Abstract:
A tethered buoy housing and deployment system includes a housing for disposition in a vessel, a tether for interconnecting a portion of the housing and a buoy, a reel mounted in the housing and rotatable to unwind the tether, means for maintaining tension on the tether as the tether is unwound, and a platform and linkage assembly adapted to support the buoy and move the buoy between a vertical disposition for storage in the housing and an angled disposition for release of the buoy into an external fluid stream.

Description:
STATEMENT OF GOVERNMENT INTEREST 
     The invention described herein may be manufactured and used by or for the Government of the United States of America for Governmental purposes without the payment of any royalties thereon or therefore. 
    
    
     CROSS REFERENCE TO OTHER PATENT APPLICATIONS 
     None. 
     BACKGROUND OF THE INVENTION 
     1) Field of the Invention 
     This invention relates to a tethered buoy housing and deployment assembly adapted to lift and rotate a buoy from a stowed location in an undersea vessel to a position wherein the buoy can be released into an underwater flow stream and thereafter retrieved and returned to the housing. 
     2) Description of the Prior Art 
     The United States Navy has developed an antenna assemblies for submarines, in which the assemblies are adapted to improve communications at maneuvering speeds and depths. One such system is the Recoverable Tethered Optical Fiber (RTOF) buoy, which is deployed to the surface and recovered by an attached tether. Current RTOF buoy system is designed to fit within a relatively large working volume. As such there is a need for a buoy system which can operate in a relatively smaller space. 
     SUMMARY OF THE INVENTION 
     It is therefore a primary object and general purpose of the present invention to provide a tethered buoy housing and deployment assembly which can be used in smaller sized environments. 
     With the above object in view, a feature of the present invention is the provision of a tethered buoy housing and deployment assembly comprising a housing for disposition in a sail portion of a submarine or similar structure of an undersea vessel, a tether for interconnecting a portion of the housing and a portion of a buoy, a tether reel mounted in the housing and rotatable to unwind the tether, means for maintaining a selected tension on the tether as the tether is unwound, a platform disposed in the housing and adapted to rise in the housing as the tether is extended, a buoy cradle for releasably retaining the buoy, and a linkage assembly mounted on the platform and adapted to move the buoy between a substantially vertical disposition for retention of the buoy and a tilted disposition for generally aligning the buoy with external water flow for release of the buoy thereinto. 
     The above and other features of the invention, including various novel details of construction and combinations of parts, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular device embodying the invention is shown by way of illustration only and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference is made to the accompanying drawings in which is shown an illustrative embodiment of the invention, from which its novel features and advantages will be apparent, and wherein corresponding reference characters indicate corresponding parts throughout the several views of the drawings, and wherein: 
         FIG. 1  is a perspective view of a housing structure of the present invention with a plurality outer plates removed in order to show inner structure components; 
         FIG. 2  is a perspective view of the inner structure of the housing of  FIG. 1 , with components of the deployment system and a buoy contained therein; 
         FIG. 3  is a perspective view of a tether and spool mechanism of the present invention; 
         FIG. 4  is a perspective view of a tether tension sensor assembly and a tether cutter of the present invention; 
         FIG. 5  is a perspective view of a tether reel and motor assembly disposed within the housing; 
         FIG. 6  is a perspective view of the components of  FIGS. 3 and 5 , in combination with a lift platform; 
         FIG. 7  is a perspective view of a buoy deployment and retrieval assembly mounted on the lift platform; and 
         FIG. 8  is a perspective view of a sail portion of a submarine with the buoy deployment system of the present invention disposed therein. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the present invention, a caged housing structure  10  is constructed of preferably 1.5 inch×1.5 inch bars  12  enclosed by plates  14  ( FIG. 1 ). Four parallel vertical bars  16 , each approximately 181.5 inches in length, are arranged so as to frame a rectangle  18  and make up corners  20 ,  22 ,  24 ,  26  of the housing structure  10 . An extra 181.5 inch long bar  28  is added to the two longer sides of the rectangle for support. Perpendicular to the vertical bars are several smaller horizontal bars  32  (either 14.25 inches or 22.5 inches in length) that support the vertical bars  12 . The bars  16 ,  32  are welded together to form a cage  34 , with the plates  14  (approximately 0.25 inches thick, and approximately either 26 inches×60.5 inches or 16.75 inches×60.5 inches) welded to the outside of the cage for added stability against shock. The assembled cage  34  is mounted on a foundation plate  38  inside sail  39  ( FIG. 8 ). 
     As shown in  FIG. 2 , at the bottom of the cage  34 , there is mounted a tether reel  40  and DC brushless pancake motor  42 . The pancake motor  42  is mounted on top of the reel  40  and rotates with the reel. A tether reel containment structure  44  protects the reel  40  and pins the reel through the center thereof, allowing the reel to spin but not move from its location. The containment structure  44  also provides support for a level wind  46  and the DC motor  48  (See  FIG. 3 ). The level wind  46  protrudes from one side of the containment structure  44 , and the DC motor  48  is mounted on top of a protrusion  50  ( FIG. 3  and  FIG. 6 ) and is locked down to avoid movement during operation. 
     When a tether  52  leaves the reel  40  and goes through the level wind  46 , a first stop on the way to a buoy  54  is a low tension sensor  56  (See  FIG. 4 ). An alignment pulley  58 , part of an array of tether path elements, at the bottom of an array of the tension sensors directs the tether  52  into a first sensor pulley  64 . The alignment pulley  58  is adapted to swivel back and forth on a pin  66  to accommodate how the tether  52  is coming off of the level wind  46 . 
