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Re: [GPSL] CNSP (K6RPT-14) flight ascent profile

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  • L. Paul Verhage
    There was a BOI flight back in 1999 that fit that profile. I try to fly with 3 PPL. I susppose the sub-pound payloads need to look at flight termination
    Message 1 of 24 , Sep 1, 2010
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      There was a BOI flight back in 1999 that fit that profile. 
       
      I try to fly with 3 PPL.  I susppose the sub-pound payloads need to look at flight termination devices.  That way you know you won't be up there when the batteries die.
       
      Paul

      On Tue, Aug 31, 2010 at 4:30 PM, Mark Conner <mconner1@...> wrote:


      This seems to happen more frequently than not for 3000g balloons, sub-1lb payloads, and flights to the 120 kft vicinity.  Or maybe it's selective memory on my part.  Does anyone recall a "normal" flight under these payload/balloon conditions, where there was not a substantial leveling off of the ascent rate before the burst altitude?

      I find it a little hard to believe that we get pinholes this frequently.

      73 de Mark N9XTN


      On Tue, Aug 31, 2010 at 16:12, Michael Willett <mw@...> wrote:


      Hi Howard,

      I also noted the leveling off at around 121,000 feet. It got my attention too. Knowing that burst happened shortly after, I would say it had a pre-burst hole that slowed the ascent rate, but not enough to over come the continued ascent to critical pressure and obtaining burst. "Captain, she can't take any more" "Give me all you've got Scotty" then blamo... :)

      The other possibility I thought of was an area of sinking air. Though air is thin up there, it still moves around, and I have encountered very large areas of sinking air when flying a plane, I can imagine those areas also exist at high altitudes.

      However, my money is on the pin hole as it nearly matches the profile I expect from using the valve system and likely matches that of Bill Brown's pin-hole experiments.

      --Michael
      K5NOT


      On 8/31/2010 1:56 PM, BASE wrote:
       

      I plotted the ascent profile for Ron's flight (see attached .jpg) from the aprs.fi raw data packets.  Something very interesting started to happen after about 2 hours and 15 minutes. 

      Any explanations?

      Howard

      --- On Tue, 8/31/10, k6rpt <Ron@...> wrote:

      From: k6rpt <Ron@...>
      Subject: [GPSL] Re: K6RPT-14 flight went well today reaching 122,649 feet.
      To: GPSL@yahoogroups.com
      Date: Tuesday, August 31, 2010, 10:47 AM

       

      I didn't do any temperature logging my payload was already about 5 oz too heavy already.

      Thanks Howard, Understanding the density of the stratosphere at 37 km ASL and helium will help in my next attempt.

      -Ron K6RPT

      --- In GPSL@yahoogroups.com, BASE <basedepauw@...> wrote:
      >
      > Ron,
      > Did you transmit any temperature data from your system?  
      > The density of the stratosphere at 37 km ASL is very small, making the density difference with the helium smaller than what might be assumed via LiftWin.  
      > Howard
      >
      > --- On Mon, 8/30/10, k6rpt <Ron@...> wrote:
      >
      > From: k6rpt <Ron@...>
      > Subject: [GPSL] K6RPT-14 flight went well today reaching 122,649 feet.
      > To: GPSL@yahoogroups.com
      > Date: Monday, August 30, 2010, 8:07 PM
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >  
      >
      >
      >
      >
      >
      >
      >
      >
      >
      > The K6RPT-14 flight went well today reaching 122,649 feet. After the flight I had to go back to work.
      >
      >
      >
      > CNSP did not plan to recover this payload. Another group's chase and recovery team, with one team member in an airplane went after it anyway. They said the terrain was difficult for recovery.
      >
      >
      >
      > I was surprised how slow it was ascending at the end of the flight? I thought we had a floater at 122k.
      >
      >
      >
      > -Ron K6RPT
      >











