Patent Publication Number: US-2022212771-A1

Title: Balloon

Description:
TECHNICAL FIELD 
     This invention relates to balloons. 
     BACKGROUND ART 
     To improve a balloon&#39;s ability to fly, an envelope should be as lightweight as possible. In general, however, a light envelope has a low strength. 
     As a technique for reinforcing a strength of an envelope, for example, Patent Document 1 discloses a balloon with a structure such that a ring or disk-shaped rigid body is placed at the top of an envelope and the envelope and load tapes are attached to the rigid body. 
     According to the disclosure of Patent Document 1, the load concentrated at the zenith of the envelope is applied to the rigid body, which enables the balloon to carry heavier loads as compared to a balloon that lacks a rigid body arrangement. 
     PRIOR ART DOCUMENT 
     Patent Document 
     
         
         Patent Document 1: U.S. patent Ser. No. 10/293,913 
       
    
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     By attaching to an envelope a member that has a greater strength than the envelope, as in the balloon disclosed in Patent Document 1, the envelope can be reinforced. 
     Heat welding or gluing is commonly used as a method of attaching to an envelope a member that has a greater strength than the envelope. For example, in the balloon disclosed in Patent Document 1, the envelope is heat-welded to a component placed at the zenith of the envelope. 
     A process of attaching a component to an envelope by heat welding or gluing is labor intensive. In addition, once a component is attached to an envelope by heat welding or gluing, the component cannot be easily removed from the envelope. 
     In view of the above-mentioned circumstances, an object of the present invention is to provide a means of easily attaching to and detaching from an envelope a component that reinforces the envelope of the balloon. 
     Means for Solving the Problem 
     The present invention includes, as a first aspect, a balloon comprising: an inner member having a greater strength than an envelope, located inside the envelope, an outer member having a greater strength than the envelope, located outside the envelope, and a tightening member that tightens the inner member and the outer member with the envelope sandwiched therebetween. 
     According to the first aspect of the invention, the inner member and the outer member each has a greater strength than the envelope, so the envelope is reinforced by the inner member and the outer member. The inner member and the outer member can be easily attached to the envelope by tightening by use of the fastening member. Also, the inner member and the outer member attached to the envelope can be easily removed from the envelope by loosening the tightening member. 
     The present invention includes, as a second aspect, a balloon according to the first aspect, wherein at least a part of the inner member that receives a load from the envelope and a part of the outer member that receives a load from the envelope are made from at least one of a metal and a plastic. 
     According to the second aspect of the invention, the envelope is reinforced by the inner member and the outer member without significantly increasing an overall weight of the balloon. 
     The present invention includes, as a third aspect, a balloon according to the first aspect, wherein the inner member and the outer member have an opening and closing mechanism that moves between a closed state that hermetically seals an inside of the envelope and an open state that forms a gas flow path between the inside of the envelope and an outside of the envelope. 
     According to the third aspect of the invention, since the opening and closing mechanism is provided on the inner member and the outer member, the envelope is not damaged when the envelope is opened or closed. 
     The present invention includes, as a fourth aspect, a balloon according to the third aspect, comprising: a flow meter attached to the inner member or the outer member to measure a flow rate of a gas discharged from the inside of the envelope to the outside of the envelope when the opening and closing mechanism is in the open state. 
     According to the fourth aspect of the invention, an amount of the gas discharged from the envelope can be specified. 
     The present invention includes, as a fifth aspect, a balloon according to the first aspect, comprising an electronic device attached to the inner member or to the outer member. 
     According to the fifth aspect of the invention, it is easier to install and remove the electronic device than in a case that the electronic device is directly mounted to the envelope. 
     The present invention includes, as a sixth aspect, a balloon according to the first aspect, wherein at least one of the inner member and the outer member forms a housing space, and the balloon comprises an electronic device housed in the housing space. 
     According to the sixth aspect of the invention, it is easier to install and remove the electronic device than to mount it directly on the envelope. Further, according to the sixth aspect of the invention, the electronic device is protected from the outside by the inner member and the outer member. 
     The present invention includes, as a seventh aspect, a balloon according to the sixth aspect, wherein the housing space is watertight and sealed. 
