Long-range UUVs

Abstract

In one aspect, the invention is a vehicle working in ambient-pressure liquid or gas medium; in a second, it is a fuel tank for such craft—usually with a housing and related propulsion; the tank is craft-mounted, at least partly outside all other parts, contacting the medium; and best at least partly pressure compliant; propulsion consumes fuel; drag depends on structure shape, and fuel volume. Shape decreases longitudinally and/or laterally, reducing drag with fuel use; housing is cylindrical, structure annular (outside the housing); drag depends partly on structure radial thickness, in turn on fuel quantity. Pressure may compress fuel against housing. The structure best is made of or has embedded skin-drag reducing material; materials (soaking-replenished) are best low-friction and/or high-compliance; the surface-noise-absorbing (for underwater craft) structure has shape and size reduction some 20 to 80% of like fixed-geometry craft.

I claim: 
     
         1 . A vehicle that operates in a liquid or gaseous medium that is at an ambient pressure; said vehicle comprising:
 components including a housing, and propulsive apparatus associated with the housing;   a fuel container mounted to the vehicle, at least partially outside all other components of the vehicle and in contact with the medium; and wherein:   the container is of a structure that is at least partially compliant, and responsive to said ambient pressure of the medium;   the propulsive apparatus consumes fuel from the fuel container;   drag of the vehicle in moving through the medium depends at least partially on shape of the container structure that is in contact with the medium; and   the shape of the container structure that is in contact with the medium depends on quantity of fuel within the container.   
     
     
         2 . The vehicle of  claim 1 , wherein:
 said container-structure shape becomes smaller in either a longitudinal or lateral dimension, or both, and produces less drag, as the fuel is consumed by operation of the vehicle.   
     
     
         3 . The vehicle of  claim 2 , wherein:
 the vehicle housing is generally cylindrical;   the container structure is annular and just outside the cylindrical housing; and   part of said drag of the vehicle depends on radial thickness of the annular container structure.   
     
     
         4 . The vehicle of  claim 3 , wherein:
 the radial thickness of the annular container structure depends upon quantity of fuel within the annular structure.   
     
     
         5 . The vehicle of  claim 4 , wherein:
 the fuel within the annular structure is compressed against the vehicle housing by said ambient pressure.   
     
     
         6 . The vehicle of  claim 2 , wherein:
 range of the vehicle in moving through the medium is maximum when the vehicle is operated at constant velocity through the medium.   
     
     
         7 . The vehicle of  claim 1 , wherein:
 the fuel container structure that is in contact with the medium is made of, or has embedded, materials that further reduce skin-friction drag.   
     
     
         8 . The vehicle of  claim 7 , wherein:
 the materials are drawn out of the surface into a boundary layer with the medium.   
     
     
         9 . The vehicle of  claim 8 , wherein:
 the materials are replenishable plural times, by soaking the container surface in them.   
     
     
         10 . The vehicle of  claim 7 , wherein the materials are selected from the group consisting of:
 Teflon or other materials having low friction;   latex or other materials having high compliance; and   mixtures, or other combinations, of low-friction and high-compliance materials.   
     
     
         11 . The vehicle of  claim 1 , wherein:
 the container surface incorporates at least one noise-absorbing material.   
     
     
         12 . The vehicle of  claim 1 , wherein:
 the vehicle is an underwater vehicle.   
     
     
         13 . The vehicle of  claim 1 , wherein:
 the container-structure has variable shape and size that provide a reduction in vehicle structural weight, between twenty and eighty percent of structural weight in a corresponding fixed-geometry vehicle.   
     
     
         14 . A vehicle that operates in a liquid or gaseous medium that is at an ambient pressure; said vehicle comprising:
 components including a housing, and propulsive apparatus associated with the housing;   a fuel container mounted to the vehicle, at least partially inside other components of the vehicle and at least partially out of contact with the medium; and wherein:   said other components of the vehicle include at least some portions that are capable of mechanical expansion and contraction;   the fuel container is of a structure that is at least partially compliant, and responsive to mechanical force from said expansion- and contraction-capable portions of the vehicle;   the propulsive apparatus consumes fuel from the fuel container;   drag of the vehicle in moving through the medium depends at least partially on shape of the vehicle structure that is in contact with the medium; and   at least part of the shape of the vehicle structure that is in contact with the medium depends on quantity of fuel within the container, by virtue of the responsiveness of the compliant container structure to the vehicle structure that is in contact with the medium.   
     
     
         15 . The vehicle of  claim 14 , wherein:
 the container structure has variable shape and size that provide a reduction in vehicle structural weight;   said reduction being between twenty and eighty percent of structural weight in a corresponding fixed-geometry vehicle.   
     
     
         16 . The vehicle of  claim 14 , wherein:
 said expansion- and contraction-capable portions of the vehicle are compliant and responsive to said ambient pressure of the medium.   
     
     
         17 . A fuel container for a vehicle that operates in a liquid or gaseous medium that is at an ambient pressure, neither the vehicle itself nor the medium being a part of the claimed invention; and wherein:
 the container is mounted to the vehicle, at least partially outside all other parts of the vehicle and in contact with the medium;   the container is of a structure that is at least partially compliant, and responsive to said ambient pressure of the medium;   drag of the vehicle in moving through the medium depends at least partially on shape of the container structure that is in contact with the medium; and   the shape of the container structure that is in contact with the medium depends on quantity of fuel within the container.   
     
     
         18 . The fuel container of  claim 17 , wherein:
 said container-structure shape becomes smaller in either a lateral or longitudinal direction, or both, and produces less drag, as the fuel is consumed by operation of the vehicle.   
     
     
         19 . The fuel container of  claim 18 , wherein the vehicle housing is generally cylindrical; and wherein:
 the container structure is annular and just outside the cylindrical housing; and   part of said drag of the vehicle depends on radial thickness of the annular container structure.   
     
     
         20 . The container structure of  claim 19 , wherein:
 the radial thickness of the annular container structure depends upon quantity of fuel within the annular structure.   
     
     
         21 . The container structure of  claim 20 , wherein:
 the fuel within the annular structure is compressed against the vehicle housing by said ambient pressure.   
     
     
         22 . The container structure of  claim 17 , wherein:
 range of the vehicle in moving through the medium is maximum when the vehicle is operated at constant velocity through the medium.   
     
     
         23 . The vehicle of  claim 17 , wherein:
 the fuel container structure that is in contact with the medium is made of, or has embedded, materials that further reduce skin-friction drag.   
     
     
         24 . The vehicle of  claim 23 , wherein:
 the materials are drawn out of the surface into a boundary layer with the medium.   
     
     
         25 . The vehicle of  claim 24 , wherein:
 the materials are replenishable plural times, by soaking the container surface in them.   
     
     
         26 . The vehicle of  claim 17 , wherein the embedded materials are selected from the group consisting of:
 Teflon or other materials having low friction;   latex or other materials having high compliance; and   mixtures, or other combinations, of low-friction and high-compliance materials.