      --
      Onwards and Upwards,
      Paul
    • Michael Willett
      That presentation was by K5NOT - from ARBONET. The phenomenon of a pressure increase before burst is documented by ARBONET and the University of Minnesota, it
      Message 2 of 24 , Sep 1, 2010
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        That presentation was by K5NOT - from ARBONET. The phenomenon of a pressure increase before burst is documented by ARBONET and the University of Minnesota, it is really there. I am not sure that it would result in the decrease in envelope expansion enough to demonstrate the near neutral buoyancy of the K6RPT-14 flight. But yes, the latex does start resisting continued expansion at the point I call "mechanical maximum" - where the latex just can not stretch anymore before tearing. Under ideal conditions, the lack of increased displacement of the envelope due to reaching the mechanical maximum would result in a floater, since the balloon envelope would start compressing the helium, possibly enough to achieve a balance between displacement and compression, thereby resulting in reduced lift. This is a very fine line though. We don't normally see this with 1000'ft/minute ascent rates, but at very low ascent rates like the K6RPT-14 balloon, this profile absolutely could be an indication that mechanical maximum was reached, the envelope resisted further expansion due to the lower initial envelope pressure, the very sparse helium mass started to compress, and the ascent started to level off. However, in this case, ascent was never fully arrested and the mechanical maximum was exceeded, resulting in an envelope failure.

        Just one thought among many viable explanations...

        We will never really know, since we don't have a profile of the K6RPT-14 envelope pressure, and no concrete evidence is available to dispute any sound idea about what happened up there.

        --Michael K5NOT



        On 8/31/2010 10:46 PM, Jerry Gable wrote:
         
        Somebody and I don't remember who presented at GPSL this year about the pressure increase in a balloon just before burst.  I found some stuff on party balloons describing this effect but nothing on weather balloons.

        A few ounces of extra pressure at lower altitudes is going to wash out in the noise but at 120K feet where the outside pressure is 0.06 PSI it could make a big difference.


        From: Mark Conner <mconner1@...>
        To: GPSL list <GPSL@yahoogroups.com>
        Sent: Tue, August 31, 2010 7:15:55 PM
        Subject: Re: [GPSL] CNSP (K6RPT-14) flight ascent profile

         

        I'm still not sure I buy the pressurization theory - I just can't see latex stretched that thin suddenly exhibiting a lot more strength.  I don't believe we see this with, say, 1500g balloons at around 100 kft. 

        A pinhole, with a minimal pressure differential behind it, wouldn't seem to vent a lot of helium in an hour or two.  I suppose one could do the math using a minimal but hopefully realistic pressure differential through a hole of various sizes and see just how long it would take, but we are probably talking several hundred to a couple thousand cubic feet at least. 

        I wonder if we have something like the Reynolds number transition that's observed at other altitudes with smaller balloons - maybe we get into a flow regime that introduces a *lot* more drag.  Or maybe a change in the balloon shape (more oblate?) that causes the drag to change due to the balloon's manufacturing and different thicknesses of the latex at different points around the surface.

        It would be interesting to collect the data for all 3000g balloon flights exceeding, say, 115 kft with light payloads and relatively low free lift to look for some commonality.  I still remember chasing Pete Sias' January 2000 flight that went from Salina to Ohio, and use it all the time as an example of a "weird" flight.

        73 de Mark N9XTN

        On Tue, Aug 31, 2010 at 18:24, Joe <nss@...> wrote:
        I'm thinking myself that with the minimal lift, and the extra rarefied atmosphere, I'm wondering if we had a close,, but not quite good enough Pressurization of the envelope. and the lift was reduced,  but not canceled.  The envelope wasn't strong enough to pressurize enough. To totally cancel the lift  But it did reduce it.

        What I'm thinking is at 120 K point was where the envelope has hit that cant stretch any more point, And now the pressure differential starts to rise.  But i need accurate numbers to calculate these numbers to see what the actual pressure differential would have had to be to act like this.


      • Joe
        I can not seem to find this answer, Does anyone know what gas was used? was it HE or H2? Joe WB9SBD -- The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com
        Message 3 of 24 , Sep 1, 2010
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          I can not seem to find this answer,

          Does anyone know what gas was used?

          was it HE or H2?

          Joe WB9SBD
          --
          Sig
          The Original Rolling Ball Clock
          Idle Tyme
          Idle-Tyme.com
          http://www.idle-tyme.com
        • Keith Kaiser
          They told me it was a 3000g balloon using Helium.
          Message 4 of 24 , Sep 1, 2010
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            They told me it was a 3000g balloon using Helium.

