Abstract:
An undersea streamline vehicle having a unique system for gliding ascent, gliding descent, both with and without engine power, and for hovering in the sea for exploratory or research purposes by the provision in the vehicle of buoyancy chambers or bladders offset from the vehicle center of gravity, wherein the chambers include a piston element in a cylinder open to the sea environment. A control system effects selected positioning of the piston, thereby to regulate inflow of the sea into the cylinder or expulsion of sea water from the cylinder, thereby to vary the buoyancy of the vehicle vis-à-vis its center of gravity to control the rate of glide of the vehicle upwardly or downwardly, or to attain a stationary hover position. Ailerons and tail planes facilitate controlled direction of travel. A compressed air system precludes leakage of seawater into the buoyancy chamber.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon a prior U.S. Provisional Application Ser. No. 60/199,835 filed Apr. 26, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     In recent years there has been considerable interest in and development of submersible craft, as submarines or under sea exploratory and rescue vehicles as all levels of commercial and military research. The underwater frontier remains a huge and much unexplored portion of the earth, with vast riches in minerals, petroleum, seabed, plant, and aquatic life. Further, covering some 70% of the globe, facile access to and use of the underwater environment remains critical to national defense as well as to increased development of the same and its instructive geological lore, habitat study, seabed and seamount mapping, and the like. 
     Humankind&#39;s adventures into ocean depths and the sky above commenced and made great strides in the 20 th  century. Nonetheless, advances in aviation and space have far exceeded progress under the sea. While there are substantial and fascinating similarities in atmospheric air travel and undersea travel, the latter has lagged in research and development, although submarine technology has moved forward from surface air-dependent undersea travel to deep-sea dwelling capability. With greater underwater serviceability, design concerns are shifting from the hydrodynamics of wave resistance and control at or near the surface to the need for uninterrupted hydrodynamic flow about the undersea vehicle, with reduced wetted surface. 
     Submarines, even in recent years with newer hull designs and nuclear and other power development, still essentially partake of an elongated cigar-like hull configuration with necessary planing surfaces for control, and a fin or sail to contain periscopes and masts. 
     Such hulls must be carefully designed to withstand deep-sea pressure as well as being volumetrically efficient. A generally flattened hull shape introduces or advances planing or gliding ability, and using the latent forces of gravity and buoyancy to induce a thrust forward. One such is shown, for example, in my U.S. Pat. No. 5,477,798 having a sleek, generally “manta ray” form with remarkable hull strength and carrying capacity. 
     Further, in exploration and utilization of ocean depths it becomes increasingly important that even the most advanced hull designs be associated with effective and reliable control systems to improve underwater maneuverability, including the ability to hover, or silently glide downwardly or upwardly, to achieve particular needs or missions. 
     While, as noted, there are certain similarities and relationships between air flight and sea hydrodynamics, it is evident that resistance to fluid flow about a submerged hull is greater than airflow resistance aloft, due to the higher viscosity of water than air. Further, as water is incompressible in sharp contrast to air, a moving undersea body creates more absolute displacement with concomitant greater resistance. As a consequence, the operation of submarines is dependent on ballasting and therefore is more comparable to that of a gas-filled blimp or dirigible, than to heavier-than-air aircraft. 
     It follows that design and control improvements as to undersea gliding, planing, maneuvering, and even hovering are needed, wherein aircraft are well advanced in these regards. While we have observed for eons the ability of fish to dive, leap, stop, and hover in the water, only recently have we been able to mechanically emulate them. Grade school science classes in past generations were rather inaccurately taught elements of submarine design. The common experiment at the time comprised a partially filled milk bottle containing an inverted test tube with sufficient air above the water level in the tube to float the test tube at the surface. The bottle was stoppered with a connection to a hydrometer bulb. Squeezing the bulb induced sufficient pressure in the bottle to compress the tube&#39;s air bubble, permitting additional water to enter through the bottom of the tube, whereby it would sink. The release of external pressure conversely increases the air volume, expelling a like amount of water, allowing the tube to resurface. This experiment in fact illustrates the fish-swimming bladder and is not current in submarine design. 
     In a submarine comparable air volumes are called “free surfaces”, which present a risk in that loss of buoyancy in a descent is inherently accelerated. For this reason, submarine ballast tanks are always vented before submerging, and inaccessible voids are filled solidly. 
     This air volume concept was observed in a tropical fish aquarium and revealed that the fish swimming bladders enhanced their performance. By a simple expansion and contraction of its bladder, a “glass fish” was observed to rise, hover, and sink, independently of other movement. Obviously, the bladder&#39;s volume was precisely controlled by the fish, allowing it to descend from and return to the surface with little effort and a minimal change in buoyancy. Such capability in a submarine would greatly enhance submarine performance. Improvements in such control ability are necessary to undersea progress at any level. 
