Patent Document

This application claims the benefit of U.S. Provisional Application No. 60/258,524, filed Dec. 29, 2000, and U.S. Provisional Application No. 60/304,736, filed Jul. 13, 2001, the entire disclosures of which are incorporated herein by reference. 
    
    
     FIELD OF INVENTION 
     The present invention is generally drawn to lighter-than-air (“LTA”) devices and respective uses thereof. 
     BACKGROUND OF THE INVENTION 
     Although there are many examples of connections between the ground and LTA devices, the barrage balloon is the only reported example of an LTA device designed primarily to control the space beneath itself. The barrage balloon was designed to damage or destroy an airplane that flew into the cable between the balloon and the ground. Today Federal Aviation Agency regulations require posting a NOTAM (Notice to Airmen) in addition to marking the aerostat or tethered balloon&#39;s tether cable whenever flown, to prevent its unintentionally serving as a barrage balloon. 
     An LTA device remains airborne because it consists primarily of a buoyant gas, such as hot air or some other gas which weighs less than the air that it displaces. For example: Under Standard Sea-level temperature and pressure conditions, one thousand cubic feet of helium displaces one thousand cubic feet of air, thus providing roughly 64 pounds of lifting force. 
     Non-limiting examples of buoyant gases to be used in LTA devices include hydrogen, helium, methane, and pipeline gas (natural gas). Hydrogen provides the most lift, but is highly flammable. Helium, which is not flammable, provides nearly as much lift as hydrogen, but is much more expensive than hydrogen. Methane is nearly half as effective a lifting gas as helium, but also is flammable. Natural Gas, because of heavy impurities, is slightly less effective than pure methane, but is widely available and very inexpensive compared to hydrogen, helium or methane. 
     Accordingly, a 10-foot diameter sphere provides a gross lift of approximately 270 pounds if filled with helium. Although a sphere is the most efficient container, enclosing the greatest volume with the least surface area, conventional balloon construction techniques require many panels and consequently many heavy seams. Thus, the fabric in a spherical balloon may weigh as much as a simple cylindrical balloon of equal volume, but with fewer seams. 
     Nineteenth century aeronauts invested a great deal of effort developing techniques using one or more appendages to provide the pilot some control over his balloon with respect to the prevailing wind and to take advantage of ocean or river currents. They repeatedly demonstrated that sails could be effectively employed to provide directional control if the balloon moved significantly slower than the relative wind. (Example: AIRSHIPS PAST AND PRESENT, Hildebrandt, A., Van Nostrand Co, New York, 1908. The first attempt to reach the North Pole by balloon (Andre&#39;s Red Balloon) combined the use of a balloon mounted sail, and a weighted line which dragged in the water or over the ice.) 
     With the introduction of the internal combustion engine, aeronauts were finally able to move independent of the wind. However, their airship&#39;s speed was limited both by propulsive power and by the effect of dynamic air pressure on the envelope and the airship appendages Conventional airships are still limited to roughly 80 miles per hour, with normal “cruising” speeds in the 30 to 40 mph range. 
     Other problems associated with conventional airships deal with changes in air temperature, pressure, and the effects of condensation and precipitation. Specifically, while traveling through fog, or more generally clouds, condensation accumulates on the surface of the envelope. Such accumulation over the large surface area of the airship adds undesirable weight to the envelope, thereby adversely affecting the airship&#39;s efficiency. In extreme cases, large amounts of water accumulation may be detrimental to the flight of the airship. Most airship designs incorporate features to prevent the dripping water from interfering with pilot visibility and to prevent ice thrown from the propeller blades from damaging the envelope. It was common military practice to fly into a summer shower near the end of a mission, primarily to cool the gas in order to bring the airship back to neutral buoyancy, and secondarily to wash the envelope. Since most flights were over-water, pilots found it more effective to use a winch to pick up ballast water when needed, rather than to hunt for rain, 
     During the first century of manned flight, balloons were normally inflated shortly before launching, and the envelope collapsed by releasing the gas at the end of the flight, in the same manner as the present-day hot-air balloons and airships. Because of the cost and complexity of rigging cold-gas airships, Santos-Dumont developed the hangar and other techniques for maintaining an inflated airship between flights. 
