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Re: [GPSL] Controlled float of a latex flight

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  • Zack Clobes
    I m copying Don s repeater very roughly on a discone in the attic here in Hutchinson, KS. The glue was some 3M stuff that was kind of tricky to get a hold of.
    Message 1 of 9 , Dec 11, 2004
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      I'm copying Don's repeater very roughly on a discone in the attic here
      in Hutchinson, KS.

      The glue was some 3M stuff that was kind of tricky to get a hold of. We
      found some stuff that worked that the maintenance ddepartment at the
      airport was using for gluing weather stripping on airplane door seals.
      The glue remained pliable and was kind of interesting to work with.


      As for cutdowns, remotely controlled RF cutdowns are the only way to
      go. We've flown our cutdown on several flights now using a Linx
      transmitter/receiver pair. The latest version of the board which hasn't
      yet flown uses two NiCh wires which are independently powered and
      controlled via a single uP. One of the wires is controlled via the RF
      link. The second wire is based on a timer (x minutes after power being
      applied to the uP). The whole system is powered from three lithium
      batteries - a coin cell for the uP, and one camera battery for each hotwire.

      The uP waits for a specific series of digital pulses from the receiver.
      The main payload sends the cutdown command for about 1 second every 30
      seconds for the duration once it's decided it wants to terminate
      flight. Termination logic can be based on anything you want - battery
      voltage, IAT, ascent rate, altitude, etc.

      The camera batteries are mounted in battery holders (soldering to those
      batteries sucks). I'm using a low-voltage FET transistor for the
      driving force.

      I also put a small piezo buzzer parallel across each of the hot wires.
      There's just enough voltage there to make some noise, and it provides an
      early warning (okay, about 2 seconds) if a cutter should fire while on
      the ground.

      Zack

      Mark Conner wrote:

      >What kind of glue? For a duration flight, it would seem the glue
      >would affect the balloon's longevity.
      >
      >I wonder if the "booster" could be flown right next to the main?
      >I'm not sure which is worse - a load line rubbing on the balloon,
      >or two balloons rubbing each other?
      >
      >I'm working on collecting parts for a short-distance
      >remotely-controlled cutdown. The remote TX would be in the main
      >payload, and the RX in the cutdown box. The BS2 (or other
      >control mechanism) would then activate the cutdown. The "design"
      >I have in mind can support two latches easily (4 with a bit more
      >effort), and these could be hooked to separate NiCr wires to cut
      >away either balloon as desired.
      >
      >I need to look some pictures from GPSL 2004 to see how Don
      >arranged his balloons. He's flying a balloon right now, BTW
      >(KA0JLF-11, simplex rptr on 145.555).
      >
      >73 de Mark N9XTN
      >
      >
      >----- Original Message -----
      >From: "Zack Clobes" <zclobes@...>
      >To: <GPSL@yahoogroups.com>
      >Sent: Saturday, December 11, 2004 11:16
      >Subject: Re: [GPSL] Controlled float of a latex flight
      >
      >
      >
      >
      >>We've experimented with this concept a little. We were
      >>successfully
      >>able to glue an eye-bolt to the top of the "MAIN" balloon and
      >>attach the
      >>"BOOSTER" above. That worked well.
      >>
      >>The problem with our flight was that we were only using a 100g
      >>"BOOSTER"
      >>and it didn't have enough net lift to provide a significant
      >>impact to
      >>the system, in fact it was quite the opposite. In other words,
      >>the 600g
      >>"MAIN" literally drug the "BOOSTER" behind it to altitude.
      >>
      >>
      >>Zack Clobes, W0ZC
      >>Project: Traveler
      >>
      >>
      >>Ralph Wallio, W0RPK wrote:
      >>
      >>
      >>
      >>>QSYing this round table to GPSL for a wider discussion ...
      >>>
      >>>Responding to Mark's discussion of the potential of 12-18hr
      >>>flights, I have
      >>>a scheme that appears to work every time ... when flown as a
      >>>thought
      >>>experiment. Mileage for others may vary significantly. Think
      >>>through this
      >>>step by step to get a feel for how a controlled float can
      >>>happen.
      >>>
      >>>The configuration uses two balloons, a "MAIN" and a "BOOSTER".
      >>>The MAIN is
      >>>filled for close to equilibrium when loaded with payload but
      >>>erroring toward
      >>>very slightly negative lift. The BOOSTER is filled for a
      >>>reasonable ascent
      >>>rate. After launch and ascent to ~80kft, the BOOSTER is cut
      >>>away leaving
      >>>only the MAIN and payload which will be close to floating
      >>>equilibrium.
      >>>
      >>>At 80kft there is a +/-20kft buffer between MAIN burst at
      >>>~100kft and
      >>>controlled airspace at 60kft. The BOOSTER only has enough lift
      >>>to yield a
      >>>reasonable ascent rate so it will not be close to burst at
      >>>80kft.
      >>>Similarly, the MAIN only has enough lift for equilibrium so it
      >>>will not
      >>>burst unless it goes well above 100kft (we are talking about a
      >>>1500-2000g
      >>>MAIN and 600-1000g BOOSTER depending on payload weight).
      >>>
      >>>This configuration should be launched at dusk so there is no
      >>>additional lift
      >>>due to solar heating. With no loss of solar heating during the
      >>>first 24hrs
      >>>the only loss of lift from the MAIN will be gas migration
      >>>through latex.
      >>>This loss of lift will need to be offset by occasional ballast
      >>>dumps. My
      >>>alleged calculations show a 6-pound payload needs to include
      >>>only ~16oz of
