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Foil Balloons

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  • Joe
    With the recent success of these foil balloons, it has made me somewhat interested in them and their possibilities for long duration flights. Their ability
    Message 1 of 21 , Sep 21, 2013
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      With the recent success of these foil balloons, it has made me somewhat interested in them and their possibilities for long duration flights. Their ability to"Superpressure"

      Now I wonder, what would be the better way to go? See I have literally thousands of feet if not miles of an aluminized mylar in rolls that are in varying widths from only 2 feet wide to almost 4 feet wide.

      Now this also has the heat sensitive adhesive backing on it too.  I just cut a large square of it, and weighed it to see what it weighs, and it comes in at 0.1768 oz per sq ft.

      Now everyone what configuration think would be best?

      Many small balloons, like a cluster balloon system?

      A long cylinder
      or
      a like tetroon type?

      Thoughts?

      Joe WB9SBD
      --
      Sig
      The Original Rolling Ball Clock
      Idle Tyme
      Idle-Tyme.com
      http://www.idle-tyme.com
    • Mike Manes
      Hi Joe, Talk to Robert Rochte KC8UCH about how to fab a tetroon from flat sheet stock. He demoed that process at the GPSL in Omaha some time ago (until the
      Message 2 of 21 , Sep 21, 2013
      • 0 Attachment
        Hi Joe,

        Talk to Robert Rochte KC8UCH about how to fab a tetroon from flat
        sheet stock. He demoed that process at the GPSL in Omaha some time
        ago (until the room started rotating - whole 'nother story!). He
        used big box thin poly drop cloth stock and Scotch tape for his
        solar ZPs and coats the inside surface with carbon black to get
        solar absorptivity up - not necessary for a SP, nor is the Al
        coating.

        NOAA's small SP's with Irridium met beacons have used 'em with good
        results.

        Here's a link to Huch's 1962 patent on tetroon fab:

        http://www.google.com/patents/US3047252?dq=3047252

        Click on the Images to see details.

        Huch is better known for his "Huch Clutch" - a means to clamp off
        a portion of a plastic balloon during fill, and improved upon by
        Norm Kjome's "Kjome Clutch", which EOSS has used.

        I think the key to success in making a SP bag is in the seam strength.
        This can be tested for burst pressure easily on the deck using
        compressed air, I'd think. The huge SPs being developed by NOAA &
        Winzen use fiberglass load tapes, IIRC, but those are for their
        typical "Buick and 4 scientists" payloads.

        GL es 73 de Mike W5VSI

        On 9/21/13 9:29 AM, Joe wrote:
        > With the recent success of these foil balloons, it has made me somewhat
        > interested in them and their possibilities for long duration flights.
        > Their ability to"Superpressure"
        >
        > Now I wonder, what would be the better way to go? See I have literally
        > thousands of feet if not miles of an aluminized mylar in rolls that are
        > in varying widths from only 2 feet wide to almost 4 feet wide.
        >
        > Now this also has the heat sensitive adhesive backing on it too. I just
        > cut a large square of it, and weighed it to see what it weighs, and it
        > comes in at 0.1768 oz per sq ft.
        >
        > Now everyone what configuration think would be best?
        >
        > Many small balloons, like a cluster balloon system?
        >
        > A long cylinder
        > or
        > a like tetroon type?
        >
        > Thoughts?
        >
        > Joe WB9SBD
        > --
        > Sig
        > The Original Rolling Ball Clock
        > Idle Tyme
        > Idle-Tyme.com
        > http://www.idle-tyme.com
      • excitontx
        Joe, I was also thinking along the same lines. If you want something to float for days, the mylar balloon foils have been optimized for strength and low gas
        Message 3 of 21 , Sep 22, 2013
        • 0 Attachment

           Joe,


          I was also thinking along the same lines.  If you want something to float for days, the mylar balloon foils have been optimized for strength and low gas diffusion, and are not bothered by UV.  I have been checking out the Balloonkts.com website, where they have some decent-sized rolls of foil at inexpensive prices.  Gary Felix, the guy that runs the site, says their foil is 48 gauge (12 um), 29g/sq yard, pull strength of 4 lbs/linear inch, and only loses 4% helium per year (can that be true? - amazing).


          A sphere is always optimal in terms of volume/surface area ratio, but it is pretty hard to construct from  long rectangles/strips of material.  A cylinder can come close to the same performance if the radius of the cylinder is large.  I wonder if anybody has worked out the volume/surface area of the tetroon?


          Mike is right, there seems to be a good number of videos on assembling tetroons, I like http://www.youtube.com/watch?v=_cVp8EKtgTA The simplicity of assembly seems to make it quite popular.


          I was wondering if it is straightforward to calculate the altitude that the balloon will float?  I imagine the altitude where the gas expands to occupy the max volume of the envelope must be close to where it will cease to be buoyant and float.  My concern in building a large mylar floater is that it needs to travel well above the aircraft lanes.  Having a balloon drift for days at aircraft altitudes, being visible on radar (metallized mylar- right?) would not be a career advancing event.


          Anybody else have any advice for us mylar newbies?

          Chuck / KG5CA



          --- In GPSL@yahoogroups.com, <nss@...> wrote:

          With the recent success of these foil balloons, it has made me somewhat interested in them and their possibilities for long duration flights. Their ability to"Superpressure"

          Now I wonder, what would be the better way to go? See I have literally thousands of feet if not miles of an aluminized mylar in rolls that are in varying widths from only 2 feet wide to almost 4 feet wide.

          Now this also has the heat sensitive adhesive backing on it too.  I just cut a large square of it, and weighed it to see what it weighs, and it comes in at 0.1768 oz per sq ft.

          Now everyone what configuration think would be best?

          Many small balloons, like a cluster balloon system?

          A long cylinder
          or
          a like tetroon type?

          Thoughts?

          Joe WB9SBD
          --
          Sig
          The Original Rolling Ball Clock
          Idle Tyme
          Idle-Tyme.com
          http://www.idle-tyme.com
        • excitontx
          Mike, Thanks for point out that patent. They did an amazing job! Chuck / KG5CA --- In GPSL@yahoogroups.com, wrote: Hi Joe, Talk to Robert Rochte
          Message 4 of 21 , Sep 22, 2013
          • 0 Attachment

             Mike,


            Thanks for point out that patent.  They did an amazing job!

            Chuck / KG5CA



            --- In GPSL@yahoogroups.com, <mrmanes@...> wrote:

            Hi Joe,

            Talk to Robert Rochte KC8UCH about how to fab a tetroon from flat
            sheet stock. He demoed that process at the GPSL in Omaha some time
            ago (until the room started rotating - whole 'nother story!). He
            used big box thin poly drop cloth stock and Scotch tape for his
            solar ZPs and coats the inside surface with carbon black to get
            solar absorptivity up - not necessary for a SP, nor is the Al
            coating.

            NOAA's small SP's with Irridium met beacons have used 'em with good
            results.

            Here's a link to Huch's 1962 patent on tetroon fab:

            http://www.google.com/patents/US3047252?dq=3047252

            Click on the Images to see details.

            Huch is better known for his "Huch Clutch" - a means to clamp off
            a portion of a plastic balloon during fill, and improved upon by
            Norm Kjome's "Kjome Clutch", which EOSS has used.

            I think the key to success in making a SP bag is in the seam strength.
            This can be tested for burst pressure easily on the deck using
            compressed air, I'd think. The huge SPs being developed by NOAA &
            Winzen use fiberglass load tapes, IIRC, but those are for their
            typical "Buick and 4 scientists" payloads.