            On Sep 1, 2010, at 9:19 AM, Joe wrote:

            I can not seem to find this answer,

            Does anyone know what gas was used?

            was it HE or H2?

            Joe WB9SBD
            --
            <CLEAN-IDLE-TYME-LOGO-100-50.jpg>
            The Original Rolling Ball Clock
            Idle Tyme
            Idle-Tyme.com
            http://www.idle-tyme.com

          • Joe
            Thank You, Joe WB9SBD The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com
            Message 5 of 24 , Sep 1, 2010
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              Thank You,

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

              On 9/1/2010 9:21 AM, Keith Kaiser wrote: They told me it was a 3000g balloon using Helium.

              On Sep 1, 2010, at 9:19 AM, Joe wrote:

              I can not seem to find this answer,

              Does anyone know what gas was used?

              was it HE or H2?

              Joe WB9SBD
              --
              <CLEAN-IDLE-TYME-LOGO-100-50.jpg>
              The Original Rolling Ball Clock
              Idle Tyme
              Idle-Tyme.com
              http://www.idle-tyme.com

            • k6rpt
              Joe, I test tested the scale before the flight and I did the fill indoors. I put a couple of pictures on the website for you to look at. The Gas was HE.
              Message 6 of 24 , Sep 1, 2010
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                Joe, I test tested the scale before the flight and I did the fill indoors. I put a couple of pictures on the website for you to look at. The Gas was HE.

                http://www.californianearspaceproject.com/photos.K6RPT-14.html

                -Ron K6RPT


                --- In GPSL@yahoogroups.com, Joe <nss@...> wrote:
                >
                > I can not seem to find this answer,
                >
                > Does anyone know what gas was used?
                >
                > was it HE or H2?
                >
                > Joe WB9SBD
                > --
                >
                > The Original Rolling Ball Clock
                > Idle Tyme
                > Idle-Tyme.com
                > http://www.idle-tyme.com
                >
              • Mike Manes
                Michael makes an excellent point. This is perzactly how a super-pressure balloon operates - by holding a fixed volume and floating at an altitude where the
                Message 7 of 24 , Sep 1, 2010
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                  Michael makes an excellent point. This is perzactly how a super-pressure
                  balloon operates - by holding a fixed volume and floating at an
                  altitude where the mass of the displaced volume of air equals the mass
                  of the balloon + gas + payload. Normally, the latex would not tolerate
                  that much tension and would burst, but with such a light neck load and
                  at that unusually high altitude, maybe it could?

                  It's also possible that a leak developed at the neck. The neck on a
                  3000 gm Totex is pretty stiff, and it's nearly impossible to fold it
                  over to tie it off after a fill. That's why EOSS uses a modified PVC
                  reducer and 1/2" NPT-M plug on 3000's.

                  Another possible causal mechanism is perforation by a meteor. I'll now
                  avert my eyes and plug my ears to escape your jeers and evil laughter.

