Abstract:
An Air-Deployable Expendable Ice Buoy (AXIB) that can withstand multiple freeze-thaw cycles and operate equally well in ice prone ocean or fresh water. The AXIB can be dropped from an airborne platform, land on an ice surface, right itself to the vertical position, anchor and stabilize itself in the ice, withstand several freeze-thaw cycles and continue to transmit data while anchored to the ice or floating in the ocean. The unique hull design of the AXIB allows it to withstand multiple freeze-thaw cycles and continue to function. The AXIB is particularly well suited for deployment and utilization in any ice zone where repeated freeze-thaw cycles occur.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority based on U.S. Provisional Application 60/931,531 filed on May 24, 2007. 
     
    
     FEDERAL RESEARCH STATEMENT 
       [0002]    This Provisional Patent Application has been developed in conjunction with NOAA 2006-1 SBIR solicitation for item 8.3.8E Inexpensive Airborne Expendable Ice Buoys (AXIB) Suitable for Marginal Ice Zone Deployment. 
     
    
     BACKGROUND OF THE INVENTION 
       [0003]    This invention relates to an Air-Deployable Expendable Ice Buoy (AXIB) and more specifically to an ice buoy that can withstand multiple freeze-thaw cycles and operate equally well in ice or in water where freezing occurs. As described herein, the AXIB can be dropped from an airborne platform, land on an ice surface, right itself to the vertical or upright position, extend an anchor into the ice, stabilize itself, withstand several freeze-thaw cycles and continue to transmit data while anchored to the ice or floating in the ocean. The unique hull design of the AXIB allows it to withstand multiple freeze-thaw cycles and continue to function. As such, the present invention is particularly adaptable and useful in areas near the edge of the floe ice, or in extreme northern or southern latitudes where survival in ocean ice or fresh water ice is required. 
       DESCRIPTION OF THE PRIOR ART 
       [0004]    Ice buoys are well known in the prior art. 
         [0005]    For example, U.S. Pat. No. 5,593,332 to Green discloses an ice penetrating communication buoy that is launched from a submarine, penetrates the ice from below using buoyancy and a thermal source, and serves as a communications medium for the submarine. 
         [0006]    Furthermore, U.S. Pat. No. 6,183,326 to Stein discloses an improved ice penetrating communication buoy that is also launched from a submarine. 
         [0007]    U.S. Pat. No. 5,319,376 to Eninger discloses another ice penetrating buoy that is launched from a submarine. 
         [0008]    U.S. Pat. No. 5,014,248 to Green et al discloses an air deployable ice penetrating sono buoy. 
         [0009]    The prior art also discloses an air droppable ice buoy manufactured in Norway by Christian Michael Research called the ICEXAIR. This device is described at http://www.cmr.no/cmr_instrumentation/index.cfm?id=180781. 
         [0010]    Other prior art of interest includes the following: 
         [0011]    U.S. Pat. No. 6,380,889 to Herrmann et al discloses an air droppable reconnaissance sonde that can set up and deploy on land and wirelessly transmit data to a receiver. 
         [0012]    U.S. Pat. No. 5,022,470 to Andersen et al discloses an air deployable thermal ice penetrating method and system. 
         [0013]    While the above cited prior art discloses and teaches many of the characteristics of the present invention, none have the combined desired attributes of air deployability, extended life, ice anchoring, and unique hull design which allows the AXIB to withstand multiple freeze-thaw cycles and remain functional. 
       SUMMARY OF THE INVENTION 
       [0014]    The present invention is directed toward an Air-Deployable Expendable Ice Buoy (AXIB) and more specifically to an ice buoy that can withstand multiple freeze-thaw cycles and operate equally well in ice or cold ocean water. Thus, the AXIB is ideally suited for marginal ice zone deployment resulting in improved availability of in-situ observation of oceanic, atmospheric, and cryospheric phenomena throughout the polar regions and other ice prone areas. 
         [0015]    The major components of the AXIB are a unique combination of an ice resistant hull, a mast, a communications package, a sensor package, a power source, a disposable air deployable cone to protect the mast, ice anchor, and erection legs. There is a cinching cable around the base of the deployment cone which clamps the cone around the top circumference of the buoy and the parachute is attached to the top of the cone. The hull is so designed that the AXIB can be deployed on ice, anchor itself to the ice, withstand a thaw such that it is buoyant in water, and survive a refreezing in such a manner that the buoy hull will not be crushed. The ability to withstand the freeze thaw cycle distinguishes the AXIB from other ice buoys which generally are useful for only one season and then they are crushed by the ice. The AXIB is designed to last for several seasons, thereby decreasing the overall life cycle cost. 
