered in light of a variety of alternative embodiments and/or additional features that will be discussed further below. 
     Collapsible hull assembly  12  is constructed as a plurality of coupled sections such as sections  12 A- 12 E. Each of sections  12 A- 12 E defines an exterior shape and interior shaped volume so that a continuous volume is defined within hull assembly  12 . The particular outer shape or inner volumetric shape of each of sections  12 A- 12 E is not a limitation of the present invention. For example, each of sections  12 A- 12 E could define an outer shape and inner volumetric shape that is cylindrical, rectangular, triangular, octagonal, etc. Further, each section can have the same shape or a different shape. In this way, the overall inner volumetric shape and outer shape of hull assembly  12  can be tailored for a specific application. 
     As mentioned above, the inner volume of hull assembly  12  can be continuous or could alternatively be divided up into compartments using bulkheads. For example, vertical dashed lines  18  (indicative of the divisions between adjoining ones of sections  12 A- 12 E in the illustrated example) could also be indicative of bulkheads. Note that the number of bulkheads and their position in hull assembly  12  is not a limitation of the present invention. 
     Each of sections  12 A- 12 E is constructed in a similar fashion. Accordingly, a description of section  12 A applies equally to each of the remaining sections. In describing section  12 A, simultaneous reference will be made to FIG. 2 which is a cross-sectional view of section  12 A taken along line  2 — 2  in FIG.  1 . 
     Section  12 A defines an outer wall structure made from an inflatable multi-wall fabric that encloses a shaped volume. For example, as shown in FIG. 2, an exterior wall  120  is formed from at least one sheet of flexible airtight and watertight material(s). Similarly, an interior wall  122  is formed from one or more flexible airtight and watertight material (s). Walls  120  and  122  are spaced apart from one another to define a sealed space  124  therebetween. Note that the fore and aft ends of section  12 A (e.g., end  126  in FIG. 1) are sealed using the same materials used for walls  120 ,  122 . Walls  120  and  122  are connected to one another by a plurality of flexible ties or links  128  which can be threads chosen from any of a plethora of well known strength materials. Links  128  hold walls  120 ,  122  in their connected relationship when sealed space  124  is filled/pressurized with one of air, water or a combination of air and water as will be explained further below. For underwater usage, it is desirable that the materials used for walls  120 ,  122  and links  128  be both strong and resistant to abrasion damage. Accordingly, KEVLAR or similar materials are preferred. 
     A variety of sealed fabric construction techniques can be used to make section  12 A. Some examples include the techniques disclosed in each of U.S. Pat. Nos. 2,912,033, 4,462,331 and 5,868,095. As noted above, each of walls  120 ,  122  can be realized by a single fabric layer or multiple material layers. In a multi-layer wall construction, one layer can be a viscous polymeric sealing gel that automatically seals any punctures. Examples of sealing layers and material formulations thereof are described in U.S. Pat. Nos. 4,501,035 and 5,295,525, respectively. 
     Prior to the filling/pressurization of sealed space  124 , walls  120 ,  122  and links  128  form a compliant outer wall structure that is collapsible. However, once sealed space  124  is filled/pressurized with air, water or a combination of air and water, section  12 A assumes its inflated shape shown in FIG.  2 . The selective filling/pressurization of sealed space  124  controls the buoyancy of section  12 A. To fill some or all of sealed space  124  with air, a tank or other source of pressurized air  20  is coupled to sealed space  124  via a valve  22 . Valve  22  can be installed using one wall  122  or both walls  120 ,  122  as described in U.S. Pat. No. 6,074,261. To purge air from sealed space  124 , a second valve  24  is provided in exterior wall  120 . Valve  24  can be controllable to vent sealed space  124  as needed. Valve  24  could also incorporate a pressure relief feature to prevent over inflation of sealed space  124 . Furthermore, valve  24  could be equipped with a diffuser so that air exiting same generates only tiny bubbles that would not be detectable at the water&#39;s surface. 
     To fill some or all of sealed space  124  with water, a valve  26  is provided to allow a flow of water into and out of sealed space  124 . To purge water from sealed space  124 , it may be necessary to provide a pump  28  coupled to valve  26 . If necessary, pump  28  can be reversible pump to draw water into sealed space  124  as well as pump it therefrom. 
     Sealed space  124  is filled/pressurized with air, water or a combination of air and water. The filling/pressurization of sealed space  124  inflates and shapes sections  12 A. At the same time, the air, water or combination of air and water in sealed space  124  determines the buoyancy of section  12 A. Since each of the remaining sections  12 B- 12 E is similarly equipped for their individual inflation and buoyancy control, hull assembly  12  can be floated, submerged and trimmed by controlling the buoyancy of each of sections  12 A- 12 E. 