     Various techniques were developed, using one or more lines for ground handling, recovery, controlling and anchoring balloons and airships. During World War I, British, Italian, and other airship operators developed multi-point high-moors; the airship was commonly tethered thirty feet in the air. Alternatively, airships were “bedded down”; tethered closely to the ground and protected by natural or manmade windbreaks or shelters if they could not be safely returned to a hangar. The Russian&#39;s reported that one of their bedded down airships (SSSR V2, on bivouac) tore loose from sixty “corkscrew” ground anchors and was blown away on Sep. 6, 1935. 
     Since the development of the mooring mast shortly after World War I, nearly all American airships have been designed to operate from a fixed or mobile mooring mast. Typically, the airship is ballasted to near-neutral buoyancy, connected to the mast by a fitting at its nose, and allowed to weathercock around the mast. High winds or unexpected wind shifts and gusting, while the airship is attached to a mooring mast, or while groundhandling crews are moving the airship, continue to be primary causes of airship losses and accidents. 
     An airship&#39;s lines, ropes and/or cables may be manhandled, fastened to powered winches on land or specially modified ships or heavy vehicles or attached to fixed and drifting anchors. Airship and aerostat lines have been used to carry electrical power, water, gas, telegraph, telephone, analog and digital electronic signals and electro-optical signals between the ground and the buoyant device. Airship&#39;s winches have been used to tow boats and sonar-bodies, to transfer passengers, and to pick up other loads from the ground and the sea. However, as previously mentioned, except for the barrage balloon, no applications were designed to control or use the space between the balloon and the earth, except to protect and secure the LTA device itself. 
     What has not been developed is a system and method to control the space between the earth and the LTA device. What is further needed is a means of controlling the height, orientation and disposition of the system as well as rapid retrieval and stowage at the onset of severe weather or whenever the operator needs to deactivate the system for some other reason. 
     Rather than using a mooring mast, or multiple lines to constrain and control the LTA device, this invention employs a flexible distributed surface, a surface which in addition to restraining and controlling the LTA device also performs, inter alia, one or more of the following useful functions: blocks light; screens, filters, and/or blocks airflow; collects and condenses aerosols; blocks or stops larger airborne particles, bugs and birds. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to provide a working surface to limit and control the movement of air between an LTA element and the earth beneath it. 
     It is another object of this invention to provide a working surface to limit and control the movement of objects or materials in the air between an LTA element and the earth beneath it. 
     It is still another object of this invention to provide a method and system to limit or control light and other radiation effects through this working surface. 
     It is still yet another object of this invention to provide a method and system for rapid erection and relocation of an extremely lightweight, large wall or curtain over/around virtually unprepared terrain or water surfaces. 
     The present invention uses an LTA device, non-limiting examples of which include balloons, aerostats or airships, to support the upper end of one or more extended working surfaces between the device and the ground or the sea. In most applications the device will be operating at very low altitudes (the working surface less than 500 feet in height) and operating in light winds (less than 15 knots). Consequently the LTA device&#39;s design and strength requirements are considerably relaxed vis-à-vis conventional airships and aerostats. 
     The working surface may be built as a part of the balloon structure, or may be designed for rapid attachment/detachment and replacement. Suitable materials for the surface range from impermeable fabrics to open web nets, depending upon the intended application. The working surface may be opaque, transparent, or translucent. The surface may be created as a unitary fabric or assembled by connecting multiple segments of similar or dissimilar fabrics. An individual working surface may incorporate embedded or attachable power and signal lines, special tensile strength members and attachment points, such as eyelets or “Velcro” pads. 
     In some applications more than one such surface may be supported by the same LTA element and connected to separate ground attachments. In other applications, surfaces may be arranged as a cascade, between two or more buoyant balloons or airships. 