            GL es 73 de Mike W5VSI

            On 9/21/13 9:29 AM, Joe wrote:
            > With the recent success of these foil balloons, it has made me somewhat
            > interested in them and their possibilities for long duration flights.
            > Their ability to"Superpressure"
            >
            > Now I wonder, what would be the better way to go? See I have literally
            > thousands of feet if not miles of an aluminized mylar in rolls that are
            > in varying widths from only 2 feet wide to almost 4 feet wide.
            >
            > Now this also has the heat sensitive adhesive backing on it too. I just
            > cut a large square of it, and weighed it to see what it weighs, and it
            > comes in at 0.1768 oz per sq ft.
            >
            > Now everyone what configuration think would be best?
            >
            > Many small balloons, like a cluster balloon system?
            >
            > A long cylinder
            > or
            > a like tetroon type?
            >
            > Thoughts?
            >
            > Joe WB9SBD
            > --
            > Sig
            > The Original Rolling Ball Clock
            > Idle Tyme
            > Idle-Tyme.com
            > http://www.idle-tyme.com
          • BASE
            Chuck, Here are the basic equations for a regular tetrahedron with edges of length a (from http://www.vitutor.com/geometry/solid/tetrahedron.html) Surface
            Message 5 of 21 , Sep 23, 2013
            • 0 Attachment
              Chuck,

              Here are the basic equations for a regular tetrahedron with edges of length a (from http://www.vitutor.com/geometry/solid/tetrahedron.html)

              Surface Area of a Regular Tetrahedron

              Area of a Regular Tetrahedron Formula

              Volume of a Regular Tetrahedron

              Volume of a Regular Tetrahedron Formula
              The ratio of Volume/Surface Area is about 0.068a for the tetrahedron.  This ratio is not as favorable as other regular shapes:

              For the sphere, Volume/Surface Area is 0.33r (where r is the radius)
              For an ideal cylinder with radius equal to height (the optimal condition), Volume to Surface Area is 0.25r.
              For a cube, Volume/Surface Area is 0.17a (where a is the edge length).

              However, the simplicity of construction of the tetroon, with fewer straight seams, makes it a very attractive shape.

              You are correct that the float altitude can be calculated for the superpressure balloon.  You need to know the mass of the payload, balloon fabric, and other attachments (parachute, cut down device??).  You also need to know the density and initial volume of the lifting gas.  The float altitude will be where the buoyant force of the lifting gas equals the weight of everything that is being floated.

              I agree that floating above 60 kft is desirable for a long duration flight.

              Howard, KC9QBN
              www.tinyurl/basedepauw



              From: "cgoldsmith@..." <cgoldsmith@...>
              To: GPSL@yahoogroups.com
              Sent: Sunday, September 22, 2013 10:14 PM
              Subject: [GPSL] RE: Foil Balloons

               
               Joe,

              I was also thinking along the same lines.  If you want something to float for days, the mylar balloon foils have been optimized for strength and low gas diffusion, and are not bothered by UV.  I have been checking out the Balloonkts.com website, where they have some decent-sized rolls of foil at inexpensive prices.  Gary Felix, the guy that runs the site, says their foil is 48 gauge (12 um), 29g/sq yard, pull strength of 4 lbs/linear inch, and only loses 4% helium per year (can that be true? - amazing).

              A sphere is always optimal in terms of volume/surface area ratio, but it is pretty hard to construct from  long rectangles/strips of material.  A cylinder can come close to the same performance if the radius of the cylinder is large.  I wonder if anybody has worked out the volume/surface area of the tetroon?

              Mike is right, there seems to be a good number of videos on assembling tetroons, I like http://www.youtube.com/watch?v=_cVp8EKtgTA The simplicity of assembly seems to make it quite popular.

              I was wondering if it is straightforward to calculate the altitude that the balloon will float?  I imagine the altitude where the gas expands to occupy the max volume of the envelope must be close to where it will cease to be buoyant and float.  My concern in building a large mylar floater is that it needs to travel well above the aircraft lanes.  Having a balloon drift for days at aircraft altitudes, being visible on radar (metallized mylar- right?) would not be a career advancing event.

              Anybody else have any advice for us mylar newbies?
              Chuck / KG5CA


              --- In GPSL@yahoogroups.com, <nss@...> wrote:

              With the recent success of these foil balloons, it has made me somewhat interested in them and their possibilities for long duration flights. Their ability to"Superpressure"

              Now I wonder, what would be the better way to go? See I have literally thousands of feet if not miles of an aluminized mylar in rolls that are in varying widths from only 2 feet wide to almost 4 feet wide.

              Now this also has the heat sensitive adhesive backing on it too.  I just cut a large square of it, and weighed it to see what it weighs, and it comes in at 0.1768 oz per sq ft.

              Now everyone what configuration think would be best?

              Many small balloons, like a cluster balloon system?

              A long cylinder
              or
              a like tetroon type?

              Thoughts?

              Joe WB9SBD
              --
              Sig
              The Original Rolling Ball Clock
              Idle Tyme
              Idle-Tyme.com
              http://www.idle-tyme.com


            • Robert Rochte
              I ve done a lot of work on superpressure balloons in particular and will try to write more on the subject later today or tonight. At the moment I ll just say
              Message 6 of 21 , Sep 23, 2013
              • 0 Attachment
                I've done a lot of work on superpressure balloons in particular and will try to write more on the subject later today or tonight. At the moment I'll just say that I don't recommend using a tetroon for a first-try at a superpressure flight. The faces of a tetroon have a huge effective radius compared to a sphere or cylinder of comparable volume. In the superpressure role, they were really only used for low-altitude (tropospheric) flights using rather thick (2-4 mil) bilaminated film. And they were only used in this role at all because of the simplicity of fabricating a large number of tetroons at low cost for use as Lagrangian trackers. My tetroons have all been solar Montgolfieres or zero-pressure helium. 

                That said, if you're talking about an extremely lightweight payload (as we recently saw in Europe) then the allowable margin of error is a lot greater and you might be able to use a tetroon with little difficulty. In my personal experience, the greatest problem you will face will be finding a way to make a gas-proof, pressure-worthy envelope out of film with adhesive on a single side. You'll see what I mean as your experiments move along. Pinholes will be another problem, but if you're only talking about a week-long flight they shouldn't be much of an issue. My alternative to bilamination was a coating of polyvinyl alcohol, although this has to be on the inside of the envelope due to the hygroscopic nature of PVA.

                And finally (for now anyway), the free lift that you have at ground - calculated relative to the total system mass (including gas in the envelope) - will be directly converted into superpressure at float (assuming a perfectly non-extensible balloon). So if you want 5% superpressure at float, you would fill your balloon so that you have a free lift of 5% at launch. 

                More later... Students on the way!  :)

                Regards,
                Robert
                KC8UCH



                --
                Robert Rochte, Director of Technology
                The Grosse Pointe Academy
                +1 313-378-0525 Mobile
                Soli Deo Gloria


                On Sat, Sep 21, 2013 at 9:10 PM, Mike Manes <mrmanes@...> wrote:
                Hi Joe,

                Talk to Robert Rochte KC8UCH about how to fab a tetroon from flat
                sheet stock. He demoed that process at the GPSL in Omaha some time
                ago (until the room started rotating - whole 'nother story!). He
                used big box thin poly drop cloth stock and Scotch tape for his
                solar ZPs and coats the inside surface with carbon black to get
                solar absorptivity up - not necessary for a SP, nor is the Al
                coating.

                NOAA's small SP's with Irridium met beacons have used 'em with good
                results.

                Here's a link to Huch's 1962 patent on tetroon fab:

                http://www.google.com/patents/US3047252?dq=3047252

                Click on the Images to see details.

                Huch is better known for his "Huch Clutch" - a means to clamp off
                a portion of a plastic balloon during fill, and improved upon by
                Norm Kjome's "Kjome Clutch", which EOSS has used.

                I think the key to success in making a SP bag is in the seam strength.
                This can be tested for burst pressure easily on the deck using
                compressed air, I'd think.  The huge SPs being developed by NOAA &
                Winzen use fiberglass load tapes, IIRC, but those are for their
                typical "Buick and 4 scientists" payloads.

