CROSS-REFERENCE [0001] This application claims the benefit of U.S. Provisional Application No. 61/249,215, filed October 6, 2009, which application is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] This invention relates to the inflation and deflation of a buoyant aerostat. In particular, it embodies a novel means of furling and storing the envelope when deflated.

BACKGROUND OF THE INVENTION

[0003] Inflation and deflation of aerostat (and balloon) envelopes in windy conditions can be extremely difficult. This difficulty increases dramatically with the size of the envelope being used. In fact, very large envelopes are inflated only when the wind near the ground is very light.

[0004] The difficulty arises because the inflation and deflation processes usually require several minutes to accomplish. In particular, if the lifting gas that fills the aerostat is hot air, a fan or blower is used to move cold air into envelope during inflation and then the air is warmed with one or more heaters. The inflation time is also extended because envelopes are often many thousands of cubic meters in volume and the opening through which the air must pass is relatively small.

[0005] The conventional method for inflating aerostat envelopes is to spread the fabric on the ground and then blow air through the mouth of the envelope using a powered fan. As the envelope inflates, it presents an increasingly large "sail area" to ground winds. Further, because all of the fabric has been spread out, the fabric of a partially inflated envelope tends to flap and undulate. This flapping can become quite severe and can put significant dynamic loads on the envelope's components. [0006] Even worse than the tendency of a partially filled envelope to flap is its tendency to collapse on the upwind side. This creates a concave surface on the side exposed to the ground winds. This collapsing tendency is informally known as "spinnakering" due to the

resemblance between the concaved envelope and the commonly used sailboat sail of the same name. A spinnakered envelope creates aerodynamic loads many times greater than an uncollapsed (convex) envelope of the same size. These increased aerodynamic loads can readily damage the envelope's components.

[0007] There are comparable risks of flapping and spinnakering during the deflation of an envelope. As the lifting gas is exhausted through a vent hole (or holes) the fabric of the envelope goes slack. In sufficient ground winds, this slack fabric will once again start to flap and spinnaker.

[0008] Movement of a partially filled envelope can be reduced somewhat through the use of tethering lines. However, tethering lines create great stress concentrations in the envelope fabric. In fact, only at the top (crown) of the envelope, where the load carrying webbing converges, is there enough structural strength to distribute the loads imparted by tethering lines. This limitation reduces the effect of tethers in controlling a partially inflated envelope.

[0009] Some techniques have been developed by recreational hot balloonists to reduce flapping and spinnakering. For example, during inflation, fabric is deployed progressively from a storage bag as the amount of air inside the envelope increases. This is called the "progressive fill" method of inflation.

[0010] Although the progressive fill method works to some degree in reducing flapping and spinnakering during inflation, its benefits are limited. In particular, the progressive fill method requires that the envelope be deployed horizontally along the ground during inflation.

In gusty or changing wind conditions, the inflated portion of the envelope will attempt to weathervane. In doing so, the portion of the fabric on the ground will either be dragged along the surface (risking damage to the fabric) or the entire envelope will attempt to roll leading to binding or twisting of the envelope fabric. Further, the only practical tether attachment point, the top (crown) of the envelope, is necessarily the last portion of the envelope to emerge from the bag. As such, tethers can not provide any effective movement control until the very end of the progressive fill process.

[0011] Comparably, during deflation, a common technique is to slide a ring or a similarly shaped device along the length of the envelope. The ring is usually started at the bottom of the envelope and slid towards the top. As the ring moves along the envelope, the fabric is gathered into a relatively tight bundle which forces the air out of a vent located at the top. By actively forcing the air towards the vent, the squeezing process can maintain some amount of internal superpressure and thus keep the envelope fabric taut and less susceptible to flapping and spinnakering.

[0012] The deflation squeezing process, while somewhat helpful in avoiding envelope flapping and spinnakering, also has drawbacks. In particular, at the conclusion of the deflation process, the envelope is left on the ground. This not only exposes the envelope to damage and moisture from the ground but also requires a significant amount of space to lay out the deflated envelope on the ground. And, like the progressive fill process, the partially filled envelope is at risk of being dragged across the surface by changes in the ground winds. [0013] Thus, a need exists for improved systems and methods for furling and unfurling an aerostat. Preferably, such improvements may allow the envelope fabric to be unfurled (deployed) and furled (gathered) in a controlled manner so as to maintain superpressure in the air inside the envelope throughout the inflation and deflation processes.

SUMMARY OF THE INVENTION

[0014] The invention provides systems and methods for furling and unfurling and aerostat envelope. Various aspects of the invention described herein may be applied to any of the particular applications set forth below or for any other types of buoyant assemblies. The invention may be applied as a standalone system or method, or as part of integrated lifting systems, such as lifting or suspending heavy objects. It shall be understood that different aspects of the invention can be appreciated individually, collectively, or in combination with each other.