     Applications include, inter alia: fog clearing/harvesting; air dam/wind break; turning vane for windmills; stirring vane for frost prevention; sail, primary or secondary ship propulsion; and various mechanical and visual barrier (filter, screen, fence and reflector) applications. 
     As a fog harvester, the present invention works best under calm or light wind conditions. The large exposed surface and its supporting balloon, with or without additional cooling, efficiently condenses and collects airborne aerosols. If there is insufficient wind, or if the purpose is to clear fog from a specific area, such as an airport runway, the entire assembly can be propelled against the wind down the entire length of the runway. 
     In another application, the invention can be attached as a segmented skirt, connecting a low-tethered balloon, such as the Lindstrand HiFlyer, which uses an eighteen cable tie-down system. The HiFlyer would then resemble a large inverted cone, but serve as an extremely large tent. 
     In its simplest application, the invention consists of a single flexible film, attached at intervals to the bottom of a cylindrical LTA balloon by its strength members (cables, cords or reinforcing tape or webbing), and also attached at its bottom to hard points on the ground, thus forming a surface in tension as a result of the lifting force of the balloon. Guys, at one or both ends of the balloon may be used to orient the balloon and thus the surface to the wind, or the balloon might be left free to respond to the wind&#39;s force and be tethered only through the working surface. 
     The balloon may be parallel to the ground or it may be adjusted to an arbitrary angle, as in a lateen sail. The ground attachments may be in a straight line, in an arc, or any other desired configuration to control the orientation of the surface and/or to adjust the area of the working surface exposed to the sun and/or wind. 
     For illustrative purposes, consider a two hundred foot long cylindrical balloon, twenty feet in diameter. Such a balloon filled with approximately 62,000 cubic feet of helium, would provide a gross lift of roughly 20 pounds per foot of length (about 10 pounds per foot if filled with methane). Under calm conditions, the working surface, a “curtain” rising from ground level to the balloon would present a nearly vertical surface. Under light wind conditions, or when the base is moved relative to the earth, the force of the apparent wind against the curtain will drive the balloon to windward, until the buoyancy, gravity, inertia, and wind forces reach an equilibrium. 
     In general, the present invention provides an LTA device comprising, a buoyant element containing LTA gas, and a flexible surface having a length and height forming a usable area, the length of the flexible surface being connected directly to the buoyant element, wherein the flexible surface is operable to use an area defined by the buoyant element and line below the flexible surface. 
     In general, the present invention further provides a method of condensing water comprising, inflating an element with sufficient LTA gas to lift the element and at least a portion of a flexible surface, the flexible surface having a length and height forming a usable area connected directly to the buoyant element, off the ground, and controllably moving the inflated buoyant element and the flexible surface through the air, wherein water condenses on the buoyant element and drips down the flexible surface. 
     The present invention still further provides a method of powering a vessel, in favorable winds, by using the working surface as a sail secured to the vessel, the sail having length and height and being connected directly to the buoyant element, and inflating the element with sufficient LTA gas to lift the element and at least a portion of the sail off the vessel, wherein wind force pushes the sail and therefore moves the vessel. 
     The present invention yet further provides a method of blocking material from entering an area, securing a flexible surface to a perimeter of the area, the flexible surface having a length and a height and being connected directly to an element, and inflating the element with sufficient LTA gas to lift the element and at least a portion of the flexible surface off the ground, wherein flexible surface lifted by the inflated element prevents material from entering the area. In one embodiment, the material blocked from entering the area is turbulent air. In another embodiment, the material blocked from entering the area is fog. In yet another embodiment, the material blocked from entering the area includes liquid or solid objects, such as insects. 
     Additional advantages of the present invention will become apparent to those skilled in the art from the following detailed description of exemplary embodiments of the present invention. The invention itself, together with further objects and advantages, can be better understood by reference to the following detailed description and the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and form a part of the specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings: 
     FIG. 1 depicts an exemplary embodiment of a LTA device in accordance with the present invention. 
     FIG. 2 depicts another exemplary embodiment of a LTA device in accordance with the present invention. 
     FIGS. 3A-3C illustrate an exemplary method of manufacturing a LTA device in accordance with an embodiment of the present invention. 