                GL es 73 de Mike W5VSI

                On 9/21/13 9:29 AM, Joe wrote:
                > With the recent success of these foil balloons, it has made me somewhat
                > interested in them and their possibilities for long duration flights.
                > Their ability to"Superpressure"
                >
                > Now I wonder, what would be the better way to go? See I have literally
                > thousands of feet if not miles of an aluminized mylar in rolls that are
                > in varying widths from only 2 feet wide to almost 4 feet wide.
                >
                > Now this also has the heat sensitive adhesive backing on it too.  I just
                > cut a large square of it, and weighed it to see what it weighs, and it
                > comes in at 0.1768 oz per sq ft.
                >
                > Now everyone what configuration think would be best?
                >
                > Many small balloons, like a cluster balloon system?
                >
                > A long cylinder
                > or
                > a like tetroon type?
                >
                > Thoughts?
                >
                > Joe WB9SBD
                > --
                > Sig
                > The Original Rolling Ball Clock
                > Idle Tyme
                > Idle-Tyme.com
                > http://www.idle-tyme.com


                ------------------------------------

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              • Joe
                Thanks Robert. Now a tetroon may not be the best, I assume the better would be of course a sphere, but good luck making that. I m now thinking cylinder. I can
                Message 7 of 21 , Sep 23, 2013
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                  Thanks Robert.

                  Now a tetroon may not be the best,

                  I assume the better would be of course a sphere, but good luck making that. I'm now thinking cylinder.

                  I can of course make a very easy 1 seam one.  A long tube more or less, that would be simple.

                  But I wonder what way would be best? A single LONG one. or multiples s in cluster one?

                  Joe
                  Sig
                  The Original Rolling Ball Clock
                  Idle Tyme
                  Idle-Tyme.com
                  http://www.idle-tyme.com
                  On 9/23/2013 8:24 AM, Robert Rochte wrote:
                  I've done a lot of work on superpressure balloons in particular and will try to write more on the subject later today or tonight. At the moment I'll just say that I don't recommend using a tetroon for a first-try at a superpressure flight. The faces of a tetroon have a huge effective radius compared to a sphere or cylinder of comparable volume. In the superpressure role, they were really only used for low-altitude (tropospheric) flights using rather thick (2-4 mil) bilaminated film. And they were only used in this role at all because of the simplicity of fabricating a large number of tetroons at low cost for use as Lagrangian trackers. My tetroons have all been solar Montgolfieres or zero-pressure helium. 

                  That said, if you're talking about an extremely lightweight payload (as we recently saw in Europe) then the allowable margin of error is a lot greater and you might be able to use a tetroon with little difficulty. In my personal experience, the greatest problem you will face will be finding a way to make a gas-proof, pressure-worthy envelope out of film with adhesive on a single side. You'll see what I mean as your experiments move along. Pinholes will be another problem, but if you're only talking about a week-long flight they shouldn't be much of an issue. My alternative to bilamination was a coating of polyvinyl alcohol, although this has to be on the inside of the envelope due to the hygroscopic nature of PVA.

                  And finally (for now anyway), the free lift that you have at ground - calculated relative to the total system mass (including gas in the envelope) - will be directly converted into superpressure at float (assuming a perfectly non-extensible balloon). So if you want 5% superpressure at float, you would fill your balloon so that you have a free lift of 5% at launch. 

                  More later... Students on the way!  :)

                  Regards,
                  Robert
                  KC8UCH



                  --
                  Robert Rochte, Director of Technology
                  The Grosse Pointe Academy
                  +1 313-378-0525 Mobile
                  Soli Deo Gloria


                  On Sat, Sep 21, 2013 at 9:10 PM, Mike Manes <mrmanes@...> wrote:
                  Hi Joe,

                  Talk to Robert Rochte KC8UCH about how to fab a tetroon from flat
                  sheet stock. He demoed that process at the GPSL in Omaha some time
                  ago (until the room started rotating - whole 'nother story!). He
                  used big box thin poly drop cloth stock and Scotch tape for his
                  solar ZPs and coats the inside surface with carbon black to get
                  solar absorptivity up - not necessary for a SP, nor is the Al
                  coating.

                  NOAA's small SP's with Irridium met beacons have used 'em with good
                  results.

                  Here's a link to Huch's 1962 patent on tetroon fab:

                  http://www.google.com/patents/US3047252?dq=3047252

                  Click on the Images to see details.

                  Huch is better known for his "Huch Clutch" - a means to clamp off
                  a portion of a plastic balloon during fill, and improved upon by
                  Norm Kjome's "Kjome Clutch", which EOSS has used.

                  I think the key to success in making a SP bag is in the seam strength.
                  This can be tested for burst pressure easily on the deck using
                  compressed air, I'd think.  The huge SPs being developed by NOAA &
                  Winzen use fiberglass load tapes, IIRC, but those are for their
                  typical "Buick and 4 scientists" payloads.

                  GL es 73 de Mike W5VSI

                  On 9/21/13 9:29 AM, Joe wrote:
                  > With the recent success of these foil balloons, it has made me somewhat
                  > interested in them and their possibilities for long duration flights.
                  > Their ability to"Superpressure"
                  >
                  > Now I wonder, what would be the better way to go? See I have literally
                  > thousands of feet if not miles of an aluminized mylar in rolls that are
                  > in varying widths from only 2 feet wide to almost 4 feet wide.
                  >
                  > Now this also has the heat sensitive adhesive backing on it too.  I just
                  > cut a large square of it, and weighed it to see what it weighs, and it
                  > comes in at 0.1768 oz per sq ft.
                  >
                  > Now everyone what configuration think would be best?
                  >
                  > Many small balloons, like a cluster balloon system?
                  >
                  > A long cylinder
                  > or
                  > a like tetroon type?
                  >
                  > Thoughts?
                  >
                  > Joe WB9SBD
                  > --
                  > Sig
                  > The Original Rolling Ball Clock
                  > Idle Tyme
                  > Idle-Tyme.com
                  > http://www.idle-tyme.com


                  ------------------------------------

                  Yahoo! Groups Links

                  <*> To visit your group on the web, go to:
                      http://groups.yahoo.com/group/GPSL/

                  <*> Your email settings:
                      Individual Email | Traditional

                  <*> To change settings online go to:
                      http://groups.yahoo.com/group/GPSL/join
                      (Yahoo! ID required)

                  <*> To change settings via email:
                      GPSL-digest@yahoogroups.com
                      GPSL-fullfeatured@yahoogroups.com

                  <*> To unsubscribe from this group, send an email to:
                      GPSL-unsubscribe@yahoogroups.com

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                • Joe
                  ok what happens with a cylinder vs length? If a 4 foot circumference cylinder was made, (4 foot is the width of the material so only 1 seam) what changes if
                  Message 8 of 21 , Sep 23, 2013
                  • 0 Attachment
                    ok what happens with a cylinder vs length?

                    If a 4 foot circumference cylinder was made, (4 foot is the width of the material so only 1 seam)

                    what changes if the cylinder is 10 feet long 20 feet long 100 feet long?

                    Joe WB9SBD
                    Sig
                    The Original Rolling Ball Clock
                    Idle Tyme
                    Idle-Tyme.com
                    http://www.idle-tyme.com
                    On 9/23/2013 7:54 AM, BASE wrote:
                    Chuck,

                    Here are the basic equations for a regular tetrahedron with edges of length a (from http://www.vitutor.com/geometry/solid/tetrahedron.html)

                    Surface Area of a Regular Tetrahedron

                    Area of a Regular Tetrahedron Formula

                    Volume of a Regular Tetrahedron

                    Volume of a Regular Tetrahedron Formula
                    The ratio of Volume/Surface Area is about 0.068a for the tetrahedron.  This ratio is not as favorable as other regular shapes:

                    For the sphere, Volume/Surface Area is 0.33r (where r is the radius)
                    For an ideal cylinder with radius equal to height (the optimal condition), Volume to Surface Area is 0.25r.
                    For a cube, Volume/Surface Area is 0.17a (where a is the edge length).

                    However, the simplicity of construction of the tetroon, with fewer straight seams, makes it a very attractive shape.

                    You are correct that the float altitude can be calculated for the superpressure balloon.  You need to know the mass of the payload, balloon fabric, and other attachments (parachute, cut down device??).  You also need to know the density and initial volume of the lifting gas.  The float altitude will be where the buoyant force of the lifting gas equals the weight of everything that is being floated.

                    I agree that floating above 60 kft is desirable for a long duration flight.