         [0016]    The AXIB is designed so that it can be dropped onto marginal ice via parachute from a plane or helicopter. When the buoy reaches the surface of the ice, an explosive cutter severs a cinching cable at the base of the deployment cone. This separates the two halves of the cone, and allows the cone halves and parachute to fall away. Upon reaching the surface, the AXIB will invariably be in other than upright position. The erection legs will then actuate and raise the AXIB to the full upright position. Once in the upright position, the ice anchor is actuated. The ice anchor utilizes an exothermic chemical reaction contained within a hollow pipe that penetrates by melting into the ice. An alternative method of anchoring can be achieved by mechanical drill, screw and/or percussive methods. Subsequent freezing will firmly secure the AXIB to the ice. The communications mast telescopes upward to elevate the sensors to the required standard height of two meters above the ice surface. The AXIB is now fully anchored and deployed and ready to begin communications. 
         [0017]    In the event the ice to which the AXIB is anchored melts, the AXIB simply floats as a sea buoy, buoyant and stable. If the water refreezes, the innovative design (utilizing conical sections, low angle lifting ribs, and a smooth, hard surface causes the buoy to lift upward rather than being crushed) of the AXIB hull allows it to withstand the forces of the freezing water and re-anchor itself to the ice without being crushed. The design of the hull allows for withstanding multiple freeze-thaw cycles while continuing to operate and continuing to provide meteorological and hydrographic data from the marginal ice zone. 
         [0018]    In an alternate mode, the AXIB can be deployed on the sea surface near the ice by parachuting it from an aircraft or placing it into the water from the deck of a ship or boat. In this mode, the AXIB would not have erection legs since it would be deployed directly into the water in an upright position. The buoy will then drift and then “freeze in” the ice as the temperature becomes colder. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0019]      FIG. 1  shows the AXIB  10  in the fully deployed position anchored on the ice  30 .  FIG. 1  also shows the ice anchor  50  deployed into and/or through the ice; the deployment of the erection legs  20 ; and the communications mast  70 . 
           [0020]      FIG. 2  is a perspective view of the fully deployed AXIB  10  in the upright position showing the deployed erection legs  20 ; the deployed ice anchor  50  in the ice  30 ; and the deployed communications mast  70 . 
           [0021]      FIG. 3  shows the AXIB  10  as it is falling to the surface of the ice  30  attached to a parachute at  110 .  FIG. 3  shows the erection legs in the undeployed position, the communications mast  70  in the undeployed position; the expanding rib hull design  15 ; and parachute bale  110 . This figure also shows in more detail the inverted cone ribbed design  15  of the hull? 
           [0022]      FIG. 4  is a closeup of the AXIB  10  showing the manner in which the two halves of the protective parachute deployment cone  100  fall off once the AXIB is deployed.  FIG. 4  also shows the communications mast  70  with the sensor  60 ; and the protective parachute deployment cone  100 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    The present invention is directed toward an Air-Deployable Expendable Ice Buoy (AXIB) and more specifically to an ice buoy that can withstand multiple freeze-thaw cycles and operate equally well in ice or polar ocean water. Thus, the AXIB is ideally suited for marginal ice zone deployment resulting in improved availability of in-situ observation of oceanic, atmospheric, and cryospheric phenomena throughout the polar regions or any other body of water that is prone to icing and thawing. 
         [0024]    Referring to  FIG. 1 , the instant invention is an Air-Deployable Expendable Ice Buoy (AXIB)  10  which is shown in the deployed position on the ice  30 . The AXIB consists primarily of a hull  15 , a multi-section telescoping mast or non-telescoping mast  70 , a sensor package  60 , a power source  80 , a detachable parachute deployment cone  100  to protect the mast and communications package during descent, an ice anchor  50 , and erection legs  20 . The hull  15  is so designed that the AXIB can be deployed on ice, anchor itself to the ice, withstand a thaw such that it is buoyant on water, and survive refreezing in such a manner that the hull will not be crushed. 
         [0025]    The design of the hull  15  is crucial to the ability of the AXIB  10  to withstand multiple freeze-thaw cycles. In order to maximize strength, the hull  15  incorporates a vertically tapered design of molded shape with compressive stiffeners. Low angle lifting ribs on the hull cause the AXIB to lift rather than compress or crush when compressed by wind or current driven ice or during a still water freeze. To maximize survival, the surface of the hull is very smooth and is generally comprised of a strong material such as hard isotropic vinylester/biaxial fiberglass laminate to allow it to lift as it is compressed by the freezing ice. Visually, the hull design is that of an inverted truncated cone with a ribbed effect. The strength and resiliency of the hull design also serves to ensure that the AXIB will survive the parachute drop from an aircraft. 
         [0026]    The angle of the tapered hull ranges from 55 to 89 degrees from the horizontal. The angle of the low angle lifting ribs varies between 5 and 45 degrees from the horizontal. 
         [0027]      FIG. 1  also shows the other key components of the AXIB. These include a pneumatic cylinder  95 , rubber erection leg bladders  85 , a telescoping ice anchor  50 , a thermally conductive tube or mechanical drill  40 , an electronic canister  90 , and battery packs  80 . 