      >>>dumped ballast to compensate for a significant cumulative loss
      >>>of lift.
      >>>
      >>>There will probably be some minor lift trimming shortly after
      >>>the BOOSTER is
      >>>cut away but the flight should be stable through the night.
      >>>Then, roughly
      >>>12hrs later, sunrise will yield solar heating lift which will
      >>>approximately
      >>>offset loss of lift due to gas migration. Ballast dumping, an
      >>>ounce at a
      >>>time, can be used to control slow descent but only when
      >>>approaching 60kft.
      >>>Save that ballast.
      >>>
      >>>Now we are at 24hrs and sunset. Loss of solar heating will
      >>>slightly reduce
      >>>lift so ballast will probably have to be dumped over night.
      >>>How much? This
      >>>is where your mileage may vary. Assuming altitude can be kept
      >>>above 60kft
      >>>the flight will last at least until sunrise some 36hrs after
      >>>launch.
      >>>
      >>>Now it is time to get real about crew fatigue. Crew shifts,
      >>>say 4hrs, will
      >>>be required to continuously monitor the flight and issue
      >>>ballast dumping
      >>>commands. All manner of things could go wrong so the
      >>>chase/recovery crew
      >>>will have to be ready to scramble through both nights (the
      >>>proverbial "hot
      >>>standby"). With sunrise on the 2nd morning crews will
      >>>negotiate a time for
      >>>flight termination. A MAIN cutdown command will be issued
      >>>accordingly.
      >>>Flight time of 40hrs seems reasonable for a 2-day weekend.
      >>>
      >>>You want to go 3 days, another 24hrs? There may be enough
      >>>ballast left to
      >>>keep the flight above 60kft through another day and night.
      >>>Regardless, the
      >>>game is over when you have run out of ballast and can no longer
      >>>keep the
      >>>flight above 60kft.
      >>>
      >>>Piece of cake, or in intelligence speak, a "slam dunk". So
      >>>when to do
      >>>this(?) Winds aloft in May and September have statistical
      >>>advantage
      >>>according to Mean Zonal Winds because during these months wind
      >>>velocity
      >>>60-100kft approaches zero. There will be a little drift during
      >>>ascent and
      >>>descent but MAIN and payload will station-keep nicely while
      >>>floating for the
      >>>vast majority of the flight.
      >>>
      >>>Payload design will have to include enough power for 48 (72?)
      >>>hours. Bill
      >>>Brown's 0.72-pound floater was designed and tested to stay on
      >>>the air for
      >>>72+hrs so we know it can be done. My response to this in Solar
      >>>Floater was
      >>>to design and fabricate a solar charging system. I haven't
      >>>made progress
      >>>for a couple of years so I hope others take on the challenge.
      >>>
      >>>TNX es 73 de Ralph Wallio, WØRPK
      >>>wallio@...
      >>>http://users.crosspaths.net/wallio/
      >>>Hubbert's Peak - The Mother of all Perfect Storms
      >>>
      >>>
      >>>
      >>>
      >>>
      >>>
      >>>
      >>>Yahoo! Groups Links
      >>>
      >>>
      >>>
      >>>
      >>>
      >>>
      >>>
      >>>
      >>>
      >>>
      >>>
      >>------------------------ Yahoo! Groups
      >>
      >>
      >>Yahoo! Groups Links
      >>
      >>
      >>
      >>
      >>
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      >>
      >>
      >>
      >>
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      >Yahoo! Groups Links
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    • Mike Manes
      Hi Ralph, WE ve tried pairs of balloons in order to achieve a controlled, moderate descent rate. Theoretically, the ballast balloon would also serve as a
      Message 2 of 9 , Dec 12, 2004
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        Hi Ralph,