     In addition to the valves in each of sections  12 A- 12 E, additional valves  30  can be provided between the sealed spaces of adjoining ones of sections  12 A- 12 E. Thus, control of valves  30  can allow two or more of sections  12 A- 12 E to function as a single section. However, should a problem develop in one section, that section can be isolated by the closing of appropriate ones of valves  30 . Individually controlled pumps (not shown) can be provided in conjunction with each of valves  30  to control a direction of flow of air, water or a combination of air and water, between adjoining sealed spaces. 
     The interior volume of hull assembly  12  can be maintained dry (i.e. air filled) or can be flooded to allow submersible vehicle  10  to operate as a wet submersible. Accordingly, a hull filling valve  32  can be provided to permit water to flow into or out of the volume defined by hull assembly  12 . A pump  34  can be coupled to valve  32  to facilitate pumping of water out of hull assembly  12 . 
     Coupled to the forward end of hull assembly  12  is nose assembly  14  defined by a rigid outer shell  140  that can be constructed in any one of a variety of ways known to those skilled in the art. The coupling of hull assembly  12  to nose assembly  14  can be accomplished in a variety of mechanical fashions without departing from the scope of the present invention. Housed within outer shell  140  are systems (e.g., steering and throttle controls, navigation systems, communication systems, etc.) referred to generally herein as command and control systems  142  that are used by onboard personnel to drive submersible vehicle  10 . Also, an ingress/egress hatch  144  is typically provided in outer shell  140  to allow personnel to enter/exit submersible vehicle  10 . The interior compartment defined by nose assembly  14  can be maintained as a wet or dry compartment. If it is desirable to keep the interior of nose assembly  14  dry at all times, an airlock  146  can be provided so that personnel can leave or enter a wet hull assembly  12 . 
     Coupled to the aft end of hull assembly  12  is tail assembly  16  that can also be constructed in any one of a variety of ways known to those skilled in the art. In general, tail assembly  16  includes a rigid outer shell  160  typically having a propulsion system  162  that includes a propeller  164  and control surfaces  166  with command and control systems  142  being coupled thereto via wires (not shown for clarity of the- illustration) for control thereof. The interior compartment defined by tail assembly  16  can be maintained as a wet or dry compartment. An additional (or alternative) ingress/egress hatch  168  and airlock  170  can also be provided in tail assembly  16 . 
     Prior to deployment of submersible vehicle  10 , hull assembly  12  is in its deflated (compliant) state without air or water filling/pressurizing sealed space  124 . In this compliant state, hull assembly  12  can be collapsed (e.g., rolled, folded in an accordion fashion, etc.) so that nose assembly  14  and tail assembly  16  can be drawn together as shown in FIG. 3 where a collapsed hull assembly  12  is fitted in and between nose assembly  14  and tail assembly  16  which are joined or latched together in a mechanical fashion. 
     After deployment and inflation of submersible vehicle  10 , it will appear as illustrated in FIG. 4 where hull assembly  12  is inflated (as described above) with air, water, or a combination thereof. When submersible vehicle  10  completes its mission, it may be necessary to retrieve/lift it out of the water. To facilitate such lifting, a boom  40  can be rigidly coupled to each of nose assembly  14  and tail assembly  16 . Hoisting points  42  can be provided on boom  40 . 
     To facilitate storage of such a lifting boom, it may be desirable to provide an extendable or telescoping boom  50  as illustrated in FIG.  5 . More specifically, boom  50  consists of extendable or telescopic sections  50 A,  50 B, etc., that can collapse when submersible vehicle  10  is in its collapsed state (FIG.  3 ). Once extended, the sections would lock together with the ends being rigidly coupled to nose assembly  14  and tail assembly  16 . 
     Additionally, or alternatively, the “boom” could be one that incorporates shock absorption as illustrated by shock absorbing boom  60  in FIG.  6 . As before, boom  60  is rigidly coupled to nose assembly  14  and tail assembly  16 . However, rather than being locked longitudinally, a shock absorber  62  is provided in line with boom  60  so that impact forces on either nose assembly  14  or tail assembly  16  can be at least partially absorbed thereby. 
     Submersible vehicle  10  can be stowed onboard a ship in its deflated state until such time that it is needed. Alternatively, submersible vehicle  10  could be air delivered in either its deflated or inflated state (i.e., with equipment and/or personnel onboard) to a remote location. For example, FIG. 7 depicts a remote deployment sequence and operation scenario for submersible vehicle  10  in its deflated and collapsed state. A similar deployment scenario for a monocoque submersible vehicle system is disclosed in U.S. patent application Ser. No. 09/800,844, filed Mar. 8, 2001, the contents of which are hereby incorporated by reference. 