     Various techniques and structures in an effort to improve underwater control of submerged vehicles are typified in the prior art by U.S Pat. No. 3,946,685 to Chadbourne et al, U.S. Pat. No. 3,665,884 to Gustafson, U.S. Pat. No. 3,752,103 to Middleton, U.S. Pat. No. 3,667,415 to Robbins, U.S. Pat. No. 5,129,348 to Rannenberg et al, or U.S. Pat. No. 5,477,674 to Somers et al, U.S. Pat. No. 4,577,583 to Green, or U.S. Pat. No. 3,157,145 to Farris, among others. Also of interest is a J.S.N.A., Japan publication, “Study on the Hydrodynamic Characteristics of Circular Submarines”, which generally suggests the capability of a vessel to glide while submerged. While these patents and publications provide diverse control teachings and systems, and lead toward improved underwater vehicles, the same do not provide a full measure of desirable underwater buoyancy, attitude, ascending and descending glide control, and the like for submarine or like undersea craft with improved laminar hydrodynamic flow. Thus, illustratively, the use in these patents of thrusters or jets for depth or attitude control has the hazard of agitating sea sediments, both disrupting the environment and sharply impeding already restricted underwater visibility. Similarly, the provision of lateral wing-like appendages overlooks the high resistance of wetted surfaces under water. 
     Buoyancy control is essential to safe and facile operation of all undersea craft, as submarines or submersible exploratory vehicles. Such control permits, for example, the use of the vehicle for recovery of heavy objects from the sea floor. See U.S. Pat. No. 3,292,564, to Lehmann by way of illustration. However, even the most pressure resistant hull is unavoidably compressed in extended deep sea descent, reducing both volume and buoyancy. Minimally, some compensation can be effected by pumping trim and drain systems. Using compressed gas to discharge ballast water, however, is not always desirable as the gas is further compressed by continued descent, is unable to fully expand at depth, and with decreasing effectiveness. In ascent, the compressed gas rapidly expands, which may and does cause a hazardous acceleration to the undersea vessel rising to the surface. The necessarily vented gas in such emergency surfacing would be lost and unrecoverable. See the U.S. Pat. No. 1,686,928 to Wardle and Rannenburg U.S. Pat. No. 5,129,348. There is a need for more rapid and positive buoyancy control. 
     In another area of underwater control, submarines establish trim with a fore and aft system of weight transfer to attain a desired longitudinal attitude. Weight transfers while underway are compensated for by diving plane angle adjustments until the fore-aft transfer of trimming water is needed to restore the planes to a neutral position. Seawater piping systems function both to admit seawater or to discharge it back to the sea. The efficiency of overboard discharge pumping is significantly reduced as depths increase. See illustratively, the system of Chadbourne U.S. Pat. No. 3,946,685. 
     SUMMARY OF THE INVENTION 
     As noted above, aircraft and undersea vehicles have certain similarities in moving through the respective fluids of air and water. The present invention embraces an undersea craft, as a submarine, which is able to “fly” under water much as airplanes fly above it and fish deftly maneuver within it, as well as hover in a substantially stationary position, as a helicopter or a fish. This is achieved by a unique integration of buoyancy adjustment, trim distribution, unique gliding body hull form, and glide and aileron control planes, for generating unpowered forward motion, both upwardly or downwardly. My prior U.S. Pat. No. 5,477,798 was an initial attempt to interrelate these elements into a hydrodynamic design to achieve precise maneuvering in a manner adaptable for both manned and remotely-operated commercial and recreational applications. other inventors have sought, at least in part, to attain such concepts, as in U.S. Pat. Nos. 1,668,928; 3,157,145; 3,292,564; 3,665,884; 3,946,685; 4,577,583; 5,159,348, and 5,477,674, inter alia. 
     The general hull shape of this invention is that of a lifting body, wherein it generates vertical forces for lift or descent, much as in an aircraft, or, for that matter, a sea creature as a skate or a ray. These forces are created by an airfoil contour, employing the Bernoulli Principle, and which generate forward thrust or movement of the vessel, which assist in countering positive or negative buoyancy. 
     As to hull proportions for airfoil contour, the above-noted Japanese publication stated that a 2-to-1 ratio of height to diameter was found optimum. The observations of a greater water resistance for a circular cross-section hull form in that publication may suggest that the hull cross-sectional profile is excessive in its resultant displacement of flow. 