        WE've tried pairs of balloons in order to achieve a controlled, moderate
        descent rate. Theoretically, the "ballast" balloon would also serve as
        a
        variable drag area "ballchute" to yield a near-constant descent rate.

        Our results were less than successful. One problem was that if the two
        lift
        lines were attached to the the apex of the 'chute where the cutters
        reside, they'ed
        get terminally twisted during ascent, thus averting cutaway of the
        "lift"
        balloon. The second was premature bursting of the "ballast: balloon(s),
        presumably
        from friction on the "lift" balloon line. The latter was cured by
        running both
        balloons next to each other, but that didn't affect the twisting
        problem.

        Finally, altho latex balloons are certainly cheaper than plastics, when
        one
        factors in the cost of a 24hr to several day chase and the risk of loss
        of the
        entire payload string, plus the risk of the whole experiment ending up
        as a
        derelict in civil airspace, why not simply do a zero-pressure plastic?
        That's
        what the pros use. To make multiday flights, ballast must be dumped to
        compensate
        for He lost during the day due to solar heating - again, following how
        manned
        gas balloons operate.

        NOAA has successfully acheived a constant descent rate from 10 mbar
        using a 4"
        diameter dump valve as the nozzle on a 3000 gm latex carrying a 6-lb
        vaporsonde
        plus a 1-lb chute and cutdown controller. EOSS tried this scheme once,
        but the
        bag blew early, and the control cable to the vave operator at the bottom
        of the
        balloon got severely twisted in the lift line and broke.

        I'm not opposed to innovation in this field, but I'd urge us to take a
        look
        at the experience and science already out there.

        73 de Mike W5VSI

        "Ralph Wallio, W0RPK" wrote:
        >
        > QSYing this round table to GPSL for a wider discussion ...
        >
        > Responding to Mark's discussion of the potential of 12-18hr flights, I have
        > a scheme that appears to work every time ... when flown as a thought
        > experiment. Mileage for others may vary significantly. Think through this
        > step by step to get a feel for how a controlled float can happen.
        >
        > The configuration uses two balloons, a "MAIN" and a "BOOSTER". The MAIN is
        > filled for close to equilibrium when loaded with payload but erroring toward
        > very slightly negative lift. The BOOSTER is filled for a reasonable ascent
        > rate. After launch and ascent to ~80kft, the BOOSTER is cut away leaving
        > only the MAIN and payload which will be close to floating equilibrium.
        >
        > At 80kft there is a +/-20kft buffer between MAIN burst at ~100kft and
        > controlled airspace at 60kft. The BOOSTER only has enough lift to yield a
        > reasonable ascent rate so it will not be close to burst at 80kft.
        > Similarly, the MAIN only has enough lift for equilibrium so it will not
        > burst unless it goes well above 100kft (we are talking about a 1500-2000g
        > MAIN and 600-1000g BOOSTER depending on payload weight).
        >
        > This configuration should be launched at dusk so there is no additional lift
        > due to solar heating. With no loss of solar heating during the first 24hrs
        > the only loss of lift from the MAIN will be gas migration through latex.
        > This loss of lift will need to be offset by occasional ballast dumps. My
        > alleged calculations show a 6-pound payload needs to include only ~16oz of
        > dumped ballast to compensate for a significant cumulative loss of lift.
        >
        > There will probably be some minor lift trimming shortly after the BOOSTER is
        > cut away but the flight should be stable through the night. Then, roughly
        > 12hrs later, sunrise will yield solar heating lift which will approximately
        > offset loss of lift due to gas migration. Ballast dumping, an ounce at a
        > time, can be used to control slow descent but only when approaching 60kft.
        > Save that ballast.
        >
        > Now we are at 24hrs and sunset. Loss of solar heating will slightly reduce
        > lift so ballast will probably have to be dumped over night. How much? This
        > is where your mileage may vary. Assuming altitude can be kept above 60kft
        > the flight will last at least until sunrise some 36hrs after launch.
        >
        > Now it is time to get real about crew fatigue. Crew shifts, say 4hrs, will
        > be required to continuously monitor the flight and issue ballast dumping
        > commands. All manner of things could go wrong so the chase/recovery crew
        > will have to be ready to scramble through both nights (the proverbial "hot
        > standby"). With sunrise on the 2nd morning crews will negotiate a time for
        > flight termination. A MAIN cutdown command will be issued accordingly.
        > Flight time of 40hrs seems reasonable for a 2-day weekend.
        >
        > You want to go 3 days, another 24hrs? There may be enough ballast left to
        > keep the flight above 60kft through another day and night. Regardless, the
        > game is over when you have run out of ballast and can no longer keep the
        > flight above 60kft.
        >
        > Piece of cake, or in intelligence speak, a "slam dunk". So when to do
        > this(?) Winds aloft in May and September have statistical advantage
        > according to Mean Zonal Winds because during these months wind velocity
        > 60-100kft approaches zero. There will be a little drift during ascent and
        > descent but MAIN and payload will station-keep nicely while floating for the
        > vast majority of the flight.
        >
        > Payload design will have to include enough power for 48 (72?) hours. Bill
        > Brown's 0.72-pound floater was designed and tested to stay on the air for
        > 72+hrs so we know it can be done. My response to this in Solar Floater was
        > to design and fabricate a solar charging system. I haven't made progress
        > for a couple of years so I hope others take on the challenge.
        >
        > TNX es 73 de Ralph Wallio, WØRPK
        > wallio@...
        > http://users.crosspaths.net/wallio/
        > Hubbert's Peak - The Mother of all Perfect Storms
        >
        >
        >
        > Yahoo! Groups Links
        >
        >
        >
        >

