Abstract:
An articulating sonobuoy is provided. The articulating sonobuoy comprises a plurality of section, and a plurality of joints connecting each of the plurality of section to adjacent sections, wherein each of the plurality of sections self-aligns by rotating about one or more of said plurality of joints changing the shape of the buoy from a stowed configuration to a streamlined deployed configuration.

Description:
TECHNICAL FIELD  
       [0001]     The present invention generally relates to buoys and, in particular, to station keeping sonobuoys.  
       BACKGROUND  
       [0002]     Sonobuoys are equipped with electronic sensors to both gather data and transmit that data. Sonobuoys have been used to detect and locate submerged submarines. They have also been used in military and private applications to take measurements regarding the environment such as water temperature, current flow, etc. Sonobuoys can be free-floating, anchored or station-keeping. For more useful collection of data, it is desirable for the sonobuoys to be either anchored or station-keeping in order to collect data from relatively the same location. Station-keeping buoys are preferred in situations where an extended anchor would not be desirable or practical.  
         [0003]     Station-keeping buoys, however, consume power quickly through the propulsion system used to keep the buoy in the same geographic location. This rapid power consumption prevents the station-keeping buoy from operating for extended periods of time. Additionally, sonobuoys used by the Navy are often launched through a small tube (i.e. typically a tube with an 8 inch diameter). The typical shape of the sonobuoys is, accordingly, cylindrical. Any deployable sonobuoys must, therefore, conserve this cylindrical shape in order to be launched from existing tubes.  
         [0004]     For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a deployable station-keeping buoy which can be launched from existing launch tubes and which significantly reduces power consumption allowing the buoy to operate for extended periods of time.  
       SUMMARY  
       [0005]     The above-mentioned problems and other problems are resolved by the present invention and will be understood by reading and studying the following specification  
         [0006]     In one embodiment, an articulating sonobuoy is provided. The articulating sonobuoy comprises a plurality of section, and a plurality of joints connecting each of the plurality of section to adjacent sections, wherein each of the plurality of sections self-aligns by rotating about one or more of said plurality of joints changing the shape of the buoy from a stowed configuration to a streamlined deployed configuration.  
         [0007]     In another embodiment, an articulating sonobuoy is provided. The articulating sonobuoy comprises a plurality of section, joint means for connecting said plurality of sections to adjacent sections, and folding means for folding said plurality of sections about said joint means such that the buoy has at least two configurations, wherein the at least two configurations include an initial stowed configuration and a deployed configuration.  
         [0008]     In yet another embodiment, an articulating sonobuoy is provided. The articulating sonobuoy comprises a plurality of sections, each section being a cross-sectional piece of a streamlined airfoil shape, and a plurality of joints connecting each of the plurality of sections to adjacent sections, wherein rotation of each of the plurality of sections about the plurality of joints changes the shape of the buoy from a cylindrical stowed configuration with a diameter between approximately 6 inches and 21 inches to a streamlined airfoil deployed configuration.  
         [0009]     In another embodiment, a method of deploying a streamlined sonobuoy through cylindrical launch tubes is provided. The method comprises aligning a plurality of sections to fit within a cylindrical launch tube, wherein each of the plurality of sections is a cross-sectional piece of a streamline shape, releasing the aligned plurality of sections through the cylindrical launch tube, and rotating each of the plurality of sections about one or more joints, wherein rotation of the plurality of sections aligns the plurality of sections to form a streamlined shape. 
     
    
     DRAWINGS  
       [0010]      FIG. 1  is a graph of drag coefficients of common shapes as a function of Reynold&#39;s number.  
         [0011]      FIG. 2  is an image of an articulating buoy in a stowed configuration according to one embodiment of the present invention.  
         [0012]      FIG. 3  is an image of an articulating buoy in a deployed configuration according to one embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0013]     In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific illustrative embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that logical, mechanical and electrical changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense.  
         [0014]      FIG. 1  is a graph of drag coefficients of common shapes as a function of Reynold&#39;s number. The typical shape of buoys and launch tubes in use is circular. The diameter of these launch tubes ranges from 6 inches to 8 inches. The circular shape presents problems for station-keeping buoys. In order for station-keeping buoys to maintain their station or geographic location for extended periods of time, the buoys need either, more stored energy onboard, a more sufficient power supply system to power a motor and navigation system, a more efficient shape or all of the aforementioned. Embodiments of the present invention address the issue of providing a more efficient shape.  