     In the operation scenario depicted in FIG. 7, a host vehicle  70  travels to the vicinity (e.g., a typical standoff range of 50-75 nautical miles) of an in-air deployment destination at which point submersible vehicle  10  (in its collapsed state and equipped for air travel) is released therefrom. In terms of clandestine operations, host vehicle  70  can be an aircraft (e.g., plane, helicopter, etc.) that can travel quickly to and from the vicinity of deployment without being easily detected by enemy surveillance. Once within the desired vicinity at a desired altitude and air speed, host vehicle  70  releases submersible vehicle  10  which is capable of maneuvering using GPS signals  201  originating from GPS satellites  200  orbiting the earth in ways that are well understood in the art. Submersible vehicle  10  can alternatively or additionally be equipped with an onboard inertial navigation system to supplement or back-up the GPS navigation capabilities in the event of GPS signal jamming problems. 
     Submersible vehicle  10  is maneuvered to a ballistic drop zone approximately above a water deployment destination referenced by numeral  300 . To accomplish such navigational maneuvering of submersible vehicle  10 , a glide wing assembly  80  is attached to nose assembly  14  and tail assembly  16  as shown. Once submersible vehicle  10  begins its terminal descent, a drag device such as a parachute  92  is used to slow the descent of submersible vehicle  10 . After impact with the water&#39;s surface at destination  300 , the entirety of glide wing assembly  80  can be removed and stored or jettisoned. 
     One embodiment of glide wing assembly  80  is shown schematically in FIG.  8 . Glide wing assembly  80  can be a wing “kit” that deploys its wings  82  to allow submersible vehicle  10  to glide and steer as a winged aircraft and then jettison (if desired) the wings at a given time or location. A variety of such wing “kits” are known in the art and are available commercially. One such commercially available system is the Longshot™ GPS Guided Wing Kit manufactured by Leigh Aero Systems, Carlsbad, California. Briefly, this wing kit includes a base  81  with wings  82  that extend therefrom once submersible vehicle  10  is free from the host aircraft. The wing kit has its own GPS system  84  for determining range and altitude. An inertial navigation system (INS)  86  can also be included as a back-up to GPS system  84 . At a desired time, a separation charge  88  can be initiated to cause the combination of base  81  and wings  82  to be jettisoned. Base  81  can incorporate a parachute assembly  90  at the aft end thereof for storing a parachute (not shown in FIG. 8) that deploys (see parachute  92  in FIG. 7) from base  81 . Once submersible vehicle  10  has reached its water surface destination  300 , parachute  92  is jettisoned. Once in the water, nose assembly  14  and tail assembly  16  are uncoupled from one another, and hull assembly  12  is filled/pressurized with air and/or water to sink submersible vehicle  10  to its operating depth. 
     The advantages of the present invention are numerous. The collapsible and inflatable wet and dry submersible vehicle is lighter than existing submersibles, and can be a wet, dry, or a combination of wet and dry submersible vehicle. The reduced weight of the vehicle provides greater operational speed and range. The present invention makes use of very lightweight and very strong inflatable unibody fabrication to effect a very strong yet lightweight hull that can be produced more efficiently and consistently that in traditional welded chassis construction without the need for metals that corrode in a seawater environment. The inflatable technique results in a hull that carries its strength on the external shell of the vehicle therefore eliminating the need for heavy internal cross-sectional aluminum bulkheads and stiffeners. The unexpected benefit of this dramatic decrease in weight while maintaining structural integrity means that the hull is now light enough to be carried and flown using commercially available GPS/INS guided wing kits upon release from conventional aircraft while having a greater range than any comparably-sized rigid hull submersible. Because internal bulkheads are not required, there is more space available for passengers and equipment. An additional benefit is that such a craft would be stealthy in flight and in the water because of eliminated radar and acoustic detectable cross-section. All of the squared off surfaces in the current “machined” chassis are eliminated and replaced with rounded edges to reduce drag and increase vehicle performance. Additionally, the use of inflatable techniques allows the chassis to take on any form necessary for efficient fluid flow characteristics and internal volume maximization. The inflated hull assembly also provides a certain degree of impact absorption not found in rigid hull construction. The elimination of most metal from the hull assembly means that it is less susceptible to corrosion than most rigid hulls. Further, because the ballast tank is the hull, more internal cargo room is made available. 
     Although the invention has been described relative to a specific embodiment thereof, there are numerous variations and modifications that will be readily apparent to those skilled in the art in light of the above teachings. For example, rather than using rigid nose and tail assemblies, the shells of each of these assemblies could also be made of the same collapsible and inflatable construction. Also, the particular fabrics used to construct the hull assembly can be chosen from known stealth fabrics or can have a stealth coating applied thereto. Still further, the submersible vehicle could achieve air delivery through the use of a glide parachute system equipped with GPS navigation control. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described.