                    Howard, KC9QBN



                    From: "cgoldsmith@..." <cgoldsmith@...>
                    To: GPSL@yahoogroups.com
                    Sent: Sunday, September 22, 2013 10:14 PM
                    Subject: [GPSL] RE: Foil Balloons

                     
                     Joe,

                    I was also thinking along the same lines.  If you want something to float for days, the mylar balloon foils have been optimized for strength and low gas diffusion, and are not bothered by UV.  I have been checking out the Balloonkts.com website, where they have some decent-sized rolls of foil at inexpensive prices.  Gary Felix, the guy that runs the site, says their foil is 48 gauge (12 um), 29g/sq yard, pull strength of 4 lbs/linear inch, and only loses 4% helium per year (can that be true? - amazing).

                    A sphere is always optimal in terms of volume/surface area ratio, but it is pretty hard to construct from  long rectangles/strips of material.  A cylinder can come close to the same performance if the radius of the cylinder is large.  I wonder if anybody has worked out the volume/surface area of the tetroon?

                    Mike is right, there seems to be a good number of videos on assembling tetroons, I like http://www.youtube.com/watch?v=_cVp8EKtgTA The simplicity of assembly seems to make it quite popular.

                    I was wondering if it is straightforward to calculate the altitude that the balloon will float?  I imagine the altitude where the gas expands to occupy the max volume of the envelope must be close to where it will cease to be buoyant and float.  My concern in building a large mylar floater is that it needs to travel well above the aircraft lanes.  Having a balloon drift for days at aircraft altitudes, being visible on radar (metallized mylar- right?) would not be a career advancing event.

                    Anybody else have any advice for us mylar newbies?
                    Chuck / KG5CA


                    --- In GPSL@yahoogroups.com, <nss@...> wrote:

                    With the recent success of these foil balloons, it has made me somewhat interested in them and their possibilities for long duration flights. Their ability to"Superpressure"

                    Now I wonder, what would be the better way to go? See I have literally thousands of feet if not miles of an aluminized mylar in rolls that are in varying widths from only 2 feet wide to almost 4 feet wide.

                    Now this also has the heat sensitive adhesive backing on it too.  I just cut a large square of it, and weighed it to see what it weighs, and it comes in at 0.1768 oz per sq ft.

                    Now everyone what configuration think would be best?

                    Many small balloons, like a cluster balloon system?

                    A long cylinder
                    or
                    a like tetroon type?

                    Thoughts?

                    Joe WB9SBD
                    --
                    Sig
                    The Original Rolling Ball Clock
                    Idle Tyme
                    Idle-Tyme.com
                    http://www.idle-tyme.com



                  • Robert Rochte
                    Hi Joe. I have a spreadsheet all set up for cylindrical superpressure balloons and will send to you when I find it (it s in my Google Drive somewhere). It will
                    Message 9 of 21 , Sep 23, 2013
                    • 0 Attachment
                      Hi Joe.

                      I have a spreadsheet all set up for cylindrical superpressure balloons and will send to you when I find it (it's in my Google Drive somewhere). It will let you plug in your numbers for areal density, film thickness, float altitude, etc, and will calculate the rest of the design. It's not pretty, because I only made it for my own use - but I think you'll find it helpful.

                      With regard to a cluster, just consider that the failure of any one envelope will bring your cluster to the ground. The advantages of the original Piccard Pleiades (mostly eliminating the Upson ring problem and thus the need for a cap) are lost on a superpressure cluster in most cases. I've tried working out the numbers using a cluster of small spheres, but for anything other than a flea-sized payload there just isn't any benefit. In fact, most of the designs that I came up with wouldn't get off the ground due to the mass penalty of extra fittings, etc.

                      -R

                      --
                      Robert Rochte, Director of Technology
                      The Grosse Pointe Academy
                      +1 313-378-0525 Mobile
                      Soli Deo Gloria


                      On Mon, Sep 23, 2013 at 9:46 AM, Joe <nss@...> wrote:
                      Thanks Robert.

                      Now a tetroon may not be the best,

                      I assume the better would be of course a sphere, but good luck making that. I'm now thinking cylinder.

                      I can of course make a very easy 1 seam one.  A long tube more or less, that would be simple.

                      But I wonder what way would be best? A single LONG one. or multiples s in cluster one?

                      Joe

                      The Original Rolling Ball Clock
                      Idle Tyme
                      Idle-Tyme.com
                      http://www.idle-tyme.com
                      On 9/23/2013 8:24 AM, Robert Rochte wrote:
                      I've done a lot of work on superpressure balloons in particular and will try to write more on the subject later today or tonight. At the moment I'll just say that I don't recommend using a tetroon for a first-try at a superpressure flight. The faces of a tetroon have a huge effective radius compared to a sphere or cylinder of comparable volume. In the superpressure role, they were really only used for low-altitude (tropospheric) flights using rather thick (2-4 mil) bilaminated film. And they were only used in this role at all because of the simplicity of fabricating a large number of tetroons at low cost for use as Lagrangian trackers. My tetroons have all been solar Montgolfieres or zero-pressure helium. 

                      That said, if you're talking about an extremely lightweight payload (as we recently saw in Europe) then the allowable margin of error is a lot greater and you might be able to use a tetroon with little difficulty. In my personal experience, the greatest problem you will face will be finding a way to make a gas-proof, pressure-worthy envelope out of film with adhesive on a single side. You'll see what I mean as your experiments move along. Pinholes will be another problem, but if you're only talking about a week-long flight they shouldn't be much of an issue. My alternative to bilamination was a coating of polyvinyl alcohol, although this has to be on the inside of the envelope due to the hygroscopic nature of PVA.

                      And finally (for now anyway), the free lift that you have at ground - calculated relative to the total system mass (including gas in the envelope) - will be directly converted into superpressure at float (assuming a perfectly non-extensible balloon). So if you want 5% superpressure at float, you would fill your balloon so that you have a free lift of 5% at launch. 

                      More later... Students on the way!  :)

                      Regards,
                      Robert
                      KC8UCH



                      --
                      Robert Rochte, Director of Technology
                      The Grosse Pointe Academy
                      +1 313-378-0525 Mobile
                      Soli Deo Gloria


                      On Sat, Sep 21, 2013 at 9:10 PM, Mike Manes <mrmanes@...> wrote:
                      Hi Joe,

                      Talk to Robert Rochte KC8UCH about how to fab a tetroon from flat
                      sheet stock. He demoed that process at the GPSL in Omaha some time
                      ago (until the room started rotating - whole 'nother story!). He
                      used big box thin poly drop cloth stock and Scotch tape for his
                      solar ZPs and coats the inside surface with carbon black to get
                      solar absorptivity up - not necessary for a SP, nor is the Al
                      coating.

                      NOAA's small SP's with Irridium met beacons have used 'em with good
                      results.

                      Here's a link to Huch's 1962 patent on tetroon fab:

                      http://www.google.com/patents/US3047252?dq=3047252

                      Click on the Images to see details.

                      Huch is better known for his "Huch Clutch" - a means to clamp off
                      a portion of a plastic balloon during fill, and improved upon by
                      Norm Kjome's "Kjome Clutch", which EOSS has used.

                      I think the key to success in making a SP bag is in the seam strength.
                      This can be tested for burst pressure easily on the deck using
                      compressed air, I'd think.  The huge SPs being developed by NOAA &
                      Winzen use fiberglass load tapes, IIRC, but those are for their
                      typical "Buick and 4 scientists" payloads.

                      GL es 73 de Mike W5VSI

                      On 9/21/13 9:29 AM, Joe wrote:
                      > With the recent success of these foil balloons, it has made me somewhat
                      > interested in them and their possibilities for long duration flights.
                      > Their ability to"Superpressure"
                      >
                      > Now I wonder, what would be the better way to go? See I have literally
                      > thousands of feet if not miles of an aluminized mylar in rolls that are
                      > in varying widths from only 2 feet wide to almost 4 feet wide.
                      >
                      > Now this also has the heat sensitive adhesive backing on it too.  I just
                      > cut a large square of it, and weighed it to see what it weighs, and it
                      > comes in at 0.1768 oz per sq ft.
                      >
                      > Now everyone what configuration think would be best?
                      >
                      > Many small balloons, like a cluster balloon system?
                      >
                      > A long cylinder
                      > or
                      > a like tetroon type?
                      >
                      > Thoughts?
                      >
                      > Joe WB9SBD
                      > --
                      > Sig
                      > The Original Rolling Ball Clock
                      > Idle Tyme
                      > Idle-Tyme.com
                      > http://www.idle-tyme.com


                      ------------------------------------

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                    • Joe
                      Cool looking forward to it. Joe Sig The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com
                      Message 10 of 21 , Sep 23, 2013
                      • 0 Attachment
                        Cool looking forward to it.