        --
        Mike Manes manes@... Tel: 303-979-4899
        "Things should be made as simple as possible, but not more so." A.
        Einstein
      • paul.verhage@boiseschools.org
        I would love to go on a chase like this. Would a Memorial Day weekend be the ideal time? Paul
        Message 3 of 9 , Dec 13, 2004
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          I would love to go on a chase like this. Would a Memorial Day weekend be the ideal
          time?

          Paul

          >
          > QSYing this round table to GPSL for a wider discussion ...
          >
          > Responding to Mark's discussion of the potential of 12-18hr flights, I have
          > a scheme that appears to work every time ... when flown as a thought
          > experiment. Mileage for others may vary significantly. Think through this
          > step by step to get a feel for how a controlled float can happen.
          >
          > The configuration uses two balloons, a "MAIN" and a "BOOSTER". The MAIN is
          > filled for close to equilibrium when loaded with payload but erroring toward
          > very slightly negative lift. The BOOSTER is filled for a reasonable ascent
          > rate. After launch and ascent to ~80kft, the BOOSTER is cut away leaving
          > only the MAIN and payload which will be close to floating equilibrium.
          >
          > At 80kft there is a +/-20kft buffer between MAIN burst at ~100kft and
          > controlled airspace at 60kft. The BOOSTER only has enough lift to yield a
          > reasonable ascent rate so it will not be close to burst at 80kft.
          > Similarly, the MAIN only has enough lift for equilibrium so it will not
          > burst unless it goes well above 100kft (we are talking about a 1500-2000g
          > MAIN and 600-1000g BOOSTER depending on payload weight).
          >
          > This configuration should be launched at dusk so there is no additional lift
          > due to solar heating. With no loss of solar heating during the first 24hrs
          > the only loss of lift from the MAIN will be gas migration through latex.
          > This loss of lift will need to be offset by occasional ballast dumps. My
          > alleged calculations show a 6-pound payload needs to include only ~16oz of
          > dumped ballast to compensate for a significant cumulative loss of lift.
          >
          > There will probably be some minor lift trimming shortly after the BOOSTER is
          > cut away but the flight should be stable through the night. Then, roughly
          > 12hrs later, sunrise will yield solar heating lift which will approximately
          > offset loss of lift due to gas migration. Ballast dumping, an ounce at a
          > time, can be used to control slow descent but only when approaching 60kft.
          > Save that ballast.
          >
          > Now we are at 24hrs and sunset. Loss of solar heating will slightly reduce
          > lift so ballast will probably have to be dumped over night. How much? This
          > is where your mileage may vary. Assuming altitude can be kept above 60kft
          > the flight will last at least until sunrise some 36hrs after launch.
          >
          > Now it is time to get real about crew fatigue. Crew shifts, say 4hrs, will
          > be required to continuously monitor the flight and issue ballast dumping
          > commands. All manner of things could go wrong so the chase/recovery crew
          > will have to be ready to scramble through both nights (the proverbial "hot
          > standby"). With sunrise on the 2nd morning crews will negotiate a time for
          > flight termination. A MAIN cutdown command will be issued accordingly.
          > Flight time of 40hrs seems reasonable for a 2-day weekend.
          >
          > You want to go 3 days, another 24hrs? There may be enough ballast left to
          > keep the flight above 60kft through another day and night. Regardless, the
          > game is over when you have run out of ballast and can no longer keep the
          > flight above 60kft.
          >
          > Piece of cake, or in intelligence speak, a "slam dunk". So when to do
          > this(?) Winds aloft in May and September have statistical advantage
          > according to Mean Zonal Winds because during these months wind velocity
          > 60-100kft approaches zero. There will be a little drift during ascent and
          > descent but MAIN and payload will station-keep nicely while floating for the
          > vast majority of the flight.
          >
          > Payload design will have to include enough power for 48 (72?) hours. Bill
          > Brown's 0.72-pound floater was designed and tested to stay on the air for
          > 72+hrs so we know it can be done. My response to this in Solar Floater was
          > to design and fabricate a solar charging system. I haven't made progress
          > for a couple of years so I hope others take on the challenge.
          >
          > TNX es 73 de Ralph Wallio, WØRPK
          > wallio@...
          > http://users.crosspaths.net/wallio/
          > Hubbert's Peak - The Mother of all Perfect Storms
          >
          >
          >
          >
          >
          >
          >
          > Yahoo! Groups Links
          >
          >
          >
          >
          >
          >
          >
        • Ralph Wallio, W0RPK
          Regarding use of BALLAST or BALLCHUTE balloons (Mike s terms), ISGC/ISU/HABET has flown a few successful missions using three balloons. Lift from a larger
          Message 4 of 9 , Dec 13, 2004
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            Regarding use of "BALLAST" or "BALLCHUTE" balloons (Mike's terms),
            ISGC/ISU/HABET has flown a few successful missions using three balloons.
            Lift from a larger MAIN (my term) is supplemented by lift from two much
            smaller PIBAL balloons.

            One smaller balloon is cut away at desired float altitude (15kft in their
            case). After science objectives are complete they cut away the second
            smaller balloon so, with negative lift, the MAIN, payload and parachute
            slowly descend to touchdown. They cut away the MAIN as necessary to limit
            track distance.

            See discussion and pictures starting at
            http://cosmos.ssol.iastate.edu/HABET/h43/h43.html. Note that both small
            balloons are tied off substantially lower than the MAIN.

            ISGC/ISU/HABET has been repeatedly successful with this configuration but
            their desired float altitude was only 15kft. I assume our collective desire
            would be to float at a much higher altitude, ~80kft as previously discussed.
            Depending on payload weight, our MAIN could be 1500-2000g and BOOSTER could
            be 600-1000g. This is not a BALLAST or BALLCHUTE configuration. We would
            be cutting away the MAIN to terminate flight and descending with a
            parachute.

            Now on to Mike's discussion, point by point:

            Cost of Plastic vs. latex:

            Latex balloons are much cheaper than plastic balloons in at least three
            ways. First, plastic balloons, especially plastic balloons equipped for
            Zero-Pressure flight, cost much more than latex balloons with equivalent
            lift. A single Z-P balloon will cost almost 10x what a MAIN and BOOSTER
            would cost. This higher cost is partially because of much higher costs for
            fabrication material and labor and partially because Raven Industries'
            Engineered Film Division has no competition to beat. See
            http://www.ravenind.com/RavenCorporate/eng_films/high_alt_balloons_index.htm.