                  73 de Mike W5VSI

                  On 9/1/2010 08:09, Michael Willett wrote:
                  >
                  >
                  >
                  > That presentation was by K5NOT - from ARBONET. The phenomenon of a pressure
                  > increase before burst is documented by ARBONET and the University of
                  > Minnesota, it is really there. I am not sure that it would result in the
                  > decrease in envelope expansion enough to demonstrate the near neutral buoyancy
                  > of the K6RPT-14 flight. But yes, the latex does start resisting continued
                  > expansion at the point I call "mechanical maximum" - where the latex just can
                  > not stretch anymore before tearing. Under ideal conditions, the lack of
                  > increased displacement of the envelope due to reaching the mechanical maximum
                  > would result in a floater, since the balloon envelope would start compressing
                  > the helium, possibly enough to achieve a balance between displacement and
                  > compression, thereby resulting in reduced lift. This is a very fine line
                  > though. We don't normally see this with 1000'ft/minute ascent rates, but at
                  > very low ascent rates like the K6RPT-14 balloon, this profile absolutely could
                  > be an indication that mechanical maximum was reached, the envelope resisted
                  > further expansion due to the lower initial envelope pressure, the very sparse
                  > helium mass started to compress, and the ascent started to level off. However,
                  > in this case, ascent was never fully arrested and the mechanical maximum was
                  > exceeded, resulting in an envelope failure.
                  >
                  > Just one thought among many viable explanations...
                  >
                  > We will never really know, since we don't have a profile of the K6RPT-14
                  > envelope pressure, and no concrete evidence is available to dispute any sound
                  > idea about what happened up there.
                  >
                  > --Michael K5NOT
                  >
                  >
                  >
                  > On 8/31/2010 10:46 PM, Jerry Gable wrote:
                  >> Somebody and I don't remember who presented at GPSL this year about the
                  >> pressure increase in a balloon just before burst. I found some stuff on
                  >> party balloons describing this effect but nothing on weather balloons.
                  >>
                  >> A few ounces of extra pressure at lower altitudes is going to wash out in
                  >> the noise but at 120K feet where the outside pressure is 0.06 PSI it could
                  >> make a big difference.
                  >>
                  >> ------------------------------------------------------------------------------
                  >> *From:* Mark Conner <mconner1@...>
                  >> *To:* GPSL list <GPSL@yahoogroups.com>
                  >> *Sent:* Tue, August 31, 2010 7:15:55 PM
                  >> *Subject:* Re: [GPSL] CNSP (K6RPT-14) flight ascent profile
                  >>
                  >> I'm still not sure I buy the pressurization theory - I just can't see latex
                  >> stretched that thin suddenly exhibiting a lot more strength. I don't
                  >> believe we see this with, say, 1500g balloons at around 100 kft.
                  >>
                  >> A pinhole, with a minimal pressure differential behind it, wouldn't seem to
                  >> vent a lot of helium in an hour or two. I suppose one could do the math
                  >> using a minimal but hopefully realistic pressure differential through a hole
                  >> of various sizes and see just how long it would take, but we are probably
                  >> talking several hundred to a couple thousand cubic feet at least.
                  >>
                  >> I wonder if we have something like the Reynolds number transition that's
                  >> observed at other altitudes with smaller balloons - maybe we get into a flow
                  >> regime that introduces a *lot* more drag. Or maybe a change in the balloon
                  >> shape (more oblate?) that causes the drag to change due to the balloon's
                  >> manufacturing and different thicknesses of the latex at different points
                  >> around the surface.
                  >>
                  >> It would be interesting to collect the data for all 3000g balloon flights
                  >> exceeding, say, 115 kft with light payloads and relatively low free lift to
                  >> look for some commonality. I still remember chasing Pete Sias' January 2000
                  >> flight that went from Salina to Ohio, and use it all the time as an example
                  >> of a "weird" flight.
                  >>
                  >> 73 de Mark N9XTN
                  >>
                  >> On Tue, Aug 31, 2010 at 18:24, Joe <nss@... <mailto:nss@...>> wrote:
                  >>
                  >> I'm thinking myself that with the minimal lift, and the extra rarefied
                  >> atmosphere, I'm wondering if we had a close,, but not quite good enough
                  >> Pressurization of the envelope. and the lift was reduced, but not
                  >> canceled. The envelope wasn't strong enough to pressurize enough. To
                  >> totally cancel the lift But it did reduce it.
                  >>
                  >> What I'm thinking is at 120 K point was where the envelope has hit that
                  >> cant stretch any more point, And now the pressure differential starts to
                  >> rise. But i need accurate numbers to calculate these numbers to see
                  >> what the actual pressure differential would have had to be to act like this.
                  >>
                  >>
                  >
                  >
                  >
                  >

                  --
                  Mike Manes mrmanes@... Tel: 303-979-4899
                  "Things should be made as simple as possible, but not more so."
                  A. Einstein
                • Joe
                  Thats what I m crunching numbers on right now Mike, a low pressure equivalent of a super pressure system. With the giant volume of this balloon. It easily has
                  Message 8 of 24 , Sep 1, 2010
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                    Thats what I'm crunching numbers on right now Mike,  a low pressure equivalent of a super pressure system.

                    With the giant volume of this balloon. It easily has the volume to be able to generate quite a LOT of weight differential.

                    The question is if the latex has enough tensile strength to hold the pressure in.

                    That part I'm working on.

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

                    On 9/1/2010 1:37 PM, Mike Manes wrote:
                    Michael makes an excellent point.  This is perzactly how a super-pressure
                    balloon operates - by holding a fixed volume and floating at an
                    altitude where the mass of the displaced volume of air equals the mass
                    of the balloon + gas + payload.  Normally, the latex would not tolerate
                    that much tension and would burst, but with such a light neck load and
                    at that unusually high altitude, maybe it could?
                    