[0015] In accordance with an aspect of the invention, systems and methods may be provided for precisely controlling the furling and unfurling of a buoyant aerostat envelope throughout the processes of envelope inflation and deflation. This invention can be used with aerostats that employ a variety of lifting gasses but is most effective with an aerostat that employs hot air.

[0016] In order to avoid envelope flapping and spinnakering during inflation or deflation the envelope fabric may be progressively unfurled (deployed) and furled (gathered) in a controlled manner so as to roughly match the amount of fabric deployed at any given point in the inflation/deflation process with the amount of air inside the envelope at that point in the process. In addition, the mouth of the envelope may be sealed to give positive control of the flow of air in and out of the envelope. By both controlling the rate of air flow while simultaneously controlling the rate of fabric deployment/gathering one can keep the air inside the envelope maintained at a pressure that is slightly above the ambient atmospheric pressure. This internal superpressure may keep the deployed fabric consistently under tension. By keeping the fabric of the balloon under continuous tension, the risk of flapping and spinnakering may be essentially eliminated or reduced.

[0017] The systems and methods may allow the envelope fabric to be unfurled (deployed) and furled (gathered) in a controlled manner so as to maintain superpressure in the air inside the envelope throughout the inflation and deflation processes. The process may also allow for tethers to be attached to the envelope at the crown throughout the inflation and deflation processes to ensure that the partially inflated envelope can be adequately restrained. It would be additionally advantageous if the furling and unfurling can be done directly from the storage unit in which the envelope fabric is kept when deflated. It would also be advantageous for the inflation and deflation to be carried out without the envelope fabric touching the ground. [0018] The invention described may permit the envelope to be inflated and deflated while the envelope is connected at both a bottom end and to tethers attached to the top of the envelope. Throughout the inflation and deflation processes, the fabric may be kept above ground level. This may advantageously reduce the risks associated with having an envelope being inflated and/or deflated while lying horizontally on the ground. [0019] The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below.

INCORPORATION BY REFERENCE

[0020] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:

[0022] Figure la shows a side view of a vertical cross-section through a vertical central axis of a furling/unfurling system with a fully inflated envelope.

[0023] Figure lb shows a side view of a vertical cross-section through a vertical central axis of a furling/unfurling system with a roughly half-inflated envelope. [0024] Figure lc shows a side view of a vertical cross-section through a vertical central axis of a furling/unfurling system with a nearly deflated envelope. [0025] Figure Id shows a side view of a vertical cross-section through a vertical central axis of a furling/unfurling system with a fully deflated envelope.

[0026] Figure 2 shows a top view of a horizontal cross-section at the plane of a mouth to bottom-end joint.

[0027] Figure 3 shows a side view of a vertical cross-section of an alternative configuration through a vertical central axis of a furling/unfurling system using an envelope guide and detachable spool frame with the envelope nearly deflated.

DETAILED DESCRIPTION OF THE INVENTION

[0028] While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.

[0029] Aerostat System

[0030] Referring to Figures la thru Figure Id and Figure 2, an aerostat system may comprise an envelope 10 that may have a roughly ovoid shaped membrane made of flexible fabric material. In alternate embodiments, an envelope may have any shape, which may include a roughly spherical shape, an elongated shape, or any other shape. The envelope may be formed of any material which may include a cloth, fabric, weave, or any other thin, flexible material. The envelope 10 may be roughly axisymmetric about its central vertical axis. Alternatively, it need not be axisymmetric about a vertical axis. The envelope 10 may have a top-most point called the crown 20. The envelope 10 may also have a roughly circular opening on the bottom called a mouth 30. The mouth 30 may be connected to a rigid structure called the bottom-end 40 at a mouth to bottom-end joint 50.

[0031] The volume inside of an inflated envelope 10, may be called an envelope cavity 55. In order to create a buoyant lifting force, the envelope cavity 55 may typically be filled with a gas with a density less than the density of the gas found in the surrounding atmosphere 135. For the process described here, the gas in the envelope cavity 55 may be air that is heated above the temperature of the surrounding atmosphere 135. Alternatively, in some

embodiments, unheated gas, such as hydrogen, helium, or any other low density gas may be provided within the envelope cavity. Any discussion of gas or air may apply to any type of gas.

[0032] The bottom-end 40 may provide direct or indirect structural support for several components including a heater 60, a fan blade 70, a fan motor 80, a gathering ring 90, a spool 100, and a spool motor 110. The fan blade 70 may be connected to a fan motor 80. The spool 100 may be connected to a spool motor 110. Any of these components may be optional.