            Second, Engineered Film will not sell Z-P plastic balloons to groups who
            have not demonstrated proficiency with plastic sounding balloons. I discuss
            this requirement, as stated by Mike Smith, in
            http://users.crosspaths.net/~wallio/Polyethylene.html. A group with no
            previous experience will have to purchase and fly multiple very expensive
            plastic sounding balloons before they are eligible to purchase an even more
            expensive Z-Ps.

            Third, again as stated by Mike Smith, Engineered Film will require this
            group to acquire substantial liability insurance specific to flight of their
            plastic balloons. This insurance is available but at very high cost,
            $1,500-2,000 when I gathered information for the discussion.

            So the cost of flying plastic is substantially higher than flying latex. We
            have the equipment, methods and experience that would directly apply to a
            latex MAIN and BOOSTER configuration.

            Twenty-four hour + chase:

            Mean Zonal Winds tells us a long chase would not be required in May and
            September. A short chase of only a few 10's of miles would start only when
            the flight is terminated. At float altitude, 60-100kft, there would be very
            little movement. See http://users.crosspaths.net/~wallio/SF_MZW_12mo.gif to
            see what Mean Zonal Winds predicts for all 12 months of the year.

            These May and September opportunities extend roughly a half month before and
            after, e.g., mid-April to min-June, but we have to wait for the right day.
            These are MEAN Zonal Winds. Actual winds on any given day could vary
            substantially from the mean. Deciding to fly a floater on a specific
            weekend, e.g. Memorial Day, will require us to accept the reality of winds
            aloft on that day (as well as surface wind, thunderstorms, et al.).
            Regardless, the chase will be short (but the chase crew needs to be on
            hot-standby during the entire flight).

            Derelict in controlled airspace:

            Flight termination mechanisms have to work regardless of whether we are
            cutting away a latex MAIN or zipping open (or inverting) a plastic Z-P.
            Either configuration could end up being derelict below 60kft in controlled
            airspace if our stuff fails. If we want to float a payload we have to
            accept the responsibility of using line cutters/burners that will work,
            probably with redundant methods.

            NOAA's dump valve:

            Their dump valve works but their goal is very different from ours. NOAA
            wants to descend very slowly which requires reduction of lift by controlled
            dumping of lifting gas.

            Our goal is to ascend, float for 12-72hrs and reliably terminate flight. We
            have a great deal of collective successful experience ascending and
            terminating. What we are adding is a second latex balloon, a second cutaway
            mechanism and ballast dumping. Therefore a ballast dumping mechanism is our
            only relatively new required stuff. When I work through the numbers I find
            16oz of dumpable ballast is reasonable for a 6-pound payload (including the
            ballast dumping mechanism).

            We can't afford to do what the big guys do while being funded by government
            budgets (read, "taxes"). We can afford to fly floaters by using our
            successful experience with latex balloons.

            TNX es 73 de Ralph Wallio, WØRPK
            wallio@...
            http://users.crosspaths.net/wallio/
            Hubbert's Peak - The Mother of all Perfect Storms
          • paul.verhage@boiseschools.org
            As long as we can do a launch that I have vacation time for, I d be happy to help with the chase and recovery. I like the latex balloon method not only
            Message 5 of 9 , Dec 13, 2004
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              As long as we can do a launch that I have vacation time for, I'd be happy to help with
              the chase and recovery. I like the latex balloon method not only because of the cost,
              but also for the fact that we just have to cut the balloon way, It will burst on its own
              when it doesn't have a payload. So it's one less thing to go wrong.