     FIG. 4 depicts yet another exemplary embodiment of a LTA device in accordance with the present invention. 
     FIG. 5 depicts yet another embodiment of LTA device in accordance with the present invention in which a plurality of flexible surfaces are attached to element. 
     FIG. 6 depicts an exemplary method of using a LTA device in accordance with the present invention as a mast-less sail for a boat. 
     FIG. 7 depicts an exemplary deployment rigging to be used with boat having a LTA device in accordance with the present invention. 
     FIG. 8A is a cross-sectional view of the winding bar of FIG. 7 with the flexible material mounted therein and fully deployed. 
     FIG. 8B is a cross-sectional view of the winding bar of FIG. 7 with the flexible material mounted therein, after the winding bar of FIG. 7 has been rotated in a direction w, for a time t. 
     FIG. 9 illustrates an exemplary system and method for assembling the flexible material with the winding bar of FIG.  7 . 
     FIG. 10 illustrates an exemplary system and method for assembling the winding bar of FIG. 7 with left cross bar. 
     FIG. 11 illustrates an exemplary system and method for assembling the winding bar of FIG. 7 with right cross bar. 
     FIG. 12 illustrates the application of a LTA device in accordance with the present invention as a fog harvester. 
     FIG. 13, illustrates the application of a LTA device in accordance with the present invention as a “tent.” 
     FIG. 14 illustrates a modified version of the application of a LTA device of FIG.  13 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these specific details. 
     FIG. 1 depicts an exemplary embodiment of a LTA device in accordance with the present invention. In FIG. 1, LTA device  100  includes buoyant element  102  containing a LTA gas, and a flexible surface  104 . Seam  106  runs along the length of buoyant element  102 , whereas seams  108  and  110  runs along the height of buoyant element  102 . 
     As for the shape of the element, for the same reasons as applied to conventional LTA devices, a sphere is the most efficient shape, i.e., it encloses the greatest volume with the least surface area. It is noted that a spherically shaped LTA device may practically be considered only in the academic sense. In particular, an LTA device must respond to several forces, and corresponding moments. Non-limiting examples of forces include gravity, buoyancy, thrust, and pressure, whereas the corresponding non-limiting examples of moments include the moments which act upon the center of gravity, center of buoyancy, center (or axis) of thrust, and center of pressure, respectively. Unfortunately, the vector quantities (Weight, Buoyancy, Thrust, and Aerodynamic lift and drag) are never co-located, and all are capable of fairly large changes in location and magnitude over relatively short periods of time. 
     Consequently, an LTA device that is generically termed “spherically shaped,” is not in actuality in the shape of a sphere. More specifically, as a result of the external forces and moments acting upon the LTA device, the shape is distorted, so as not to resemble a sphere. However, the terms “sphere” and “spherical” are used herein to describe an LTA device that would be a sphere, absent the effect of external forces and moments. 
     Similarly, for the same reasons as applied to conventional LTA devices, a simple cylindrical, or tubular, balloon of equal volume may be lighter than a spherical balloon as a result of fewer seams. Further, for the same reasons as described above with respect to a spherical LTA, a cylindrical or tubular LTA may not have, in actuality, the shape of a cylinder or tube, respectively. However, the terms “cylindrical” and “tubular” are used herein to describe an LTA device that would be a cylinder or tube, absent the effect of external forces and moments. 
     Of course, most any shape element may be used for an LTA device in accordance with the present invention, so long as its size and shape permit sufficient lift for the element itself in addition to the flexible material attached thereto. 
     The flexible material may be created as a unitary fabric or assembled by connecting multiple segments of similar or dissimilar fabrics. An individual working surface may incorporate embedded or attachable power and signal lines, special tensile strength members and attachment points, such as eyelets or “Velcro” pads. 