     The present invention, however, uniquely embraces a ratio of length, width and heighth on the order of four-to-two-to-one (4-2-1 LWH) which is chosen primarily for its relative and improved airfoil configuration. This innovative hull form can be describes as “lozenge-shaped”. Model testing has verified such a hull form performance to be competitive. 
     The submarine of this invention is provided with one or more, preferably two relatively large buoyancy chambers, which may also be termed as “swimming bladders”, as are common most fish of the sea. The chambers or bladders are preferably sized for a displacement change of about 3%, and are minimally affected by depth excursion. 
     The buoyancy chambers or bladders are located forwardly of the submarine&#39;s center of buoyancy, thereby to enhance attitude control. These chambers employ power-operated pistons to vary the chamber displacement. While the displacement pistons in the chambers are open to the sea, they are adequately sealed to resist the pressure of the vessel&#39;s depth excursions, establishing a constancy of the chamber&#39;s buoyancy. Alternate means for piston actuation may be employed, however, as hydraulic, electric, or pneumatic. However, the availability and quick response of a hydraulic system is preferred. Should the pistons move to full extension, and the system design be exceeded by inadvertent depth excursion, the pistons are mechanically secured by self-actuated devices. Yet further, the drains of the buoyancy chambers are open to within the pressure hull boundary, are specifically isolatable, and are interconnected with an emergency air pressure system to assure against leakage and failure. While the primary buoyancy bladder or bladders are as indicated just forward of the center of buoyancy, the invention further contemplates using trim tanks disposed near the nose of the undersea craft and toward or adjacent the rear of the vehicle, thereby to provide further versatility of glide control and ship trim. 
     Some additional attitude control arrangements are deemed advisable and necessary for the efficient operation of the invention, and are best accomplished by coordinating the same with existing and known ship systems: 
     a. Trim and Drain System—pump operated, and generally employed for evacuation of bilges, and the transfer of fluids between internal tankage. Its high-pressure capability is necessary for the intake and discharging of sea water, and to correct for significant displacement changes, such as flooding. 
     b. Steering and Driving System—the same commonly employs hydraulically operated planes for vertical and horizontal changes of the vessel&#39;s direction. 
     c. Ballast Blow and Venting System—a ballast blow air system of known form is able to quickly void the ballast tanks of seawater through bottom-located flood valves, and also have mechanically operated ballast tank vent valves which are opened to vent all contained air, and thereby allow the vessels&#39; submergence. 
     d. Ships Hydraulic Service System—commonly a principal source of power used to operate remote actuators, valves, winches, and other devices, enabling control thereof from a central location. 
     There are a number of pressure hull construction configurations which are adaptable to the instant buoyancy control system of this invention, including the clustered spherical chambers of my earlier patent, and as generally illustrated in the drawings. Other shapes include diverse toroidal, spherical, conical, or cylindrical structures, and various combinations thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 a  is a diagrammatic cross-sectional showing of an illustrative undersea vehicle showing the location and relationship of the hover and glide control components in a static or hovering condition, and when underway under propulsion; 
     FIG. 1 b  is similar to FIG. 1, but showing the hover and glide control components as employed for an unpowered forward gliding descent; 
     FIG. 1 c  is similar to FIG. 2, but showing the hover and glide control components as employed for an unpowered forward gliding ascent; 
     FIG. 2 is a general top plan diagrammatic view of the submarine showing the hover and glide components as arranged in a marine research submarine general arrangement of internal elements; better showing an internal clustered spherical construction as in U.S. Pat. No. 5,477,798; and, 
     FIG. 3 is a diagrammatic system detail of a hydraulically operated buoyancy chambers, and showing the fluid line interrelationship with other ship systems. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     To facilitate quick reference to the drawings and the following description, a glossary of reference numerals is as follows: 
       10 —undersea vehicle or submarine 
       12 —airfoil contour outer hull 
       14 —clustered cell pressure hull 
       16 —domed central compartment 
       18 —hull access trunk 
       20 —fairwater external structure 
       22 —controllable stern plane 
       24 —rudders 
       26 —individual controllable ailerons 
       28 —buoyancy adjusters 
       30 —emergency ballast blow air tanks 
       32 —buoyancy air cylinders 
       34 —buoyancy air pistons 
       36 —hydraulic actuating cylinders 
       38 —hydraulic cylinder pistons 
       40 —rods interconnecting pistons 
       42 —self-actuated locking devices 
       44 —hydraulic supply and return, above piston 
       46 —hydraulic supply and return, below piston 
       48 —manifold for variable buoyancy operation 
       50 —three-position isolating valves 
       52 —hydraulic supply header 
       54 —hydraulic return header 
       56 —emergency ballast air isolation valve 
       58 —buoyancy air cylinder drain isolation valve 
       60 —engine and machinery compartments 
       62 —forward trim tanks 
       64 —aft trim tanks 
     Referring to the drawings, the general outline of the undersea vehicle  10  in accordance with the invention is seen generally in side elevation in FIGS. 1 a,    1   b,  and  1   c,  and in plan view in FIG. 2, from which are evident the streamlined airfoil contour which generates forward and vertical moments as required for gliding. As seen in FIG. 2, the relatively short overall length (LOA) and relatively broad beam of the vessel establishes that planing surface necessary for the glide of the undersea vehicle. Additionally, the outer hull form has a reduced wetted surface area, thus lowering its frictional resistance. 