Furthermore, multiple components may be provided or additional components may be provided.

[0033] The bottom-end 40 may include a rigid or semi-rigid structure or frame. The bottom-end 40 may include structural support features that may contact any of the components described. The bottom-end 40 may have any shape. For example, the bottom-end 40 may have a roughly cylindrical or prismatic shape. Similarly, the mouth to bottom-end joint 50 may have any shape or dimension. In some embodiments, the mouth to bottom-end joint 50 may have a smaller cross-section than the bottom-end 40. Alternatively, it may have the same cross section or a larger cross-section. The mouth to bottom-end joint 50 may have any shape, including but not limited to a circle, an ellipse, a triangle, a square, a rectangle, a pentagon, a hexagon, or an octagon. [0034] The fan blade 70 may be positioned to direct air into or out of the envelope cavity 55. For example, during a deflation and furling process, the fan blade 70 may rotate in a first direction, which may assist with drawing air out of the envelope cavity 55. During an inflation and unfurling process, the fan blade 70 may rotate in a second, opposite direction to draw more air from the surrounding atmosphere 135 through the mouth 30 of the envelope 10 and into the envelope cavity 55. In some embodiments, one or more baffles may be provided to guide the airflow driven by the fan blade 70. The baffles may be placed above and/or below the fan blade 70.

[0035] A spooling line 120 may connect the spool 100 at one end. The spooling line 120 may pass through the gathering ring 90 and may connect at the other end to the crown 20 of the envelope 10. The spooling line 120 and spool 100 may be oriented such that the spooling line 120 will wrap around the spool 100 when the spooling motor 110 rotates the spool 100.

[0036] In alternate embodiments, the spooling line 120 may contact the envelope 10 at any point along an inner surface of the envelope 10. This may or may not be at the crown. See, e.g., U.S. Patent No. 4,420,130, which is hereby incorporated by reference in its entirety. In some embodiments, the spooling line 120 may contact the envelope at a top, inner region of the envelope 10. Alternatively, the spooling line 120 may contact the envelope 10 at a side or bottom region. In some embodiments, the spooling line 120 may consist of a single line while in other embodiments it may comprise multiple lines. In some instances, a single line may branch off into multiple lines that may contact the envelope at different points or at the same point.

[0037] A spooling line 120 can also be used to support all or some of a payload. As previously mentioned, an aerostat may be used to lift and/or suspend a payload. The payload may be connected to the aerostat in any manner. In some instances, the payload may be connected to the aerostat via the spooling line 120. The payload may include heavy objects, such as objects weighing 0.1 tons, 0.5 tons, 1 ton, 2 tons, 3 tons, 5 tons, 10 tons, 50 tons, 100 tons, 200 tons, or 500 tons.

[0038] Several tether lines 130 may connect at one end to the crown 20 of the envelope 10 and at the other end to ground 140 at the ground attachment points 150.

[0039] Any number of ground attachment points 150 may be utilized. For example, one, two, three, four, five, six, seven, eight, ten, twenty, or more ground attachment points may be used. The ground attachment points may be spaced in any manner. For example, the ground attachment points may be spaced evenly around the envelope.

[0040] A ground attachment point 150 may be a fixed point on the ground 140. For example, the ground attachment point may include any mechanism that may keep a tether 130 connected to the ground. This may include mechanisms such as loops, hooks, clips, weights, anchors, ties, and so forth. In some embodiments, a ground attachment point 150 may include a winching mechanism that may enable the length of a tether to increase and/or decrease as the winch turns. Other mechanisms may be provided that may allow the length of the tether 130 to increase and/or decrease (e.g., as the tether 130 is extended or retracted). The mechanisms may be power controlled (e.g., powered winches) or hand-controlled (e.g., winding winches by hand). Also, such mechanisms may be manually operated by a user, or may be automatically adjusted by a controller. The mechanisms can be controlled locally or remotely. Multiple mechanisms may be controlled from a central location. A ground attachment point 150 may be any form of tethering anchor.

[0041] In some embodiments, a ground attachment point 150 need not be fixed to the ground 140, but may be fixed to any other stable surface. For example, the ground attachment point 150 may be on a structure that is fixed relative to the ground 140. Any depiction of the ground 140 may refer to any other reference point. The reference point may be fixed with respect to the ground 140 or any other frame of reference. [0042] The tethering lines 130 may be connected to the crown 20 of the envelope 10 at the outside surface of the envelope 10, or on the inside surface of the envelope. If the tethering lines 130 are attached to the inside surface of the envelope 10, they may pass through the surface of the envelope 10. The tethering lines 130 may connect to any other portion of the envelope 10, e.g., a top region, or side or bottom region, on an outside or inside surface of the envelope 10. They may all be connected at the same point or at multiple points on the envelope 10.