     According to the seventh aspect of the invention, when the balloon lands on water, the electronic device is not inundated with the water. 
     The present invention includes, as an eighth aspect, a balloon according to the first aspect, wherein the inner member and the outer member are located at a zenith of the envelope. 
     According to the eighth aspect of the invention, a load concentrated at the zenith of the envelope is applied to the inner member and the outer member. As a result, the envelope according to the eighth aspect can withstand greater loads than an envelope of a conventional balloon. 
     The present invention includes, as a ninth aspect, a balloon according to the eighth aspect, comprising: one or more load tapes connected to at least one of the inner member and the outer member and partially attached to the envelope, wherein a strength each of the inner member and the outer member is greater than a strength of the one or more load tapes. 
     According to the ninth aspect of the invention, since most of a load is applied to the load tapes, a strength of which is greater than that of the envelope, a balloon with a greater carrying capacity can be attained. 
    
    
     
       BRIEF EXPLANATION OF THE DRAWINGS 
         FIG. 1  shows an exterior view of a balloon according to an exemplary embodiment of the present invention. 
         FIGS. 2A to 2E  show a rigid member according to the exemplary embodiment of the present invention. 
         FIGS. 3A to 3C  show a balloon according to a modification of the present invention. 
         FIGS. 4A to 4F  show a balloon according to a modification of the present invention. 
         FIGS. 5A and 5B  show an operation of a rigid member according to a modification of the present invention. 
         FIGS. 6A and 6B  shows an operation of a rigid member according to a modification of the present invention. 
         FIG. 7  shows a rigid member and a wireless communication device housed in the rigid member according to a modification of the present invention. 
         FIG. 8  shows a rigid member and a flow meter housed in the rigid member according to a modification of the present invention. 
         FIG. 9  shows a rigid member and a wireless communication device housed in the rigid member according to a modification of the present invention. 
         FIG. 10  shows an exterior view of a balloon according to a modification of the present invention. 
         FIG. 11  shows an exterior view of a balloon according to a modification of the present invention. 
     
    
    
     MODES FOR CARRYING OUT THE INVENTION 
     Exemplary Embodiment 
       FIG. 1  shows an exterior view of Balloon  1  according to an exemplary embodiment of the present invention. Balloon  1  is a gas balloon. Balloon  1  has Envelope  11 , Rigid Member  12  located at the zenith of Envelope  11 , Suspension Ropes  13  attached to the outer surface of Envelope  11  and hanging downwards, and Housing  14  suspended by Suspension Ropes  13 . 
     Envelope  11  is a spherical or droplet-shaped hollow bag that contains a lighter-than-air gas such as helium gas. Envelope  11 , for example, is made of plastic films. 
     Rigid Member  12  is a member that reinforces Envelope  11 . Thus, Rigid Member  12  has a greater strength than Envelope  11 . In this embodiment, Rigid Member  12  is located at the zenith of Envelope  11  and serves to receive loads concentrated at the zenith. 
     Suspension Ropes  13  are ropes that connect Envelope  11  to Housing  14  and serve to transfer buoyancy generated in Envelope  11  to Housing  14 . 
     Housing  14  is a cage or box-like component that holds cargo to be transported. Housing  14  may, for example, house members of crew. A load corresponding to a weight of Housing  14  and cargo contained in Housing  14  is applied to Envelope  11  via Suspension Ropes  13 . Although the load applied to Envelope  11  is concentrated at the zenith, Rigid Member  12  bears the load, thus preventing Envelope  1 I from becoming torn at the zenith. Accordingly, Balloon  1  has a greater carrying capacity as compared to conventional balloons that lack Rigid Member  12 . 
     Rigid Member  12  has an inner member located inside Envelope  11 , an outer member located outside Envelope  11 , and a tightening member that is tightened to clamp Envelope  11  between the inner and outer members. 
       FIGS. 2A to 2E  show a configuration of Rigid Member  12 . Rigid Member  12  consists of Inner Member  121 , Rubber Seal  122  which is a sealing member for Inner Member  121 , Outer Member  123 , Rubber Seal  124  which is a sealing member for Outer Member  123 , and sets of Bolts  125  and Nuts  126  for tightening Inner Member  121  and Outer Member  123 . The sets of Bolts  125  and Nuts  126  are an example of a tightening member. 