                        Joe
                        Sig
                        The Original Rolling Ball Clock
                        Idle Tyme
                        Idle-Tyme.com
                        http://www.idle-tyme.com
                        On 9/23/2013 9:16 AM, Robert Rochte wrote:
                        Hi Joe.

                        I have a spreadsheet all set up for cylindrical superpressure balloons and will send to you when I find it (it's in my Google Drive somewhere). It will let you plug in your numbers for areal density, film thickness, float altitude, etc, and will calculate the rest of the design. It's not pretty, because I only made it for my own use - but I think you'll find it helpful.

                        With regard to a cluster, just consider that the failure of any one envelope will bring your cluster to the ground. The advantages of the original Piccard Pleiades (mostly eliminating the Upson ring problem and thus the need for a cap) are lost on a superpressure cluster in most cases. I've tried working out the numbers using a cluster of small spheres, but for anything other than a flea-sized payload there just isn't any benefit. In fact, most of the designs that I came up with wouldn't get off the ground due to the mass penalty of extra fittings, etc.

                        -R

                        --
                        Robert Rochte, Director of Technology
                        The Grosse Pointe Academy
                        +1 313-378-0525 Mobile
                        Soli Deo Gloria


                        On Mon, Sep 23, 2013 at 9:46 AM, Joe <nss@...> wrote:
                        Thanks Robert.

                        Now a tetroon may not be the best,

                        I assume the better would be of course a sphere, but good luck making that. I'm now thinking cylinder.

                        I can of course make a very easy 1 seam one.  A long tube more or less, that would be simple.

                        But I wonder what way would be best? A single LONG one. or multiples s in cluster one?

                        Joe

                        The Original Rolling Ball Clock
                        Idle Tyme
                        Idle-Tyme.com
                        http://www.idle-tyme.com
                        On 9/23/2013 8:24 AM, Robert Rochte wrote:
                        I've done a lot of work on superpressure balloons in particular and will try to write more on the subject later today or tonight. At the moment I'll just say that I don't recommend using a tetroon for a first-try at a superpressure flight. The faces of a tetroon have a huge effective radius compared to a sphere or cylinder of comparable volume. In the superpressure role, they were really only used for low-altitude (tropospheric) flights using rather thick (2-4 mil) bilaminated film. And they were only used in this role at all because of the simplicity of fabricating a large number of tetroons at low cost for use as Lagrangian trackers. My tetroons have all been solar Montgolfieres or zero-pressure helium. 

                        That said, if you're talking about an extremely lightweight payload (as we recently saw in Europe) then the allowable margin of error is a lot greater and you might be able to use a tetroon with little difficulty. In my personal experience, the greatest problem you will face will be finding a way to make a gas-proof, pressure-worthy envelope out of film with adhesive on a single side. You'll see what I mean as your experiments move along. Pinholes will be another problem, but if you're only talking about a week-long flight they shouldn't be much of an issue. My alternative to bilamination was a coating of polyvinyl alcohol, although this has to be on the inside of the envelope due to the hygroscopic nature of PVA.

                        And finally (for now anyway), the free lift that you have at ground - calculated relative to the total system mass (including gas in the envelope) - will be directly converted into superpressure at float (assuming a perfectly non-extensible balloon). So if you want 5% superpressure at float, you would fill your balloon so that you have a free lift of 5% at launch. 

                        More later... Students on the way!  :)

                        Regards,
                        Robert
                        KC8UCH



                        --
                        Robert Rochte, Director of Technology
                        The Grosse Pointe Academy
                        +1 313-378-0525 Mobile
                        Soli Deo Gloria


                        On Sat, Sep 21, 2013 at 9:10 PM, Mike Manes <mrmanes@...> wrote:
                        Hi Joe,

                        Talk to Robert Rochte KC8UCH about how to fab a tetroon from flat
                        sheet stock. He demoed that process at the GPSL in Omaha some time
                        ago (until the room started rotating - whole 'nother story!). He
                        used big box thin poly drop cloth stock and Scotch tape for his
                        solar ZPs and coats the inside surface with carbon black to get
                        solar absorptivity up - not necessary for a SP, nor is the Al
                        coating.

                        NOAA's small SP's with Irridium met beacons have used 'em with good
                        results.

                        Here's a link to Huch's 1962 patent on tetroon fab:

                        http://www.google.com/patents/US3047252?dq=3047252

                        Click on the Images to see details.

                        Huch is better known for his "Huch Clutch" - a means to clamp off
                        a portion of a plastic balloon during fill, and improved upon by
                        Norm Kjome's "Kjome Clutch", which EOSS has used.

                        I think the key to success in making a SP bag is in the seam strength.
                        This can be tested for burst pressure easily on the deck using
                        compressed air, I'd think.  The huge SPs being developed by NOAA &
                        Winzen use fiberglass load tapes, IIRC, but those are for their
                        typical "Buick and 4 scientists" payloads.

                        GL es 73 de Mike W5VSI

                        On 9/21/13 9:29 AM, Joe wrote:
                        > With the recent success of these foil balloons, it has made me somewhat
                        > interested in them and their possibilities for long duration flights.
                        > Their ability to"Superpressure"
                        >
                        > Now I wonder, what would be the better way to go? See I have literally
                        > thousands of feet if not miles of an aluminized mylar in rolls that are
                        > in varying widths from only 2 feet wide to almost 4 feet wide.
                        >
                        > Now this also has the heat sensitive adhesive backing on it too.  I just
                        > cut a large square of it, and weighed it to see what it weighs, and it
                        > comes in at 0.1768 oz per sq ft.
                        >
                        > Now everyone what configuration think would be best?
                        >
                        > Many small balloons, like a cluster balloon system?
                        >
                        > A long cylinder
                        > or
                        > a like tetroon type?
                        >
                        > Thoughts?
                        >
                        > Joe WB9SBD
                        > --
                        > Sig
                        > The Original Rolling Ball Clock
                        > Idle Tyme
                        > Idle-Tyme.com
                        > http://www.idle-tyme.com


                        ------------------------------------

                        Yahoo! Groups Links

                        <*> To visit your group on the web, go to:
                            http://groups.yahoo.com/group/GPSL/

                        <*> Your email settings:
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                        <*> To change settings online go to:
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                        <*> To change settings via email:
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                      • BASE
                        Joe, The simple answer is that the performance, as compared to a spherical shape enclosing the same volume gets worse. Here are some quick numbers: The
                        Message 11 of 21 , Sep 23, 2013
                        • 0 Attachment
                          Joe,

                          The simple answer is that the performance, as compared to a spherical shape enclosing the same volume gets worse.

                          Here are some quick numbers:

                          The circumference of the cylinder is 4 feet.  This makes the radius of the cylinder 0. 64 feet.  

                          Cylinder height (ft)     Cylinder Volume(cu. ft)  Cylinder Surface Area(sq.ft)  Equal Volume Sphere S.A.(sq.ft)
                                     4                                   5.1                                      18.6                                           14.3
                                     6                                   7.6                                      26.6                                           18.7
                                   10                                 12.7                                      42.6                                           26.2
                                   20                                 25.5                                      82.6                                           41.4
                                 100                               127.3                                    402.6                                        119.6

                          Short height cylinders are not much worse than the sphere, but as the height increases things you have a lot more surface for equal volumes.

                          Howard



                          From: Joe <nss@...>
                          To: BASE <hlbrooks@...>
                          Cc: BASE <basedepauw@...>; "cgoldsmith@..." <cgoldsmith@...>; "GPSL@yahoogroups.com" <GPSL@yahoogroups.com>
                          Sent: Monday, September 23, 2013 9:49 AM
                          Subject: Re: [GPSL] RE: Foil Balloons

                          ok what happens with a cylinder vs length?