     As for the flexible material, the types, sizes, shapes, and other characteristics of materials may be chosen depending on the intended use of the LTA device Non-limiting examples of materials that may be used in accordance with the present invention include existing gas tight fabrics such as those used in the present generation of airships and aerostats. The sizes and shapes of flexible materials of a LTA device in accordance with the present invention may be chosen to fit design parameters commensurate with the designed lift of the buoyant element. Non-limiting examples of characteristics of materials to be considered when choosing the flexible materials of a LTA device in accordance with the present invention include density, tensile strength, elasticity, reflectance, transparency, opacity, color, cost, and durability in field service. 
     As described above, the choice of the material for the flexible material of the LTA device in accordance with the present invention may be dependent, among other things, upon the intended use of the LTA device. For example, for use as a fog harvester, a porous material having proficient hydrophobic properties should be chosen, so as to permit the condensed water to drip down the flexible surface to a water collector at the bottom. For use as an air dam/wind break, a material with high tensile strength and low elasticity may be chosen so as to be sturdy without stretching under the wind force. For use as a turning vane for windmills, as a stirring vane for frost prevention, or as a sail, primary or secondary ship propulsion, the material should be highly flexible so that it can be folded and stowed for extended periods without damage. For use as a visual barrier (e.g. a privacy screen or alternatively a movie screen) a material may be chosen having a desired reflectance, transparency, opacity, and color. For use as various mechanical barriers, a material may be chosen having a desired filtration ability in light of the particulate to be filtered; a porous membrane for filtering vapor or small pollen and dust particles, a screen for larger items such as bugs, leaves and construction debris, and netting for birds and large items. 
     FIG. 2 depicts another exemplary embodiment of a LTA device in accordance with the present invention. In FIG. 2, LTA device  200  includes buoyant element  202  having two end faces  208  and  210  and containing an LTA gas, and a flexible surface  204 . Seam  206  runs along the length of buoyant element  202 , whereas seams  212  and  214  runs along the circumference of each respective end face  208  and  210 . 
     FIGS. 3A-3C illustrate an exemplary method of manufacturing a LTA device in accordance with an embodiment of the present invention. 
     A top portion of sheet  300  of material, as depicted in FIG. 3A, is rolled onto itself to form a tubular element, as depicted in FIG.  3 A. Sheet  300  may be a unitary piece of material. Alternatively, Sheet  300  may be a composition of a plurality of segmented pieces attached together by known methods, non-limiting examples of which include sewing, buttons, pressure sensitive adhesives, thermo-sensitive adhesives, etc. As for the composition of sheet  300 , many materials may be used, limited by factors such as their respective density, cost, and availability, in addition to their respective characteristics pertaining to a particular intended use as will be described further below. 
     Once the top portion of sheet  300  is rolled onto itself, it may be attached along a seam  302 . The seam  302  may be created by known methods, non-limiting examples of which include sewing, buttons, pressure sensitive adhesives, thermo-sensitive adhesives, etc. End portions  304  and  306 , which may or may not be comprised of a material different than that of sheet  300 , may then be attached to both open ends of the rolled top portion of sheet  300  by known methods along respective seams  308  and  310 . A device  314  is thus produced, comprising element  306  and flexible surface  312 . 
     In the embodiment of FIG. 1, end portions are not attached to both open ends of the rolled top portion of the sheet. Alternatively, in this embodiment, the end portions of the rolled top portion of the sheet are closed with seams  108  and  110  by known methods. 
     Non-limiting examples of other methods of attaching the flexible material to the element, as opposed to direct attachment, include remote attachment with lines, chains, netting, etc. 
     FIG. 4 depicts yet another exemplary embodiment of a LTA device in accordance with the present invention. Specifically, FIG. 4 illustrates how a preexisting LTA device may be modified include a usable flexible surface in accordance with the present invention. In FIG. 4, LTA device  400  includes; spherical balloon  402  containing a LTA gas, and a flexible surface  404 . Seam  406  runs along the lower perimeter of buoyant element  402 . 