     Inner Member  121  and Outer Member  123  are of the same material and structure. Rubber Seal  122  and Rubber Seal  124  are of the same material and structure. Accordingly, while description is given below of the materials and structures of Inner Member  121  and Rubber Seal  122 , description of the materials and structures of Outer Member  123  and Rubber Seal  124  is omitted. 
       FIG. 2A  shows the front side of Inner Member  121 , while  FIG. 2B  shows the back side of Inner Member  121 . Inner Member  121  is disk-shaped as a whole, and is made of plastic. Inner Member  121  has Holes H 1  into each of which Bolt  125  is inserted. On the back side of Inner Member  121 , there is Groove G 1  that extends around the entire circumference outside of Holes H 1 . Groove G 1  is a groove provided for fitting Rubber Seal  122 . 
       FIG. 2C  shows Rubber Seal  122 . Rubber Seal  124  is made of an elastic material such as rubber. Rubber Seal  122  is donut-shaped in plan view and rectangular as viewed in cross section. A width of Rubber Seal  122 , i.e. a horizontal length of a cross section of Rubber Seal  122 , is approximately the same as the width of Groove G 1  of Inner Member  121 . A height of Rubber Seal  122 , i.e. a vertical length of a cross section of Rubber Seal  122 , is greater than a depth of Groove G 1 . Therefore, when Rubber Seal  122  is fitted into Groove G 1 , a part of Rubber Seal  122  protrudes outside of Groove G 1 . The outwardly protruding portion of Rubber Seal  122  is pushed into Groove G 1  upon tightening, and adheres to Envelope  11  under force to return to its original shape. As a result, gas that would otherwise leak from Holes H 2  provided in Envelope  11  to accommodate Bolts  125  is sealed by Rubber Seal  122 . 
       FIG. 2D  shows the zenith of Envelope  11 . Envelope  11  has Holes H 2  (not shown in  FIG. 2D ) in its zenith for accommodating Bolts  125  at positions corresponding to Holes H 1  of Inner Member  121 . 
     Rigid Member  12  is attached to Envelope  11 , for example, as follows. First, a user places Inner Member  121  with Rubber Seal  122  attached at a position where Holes H 1  of Inner Member  121  and Holes H 2  of Envelope  11  are connected, with the back side of Inner Member  121  facing the inner side of Envelope  11 . The user also places Outer Member  123  with Rubber Seal  124  attached at a position where Holes H 1  of Outer Member  123  and Holes H 2  of Envelope  11  are connected, with the back side of Outer Member  123  facing the outer side of Envelope  11 . In this state, the user inserts Bolts  125  coated with sealant into Holes H 1  of Outer Member  123 , Holes H 2  of Envelope  11 , and Holes H 1  of Inner Member  121 , which are connected, from the outside. Then, the user tightens Bolts  125  against Nuts  126 , such that Nuts  126  tighten against Bolts  125  from the inside. The sealant applied to Bolts  125  serves to close a slight gap between Bolts  125  and Holes H 1 . When the user tightens Bolts  125  and Nuts  126 , Inner Member  121  and Outer Member  123  sandwich Envelope  11 , and Rigid Member  12  is attached to Envelope  11 . 
     In the above explanation, it is assumed that Holes H 2  are pre-punched in Envelope  11  to accommodate Bolts  125 . However, Holes H 2  may be punched during the installation of Rigid Member  12  to Envelope  11 . In this case, with Envelope  11  placed against and sandwiched between Inner Member  121  and Outer Member  123 , the user punches Holes H 2  in portions of Envelope  11  that do not connect Holes H 1  of Outer Member  123  with Holes H 1  of Inner Member  121 . The user then inserts Bolts  125  into Holes H 1  of Outer Member  123  and Holes H 1  of Inner Member  121 , for connection. 
       FIG. 2E  shows in cross section a view of the zenith portion of Balloon  1  at the single-pointed position in  FIG. 2E  in the direction of arrow A. 