     The sensor pulleys  64 ,  68 ,  70 ,  72  are arranged such that the top and bottom pulleys  72 ,  64  are locked in place, while the two middle pulleys  68 ,  70  can translate laterally, left to right (side-to-side) within apertures  73 . The two middle pulleys  68 ,  70  sense how far their centers of rotation are away from each other and an operationally-connected inboard computer (not shown) translates the distance into tether tension. When the tension is too low or too high, an operator is signaled there is a problem. 
     The tether  52  comes in from the alignment pulley  58  and extends clockwise around the bottom sensor pulley  64 , counterclockwise around the next pulley up  68 , clockwise around the next pulley  70 , and counterclockwise around the top sensor pulley  72 . 
     When the tether  52  leaves the top pulley  72 , the tether moves through a tether cutter  74  before continuing on. The tether cutter  74  is used in situations where the buoy  54  cannot be saved. The tether cutter  74  is activated by a small solenoid with a stored-energy device. 
     The path from the reel  40  to the buoy  54  is provided by the tether path elements  60 , as shown in  FIG. 6 . When the tether  52  leaves the level wind  46 ; the first of the tether path elements encountered is the alignment pulley  58 , and thereafter the sensor pulleys  64 ,  68 ,  70 ,  72 . As the tether  52  leaves the tether cutter  74  on the other end of the low tension sensor  56 ; the tether passes through one of two small rollers on its way to a lift platform  76  to ensure that the tether  52  travels the correct path without changing direction. 
     Roller  78  can be added proximate to the sensor pulley  72  while another roller (not shown) can be mounted proximate to platform pulleys  82 ,  84 . Following the platform pulleys, the tether  52  passes through an orifice  86  in a lift platform  76 , where the tether  52  passes through a further roller  88  for alignment ( FIG. 7 ) before connecting to the buoy  54  through a buoy cradle  92 . 
     The lift platform  76  is a base for a linkage deployment and retrieval mechanism  94 . The platform  76  may be made from 1.0 inch thick steel. Holes  96  are disposed at each end of the platform  76  for lift platform support rods  98 . The rods  98  are provided with rubber support rod translation brakes  100  located on the rods, to avoid over-and-under extension of a hydraulic lift cylinder  118 . 
     The lift platform  76  is raised to a proper height by a five-stage double-acting hydraulic cylinder  110  and guided along the correct path by the lift platform support rods  98 . Prior to rotation, an inner lifting link  112  of varying relative length is in a lowered position, so that a linkage brake  114  is resting on a base link  116 . 
     To achieve rotation, the lifting link  112  is raised. This is effected by the electrical lift cylinder  118  and a DC motor  119 . The cylinder  110  may be driven by a one-horsepower, three-phase AC induction brake motor  115 . 
     The motor  115  is supported by the lift platform  76 . This arrangement prevents a large moment from being applied to the motor  119 . The lift cylinder  118  is vertically actuated by the motor  119  and pushes up on the link  112  of varying relative length, causing the link with the buoy cradle  92  attached thereto, to rotate into position. 
     The tethered buoy housing and deployment system satisfies the requirements for an outboard antenna system. The maximum hydraulic power supplied by the platform is seventy-six gal/min at 3000 psi, which is more than is required to power the five-stage double-acting hydraulic cylinder  110 . The available electricity is also sufficient to run the DC motors in the system. 
     The above described system is sufficiently robust to handle hydrodynamic loading. The electric lift cylinder  118  and DC motor  119  are able to actuate deployment and retrieval in the same scenario. 
     At a platform depth and speed determined to be optimal by the submarine for use of the RTOF, deployment is initiated. At this point, closure doors on the sail  39  are opened and the five-stage double-acting hydraulic cylinder  110  is actuated through inboard controls (See  FIG. 8 ). The hydraulic cylinder  110  pushes the lift platform  76  to a pre-specified height. At this point, the electric lift cylinder  118  and DC motor  119  take over. 
     Using inboard controls, the lift cylinder  118  is raised to the point at which the deployment mechanism  94  lines up the buoy  54  with the external water flow. The tether reel  40  then releases back tension on the tether  52 , which allows the flow caused by the moving submarine to carry the buoy  54  out of the buoy cradle  92 . The inherent lift buoyancy of the buoy  54  then lifts the buoy to the surface. 
     When the RTOF is released, it remains stationary on the surface while the reel releases the tether  52  in accordance with the forward velocity of the carrying vessel. When the tether  52  runs out, the buoy slips under the surface quickly, leaving a minimal wake. 
     The buoy  54  remains stationary on the surface of the ocean while the carrying vessel moves forward; thereby, causing the tether  52  to unfurl. Once the end of the tether  52  is reached, the tether reel  40  and DC brushless pancake motor  48  quickly pull the buoy  54  under the surface and reels the buoy back in. When the buoy  54  is pulled back in to the buoy cradle  92 ; the electric lift cylinder  118  is lowered, rotating the buoy back to the vertical stowage position. The five-stage double-acting hydraulic cylinder  110  is then lowered and closure doors  120  are shut, completing the full stowage operation of the system. 
     It will be understood that many additional changes in the details, materials, steps and assignment of parts, which have been herein described and illustrated in order to explain the nature of this invention, may be made by those skilled in the art within the principles and scope of the invention as expressed in the appended claims.