                          If a 4 foot circumference cylinder was made, (4 foot is the width of the material so only 1 seam)

                          what changes if the cylinder is 10 feet long 20 feet long 100 feet long?

                          Joe WB9SBD
                          Sig
                          The Original Rolling Ball Clock
                          Idle Tyme
                          Idle-Tyme.com
                          http://www.idle-tyme.com
                          On 9/23/2013 7:54 AM, BASE wrote:


                          Chuck,

                          Here are the basic equations for a regular tetrahedron with edges of length a (from http://www.vitutor.com/geometry/solid/tetrahedron.html)

                          Surface Area of a Regular Tetrahedron

                          Area of a Regular Tetrahedron Formula

                          Volume of a Regular Tetrahedron

                          Volume of a Regular Tetrahedron Formula
                          The ratio of Volume/Surface Area is about 0.068a for the tetrahedron.  This ratio is not as favorable as other regular shapes:

                          For the sphere, Volume/Surface Area is 0.33r (where r is the radius)
                          For an ideal cylinder with radius equal to height (the optimal condition), Volume to Surface Area is 0.25r.
                          For a cube, Volume/Surface Area is 0.17a (where a is the edge length).

                          However, the simplicity of construction of the tetroon, with fewer straight seams, makes it a very attractive shape.

                          You are correct that the float altitude can be calculated for the superpressure balloon.  You need to know the mass of the payload, balloon fabric, and other attachments (parachute, cut down device??).  You also need to know the density and initial volume of the lifting gas.  The float altitude will be where the buoyant force of the lifting gas equals the weight of everything that is being floated.

                          I agree that floating above 60 kft is desirable for a long duration flight.

                          Howard, KC9QBN



                          From: "cgoldsmith@..." <cgoldsmith@...>
                          To: GPSL@yahoogroups.com
                          Sent: Sunday, September 22, 2013 10:14 PM
                          Subject: [GPSL] RE: Foil Balloons

                           
                           Joe,

                          I was also thinking along the same lines.  If you want something to float for days, the mylar balloon foils have been optimized for strength and low gas diffusion, and are not bothered by UV.  I have been checking out the Balloonkts.com website, where they have some decent-sized rolls of foil at inexpensive prices.  Gary Felix, the guy that runs the site, says their foil is 48 gauge (12 um), 29g/sq yard, pull strength of 4 lbs/linear inch, and only loses 4% helium per year (can that be true? - amazing).

                          A sphere is always optimal in terms of volume/surface area ratio, but it is pretty hard to construct from  long rectangles/strips of material.  A cylinder can come close to the same performance if the radius of the cylinder is large.  I wonder if anybody has worked out the volume/surface area of the tetroon?

                          Mike is right, there seems to be a good number of videos on assembling tetroons, I like http://www.youtube.com/watch?v=_cVp8EKtgTA The simplicity of assembly seems to make it quite popular.

                          I was wondering if it is straightforward to calculate the altitude that the balloon will float?  I imagine the altitude where the gas expands to occupy the max volume of the envelope must be close to where it will cease to be buoyant and float.  My concern in building a large mylar floater is that it needs to travel well above the aircraft lanes.  Having a balloon drift for days at aircraft altitudes, being visible on radar (metallized mylar- right?) would not be a career advancing event.

                          Anybody else have any advice for us mylar newbies?
                          Chuck / KG5CA


                          --- In GPSL@yahoogroups.com, <nss@...> wrote:

                          With the recent success of these foil balloons, it has made me somewhat interested in them and their possibilities for long duration flights. Their ability to"Superpressure"

                          Now I wonder, what would be the better way to go? See I have literally thousands of feet if not miles of an aluminized mylar in rolls that are in varying widths from only 2 feet wide to almost 4 feet wide.

                          Now this also has the heat sensitive adhesive backing on it too.  I just cut a large square of it, and weighed it to see what it weighs, and it comes in at 0.1768 oz per sq ft.

                          Now everyone what configuration think would be best?

                          Many small balloons, like a cluster balloon system?

                          A long cylinder
                          or
                          a like tetroon type?

                          Thoughts?

                          Joe WB9SBD
                          --
                          Sig
                          The Original Rolling Ball Clock
                          Idle Tyme
                          Idle-Tyme.com
                          http://www.idle-tyme.com







                        • Robert Rochte
                          It s not just volumetric efficiency, though - the cylindrical superpressure will have twice the skin stress of a sphere the same diametre. For small envelopes,
                          Message 12 of 21 , Sep 23, 2013
                          • 0 Attachment
                            It's not just volumetric efficiency, though - the cylindrical superpressure will have twice the skin stress of a sphere the same diametre. For small envelopes, the trade-off of greatly simplified construction may be worth it. On the other hand, precisely weighing-off  (remember, free lift turns into superpressure!) and then launching a 75 foot long tube is not a lot of fun (AMHIK).  -R

                            --
                            Robert Rochte, Director of Technology
                            The Grosse Pointe Academy
                            +1 313-378-0525 Mobile
                            Soli Deo Gloria


                            On Mon, Sep 23, 2013 at 10:42 AM, BASE <basedepauw@...> wrote:
                            Joe,

                            The simple answer is that the performance, as compared to a spherical shape enclosing the same volume gets worse.

                            Here are some quick numbers:

                            The circumference of the cylinder is 4 feet.  This makes the radius of the cylinder 0. 64 feet.  

                            Cylinder height (ft)     Cylinder Volume(cu. ft)  Cylinder Surface Area(sq.ft)  Equal Volume Sphere S.A.(sq.ft)
                                       4                                   5.1                                      18.6                                           14.3
                                       6                                   7.6                                      26.6                                           18.7
                                     10                                 12.7                                      42.6                                           26.2
                                     20                                 25.5                                      82.6                                           41.4
                                   100                               127.3                                    402.6                                        119.6

                            Short height cylinders are not much worse than the sphere, but as the height increases things you have a lot more surface for equal volumes.

                            Howard



                            From: Joe <nss@...>
                            To: BASE <hlbrooks@...>
                            Cc: BASE <basedepauw@...>; "cgoldsmith@..." <cgoldsmith@...>; "GPSL@yahoogroups.com" <GPSL@yahoogroups.com>
                            Sent: Monday, September 23, 2013 9:49 AM
                            Subject: Re: [GPSL] RE: Foil Balloons

                            ok what happens with a cylinder vs length?

                            If a 4 foot circumference cylinder was made, (4 foot is the width of the material so only 1 seam)

                            what changes if the cylinder is 10 feet long 20 feet long 100 feet long?

                            Joe WB9SBD

                            The Original Rolling Ball Clock
                            Idle Tyme
                            Idle-Tyme.com
                            http://www.idle-tyme.com
                            On 9/23/2013 7:54 AM, BASE wrote:


                            Chuck,

                            Here are the basic equations for a regular tetrahedron with edges of length a (from http://www.vitutor.com/geometry/solid/tetrahedron.html)

                            Surface Area of a Regular Tetrahedron

                            Area of a Regular Tetrahedron Formula

                            Volume of a Regular Tetrahedron

                            Volume of a Regular Tetrahedron Formula
                            The ratio of Volume/Surface Area is about 0.068a for the tetrahedron.  This ratio is not as favorable as other regular shapes:

                            For the sphere, Volume/Surface Area is 0.33r (where r is the radius)
                            For an ideal cylinder with radius equal to height (the optimal condition), Volume to Surface Area is 0.25r.
                            For a cube, Volume/Surface Area is 0.17a (where a is the edge length).

                            However, the simplicity of construction of the tetroon, with fewer straight seams, makes it a very attractive shape.

                            You are correct that the float altitude can be calculated for the superpressure balloon.  You need to know the mass of the payload, balloon fabric, and other attachments (parachute, cut down device??).  You also need to know the density and initial volume of the lifting gas.  The float altitude will be where the buoyant force of the lifting gas equals the weight of everything that is being floated.

                            I agree that floating above 60 kft is desirable for a long duration flight.