         [0028]    In an alternate mode, the AXIB can be deployed on the sea surface near the ice by parachuting it from an aircraft or placing it into the water from the deck of a ship or boat. In this mode, the AXIB would not have erection legs  20  since it would be deployed directly into the water in an upright position. All other attributes of the AXIB remain the same. The buoy will then drift and freeze into the ice as the temperature becomes colder. 
         [0029]      FIG. 2  is a perspective view that shows the AXIB  10  in the fully deployed position with the erection legs  20  fully deployed; the ice anchor assembly  50  deployed into the ice; and the communications mast  70  raised such that the sensor package is at the industry standard height of two meters above the ice surface. One of the key attributes of the ice anchor/ballast rod assembly  50  is that it acts as a stabilizer for the AXIB. This stabilizing effect maintains the buoy in a position such that the crushing forces of the ice and wind are perpendicular to the vertical axis of the AXIB. Therefore, the crushing forces of wind and ice tend to push the AXIB up and the ice anchor/ballast rod assists in keeping the crushing force perpendicular to the vertical axis which essentially helps to direct this force to the lifting angles and tapered shape of the hull. Low interface friction between the hull and the ice forces the hull rise upward rather than being crushed. 
         [0030]    Referring to  FIG. 3 , the AXIB  10  is shown as it is descending from an aircraft and approaching the ice  30 . The descending AXIB  10  is attached to the parachute (not shown) at the bale  110 .  FIG. 3  also shows the protective shell surrounding the communications mast  70  and sensor package  60 . 
         [0031]    The AXIB  10  is designed to be dropped from an aircraft cruising at a range of speeds and altitudes. Descent is stabilized and slowed by a parachute. This is sufficient to ensure full inflation of the parachute and slow vertical descent to an acceptable rate. The parachute is deployed after launch from the aircraft by a lanyard connected to the aircraft or by other similar means. Deceleration will be appropriate for the shock mounted instrument package. A cinching cable (not shown) is placed circumferentially in a groove  75  around the bottom of the deployment cone in order to hold the cone together during deployment and descent. 
         [0032]    Referring to  FIG. 4 , the manner in which the protective parachute deployment cone  100  falls away from the mast  70  and sensor package  60  is shown. The cone  100  is attached to the hull of the buoy by a cinching cable. Upon signal, explosive cutters that are attached to the shell will cut the cable that holds the cone in place, thereby allowing the two halves to fall harmlessly off and away from the AXIB. 
         [0033]    After contact with the ice, the initial position of the buoy will be with the vertical axis at less than 90 degrees to the horizontal due to the tapered hull configuration of the buoy and the low center of gravity. In order to erect and stabilize the buoy to the vertical position for operation, an erection and anchoring system will be employed. This system consists of erector legs  20  and an ice anchor  50 . Initially the erector legs  20  are folded along the buoy body and are hinged at their lower extremities. After separation of the parachute, the legs slowly rotate and fully extend perpendicularly from the body. Due to the low center of gravity of the buoy, the buoy will rotate to a vertical position with the erector legs in full horizontal contact with the ice. After deployment of the erector legs, an anchoring device  50  will extend into the ice from the bottom end of the erect buoy to permanently anchor the buoy to the ice. Stability is achieved by the ice refreezing around the anchor. Ice surface irregularity can be tolerated to some degree by the erection and anchoring system. The mast will remain housed until the buoy is stabilized in the ice, and the buoy will withstand substantial wind loads when fully deployed on the ice. 
         [0034]    A key feature of the communications mast is the flexible mast joint which allows the mast to flex in excess of 180 degrees. 
         [0035]    The buoy hull is sufficiently buoyant to float with sufficient freeboard without additional flotation. The AXIB will float vertically with the mast at the required two meter height and the legs and bladders ejected. 
         [0036]    As water freezes around the buoy, it will remain in a vertical flotation position with the mast extended to two meters and does not require any further intervention. There are internal stiffeners to provide additional compressive strength. There is an internal liner to protect the electronics. If the watertight integrity is breached, foam surrounding the liner will maintain sufficient reserve buoyancy. 
         [0037]    The communications/sensor package consists of commercially available sensor and communications equipment. Long life battery components allow the AXIB to function for at least two years. 
         [0038]    The AXIB was successfully tested in freeze-thaw conditions in the winter of 2007-2008 and survived freeze in and the forces of wind driven sheet ice during the spring breakup. 
         [0039]    There is significant international interest in the instant invention. The inventors will discuss their invention at the National Ice Center in Suitland, Md. in May 2008. In addtiion, the inventors have been invited to present the instant invention at Eighteenth Annual Meeting of the Participants of the International Arctic Buoy Programme at Toulouse, France in June 2008.