     In the diagrammatic views of the invention, those components contributing to the functionality and operation of the vehicle are shown. Details of control stations, crew quarters, power plants, etc., are not necessary for understanding of the invention. 
     The outer hull  12  of the vehicle  10  as seen in the drawings has an inner pressure hull comprised in the form shown of a cluster of six truncated spherical cells  14  disposed about a central domed compartment  16  (FIG. 2) which has a somewhat polygonal appearance from its intersections and connections to the surrounding cells  14 . Additional pairs of aft cells  60  on port and starboard generally establish drive shaft centerlines, and contain the propulsion and ship&#39;s service machinery. These arrangements are similar to those in my prior U.S. Pat. No. 5,477,798 to which reference may be had for greater detail, wherein the several cells  14 ,  16 ,  60  contain various operating systems of the vehicle, as well as provide crew work stations, laboratories, galley, and sleep areas, for example. 
     The slipstream flow about hull  12  is interrupted only by an upper fairwater structure  20  in the nature of a vertical sail which includes the hull&#39;s access hatch at  18 , and also by a pair of rearwardly extending lower skegs having the rudders  24  associated therewith. 
     In the disclosed form of the invention, the buoyancy chambers  28 ,  28  are optimally placed forwardly of the static center of gravity “CG” as seen in FIGS. 1 a,    1   b  and  1   c.  The fluid connections to the buoyancy adjusters  28  are seen in FIG. 3, as are also the emergency ballast blow air tanks  30 , the forward trim tanks  62  and the aft trim tanks  64 , which latter are also well seen in FIGS. 1 a-c.    
     The hull is further provided with an aft horizontal plane  22  (FIG. 2) and aft port and starboard ailerons  26 . These control surfaces act to reshape the vehicle&#39;s airfoil contour when angled up or down as seen in FIGS. 1 b  and  1   c,  whereby forward motion water flow tends to generate a downward thrust (FIG. 1 b ) or upward thrust (FIG. 1 c ). Other control means may be additionally provided as desired, as jet or fluid thrusters, for example, to augment or even replace the control surfaces. 
     Thus, in FIG. 1 b,  the vehicle is configured for a downward forward dive or descent with the rear planes  22  and the ailerons  26  angled downward, and, the upper air cylinder portion  32  of the buoyancy chambers  28  are flooded to initiate the descent, relocating the center of gravity CG forward and the center of buoyancy CB aft. As seen in FIG. 1 b,  the aft trim tanks  64  are voided into the forward trim tanks  62  to assist the descent and prevent stalling of the airfoils. The desired rate of gliding or powered descent is controlled by the positioning of the control surfaces, as well as by ballast adjustments. 
     Conversely, in FIG. 1 c,  for a gliding ascent, the relationships are reversed, with the buoyancy air chambers  32  evacuated, the planes and ailerons  22 ,  26  at an up angle, and the contents of the forward trim tanks  62  pumped aft to tanks  64 , thereby relocating the CB forward and the CG aft. The ship would stay at level trim during the ascent/descent cycles and as maneuvered by its planes. Gliding in either direction is independent of positive engine propulsion to the screws. 
     As seen in the fluid connection diagram of FIG. 3, the buoyancy air cylinders  32  are fixed to the pressure hull shells  14 ,  16  in watertight manner and extend to the outer hull  12 , with the outer face of the pistons  34  open to the sea. The piston rods or shafts  40  are interconnected between the air cylinder pistons  34  and the pistons  38  in hydraulic cylinders  36 . Sufficient spacing is provided between the cylinders  32  and  36  to enable assembly, attachment, and maintenance. Hydraulic cylinders  36  are also fixed to and thereby integral with the hull in alignment with air cylinders  32 . 