                            Howard, KC9QBN



                            From: "cgoldsmith@..." <cgoldsmith@...>
                            To: GPSL@yahoogroups.com
                            Sent: Sunday, September 22, 2013 10:14 PM
                            Subject: [GPSL] RE: Foil Balloons

                             
                             Joe,

                            I was also thinking along the same lines.  If you want something to float for days, the mylar balloon foils have been optimized for strength and low gas diffusion, and are not bothered by UV.  I have been checking out the Balloonkts.com website, where they have some decent-sized rolls of foil at inexpensive prices.  Gary Felix, the guy that runs the site, says their foil is 48 gauge (12 um), 29g/sq yard, pull strength of 4 lbs/linear inch, and only loses 4% helium per year (can that be true? - amazing).

                            A sphere is always optimal in terms of volume/surface area ratio, but it is pretty hard to construct from  long rectangles/strips of material.  A cylinder can come close to the same performance if the radius of the cylinder is large.  I wonder if anybody has worked out the volume/surface area of the tetroon?

                            Mike is right, there seems to be a good number of videos on assembling tetroons, I like http://www.youtube.com/watch?v=_cVp8EKtgTA The simplicity of assembly seems to make it quite popular.

                            I was wondering if it is straightforward to calculate the altitude that the balloon will float?  I imagine the altitude where the gas expands to occupy the max volume of the envelope must be close to where it will cease to be buoyant and float.  My concern in building a large mylar floater is that it needs to travel well above the aircraft lanes.  Having a balloon drift for days at aircraft altitudes, being visible on radar (metallized mylar- right?) would not be a career advancing event.

                            Anybody else have any advice for us mylar newbies?
                            Chuck / KG5CA


                            --- In GPSL@yahoogroups.com, <nss@...> wrote:

                            With the recent success of these foil balloons, it has made me somewhat interested in them and their possibilities for long duration flights. Their ability to"Superpressure"

                            Now I wonder, what would be the better way to go? See I have literally thousands of feet if not miles of an aluminized mylar in rolls that are in varying widths from only 2 feet wide to almost 4 feet wide.

                            Now this also has the heat sensitive adhesive backing on it too.  I just cut a large square of it, and weighed it to see what it weighs, and it comes in at 0.1768 oz per sq ft.

                            Now everyone what configuration think would be best?

                            Many small balloons, like a cluster balloon system?

                            A long cylinder
                            or
                            a like tetroon type?

                            Thoughts?

                            Joe WB9SBD
                            --

                            The Original Rolling Ball Clock
                            Idle Tyme
                            Idle-Tyme.com
                            http://www.idle-tyme.com








                          • James Ewen
                            ... Well, when you increase the length of the cylinder, it obviously gets longer, and you have more volume enclosed. Take a trip back to junior high school
                            Message 13 of 21 , Sep 23, 2013
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                              On Mon, Sep 23, 2013 at 7:49 AM, Joe <nss@...> wrote:

                              > ok what happens with a cylinder vs length?
                              >
                              > If a 4 foot circumference cylinder was made, (4 foot is the width of the material so only 1 seam)
                              >
                              > what changes if the cylinder is 10 feet long 20 feet long 100 feet long?

                              Well, when you increase the length of the cylinder, it obviously gets
                              longer, and you have more volume enclosed.

                              Take a trip back to junior high school math:

                              http://math.about.com/od/formulas/ss/surfaceareavol_3.htm

                              Your surface area to volume ratio decreases as you get further and
                              further away from a sphere.


                              --
                              James
                              VE6SRV
                            • Joe
                              Well yeah Duh? I was meaning, envelope stresses, envelope area vs volume, etc. Joe WB9SBD Sig The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com
                              Message 14 of 21 , Sep 23, 2013
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                                Well yeah Duh?  I was meaning, envelope stresses,  envelope area vs volume,  etc.

                                Joe WB9SBD
                                Sig
                                The Original Rolling Ball Clock
                                Idle Tyme
                                Idle-Tyme.com
                                http://www.idle-tyme.com
                                On 9/23/2013 11:15 AM, James Ewen wrote:
                                On Mon, Sep 23, 2013 at 7:49 AM, Joe <nss@...> wrote:
                                
                                
                                ok what happens with a cylinder vs length?
                                
                                If a 4 foot circumference cylinder was made, (4 foot is the width of the material so only 1 seam)
                                
                                what changes if the cylinder is 10 feet long 20 feet long 100 feet long?
                                
                                Well, when you increase the length of the cylinder, it obviously gets
                                longer, and you have more volume enclosed.
                                
                                Take a trip back to junior high school math:
                                
                                http://math.about.com/od/formulas/ss/surfaceareavol_3.htm
                                
                                Your surface area to volume ratio decreases as you get further and
                                further away from a sphere.
                                
                                
                                

                              • James Ewen
                                ... I guess you never bothered to follow the link then... it gave you the basic calculations for area vs. volume. Envelope stresses were never covered in
                                Message 15 of 21 , Sep 23, 2013
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                                  On Mon, Sep 23, 2013 at 10:22 AM, Joe <nss@...> wrote:

                                  > Well yeah Duh? I was meaning, envelope stresses, envelope area vs volume, etc.

                                  I guess you never bothered to follow the link then... it gave you the
                                  basic calculations for area vs. volume.

                                  Envelope stresses were never covered in junior high school. If you do
                                  hang a lot of mass from a tie off point at one end of the cylinder,
                                  you will pinch the end down to a point, changing the shape.

                                  At some point, you could potentially tear the end off the cylinder
                                  once your mass exceeds the strength of the material. I doubt however
                                  that you would ever get to that point with a 4 foot circumference
                                  cylinder. The law of diminishing returns would keep your total payload
                                  mass too low.

                                  --
                                  James
                                  VE6SRV
                                • Mike Manes
                                  Hi Chuck, While researching tetroons, I found a link on Wikipedia that detailed the surface area, volume & mass of a tetrahedral balloon envelope - but sadly,
                                  Message 16 of 21 , Sep 23, 2013
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                                    Hi Chuck,

                                    While researching tetroons, I found a link on Wikipedia that
                                    detailed the surface area, volume & mass of a tetrahedral balloon
                                    envelope - but sadly, I can't pull it back. Might give it a shot
                                    yourself. Most of the tetroon stuff I found was related to hot air
                                    balloons, but same principles should work for a gas balloon.

                                    73 de Mike W5VSI

                                    On 9/22/13 8:14 PM, cgoldsmith@... wrote:
                                    > I wonder if anybody has worked out the volume/surface area of the tetroon?
                                  • wb8elk
                                    Joe, I visitied Vin Lally at NCAR in the late 1980 s and he gave me a reprint of his detailed article about designing and performance of Tetroons. I ll look
                                    Message 17 of 21 , Sep 23, 2013
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                                      Joe,
                                       
                                       I visitied Vin Lally at NCAR in the late 1980's and he gave me a reprint of his detailed article about designing and performance of Tetroons. I'll look for that article since it was a good one. You might be able to find it in the NCAR archives somewhere. Try searching for Vin Lally Tetroon.
                                       
                                      - Bill WB8ELK
                                       
                                       
                                       
                                      Chuck,

                                      Here are the basic equations for a regular tetrahedron with edges of length a (from http://www.vitutor.com/geometry/solid/tetrahedron.html)

                                      Surface Area of a Regular Tetrahedron

                                      Area of a Regular Tetrahedron Formula

                                      Volume of a Regular Tetrahedron

                                      Volume of a Regular Tetrahedron Formula
                                      The ratio of Volume/Surface Area is about 0.068a for the tetrahedron.  This ratio is not as favorable as other regular shapes:

                                      For the sphere, Volume/Surface Area is 0.33r (where r is the radius)
                                      For an ideal cylinder with radius equal to height (the optimal condition), Volume to Surface Area is 0.25r.
                                      For a cube, Volume/Surface Area is 0.17a (where a is the edge length).

                                      However, the simplicity of construction of the tetroon, with fewer straight seams, makes it a very attractive shape.

                                      You are correct that the float altitude can be calculated for the superpressure balloon.  You need to know the mass of the payload, balloon fabric, and other attachments (parachute, cut down device??).  You also need to know the density and initial volume of the lifting gas.  The float altitude will be where the buoyant force of the lifting gas equals the weight of everything that is being floated.