[0043] Figure 2 shows a top view of the aerostat system from a horizontal cross-section at the plane of a mouth to bottom-end joint 50. The mouth to bottom-end joint 50 may form a perimeter of the horizontal cross section. In some embodiments, the mouth to bottom-end joint 50 may have the same cross-sectional area and/or shape as the bottom-end 40. Alternatively, the cross sectional area and/or shape of the mouth to bottom-end joint 50 and the bottom-end 40 may differ.

[0044] A bottom-end 40 may include a heater 60, a fan 70 which may be driven by a fan motor 80, a gathering ring 90, a spool 100 which may be driven by a spool motor 110, which may receive a spooling line 120 that may wrap around the spool 100.

[0045] The heater 60, fan 70, and spool 100 may have any placement relative to one another. For example, in some embodiments, the heater 60 and fan blade 70 may be at opposite sides from one another. Alternatively, they may be adjacent to one another. In some instances, a spool 100 may be located near the center of the bottom-end 40. The spool 100 may be located so that the spooling line 120 may be located near the center of the bottom end

40, and so that the spooling line 120 may wrap around the spool 100. The gathering ring 90 may be located near the center of the bottom end 40. The gathering ring 90 may be placed above the spool 100, so that a spooling line 120 may extend relatively vertically through the gathering ring 90, down to the spool 100. Alternatively, the spooling line 120 may extend at an angle through the gathering ring 90 down to the spool 100. [0046] When an envelope 10 is inflated, it may or may not have a greater horizontal cross- sectional area than the mouth to bottom-end joint 50. The envelope 10 may or may not have a similar cross-sectional shape to the mouth to bottom-end joint 50.

[0047] Deflation/Furling

[0048] Figures la through Id when viewed in the sequence Figure la, Figure lb, Figure lc, and Figure Id may illustrate a complete deflation and furling process. In some

embodiments, when viewed in reverse (e.g., the sequence of Figure Id, Figure lc, Figure lb, and Figure la), the figures may illustrate a complete inflation and unfurling process.

[0049] Figure la shows the envelope 10 in a fully inflated state. The aerostat envelope 10 may have an inflated inner surface and an inflated outer surface. The spooling line 120 may be connected to the envelope along the inflated inner surface. In some instances, the spooling line 120 may connect to the inflated inner surface of the envelope 10 at the crown 20.

[0050] The deflation and furling process may be initiated when the spool motor 110 rotates the spool 100. Because the spooling line 120 may be attached to the spool, the spooling line 120 may wrap around the rotating spool 100. As the spooling line 120 may wrap around the spool 100 it may pull the crown 20 of the envelope 10 downward. As the crown 20 of the envelope 10 is pulled downward it may cause the volume of the envelope cavity 55 to decrease, which in turn may force the gas in the envelope cavity 55 through the mouth 30 of the envelope 10 and out to the surrounding atmosphere 135.

[0051] In some implementations, the force of gravity pulling on the envelope 10 fabric combined with the pressure created by the furling process may be sufficient to drive the air out of the mouth 30 of the envelope 10.

[0052] If necessary, the option exists to operate the fan motor 80 to rotate the fan blade 70 so as to speed the deflation process by pulling air from the envelope cavity 55 and exhausting it to the surrounding atmosphere 135. In order to pull air from the envelope cavity 55, the fan blade 70 may be rotating in a first direction, which may be a different direction from which the fan blade 70 would rotate when being used to inflate the envelope 10.

[0053] The option exists to construct vents into the surface of the envelope 10 that can be opened during the deflation and furling process so as to directly connect the envelope cavity 55 and the surrounding atmosphere 135. Opening such vents would create a larger area through which the air can pass during the deflation and furling process, thus potentially speeding up the deflation and furling process. Opening the vents may occur manually or automatically.

[0054] In some embodiments, a heater 60 may or may not be on during the deflation process. A heater may include any mechanism to heat a gas that may be within the envelope cavity 55. The heater may or may not use a flame.

[0055] Figure lb shows the envelope 10 in a partially deflated state with a portion of the spooling line 120 wrapped around the spool 100. For example, at this state, the spooling line 120 may have gone through a gathering ring while the envelope 10 may not yet be deflated enough to be pulled through the gathering ring 90.

[0056] When an envelope 10 is partially deflated, a portion of the envelope connected to the spooling line 120 may be pulled inward. For example, if the crown 20 is connected to the spooling line 120, the crown 20 may be pulled inward. This may cause the top portion of the envelope 10 to become concave. A part of the envelope 10 may be pulled in without contacting the ground 140. The envelope 10 may maintain superpressure, which may keep the envelope 10 from collapsing. Even as the top of the envelope 10 is pulled in, the remaining envelope cavity 55 may still be sufficiently pressured to keep the envelope 10 relatively taut.