     FIG. 5 depicts yet another embodiment of LTA device  500  in accordance with the present invention in which a plurality of flexible surfaces  504  and  506  are attached to element  502 . Anchors  510  and  514  are attached to respective flexible surfaces  504  and  506  by lines  508  and  512 , respectively. As such, flexible surfaces  504  and  506  may be disposed at a desired distance X, thereby providing a floating enclosure for containing flow of materials such as wind or artificial snow from a snow making machine. Furthermore, the LTA device  500  may be moved, while retaining its shape, by moving the anchors such as by towing each with a vehicle. 
     Further applications of a LTA device in accordance with the present invention will now be discussed. 
     FIG. 6 depicts an exemplary method of using a LTA device in accordance with the present invention as a mast-less sail for a boat. In FIG. 6, LTA device  602  includes; element  606  containing a LTA gas, and a flexible surface  608 , wherein the LTA device  602  attached to the deployment rigging  626 , which is pivotally mounted to boat  604 . Seam  610  runs along the length of buoyant element  606 , whereas seams  618  and  620  runs along the circumference of each respective end face  612  and  614 . Control lines  622  and  624  may optionally be added to inhibit twisting of the element  606  relative to the deployment rigging  626 . 
     In operation as a mast-less sail, as exemplified in FIG. 6, first the element  606  must be inflated with a LTA gas. Once inflated, the buoyancy of element  606  enables deployment of the mast-less sail, which will be discussed in detail below. 
     FIG. 7 depicts an exemplary deployment rigging to be used with boat having a LTA device in accordance with the present invention. The deployment rigging  626  includes left and right crossbars  702  and  704  respectfully, meet at a T-section  706 , which is mounted into rotatable base plate  708 , which is fastened into the deck of the boat. Winding bar  714  is rotatably mounted between crossbars  702  and  704 . End plates  710  and  712 , concentrically mounted to the winding bar  714 , assure even retracting and deploying of the flexible material. Gear  728 , additionally concentrically mounted to winding bar  714 , is meshed with chain  726 . Motor  716  provides power to turn the winding bar  714  in either one of a retracting and deploying direction. A manual crank may be used in place of motor  716 . The power transmission system includes chain  718 , receiving gear  722 , transfer bar  720 , gear  724  and chain  726 . The transfer bar  720  is mounted to crossbar  704  by support members  730  and  732 . 
     In operation, motor  716  drives chain  718  to rotate transfer bar  720  via gear  722 . The rotation of transfer bar  720 , and consequently gear  724 , drives chain  726 , which then rotates winding bar  714 , via gear  728 , to thereby retract or deploy the flexible material. Motor  716  thus fully deploys or detracts the flexible material, thereby raising or lowering the mast-less sail Once deployed, the mast-less sail may be steered by rotating the rotatable base plate  708 , such as with a controllable motor (not shown). 
     FIG. 8A is a cross-sectional view of the winding bar  714  with the flexible material  608  mounted therein and fully deployed. As seen in FIG. 8A, the flexible material includes an end  802 , which contains a member  806 , wherein circumference of end  802  is too large to pass through slit  804  in the winding bar  714 . FIG. 8B is a cross-sectional view of the winding bar  714  with the flexible material  608  mounted therein, after the winding bar  714  has been rotated in a direction w, for a time t. 
     FIG. 9 illustrates an exemplary system and method for assembling the flexible material  608  with the winding bar  714 . As illustrated in FIG. 9, endplate  710  is removeably mounted to winding bar  714  via a collar  906 , that contains projections  908  that slidably mate with slots  904  in winding bar  714 . As a result of the mated connection of projections  908  and the slots  904 , as the winding bar  714  rotates, endplate  710  additionally rotates. Endplate  710  additionally includes mounting bar  910  to be mounted into left crossbar  702 . With endplate  710  removed from winding bar  714 , the flexible material  608  may be inserted into winding bar  714  by guiding the end  802  into inlet  902  such that the remainder of the flexible material may slide along slit  804 . Once the flexible material  608  is inserted into the winding bar  714 , endplate  710  is remounted to contain the flexible material  608  therein. 