              Paul

              >
              > Regarding use of "BALLAST" or "BALLCHUTE" balloons (Mike's terms),
              > ISGC/ISU/HABET has flown a few successful missions using three balloons.
              > Lift from a larger MAIN (my term) is supplemented by lift from two much
              > smaller PIBAL balloons.
              >
              > One smaller balloon is cut away at desired float altitude (15kft in their
              > case). After science objectives are complete they cut away the second
              > smaller balloon so, with negative lift, the MAIN, payload and parachute
              > slowly descend to touchdown. They cut away the MAIN as necessary to limit
              > track distance.
              >
              > See discussion and pictures starting at
              > http://cosmos.ssol.iastate.edu/HABET/h43/h43.html. Note that both small
              > balloons are tied off substantially lower than the MAIN.
              >
              > ISGC/ISU/HABET has been repeatedly successful with this configuration but
              > their desired float altitude was only 15kft. I assume our collective desire
              > would be to float at a much higher altitude, ~80kft as previously discussed.
              > Depending on payload weight, our MAIN could be 1500-2000g and BOOSTER could
              > be 600-1000g. This is not a BALLAST or BALLCHUTE configuration. We would
              > be cutting away the MAIN to terminate flight and descending with a
              > parachute.
              >
              > Now on to Mike's discussion, point by point:
              >
              > Cost of Plastic vs. latex:
              >
              > Latex balloons are much cheaper than plastic balloons in at least three
              > ways. First, plastic balloons, especially plastic balloons equipped for
              > Zero-Pressure flight, cost much more than latex balloons with equivalent
              > lift. A single Z-P balloon will cost almost 10x what a MAIN and BOOSTER
              > would cost. This higher cost is partially because of much higher costs for
              > fabrication material and labor and partially because Raven Industries'
              > Engineered Film Division has no competition to beat. See
              > http://www.ravenind.com/RavenCorporate/eng_films/high_alt_balloons_index.htm.
              >
              > Second, Engineered Film will not sell Z-P plastic balloons to groups who
              > have not demonstrated proficiency with plastic sounding balloons. I discuss
              > this requirement, as stated by Mike Smith, in
              > http://users.crosspaths.net/~wallio/Polyethylene.html. A group with no
              > previous experience will have to purchase and fly multiple very expensive
              > plastic sounding balloons before they are eligible to purchase an even more
              > expensive Z-Ps.
              >
              > Third, again as stated by Mike Smith, Engineered Film will require this
              > group to acquire substantial liability insurance specific to flight of their
              > plastic balloons. This insurance is available but at very high cost,
              > $1,500-2,000 when I gathered information for the discussion.
              >
              > So the cost of flying plastic is substantially higher than flying latex. We
              > have the equipment, methods and experience that would directly apply to a
              > latex MAIN and BOOSTER configuration.
              >
              > Twenty-four hour + chase:
              >
              > Mean Zonal Winds tells us a long chase would not be required in May and
              > September. A short chase of only a few 10's of miles would start only when
              > the flight is terminated. At float altitude, 60-100kft, there would be very
              > little movement. See http://users.crosspaths.net/~wallio/SF_MZW_12mo.gif to
              > see what Mean Zonal Winds predicts for all 12 months of the year.
              >
              > These May and September opportunities extend roughly a half month before and
              > after, e.g., mid-April to min-June, but we have to wait for the right day.
              > These are MEAN Zonal Winds. Actual winds on any given day could vary
              > substantially from the mean. Deciding to fly a floater on a specific
              > weekend, e.g. Memorial Day, will require us to accept the reality of winds
              > aloft on that day (as well as surface wind, thunderstorms, et al.).
              > Regardless, the chase will be short (but the chase crew needs to be on
              > hot-standby during the entire flight).
              >
              > Derelict in controlled airspace:
              >
              > Flight termination mechanisms have to work regardless of whether we are
              > cutting away a latex MAIN or zipping open (or inverting) a plastic Z-P.
              > Either configuration could end up being derelict below 60kft in controlled
              > airspace if our stuff fails. If we want to float a payload we have to
              > accept the responsibility of using line cutters/burners that will work,
              > probably with redundant methods.
              >
              > NOAA's dump valve:
              >
              > Their dump valve works but their goal is very different from ours. NOAA
              > wants to descend very slowly which requires reduction of lift by controlled
              > dumping of lifting gas.
              >
              > Our goal is to ascend, float for 12-72hrs and reliably terminate flight. We
              > have a great deal of collective successful experience ascending and
              > terminating. What we are adding is a second latex balloon, a second cutaway
              > mechanism and ballast dumping. Therefore a ballast dumping mechanism is our
              > only relatively new required stuff. When I work through the numbers I find
              > 16oz of dumpable ballast is reasonable for a 6-pound payload (including the
              > ballast dumping mechanism).
              >
              > We can't afford to do what the big guys do while being funded by government
              > budgets (read, "taxes"). We can afford to fly floaters by using our
              > successful experience with latex balloons.
              >
              > TNX es 73 de Ralph Wallio, WØRPK
              > wallio@...
              > http://users.crosspaths.net/wallio/
              > Hubbert's Peak - The Mother of all Perfect Storms
              >
              >
              >
              >
              >
              >
              >
              >
              >
              > Yahoo! Groups Links
              >
              >
              >
              >
              >
              >
              >
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