         [0015]     As shown in  FIG. 1 , circle  102 -A, the typical shape of buoys, has a high drag coefficient. Due to that high coefficient, a large portion of power is lost through drag. Additionally, as  FIG. 1  shows, other shapes have significantly lower drag coefficients and hence would be more efficient and lose less power due to drag. Each shape  102 -A,  104 -A . . .  112 -A is associated with a graph  102 -B,  104 -B . . .  112 -B representative of drag coefficient as a function of Reynold&#39;s number, respectively. For example, circle  102 -A is associated with graph line  102 -B while ellipse  104 -A is associated with graph line  104 -B. Additionally, the length and width dimensions for each shape are shown in  FIG. 1  as a multiple of length D. For example, circle  102 -A has length D and width D while ellipse  104 -A has length D and width 0. 5 D or ½ the length of D.  
         [0016]     Of the shapes shown in  FIG. 1 , circle  102 -A has the highest drag coefficient and shape  110 -A has the lowest drag coefficient. Although shape  112 -A is a flat plate and has a lower coefficient than shape  110 -A, it is included for reference purposes only because its extremely thin shape limits it from being used for most practical purposes. Ellipses  104 -A and  106 -A have lower drag coefficients. As understood by comparing the widths of ellipses  104 -A and  106 -A, the drag coefficient for ellipses  104 -A and  106 -A decreases as the ratio of width-to-length decreases. Shapes  108 -A and  110 -A are streamlined airfoil shapes with even smaller width-to-length ratios. As can be seen, both airfoil  108 -A and airfoil  110 -A have significantly lower drag coefficients than circle  102 -A and ellipses  104 -A and  106 -A. Airfoils  108 -A and  110 -A are representative of National Advisory Committee for Aeronautics (NACA) 0018 and NACA 0009 airfoil shapes. Therefore, it would be advantageous to develop buoys with a streamlined airfoil shape since this would reduce drag and consequently conserve power.  
         [0017]     Unfortunately, a streamlined airfoil shape, with similar weight and displacement of a typical cylindrical sonobuoy, will not fit in a launch tube with a diameter of 6 inches to 8 inches. If the length D of the airfoil is reduced to fit within the diameter of the launch tube, the width or thickness of the airfoil will also be significantly reduced to preserve the correct shape. If airfoil  108 -A has a length D equal to 6 inches, the maximum width of airfoil  108 -A would be a mere 1.08 inches. The prohibitively small area in such an airfoil would render the airfoil useless for all practical purposes due to the lack of area for necessary electronic and mechanical components. Additionally, the buoy must be capable of being launched from up to 30,000 feet and such a small size could cause it to be blown far off course.  
         [0018]     Embodiments of the present invention, however, enable a buoy with a streamlined airfoil shape to fit into existing launch tubes, which have a diameter between 6 inches to 8 inches, while still being of sufficient size to house necessary electronic and mechanical components. Additionally, it can be launched from aircraft at 30,000 feet or from submarines and surface ships. Therefore, embodiments of the present invention enable station-keeping buoys to station-keep for extended periods of time. In some embodiments, the station-keeping buoys are enabled to station-keep for periods of up to 30 days. Additionally, embodiments of the present invention require few to no adjustments for launch tubes to accommodate buoys made according to embodiments of the present invention which saves both time and money.  
         [0019]      FIG. 2  is an image of an articulating buoy  200  in a stowed configuration according to one embodiment of the present invention. The term articulating refers to the fact that buoy  200  is composed of individual sections flexibly connected. Buoy  200  is composed of multiple sections  202 - 1  . . .  202 -N and section  204 . In one embodiment, buoy  200  is composed of 8 sections. Each of sections  202 - 1  . . .  202 -N and section  204  are water-tight sealed preventing water from entering the sections. In one embodiment, section  204  houses a battery compartment. In other embodiments section  204  is used to house other electronic components. In some embodiments, one or more of sections  202 - 1  . . .  202 -N house other components, such as a navigation and control unit, a propulsion system, a radio transmitter, sonar equipment, etc. Additionally, in some embodiments, one or more of sections  202 - 1  . . .  202 -N do not house any components but are used primarily to support floatation and maintain stability of the buoy through means known to one of skill in the art, such as water ballast to support stabilization or air pockets to support floatation. In an embodiment using water ballast each of sections  202 - 1  . . .  202 -N and  204  is individually sealed and any electrical components housed within a section are also water-tight sealed such that only a portion of each section is able to take in water for the water ballast and electronic components are not exposed to water. In all embodiments, buoy  200  is properly weighted to maintain buoy  200  afloat and stable. Sections  202 - 1  . . .  202 -N and section  204  are connected to adjacent sections through joint means (shown in  FIG. 3 ). In one embodiment, the joint means comprise pivot hinges. In other embodiments, other appropriate joint means are used.  