[0057] Figure lc shows the envelope 10 in a nearly deflated state. At this point in the deflation process, the continued rotation of the spool 100 has wrapped all of the spooling line

120 around the spool. In doing so the crown 20 (or at least some portion of the envelope 10 connected to a spooling line) of the envelope 10 may have been drawn through the mouth 30 of the envelope 10 and through the gathering ring 90. Thus, a top portion of the aerostat envelope 10 may be deflated first, while maintaining superpressure at a lower portion. The portion of the envelope 10 below the gathering ring 90 and the portion of the tethering lines 130 that are attached to the crown 20 of the envelope 10 may have been gathered into a relatively tight bundle of material called the envelope bundle 160. The continued rotation of the spool 100 may cause the envelope bundle 160 to wrap around the spool 100.

[0058] When at least a portion of the aerostat envelope 10 connected is drawn through the mouth 30 to form at least part of an envelope bundle 160, that the inflated inner surface portion of envelope 10 (i.e., when the envelope 10 is inflated, the inner surface facing the envelope cavity 55) may form an exterior surface of the envelope bundle 160.

[0059] The gathering ring 90 may have a circular or non-circular shape, e.g., triangle, oval, square, or hexagon. It may have a closed shape or an open shape (e.g., a semi-circular shape, a curved shape, a bent shape). For example, if a spool 100 is offset to a side, the gathering ring 90 may be semi-circular.

[0060] In some embodiments, the gathering ring 90 may be optional and may not be required to draw the envelope 10 and tethering lines 130 around the spool 100. For example, the envelope bundle 160 may be directly drawn around the spool 100 without a gathering ring 90. In some instances, other mechanisms may be used to assist with guiding the envelope bundle 160 around the spool 100 (e.g., tubes, mesh, nets, funnels, bars, etc.). In some instances, a plurality of gathering rings 90 may be used, or a combination of a gathering ring 90 and any other mechanisms that may assist with drawing the envelope bundle 160 to a desired location around the spool 100.

[0061] The gathering ring 90 may be positioned at any location within a bottom-end 40 or near the bottom-end 40. For example, the gathering ring 90 may be positioned above the plane of the mouth to bottom-end joint 50. Alternatively, the gathering ring 90 may be placed at or below the plane of the mouth to bottom-end joint 50. The gathering ring 90 may also be placed roughly towards the center of a horizontal cross-section of the bottom-end joint 50, or may be offset to a side.

[0062] The surface of the envelope 10 that is immediately adjacent to the envelope cavity 55 when the envelope 10 is inflated forms the outer surface of the envelope bundle 160.

Likewise, the surface of the envelope 10 that is immediately adjacent to the surrounding atmosphere 135 when the envelope 10 is inflated is facing inward after it has been drawn into the envelope bundle 160. In some embodiments, when an envelope 10 is fully inflated, it may have an inner surface and an outer surface. After the envelope 10 has been somewhat deflated, the inner surface when inflated may form the outside of the deflated envelope bundle 160, while the outer surface while inflated may be on the inside of the deflated envelope bundle 160. In some instances, one or more tethers 130 may be on the inside of the envelope bundle 160.

[0063] The spool motor 110 may continue to rotate of the spool 100 until nearly all of the fabric of the envelope 10 has been drawn through the gathering ring 90. As through spool 100 continues rotating, the spool line 120 and the envelope bundle 160 may be wrapped around the spool 100. The spool line 120 may be connected to the envelope bundle 160 at the crown 20. Alternatively, the spool line 120 may be connected to the envelope bundle 160 at any point, and may or may not overlap with the envelope bundle 160 that is wound around the spool 100.

[0064] Figure Id shows the envelope 10 in a fully deflated condition. Nearly all or all of the fabric of the envelope 10 may have been gathered into the envelope bundle 160 that may be wrapped around the spool 100.

[0065] Throughout the deflation process, the speed of rotation of the spool 100 can be adjusted so as to match the rate at which air is exhausted in such a way as to insure that the pressure of the gas in the envelope cavity 55 remains greater than the pressure of the gas in the surrounding atmosphere 135. In some embodiments, one or more sensor may be provided that may determine the pressure of the gas within the envelope cavity 55. Measurements from the one or more sensors may be used to control the speed of rotation of the spool 100. This may occur automatically or manually. In some other embodiments, the spool 100 speed may be controlled manually or automatically without relying on a pressure reading of the gas within the envelope 10. In some embodiments, the speed of rotation of the spool 100 may be determined based on an anticipated pressure of the gas based on operational parameters for deflating the aerostat. The speed of the rotation of the spool 100 may be controlled locally or remotely.