     The hydraulic supply  52  and return  54  headers are connected to the ship&#39;s steering and driving power plant (not shown), and supply the variable buoyancy chamber operating manifold  48 . The manifold&#39;s three conventional positions extend, retract, or restrain the hydraulic pistons  38  for a positive control of the volumetric content of the buoyancy air chamber  32 . The dual acting hydraulic supply and return headers attach, with alternating flow, to opposite chambers of the hydraulic actuation cylinders  36 . 
     Some seepage past the air cylinder piston  34  may be anticipated after a period of normal use, and is continuously drained from cylinder  32  to a drain collecting tank within the pressure hull. Periodically, such drainage is evacuated via the ship&#39;s Trim and Drain System. Should this drainage become unacceptably frequent, or suffer failure before scheduled maintenance, one or both buoyancy adjusters  28  can be isolated and sealed by a charge from the emergency ballast blow air flask  30 . In so doing, the hydraulic piston  38  must be fully extended and restrained, and the 3-position valving  50  reset to isolate the inoperative buoyancy chamber. The emergency ballast air charging valve  56  is interlocked with the buoyancy air cylinder drain valve  58  to assure the isolation of the submarine interior atmosphere from this high pressure air discharge. The adjustable buoyancy system of the invention, with two available chambers  28 , is thus still able to operate at 50% capacity in an emergency mode with one chamber  28  shut down the piston shaft is held secure by a self-actuating locking or clamping device  42  disposed adjacent the shaft  40  between the air and hydraulic cylinders. 
     A unique advantage of the quick-acting buoyancy chamber system  28  of the invention is to enable a weight exceeding three percent of the ship&#39;s displacement to be salvaged from the ocean floor. The added buoyancy of the system coupled with the ship&#39;s variable ballast capacity, and a partial blowing of the ship&#39;s ballast tanks, in combination can extract and lift a significantly heavy salvage mass on the sea floor. In like manner, it is seen that any submerged weight is reduced by the weight of its displaced volume of water. Accordingly, this capacity can be employed to deliver material to a dive site, habitat, or undersea mining operation. 
     The undersea vehicle of the present invention, as most other submarines, is engineered under normal load to have a Center of Gravity at a point below the longitudinal axis, at CG in FIGS. 1 a,    1   b  and  1   c.  The craft also has a Center of Buoyancy above the CG, shown as CB. Both of these should have a nearly common longitudinal location as seen in FIG. 1 a.  When at surface, the CB is significantly as above the CG, but when submerged, the ship&#39;s buoyancy and weight are equalized, bringing these two centers closer to each other, and making the vehicle relatively unstable fore and aft. 
     Operational weight redistributions must therefore be constantly recompensated with horizontal plane angle adjustments as the vessel is underway. When in hover, the horizontal planes are ineffective as the same require slipstream overflow for moment generation. In hover, and for significant weight redistributions, compensation is effected by transferring water fore and aft between the trim tanks  62  and  64 . These tanks are isolated from sea pressure, and normally filled to about half volume when hovering or in normal operation. 
     The size of the buoyancy air cylinders  32 , the hydraulic cylinders  36 , the number thereof, and the stroke travel of the interconnecting piston shaft  40  are essentially determined by the displacement of the submarine and its required buoyancy differential. While the pressures of the ship&#39;s hydraulic and air systems are determined for the operational intent of specific submersibles, they also affect the present invention&#39;s capability for maneuver and depth. Only by way of illustration, the upper cylinder  32  open to the sea may have an inside diameter on the order of  48 ″. As a consequence, the water displacement (or intake) weight and volume is substantial, which has a pronounced and determinable effect on the vehicle  10 . In like manner, and illustratively, at a significant operating depth of about 3,000 feet, the sea pressure is on the order of 1,333 psig, while at a cruising depth of 4,500 feet, for example, the sea pressure is about 2,000 psig. For example, air pressure may be available at 4,500 psig for each chamber  28  to prevent seepage. The inventive system as disclosed herein employing pressures utilized in the present fluid art provide a faster operating, more depth capable, and more casualty responsive system than others now known and currently employed. 
     It is advantageous to provide the buoyancy chambers as shown as open to the sea along the streamline top surface of the hull as compared to a location on the hull bottom. Firstly, with the cylinder  32  on top, there is no likelihood of the ejection of seawater disturbing, occluding, or even damaging the seabed or objects thereon during research or recovery, as would occur on piston  34  movement with the cylinders opening downwardly on the bottom of the submarine. Secondly, the inrushing seawater will not ingest bottom sediments with the vessel at or adjacent to the sea floor. 
     While I have disclosed a preferred form of my invention, it is evident that the structures and concept thereof may be employed in other or similar undersea vehicles within the scope of the appended claims.