     Rigid Member  12  can be easily attached to Envelope  11  by tightening Bolts  125  and Nuts  126 . Rigid Member  12 , and can be easily removed from Envelope  11  by loosening and removing Bolts  125  and Nuts  126 . The type of fastening member is not limited to the combination of Bolts  125  and Nuts  126 . For example, threaded holes may be provided in Inner Member  121  instead of Holes H 2 , and Bolts  125  may be screwed into the threaded holes. 
     [Modifications] 
     The above-described Balloon  1  is of an exemplary embodiment of the present invention, and may be modified in various ways. Following are examples of modifications of the above-described embodiment. Two or more of the above-described embodiment and the following modifications may be combined. 
     (1) Balloon  1  is not limited to a gas balloon. For example, Balloon  1  may be a hot-air balloon. In that case, Envelope  11  accommodates a heated gas such as air that is continuously supplied from below instead of a lighter-than-air gas such as helium gas. 
     (2) The material of Envelope  11  is not limited to a plastic. For example, Envelope  11  may be made of a fabric or other material that is treated to be non-permeable by air. 
     (3) Inner Member  121  and Outer Member  123  may be made of a fiber reinforced plastic such as a carbon fiber reinforced plastic, fiberglass reinforced plastic, etc. 
     (4) Materials of Inner Member  121  and Outer Member  123  are not limited to plastic. For example, Inner Member  121  or Outer Member  123  may be made of metal, ceramic, wood, etc. However, from a standpoint of strength per unit weight and ease of processing, plastics or light metals are suitable for use as materials for Inner Member  121  and Outer Member  123 . 
     (5) Inner Member  121  and Outer Member  123  may be made from multiple materials. For example, Inner Member  121  and Outer Member  123  may be made of a combination of plastic and metal. The entirety of Inner Member  121  or Outer Member  123  need not be highly rigid. It is sufficient if at least a part of Inner Member  121  and Outer Member  123  that receives load from Envelope  11  is made of a material that has a greater strength than Envelope  11 , such as a metal or a rigid plastic. 
     (6) Shapes of Inner Member  121  and Outer Member  123  are not limited to a flat disk shape. For example, a shape of Inner Member  121  and Outer Member  123  may be a curved disk shape that fits the shape of Envelope  11 . A shape of Inner Member  121  and Outer Member  123  may be different. For example, Inner Member  121  may be a flat disk shape while Outer Member  123  may be a non-flat shape, such as a conical shape, a hemispherical shape, or a shape obtained by cutting a sphere in a plane thinner than a hemisphere. It is desirable for Outer Member  123  to have a shape that in plan view rises toward the center, such as a conical shape, since such a shape reduces aerodynamic drag at the zenith of Envelope  11  when Balloon  1  rises. 
     Shapes of Inner Member  121  and Outer Member  123  in plan view are not limited to a circle. For example, shapes of Inner Member  121  and Outer Member  123  in plan view may be a polygonal shape. Shapes of Inner Member  121  and Outer Member  123  in plan view may have an open area such as a doughnut shape. 
     (7) If Balloon  1  is equipped with load tapes attached to Envelope  11 , the load tapes should be connected to Rigid Member  12 . In this case, a strength of Rigid Member  12  should be greater than that of the load tapes. 
       FIGS. 3A to 3C  show the zenith portion of an example of Balloon  1  according to this modification.  FIG. 3A  shows the zenith portion of Envelope  11  viewed from the outside.  FIG. 3B  shows a cross section of the zenith portion of Balloon  1  at the single-pointed position in  FIG. 3A  in the direction of arrow B.  FIG. 3C  shows a cross section of the zenith portion of Balloon  1  at the single-pointed position in  FIG. 3A  in the direction of arrow C. In this modification, Load Tapes  15  are attached to the outside of Envelope  11 . Suspension Ropes  13  are connected to Load Tapes  15 , so that a load generated by Housing  14  and cargo in Housing  14  is not applied directly to Envelope  11 , but rather is applied to Load Tapes  15 . 
     In this modification, Inner Member  121  and Outer Member  123  are ring-shaped. Each of Load Tapes  15  is attached to the outer surface of Envelope  11  by, for example, adhesion, until close to the zenith of Envelope  11 . The end of each of Load Tapes  15  after reaching close to the zenith of Envelope  11  is connected to Outer Member  123  by being passed through Length-adjustment Member  127  and is then folded upward to pass between Inner Member  121  and Outer Member  123  to cover the inner side of Outer Member  123 , and is then again passed through Length-adjustment Member  127 . In this state, Inner Member  121  and Outer Member  123  are tightened by Bolts  125  and Nuts  126 , to secure Envelope  11  and Load Tape  15  there between. 