[0066] At any point during the deflation and furling process, the gas (e.g., air) remaining in the envelope cavity 55 can be heated by operating the heater 60. Heating the air in the envelope cavity 55 may create a buoyant force on the fabric of the envelope 10 which can keep the fabric of the envelope 10 from settling to the ground 140 as the deflation process proceeds. Similarly, at any point, a fan 70 may be operating which may assist with keeping the envelope 10 from settling to the ground 140. The heater 60 and/or fan blade 70 may be constantly on, or may be turned on or off selectively to achieve a desired pressure within the envelope cavity 55. Alternatively, the strength (e.g., power of the heater 60 or speed of the fan blade 70) may be adjusted to achieve the desired pressure within the envelope cavity 55. In other embodiments, the gas within the envelope 10 may be maintained at a temperature and/or pressure which may be sufficient to keep the envelope 10 from settling to the ground 140. In other embodiments, gases may be provided from a high pressure power source (e.g., providing air or helium from a tank).

[0067] Throughout the deflation and furling process the mouth 30 of the envelope 10 may remain continuously attached to the bottom end 40 at the mouth to bottom-end joint 50.

Likewise, throughout the deflation and furling process, the tethering lines 130 may remain connected to the crown 20 of the envelope 10. No components need to be attached or de- attached at any point during the deflation and furling process. In some embodiments, after the envelope 10 has been completely deflated, the mouth 30 may remain attached to the bottom- end 40. Alternatively, after the envelope 10 has been completely deflated, the mouth 30 may be detached from the bottom-end 40. In some instances, the envelope bundle 160 may be wrapped completely around the spool 100 and may or may not be removed from the bottom- end 40.

[0068] In some embodiments, the spool 100 may be located in the bottom-end 40 below the mouth 30 of the envelope 10. Thus, the envelope may be completely drawn through the mouth 30. In other embodiments, the spool 100 may be located above the mouth 30 of the envelope 10, within an envelope cavity 55. In such configurations, most of the envelope 10 may be wrapped around the spool 100 within the envelope 10 without passing through the mouth 30. In some instances, after most of the envelope 10 is wrapped around the spool 100, the envelope 10 may be detached from the bottom-end 40 and drawn up and wrapped around the spool 100, so that the mouth 30 may pass over the spool 100 and the portion of the envelope 10 wrapped around the spool 100.

[0069] Depending upon the precise shape of the envelope 10 and the placement of the ground attachment points 150, it may or may not be necessary to extend or retract the tethering lines 130 as the deflation process proceeds.

[0070] Depending upon the size and shape of the envelope 10 and the size and shape of the spool 100, it may be necessary to add a mechanism that assists in the even distribution of the envelope bundle 160 along the length of the spool 100. One example of such a mechanism would be a follower as is commonly employed on a variety of winch designs.

[0071] Inflation/Unfurling

[0072] The inflation and unfurling process may essentially be the reverse of the deflation and furling process. Figures la through Id when viewed in the sequence Figure Id, Figure lc, Figure lb, and Figure la may illustrate a complete inflation and unfurling process. [0073] Figure Id shows the envelope 10 in the fully deflated state with the vast majority of the material of the envelope 10 located within the envelope bundle 160 that is wrapped around the spool 100.

[0074] In some embodiments, prior to entering the state shown in Figure Id, the envelope bundle 160 may be wrapped around the spool 100 so that most or all of the envelope 10 is wrapped around the spool 100. The mouth 30 of the envelope 10 may have already been attached to the bottom-end 40. Alternatively, the wrapped envelope bundle 160 may be loaded into the bottom-end 40 and/or the mouth 30 of the envelope 10 may be connected to the mouth to bottom-end joint 50 of the bottom end 40.

[0075] The inflation and unfurling process may be driven by a fan motor 80 rotating a fan blade 70 so as to draw air from the surrounding atmosphere 135, through the mouth 30 and into the envelope cavity 55. The pneumatic pressure that is created inside the envelope cavity 55 may be sufficient to cause the spool 100 to rotate. Thus, even if a spool motor 110 were not turned on, the spool 100 may rotate on its own based the air pressure within the envelope cavity 55.