         [0020]     Buoy  200  is referred to as station-keeping because it can maintain itself in a particular geographic location or station. In some embodiments, one of sections  202  comprises a navigation and control unit  222  that utilizes Global Positioning System (GPS) technology. Additionally, in some embodiments, one of sections  202  comprises a propulsion system  224  which functions in conjunction with a navigation and control  222  unit to maintain buoy  200  in a particular geographic location. In one embodiment, this location is fixed and determined prior to launch. In other embodiments, the location is changeable remotely. For example, in some embodiments, a user operates a remote unit  220  to transmit signals to buoy  200  via wireless link  226  in order to control the location. In yet other embodiments, the geographic location is determined according to the location of impact with the water surface. A propeller based propulsion system is used in one embodiment to maintain the geographic location. In other embodiments, a jet propulsion system is used.  
         [0021]     In some embodiments, sleeve  206  is an integral part of buoy  200  used to house buoy  200 . In other embodiments, sleeve  206  is not used and is not a part of buoy  200 . Sleeve  206  facilitates storing, transporting and launching buoy  200 . In one embodiment, buoy  200  is removed from sleeve  206  prior to launch. In other embodiments, buoy  200  is launched while inside sleeve  206 . In such embodiments, sleeve  206  is removed after launch. In one embodiment, sleeve  206  is removed through remote control via remote unit  220 . In other embodiments, sleeve  206  is designed to open and release buoy  200  automatically upon occurrence of a particular event, such as impact with the water surface. Sleeve  206  and buoy  200  are made from any appropriate metal, metal alloy, plastic, foam or other appropriate material.  
         [0022]      FIG. 3  is an image of an articulating buoy in a deployed configuration according to one embodiment of the present invention. Once deployed, sections  202 - 1  . . .  202 -N and section  204  fold to form an articulating buoy as depicted in  FIG. 3 . Each of sections  202 - 1  . . .  202 -N and  204  folds about one of joints  306 - 1  . . .  306 -N. In one embodiment, sections  202 - 1  . . .  202 -N fold in a fashion similar to the manner in which a Jacob&#39;s Ladder is folded together. In one embodiment, section  204  is folded underneath sections  202 - 1  . . .  202 -N maintaining the streamlined shape. As can be seen more clearly in  FIG. 3 , sections  202 - 1  . . .  202 -N and section  204  do not all have the same shape. Instead, each of sections  202 - 1  . . .  202 -N and  204  is a cross-sectional piece of a streamlined shape such that when sections  202 - 1  . . .  202 -N and  204  are rotated about joints  306 - 1  . . .  306 -N sections  202 - 1  . . .  202 -N and  204  are aligned to form a streamlined shape. In the embodiment in  FIG. 3 , a streamlined airfoil shape is used. The airfoil shape is not limited to a particular National Advisory Committee for Aeronautics (NACA) series airfoil shape. Embodiments of the present invention are compatible with any appropriate NACA series. In some embodiments a NACA 0015 shape is used. NACA 0015 is a symmetrical shape. In other embodiments, other symmetrical airfoil shapes are used. Symmetrical airfoil shapes are typically less subject to drift than asymmetrical or chambered shapes. However, in other embodiments a chambered airfoil shape is used. In other embodiments a NACA 67-015 laminar airfoil shape is used. In other embodiments, a NACA 67-018 laminar airfoil shape is used. In particular, in one embodiment, buoy  200  has a 30 inch chord length, 24 inch span and 5.4 inch maximum thickness. Additionally, in other embodiments, other streamlined shapes not including any NACA series airfoil shape are used.  
         [0023]     For illustrative purposes only, gaps between each of sections  202 - 1  . . .  202 -N are displayed in  FIG. 3 . In practice, each of sections  202 - 1  . . .  202 -N and  204  will be flush against adjacent sections when in a deployed configuration. Additionally, for illustrative purposes only, joints  306 - 1  . . .  306 -N have been drawn as protruding out from sections  202 - 1  . . .  202 -N and  204 . In practice, joints  306 - 1  . . .  306 -N are integrated into sections  202 - 1  . . .  202 -N and  204  such that joints  306 - 1  . . .  306 -N are flush with the surface of sections  204  and  202 - 1  . . .  202 -N leaving no substantial gap between sections  202 - 1  . . .  202 -N and  204 .  