     (8) Inner Member  121  and Outer Member  123  may be configured with an opening and closing mechanism that switches between a closed state that hermetically seals the inside of Envelope  11  and an open state that forms a gas flow path between the inside of Envelope  11  and the outside of Envelope  11 . 
       FIGS. 4A to 4F  show the zenith portion of an example of Balloon  1  according to this modification.  FIG. 4A  shows the zenith portion of Envelope  11  viewed from the outside. In this modification, Envelope  11  has Hole H 3  at the zenith. Hole H 3  is normally sealed by Lid  128  of Rigid Member  12 , but when a member of crew in Housing  14  pulls Control Cable  16  connected to Lid  128 , Lid  128  is opened and gas in Envelope  11  is discharged from Envelope  11  through Hole H 3 . 
     According to this modification, Rigid Member  12  has Inner Member  121 , Rubber Seal  122 , Outer Member  123 , Rubber Seal  124 , Bolts  125  and Nuts  126 . In addition, Rigid Member  12  has Lid  128 , Rubber Seal  129  that acts as a sealing member for Lid  128 , Nuts  130 , and Springs  131 . 
     According to this modification, Inner Member  121  and Outer Member  123  differ from those according to the embodiment in that their shapes in plan view are donut shaped, namely, with Hole H 4  in the center of a disk shape.  FIG. 4B  shows the front side of Inner Member  121  according to this modification, and  FIG. 4C  shows the back side of Inner Member  121  according to this modification. The structure of Outer Member  123  is identical to that of Inner Member  121 . 
     Bolts  125  according to this modification have a longer threaded section than those of Bolts  125  according to the embodiment. 
     A structure each of Rubber Seal  122  and Rubber Seal  124  according to this modification are the same as Rubber Seal  122  and Rubber Seal  124  according to the embodiment. A structure of Rubber Seal  129  is the same as that each of Rubber Seal  122  and Rubber Seal  124 . 
       FIG. 4D  shows the front side of Lid  128 , and  FIG. 4E  shows the back side of Lid  128 .  FIG. 4F  shows a cross section of the zenith portion of Balloon  1  at the single-pointed position in  FIG. 4E  in the direction of arrow D. Lid  128  is disk-shaped as a whole. Lid  128  has a U-shaped Hook  1281  in the center of its surface. One end of Control Cable  16  is connected to Hook  1281 . 
     Lid  128  is divided into Outer Portion R 1  of a predetermined width inward from the outer edge, and Inner Portion R 2  inward from Outer Portion R 1 . Outer Portion R 1  protrudes inward from Inner Portion R 2 . Outer Portion R 1  has Groove G 2  for fitting Rubber Seal  129 . Inner Portion R 2  has Holes H 5  into which Bolts  125  are inserted. Outer Portion R 1  protrudes inward from Inner Portion R 2  to avoid collision between Lid  128  and Nuts  126  when Lid  128  is attached to Envelope  11  from inside Inner Member  121 . 
     Springs  131  are, for example, metallic strip springs. Springs  131  are mounted to cover shafts of Bolts  125  inserted into Holes H 5  of Lid  128 . Springs  131  are fastened to Bolts  125  by Nuts  130  into which Bolts  125  are screwed. Springs  131  act to press Lid  128  against Inner Member  121  and cause Rubber Seal  129  to seal Envelope  11 . 
       FIGS. 5A and 5B  show an operation of Rigid Member  12  according to this modification. As long as Control Cable  16  connected to Hook  1281  is not pulled by the member of crew in Housing  14 , Lid  128  is pressed against Inner Member  121  under elastic force of Springs  131 , as shown in  FIG. 5A , and gas contained in Envelope  11  is prevented from leaking out of Envelope  11 . This state is referred to as a closed state. When the member of crew pulls Control Cable  16 , Lid  128  separates from Inner Member  121  under the elastic force of Springs  131  and a gas flow path is created between Inner Member  121  and Lid  128 , as shown in  FIG. 5B . This state is referred to as an open state. When the member of crew stops pulling on Control Cable  16 , Rigid Member  12  returns to the closed state. 