     FIG. 10 illustrates an exemplary system and method for assembling the winding bar  714  with left cross bar  702 . As illustrated in FIG. 10, the end of crossbar  702  includes a locking latch portion  1002 , having a receiving groove  1004  therein. Although a locking mechanism is not shown, any known locking mechanism may be used. Once latch portion  1002  is opened, mounting bar  910  of endplate  710  may be inserted to rest on a groove  1004  located therein. A second groove, not shown, formed in the non-latch portion of the end of crossbar  702  additionally receives the mounting bar  910  when the latch portion is closed. Of course, various lubricants, bearings, or other friction reducing mechanisms may be used at the junction of the left cross bar  702  and endplate  710 , in order to decrease friction and permit smooth rotation of the winding bar  714 . 
     FIG. 11 illustrates an exemplary system and method for assembling the winding bar  714  with right cross bar  704 . As illustrated in FIG. 11, the end of crossbar  704  includes a locking latch portion  1104 , having a receiving groove  1106  therein. Although a locking mechanism is not shown, any known locking mechanism may be used. Once latch portion  1104  is opened, mounting bar  1102  of endplate  712  may be inserted to rest on a groove  1104  located therein. A second groove, not shown, formed in the non-latch portion of the end of crossbar  704  additionally receives the mounting bar  1102  when the latch portion is closed. Of course, various lubricants, bearings, or other friction reducing mechanisms may be used at the junction of the left cross bar  704  and endplate  712 , in order to decrease friction and permit smooth rotation of the winding bar  714 . 
     In the exemplary embodiment of the winding bar as described above with reference to FIGS. 10-11, the winding bar is loaded into the crossbars in a direction between the direction facing down and a direction facing the rear of the boat. This loading direction is chosen to maximize the integrity of the latches in the crossbars retain the winding bar. More specifically, the buoyancy of the mast-less sail will produce a force pulling the winding bar in a direction up from the deck of the ship, while the wind will produce a force pulling the winding bar in a direction toward the front of the ship. As such, the exemplary embodiment of the present invention provides the integral portion of the end of the crossbars to withstand such pulling forces, whereas the latches in the crossbars merely retain the winding bar. However, the latches may be provided in any position of the crossbar in order to provide numerous winding bar mounting designs. 
     Deployment of an LTA device is not limited to the exemplary embodiment as described above with respect to FIGS. 7-11. On the contrary, any deployment and corresponding retrieval technique known in the sailing industry may be used. A non-limiting example of which includes reefing. 
     In another exemplary method of using an LTA device in accordance with the present invention as a mast-less sail. For example, the combination of element and flexible surface is mounted to the port or starboard side of the vessel. In particular, one end of the flexible surface is fastened to the vessel. Non-limiting examples of means for fastening may include a plurality of lines and individually controlled winches, or any other known spar, boom, or sail deployment system. The other end of the flexible surface is connected to the element as described, for example, above. Mounting the LTA device along the hull of the ship lowers the applied force and reduces the healing moment, over that of conventional mast-sail systems. Furthermore, such a use of an LTA device in accordance with the present invention may be employed to propel other objects through fluids. 
     In another application, for example as a fog harvester, an LTA in accordance with the present invention may work best under calm or light wind conditions. The large exposed surface and its supporting balloon, with or without additional cooling, efficiently condenses and collects airborne aerosols. If there is insufficient wind, or if the purpose is to clear fog from a specific area, such as an airport runway, the entire assembly  1202  can be propelled against the wind down the entire length of the runway, for example by way of towing from a vehicle  1204 , as illustrated in FIG.  12 . 
     In another application, as illustrated in FIG. 13, an LTA  1300  in accordance with the present invention includes a low-tethered (Low-Tethered as differentiated from high tethered . . . fastened close to the ground.) balloon  1302  having an attached segmented skirt  1304 , wherein the LTA  1300  may be used as a tent. FIG. 14 illustrates a modification of the LTA device of FIG. 13, wherein a displacement ring  1402  is provided to increase the usable area under the low-tethered balloon  1302 . 
     Although certain specific embodiments of the present invention have been disclosed, it is noted that the present invention may be embodied in other forms without departing from the spirit or essential characteristics thereof The present embodiments are therefor to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Technology Category: 7