         [0024]     In a folded, deployed configuration, front portion  310  of buoy  200  is maintained facing the direction of current flow. This is achieved through a propulsion system, navigation and control unit and various sensors as known to one of skill in the art. Each of these components is housed in at least one of sections  202 - 1  . . .  202 -N and  204 . In one embodiment, a propulsion system is located in a section in a rear portion  312  of buoy  200 . In one such embodiment, section  202 - 1  houses the propulsion system. In another such embodiment, other rear sections house the propulsion system. In other embodiments, more than one section may house a propulsion system  
         [0025]     As depicted in  FIG. 3 , in some embodiments, a portion of buoy  200  is maintained above the water surface level. In one embodiment, the draft is 18 inches. Also, in one embodiment, flat surface area  308  of one or more sections  202 - 1  . . .  202 -N is equipped with solar cell paneling used to collect energy and recharge a battery.  
         [0026]     Various means are employed in different embodiments to fold buoy  200  such that buoy  200  self-aligns into at least two configurations, a stowed configuration and a deployed configuration. In some embodiments, joints  306 - 1  . . .  306 -N include stored energy hinges biased to a deployed configuration such that once external forces which maintain buoy  200  in a stowed configuration are removed, buoy  200  automatically folds into a deployed configuration. In one such embodiment, an external force used to maintain buoy  200  in a stowed configuration is provided by sleeve  206 . Once buoy  200  is removed from sleeve  206 , in such an embodiment, buoy  200  will automatically fold into a deployed configuration due to the bias in joints  306 - 1  . . .  306 -N. In another embodiment, locking pins are used to maintain buoy  200  in a stowed configuration. Once the locking pins are removed in such an embodiment, buoy  200  folds to a deployed configuration due to the bias in the joints.  
         [0027]     In other embodiments, joints  306 - 1  . . .  306 -N are mechanically powered by a motor  314  such that a force acts on joints  306 - 1  . . .  306 -N and sections  202 - 1  . . .  202 -N to cause buoy  200  to fold into a deployed configuration with each of sections  202 - 1  . . .  202 -N and  204  folding about one or more of joints  306 - 1  . . .  306 -N. In one such embodiment, the mechanically powered joints are activated and controlled remotely. In another such embodiment, the mechanically powered joints are activated automatically by occurrence of a particular event, such as impact with the water surface. In yet other embodiments, each of sections  202 - 1  . . .  202 -N and  204  are weighted such that the natural alignment of heavier portions sinking below the water surface and lighter portions rising to the water surface causes buoy  200  to fold into the streamlined deployed configuration. In yet other embodiments, other appropriate means are used for folding buoy  200  into a deployed configuration.  
         [0028]     Buoy  200  has various advantages over prior buoys. In a stowed configuration, buoy  200  is capable of being launched from existing launch tubes. In some embodiments, the diameter of buoy  200  in a stowed configuration is 6 inches and the length is 163 inches, enabling buoy  200  to be launched from existing launch tubes in aircraft and submarines which have a diameter of 6 inches to 8 inches. Additionally, in one such embodiment, buoy  200  weighs 100 pounds which gives buoy  200  the capability of being launched by just one person. In other embodiments, buoy  200  is larger with a 21 inch diameter enabling it to be launched from existing torpedo tubes which have a diameter of 21 inches or more.  
         [0029]     In a deployed configuration, buoy  200  is optimized for drag reduction by using a streamlined shape. By reducing drag, buoy  200  consumes less power as a station-keeping buoy through a propulsion system. In turn, by consuming less power, buoy  200  has a longer station-keeping duration than typical station-keeping buoys. In one embodiment, buoy  200  can station-keep for 30 days. Thus, through the combination of a streamlined deployed configuration and a cylindrical stowed configuration, embodiments of the present invention provide a much needed solution to the problem of providing a buoy which reduces power consumption through a more efficient shape and yet can still be launched from existing launch tubes which have a diameter ranging from approximately 6 inches to approximately 21 inches.  
         [0030]     Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement, which is calculated to achieve the same purpose, may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of the present invention. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.