     In the example described above, Lid  128  is opened and closed by pulling on Control Cable  16 , but Lid  128  may be opened and closed by other methods.  FIGS. 6A and 6B  show an operation of Rigid Member  12  with a configuration in which Lid  128  is opened and closed by Hydraulic Actuator  132 . A rod of Hydraulic Actuator  132  is normally retracted, as shown in  FIG. 6A . When the member of crew pulls a lever in Housing  14 , a pressure of hydraulic fluid pumped through Tube  133  pushes outward the rod of Hydraulic Actuator  132 . As a result, a gap is created between Inner Member  121  and Lid  128 , as shown in  FIG. 6B . When the member of crew releases the lever, pressure of hydraulic fluid acting on the rod of Hydraulic Actuator  132  is released, and the elastic force of Springs  131  causes the rod to retract and return to the closed state as shown in  FIG. 6A . 
     According to this modification, Inner Member  121  and Outer Member  123  serve as an exhaust mechanism, and thus there is no need to provide a separate exhaust mechanism. 
     (9) Balloon  1  may be equipped with an electronic device attached to Inner Member  121  or Outer Member  123 . Types of electronic device that can be attached to Inner Member  121  or Outer Member  123  include, but are not limited to, a radio communication device that communicates wirelessly with a device on the ground, a control device that controls operations of other devices mounted to Balloon  1 , a measuring device, a photographic device, a light emitting device, a sound emitting device, and a radio wave generator that emits radio waves to notify a current position of Balloon  1 . 
     Types of measuring device that can be attached to Inner Member  121  or Outer Member  123  include, but are not limited to, an anemometer, thermometer, hygrometer, UV meter, radiation meter, GNSS (Global Navigation Satellite System) positioning device, etc. 
     Methods of attaching the electronic device to Inner Member  121  or Outer Member  123  include, but are not limited to, tightening with bolts and nuts or screws, adhering with adhesives or double-sided tape, etc. 
     In this modification, an electronic device that is usually placed in a housing of a conventional balloon is attached to Rigid Member  12 . As a result, a load pulling Envelope  11  downward is reduced by a weight of the electronic device. 
     If the electronic device is directly attached to Envelope  11 , a strength of Envelope  11  may not be able to withstand the weight of the electronic device, or a protruding part of the electronic device may come into contact with and damage Envelope  11 . According to this modification, such problems do not occur because the electronic device is attached to Inner Member  121  or Outer Member  123 , which are made of a material having a greater strength than Envelope  11 . 
     Also, for certain types of electronic device, it is preferable to place them at the zenith of Envelope  11  rather than in Housing  14 . 
     In general, it is desirable for a measurement to be performed by a measuring device under a constant measurement environment so as to obtain reliable comparative measurement results. The environment inside the housing varies depending on its size and a number of members of crew and devices housed therein. In contrast, the environment at the zenith of the envelope does not change significantly between balloons. Therefore, according to this modification in which the measuring device is placed at the zenith of the envelope, it is easy to compare results of measurements performed using different balloons. 
     If a light emitting device, a sound emitting device, a radio wave generating device, etc. is attached to Rigid Member  12  at the zenith of Envelope  11 , when Balloon  1  returns to the ground or to water, there is less chance of the device being covered by Envelope  11 , and signals emitted by the device can be readily detected. 
     The electronic device attached to Inner Member  121  or Outer Member  123  may be mounted outside of Inner Member  121  or Outer Member  123 , and thus exposed to the outside. Alternatively, the electronic device attached to Inner Member  121  or Outer Member  123  may be accommodated in a housing space formed by Inner Member  121  and Outer Member  123 . In this case, the electronic device is protected from the outside. When Inner Member  121  and Outer Member  123  form a housing space, the housing space may be watertight and sealed. In this case, when Balloon  1  lands on water, the electronic device will not be inundated with the water. 