[0076] The envelope bundle 160 may have an interior surface and an exterior surface. When fully deflated, the exterior surface of the envelope bundle may be the surface on the exterior of the bundle. When the mouth 30 of the envelope bundle is connected to the bottom- end, the exterior surface of the envelope bundle may be facing downward. When a fan blade is rotating and/or a heater is operating, an increased gaseous pressure may be provided to the exterior surface of the envelope bundle in close proximity to the mouth of the bundle, where the envelope may be spread out. This portion of the envelope bundle may be over a gathering ring 90. The increased gaseous pressure may cause at least a portion of the aerostat envelope to inflate. This may cause at least a portion of the envelope bundle interior surface to pass through the mouth to form an inflated inner surface of the aerostat envelope. Thus, the exterior surface of the envelope bundle may form the inner surface of the inflated aerostat envelope, facing the envelope cavity 55.

[0077] The spool motor 110 can be use to selectively resist or assist the rotation of the spool 100 to such a degree so as to insure that the gas pressure in the envelope cavity 55 is greater than the gas pressure in the surrounding atmosphere 135. In some embodiments, a spool motor 110 may only operate in one direction (e.g., a spool motor 110 may only turn clockwise or counterclockwise, such as a stepper motor). In such situations, the spool motor 110 may be used to wind the envelope bundle 160 during a furling process, but may be disengaged during an unfurling process, and the spool 100 may turn in the opposite direction as directed during furling based on the pressure within the envelope cavity 55. In other situations, a spool motor 110 may operate in either direction (e.g., selectively turn both clockwise and counterclockwise). In such situations, the spool motor 110 may be used to wind the envelope bundle 160 during a furling process, and may actively turn in the other direction during the unfurling process to assist with the inflation. In any instance, the spool motor 110 may provide some force in the direction that it turns during furling in order to resist the rotation of the spool 100 as the envelope 10 is being inflated. The controlled force being applied by the spool motor 110 in either direction may assist with controlling the inflation of the envelope 10, so that the gas within the envelope cavity 55 may be maintained at a desired pressure. This may also assist with the speed of the inflation process.

[0078] During the inflation process, in some instances, the spooling motor 110 may not be used but rather some other form of mechanical brake may be used to resist rotation of the spool

100. This other mechanical brake may assist with controlling the inflation process.

[0079] In some embodiments, throughout the inflation process, one or more sensor may be provided that may determine the pressure of the gas within the envelope cavity 55.

Measurements from the one or more sensors may be used to control the spool motor 110. This may occur automatically or manually. Alternatively, the spool motor 110 may be controlled manually or automatically without relying on a pressure reading of the gas within the envelope 10. In some embodiments, the spool motor 110 control may be determined based on an anticipated pressure of the gas based on operational parameters for inflating the aerostat. The spool motor 110 may be controlled locally or remotely.

[0080] As the inflation and unfurling process continues, the system may eventually reach the state depicted in Figure lc. As the fan blade 70 moves more air into the envelope cavity 55, the envelope cavity 55 may be allowed to expand in a controlled fashion as more material in the envelope bundle 160 is unfurled from the spool 100 and moves through the gathering ring 90 and passes through the mouth 30 of the envelope 10.

[0081] As the inflation and unfurling process continues, the fan blade 70 may draw more air from the surrounding atmosphere 135 through the mouth 30 of the envelope 10 and into the envelope cavity 55. As previously mentioned, the fan motor 80 may be operating in an opposite direction from the fan motor 80 direction during a deflating and furling process. As the fan motor 80 operates in the opposite direction, the fan blade 70 may also operate in the opposite direction.

[0082] The system may eventually reach the state depicted in Figure lb. At this point the entire envelope bundle 160 may have been drawn through both the gathering ring 90 and the mouth 30 of the envelope 10. The spooling line 120 may be attached at one end to the crown 20 of the envelope 10. The spooling line 120 may pass through the mouth 30 of the envelope 10 and the gathering ring 90. The spooling line 120 may attach at the other end to the spool 100. The rate of expansion of the envelope cavity 55 may be controlled by the speed of rotation of the spool 100 as resisted or assisted by the spool motor 110.

[0083] As the inflation and unfurling process continues, the rotating fan blade 70 may draw more air from the surrounding atmosphere 135 through the mouth 30 of the envelope 10 and into the envelope cavity 55. [0084] The system may eventually reach the state depicted in Figure la. At this point the envelope cavity 55 may reach full capacity and the envelope 10 may be fully inflated.

[0085] At any point during the inflation and unfurling process, the air in the envelope cavity 55 can be heated by operating the heater 60. Heating the air in the envelope cavity 55 may create a buoyant force on the fabric of the envelope 10 which may keep the fabric of the envelope 10 from settling to the ground 140 as the inflation process proceeds.