                                      I agree that floating above 60 kft is desirable for a long duration flight.

                                      Howard, KC9QBN



                                      From: "cgoldsmith@..." <cgoldsmith@...>
                                      To: GPSL@yahoogroups.com
                                      Sent: Sunday, September 22, 2013 10:14 PM
                                      Subject: [GPSL] RE: Foil Balloons

                                       
                                       Joe,

                                      I was also thinking along the same lines.  If you want something to float for days, the mylar balloon foils have been optimized for strength and low gas diffusion, and are not bothered by UV.  I have been checking out the Balloonkts.com website, where they have some decent-sized rolls of foil at inexpensive prices.  Gary Felix, the guy that runs the site, says their foil is 48 gauge (12 um), 29g/sq yard, pull strength of 4 lbs/linear inch, and only loses 4% helium per year (can that be true? - amazing).

                                      A sphere is always optimal in terms of volume/surface area ratio, but it is pretty hard to construct from  long rectangles/strips of material.  A cylinder can come close to the same performance if the radius of the cylinder is large.  I wonder if anybody has worked out the volume/surface area of the tetroon?

                                      Mike is right, there seems to be a good number of videos on assembling tetroons, I like http://www.youtube.com/watch?v=_cVp8EKtgTA The simplicity of assembly seems to make it quite popular.

                                      I was wondering if it is straightforward to calculate the altitude that the balloon will float?  I imagine the altitude where the gas expands to occupy the max volume of the envelope must be close to where it will cease to be buoyant and float.  My concern in building a large mylar floater is that it needs to travel well above the aircraft lanes.  Having a balloon drift for days at aircraft altitudes, being visible on radar (metallized mylar- right?) would not be a career advancing event.

                                      Anybody else have any advice for us mylar newbies?
                                      Chuck / KG5CA


                                      --- In GPSL@yahoogroups.com, <nss@...> wrote:

                                      With the recent success of these foil balloons, it has made me somewhat interested in them and their possibilities for long duration flights. Their ability to"Superpressure"

                                      Now I wonder, what would be the better way to go? See I have literally thousands of feet if not miles of an aluminized mylar in rolls that are in varying widths from only 2 feet wide to almost 4 feet wide.

                                      Now this also has the heat sensitive adhesive backing on it too.  I just cut a large square of it, and weighed it to see what it weighs, and it comes in at 0.1768 oz per sq ft.

                                      Now everyone what configuration think would be best?

                                      Many small balloons, like a cluster balloon system?

                                      A long cylinder
                                      or
                                      a like tetroon type?

                                      Thoughts?

                                      Joe WB9SBD
                                      --

                                      The Original Rolling Ball Clock
                                      Idle Tyme
                                      Idle-Tyme.com
                                      http://www.idle-tyme.com



                                    • Joe
                                      this one? http://en.wikipedia.org/wiki/Tetrahedron Joe WB9SBD Sig The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com
                                      Message 18 of 21 , Sep 23, 2013
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                                        this one?

                                        http://en.wikipedia.org/wiki/Tetrahedron

                                        Joe WB9SBD
                                        Sig
                                        The Original Rolling Ball Clock
                                        Idle Tyme
                                        Idle-Tyme.com
                                        http://www.idle-tyme.com
                                        On 9/23/2013 1:36 PM, Mike Manes wrote:
                                        Hi Chuck,
                                        
                                        While researching tetroons, I found a link on Wikipedia that
                                        detailed the surface area, volume & mass of a tetrahedral balloon
                                        envelope - but sadly, I can't pull it back.  Might give it a shot
                                        yourself.  Most of the tetroon stuff I found was related to hot air
                                        balloons, but same principles should work for a gas balloon.
                                        
                                        73 de Mike W5VSI
                                        
                                        On 9/22/13 8:14 PM, cgoldsmith@... wrote:
                                        
                                        I wonder if anybody has worked out the volume/surface area of the tetroon?
                                        
                                        
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                                      • Sheldon Cooper
                                        A fairly recent development in foil balloon film technology that claims to reduce He leakage by 3 to 5 times, not simply due to the impervious nature of the
                                        Message 19 of 21 , Sep 23, 2013
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                                          A fairly recent development in foil balloon film technology that claims to reduce He leakage by 3 to 5 times, not simply due to the impervious nature of the film, but from better seam bonding.  Trade name is Anagram XL (XtraLife), film manufacturer is Toray Plastics, balloon manufacturer using it is Anagram.  I believe patent US8236399 at Google Patent server describes it:

                                          http://tinyurl.com/k43wfom


                                          Anagram responded to my email and said they do produce plain silver 36" diameter round (not spherical) foil balloons.  I have no idea how to go about obtaining sheets of this material in hobbyist quantities.
                                        • Mike Manes
                                          Hi guys, One advantage of the tetroon is that it s simple to figure out where to attach the beacon load; not so simple for a cylinder, where the load would
                                          Message 20 of 21 , Sep 23, 2013
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                                            Hi guys,

                                            One advantage of the tetroon is that it's simple to figure out
                                            where to attach the beacon load; not so simple for a cylinder, where
                                            the load would tend to collapse the bottom of the cylinder unless it
                                            were reinforced with a spreader ring.

                                            re making one that floats above the NAS (above 60K'): that will require
                                            an envelope volume about 10X that of the fill, and that may get pretty
                                            heavy.

                                            The tough part in making any SP balloon is getting adequate seam
                                            strength to tolerate peak gas pressure during the day while remaining
                                            fully inflated overnight. The thermodynamics boggles ...

                                            73 de Mike W5VSI

                                            On 9/23/13 8:42 AM, BASE wrote:
                                            > Joe,
                                            >
                                            > The simple answer is that the performance, as compared to a spherical
                                            > shape enclosing the same volume gets worse.
                                            >
                                            > Here are some quick numbers:
                                            >
                                            > The circumference of the cylinder is 4 feet. This makes the radius of
                                            > the cylinder 0. 64 feet.
                                            >
                                            > Cylinder height (ft) Cylinder Volume(cu. ft) Cylinder Surface
                                            > Area(sq.ft) Equal Volume Sphere S.A.(sq.ft)
                                            > 4 5.1 18.6
                                            > 14.3
                                            > 6 7.6
                                            > 26.6 18.7
                                            > 10 12.7 42.6
                                            > 26.2
                                            > 20 25.5 82.6
                                            > 41.4
                                            > 100 127.3 402.6
                                            > 119.6
                                            >
                                            > Short height cylinders are not much worse than the sphere, but as the
                                            > height increases things you have a lot more surface for equal volumes.
                                            >
                                            > Howard
                                            >
                                          • Mike Manes
                                            Yeah, that s where I started. The details on volume, mass, area and heat transfer may be in one of those links or its references. - Mike
                                            Message 21 of 21 , Sep 23, 2013
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                                              Yeah, that's where I started. The details on volume, mass, area and
                                              heat transfer may be in one of those links or its references.
                                              - Mike

                                              On 9/23/13 1:19 PM, Joe wrote:
                                              > this one?
                                              >
                                              > http://en.wikipedia.org/wiki/Tetrahedron
                                              >
                                              > Joe WB9SBD
                                              > Sig
                                              > The Original Rolling Ball Clock
                                              > Idle Tyme
                                              > Idle-Tyme.com
                                              > http://www.idle-tyme.com
                                              > On 9/23/2013 1:36 PM, Mike Manes wrote:
                                              >> Hi Chuck,
                                              >>
                                              >> While researching tetroons, I found a link on Wikipedia that
                                              >> detailed the surface area, volume & mass of a tetrahedral balloon
                                              >> envelope - but sadly, I can't pull it back. Might give it a shot
                                              >> yourself. Most of the tetroon stuff I found was related to hot air
                                              >> balloons, but same principles should work for a gas balloon.
                                              >>
                                              >> 73 de Mike W5VSI
                                              >>
                                              >> On 9/22/13 8:14 PM,cgoldsmith@... wrote:
                                              >>> I wonder if anybody has worked out the volume/surface area of the tetroon?
                                              >>
                                              >
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