       FIG. 7  shows an example where Rigid Member  12  forms a housing space. In Rigid Member  12  shown in  FIG. 7 , Outer Member  123  is box-shaped, and Housing Space S is formed inside it. In  FIG. 7 , Main Body  171  of Wireless Communication Device  17  is arranged as an example of an electronic device to be housed in Housing Space S. Antenna  172  of Wireless Communication Device  17  is positioned to protrude outside Outer Member  123  to avoid shielding of radio waves by Rigid Member  12 . A gap between a hole in Outer Member  123  for accommodating Antenna  172  and Antenna  172  may be sealed by a sealing member. 
       FIG. 8  shows an example where Flow Meter  18  is placed in Housing Space S. In this example, Outer Member  123  has a hole for exhausting air, and Shut-off Valve  19  is arranged to seal the hole. In Housing Space S, there are located Tube  20 , which forms a flow path for gas discharged from inside Envelope  11  to outside Envelope  11  when Shut-off Valve  19  is opened, and Flow Meter  18 , which measures a flow rate ofgas flowing inside Tube  20 . Shut-off Valve  19  may be a solenoid valve that opens and closes in response to a radio signal transmitted from a device in Housing  14 . According to Balloon  1 , which is equipped with Flow Meter  18  as shown in  FIG. 8 , an amount of gas discharged from Envelope  1  can be specified. 
     A location where Housing Space S is formed is not limited to inside Outer Member  123 , but Housing Space S may be formed inside Inner Member  121 . 
     Housing Space S may be formed by Inner Member  121  and Outer Member  123 . For example, as shown in  FIG. 9 , Outer Member  123  may be configured as a box shape with an opening in one of its six sides that is in contact with Envelope  11 , and Inner Member  121  may serve as a lid to close the opening of Outer Member  123 . In this case, the portion of Envelope  11  corresponding to the opening of Outer Member  123  is hollowed out. According to this modification, an electronic device can be easily placed in and removed from Housing Space S. 
     Inner Member  121  may be configured as a box shape with an opening in the six sides that is in contact with Envelope  11 , and Outer Member  123  may serve as a lid to close the opening of Inner Member  121 . 
     (10) A location of Rigid Member  12  is not limited to the zenith of Envelope  11 .  FIG. 10  shows Balloon  1  with Rigid Member  12  located at the bottom of Envelope  11 . 
     For example, when Rigid Member  12  has the exhaust mechanism of modification (8), Control Cable  16 , one end of which is attached to Hook  1281 , hangs down under gravity toward Housing  14 , making it easier to handle Control Cable  16  than when Rigid Member  12  is located at the zenith. 
     Rigid Member  12  according to modification (9) has an electronic device attached thereto or housed therein. When a weight of the electronic device is heavy, if Rigid Member  12  is placed at the bottom of Envelope  11 , a center of gravity of Balloon  1  becomes lower than if the electronic device is placed at the zenith, and a posture of Balloon  1  is thus more stable. 
       FIG. 11  shows Balloon  1  with Rigid Member  12  located at a lateral part of Envelope  11 . For example, a measuring device that measures a force striking Envelope  11  from the side should be located at a lateral part of Envelope  11 . Also, a communication device that communicates with devices on the ground by electromagnetic waves may obtain high antenna gain by being equipped with a horizontally extending antenna. In such cases, the electronic device should be mounted to or housed in Rigid Member  12 , which is located at the lateral part of Envelope  11 . 
     (11) The structures and shapes of Rigid Member  12  shown in the above description of embodiment and modifications are examples and may be changed in various ways. 
     DESCRIPTION OF REFERENCE NUMERALS 
     
         
           1 : Balloon 
           11 : Envelope 
           12 : Rigid Member 
           13 : Suspension Rope 
           14 : Housing 
           15 : Load Tape 
           16 : Control Cable 
           17 : Wireless Communication Device 
           18 : Flow Meter 
           19 : Shut-off Valve 
           20 : Tube 
           121 : Inner Member 
           122 : Rubber Seal 
           123 : Outer Member 
           124 : Rubber Seal 
           125 : Bolt 
           126 : Nut 
           127 : Length-adjustment Member 
           128 : Lid 
           129 : Rubber Seal 
           130 : Nut 
           131 : Spring 
           132 : Hydraulic Actuator 
           133 : Tube 
           171 : Main Body 
           172 : Antenna 
           1281 : Hook