[0086] Similarly, at any point during the inflation and unfurling process, the rotating fan blade 70 may be drawing air from the surrounding atmosphere 135 into the envelope cavity 55. The speed of the fan motor 80 may be controlled to provide a desired inflation rate. The speed of the fan may or may not respond to sensors providing pressure measurements for the envelope cavity 55. The speed of the fan motor 80 may be controlled manually or

automatically. The fan motor 80 may also be controlled locally or remotely. The direction of the fan motor 80 may be controlled when switching between a deflation and inflation process, and vice versa.

[0087] Throughout the inflation and unfurling process the mouth 30 of the envelope 10 may remain continuously attached to the bottom end 40 at the mouth to bottom-end joint 50. Likewise, throughout the inflation and unfurling process, the tethering lines 130 may remain connected to the crown 20 of the envelope 10. No components need to be attached or deattached at any point during the inflation and unfurling process. However, depending upon the precise shape of the envelope 10 and the placement of the ground attachment points 150, it may or may not be necessary to extend or retract the tethering lines 130 as the inflation and unfurling process proceeds.

[0088] Alternative Configuration Example

[0089] The configuration depicted in Figures la thru Id can be modified in several useful ways. For example, Figure 3 shows one possible modification with an envelope 10 at approximately the same level of inflation as depicted in Figure lc. An envelope cavity 55 may be partially inflated and much of the fabric of the envelope 10 may be gathered into an envelope bundle 160. The configuration shown in Figure 3 differs from Figure lc in that the spool 100 may be structurally supported by the spool frame 180 that may be adjacent to the bottom-end 40. In addition, an envelope guide 170 may be positioned in the bottom-end 40 between the gathering ring 90 and the spool 100. In the configuration depicted in Figure 3, the envelope bundle 160 may pass through the gathering ring 90 and may make a partial turn around the envelope guide 170 before reaching the spool 100.

[0090] The envelope guide 170 may be realized as either a rotating sheave or as a fixed guide. Thus, the envelope guide 170 may be rotatable so that when a spooling line 120 and/or envelope bundle 160 passes over the envelope guide 170, the envelope guide 170 may rotate with the motion of the passing surface. In some instances, the envelope guide 170 may passively rotate (e.g., frictional forces from the passing surface may cause the envelope guide 170 to rotate). Alternatively, the envelope guide 170 may actively rotate (e.g., a motor may be provided with the envelope guide 170 that may cause the envelope guide 170 to rotate to correspond to the anticipated speed of the spooling line 120 and/or envelope bundle 160 passing over. In some instances, the envelope guide 170 may be fixed so that it does not rotate. For example, the envelope guide 170 may be a bar or similar surface that may enable the surface to pass over. In some instances, a fixed envelope guide 170 may have a relatively low frictional coefficient that may enable the passing surface to slide over easily.

[0091] The configuration shown in Figure 3 may allow inflation and deflation processes to proceed in essentially the same manner as shown in Figures la thru Id.

[0092] When the envelope 10 is fully inflated, the configuration shown in Figure 3 may permit the spool frame 180 to be readily separated from the bottom-end 40 by detaching the spooling line 120 from the spool 100.

[0093] Similarly, when the envelope 10 is fully deflated the configuration in Figure 3 may permit easy separation of the spool frame 180 from the bottom-end 40 by detaching the mouth 30 of the envelope 10 from the bottom-end 40 at the mouth to bottom end joint 50. This separation may allow the bottom-end 40 to be transported on the ground independently of the furled envelope 10 in the form of the envelope bundle 160 that is wrapped around the spool 100 that may be structurally supported by the spool frame 180. Similarly, the spool may be separated from the spool frame 180 so that the wrapped envelope bundle 160 may be removed and transported separately from the spool frame 180.

[0094] In other variations of the invention, the spool 110 may have any location relative to the envelope 10 and bottom-end 40. For example, the spool 100 may be placed in a spool frame 180. The spool frame 180 may be located in close proximity to or some distance from the bottom-end. The spool 100 may be at any height in relation to the envelope 10 and bottom- end 40. Any number of envelope guides 170 may be provided to assist with directing a spooling line 120 and/or envelope bundle 160 to or from the spool 100. For example, one, two, three, four, five, six, or more envelope guides 170 may be used at various positions.

[0095] It should be understood from the foregoing that, while particular implementations have been illustrated and described, various modifications can be made thereto and are contemplated herein. It is also not intended that the invention be limited by the specific examples provided within the specification. While the invention has been described with reference to the aforementioned specification, the descriptions and illustrations of the preferable embodiments herein are not meant to be construed in a limiting sense. Furthermore, it shall be understood that all aspects of the invention are not limited to the specific depictions, configurations or relative proportions set forth herein which depend upon a variety of conditions and variables. Various modifications in form and detail of the embodiments of the invention will be apparent to a person skilled in the art. It is therefore contemplated that the invention shall also cover any such modifications, variations and equivalents.