                    It's also possible that a leak developed at the neck.  The neck on a
                    3000 gm Totex is pretty stiff, and it's nearly impossible to fold it
                    over to tie it off after a fill.  That's why EOSS uses a modified PVC
                    reducer and 1/2" NPT-M plug on 3000's.
                    
                    Another possible causal mechanism is perforation by a meteor. I'll now
                    avert my eyes and plug my ears to escape your jeers and evil laughter.
                    
                    73 de Mike W5VSI
                    
                    On 9/1/2010 08:09, Michael Willett wrote:
                    
                    
                    
                    That presentation was by K5NOT - from ARBONET. The phenomenon of a pressure
                    increase before burst is documented by ARBONET and the University of
                    Minnesota, it is really there. I am not sure that it would result in the
                    decrease in envelope expansion enough to demonstrate the near neutral buoyancy
                    of the K6RPT-14 flight. But yes, the latex does start resisting continued
                    expansion at the point I call "mechanical maximum" - where the latex just can
                    not stretch anymore before tearing. Under ideal conditions, the lack of
                    increased displacement of the envelope due to reaching the mechanical maximum
                    would result in a floater, since the balloon envelope would start compressing
                    the helium, possibly enough to achieve a balance between displacement and
                    compression, thereby resulting in reduced lift. This is a very fine line
                    though. We don't normally see this with 1000'ft/minute ascent rates, but at
                    very low ascent rates like the K6RPT-14 balloon, this profile absolutely could
                    be an indication that mechanical maximum was reached, the envelope resisted
                    further expansion due to the lower initial envelope pressure, the very sparse
                    helium mass started to compress, and the ascent started to level off. However,
                    in this case, ascent was never fully arrested and the mechanical maximum was
                    exceeded, resulting in an envelope failure.
                    
                    Just one thought among many viable explanations...
                    
                    We will never really know, since we don't have a profile of the K6RPT-14
                    envelope pressure, and no concrete evidence is available to dispute any sound
                    idea about what happened up there.
                    
                    --Michael K5NOT
                    
                    
                    
                    On 8/31/2010 10:46 PM, Jerry Gable wrote:
                    
                    Somebody and I don't remember who presented at GPSL this year about the
                    pressure increase in a balloon just before burst.  I found some stuff on
                    party balloons describing this effect but nothing on weather balloons.
                    
                    A few ounces of extra pressure at lower altitudes is going to wash out in
                    the noise but at 120K feet where the outside pressure is 0.06 PSI it could
                    make a big difference.
                    
                    ------------------------------------------------------------------------------
                    *From:* Mark Conner <mconner1@...>
                    *To:* GPSL list <GPSL@yahoogroups.com>
                    *Sent:* Tue, August 31, 2010 7:15:55 PM
                    *Subject:* Re: [GPSL] CNSP (K6RPT-14) flight ascent profile
                    
                    I'm still not sure I buy the pressurization theory - I just can't see latex
                    stretched that thin suddenly exhibiting a lot more strength.  I don't
                    believe we see this with, say, 1500g balloons at around 100 kft.
                    
                    A pinhole, with a minimal pressure differential behind it, wouldn't seem to
                    vent a lot of helium in an hour or two.  I suppose one could do the math
                    using a minimal but hopefully realistic pressure differential through a hole
                    of various sizes and see just how long it would take, but we are probably
                    talking several hundred to a couple thousand cubic feet at least.
                    
                    I wonder if we have something like the Reynolds number transition that's
                    observed at other altitudes with smaller balloons - maybe we get into a flow
                    regime that introduces a *lot* more drag.  Or maybe a change in the balloon
                    shape (more oblate?) that causes the drag to change due to the balloon's
                    manufacturing and different thicknesses of the latex at different points
                    around the surface.
                    
                    It would be interesting to collect the data for all 3000g balloon flights
                    exceeding, say, 115 kft with light payloads and relatively low free lift to
                    look for some commonality.  I still remember chasing Pete Sias' January 2000
                    flight that went from Salina to Ohio, and use it all the time as an example
                    of a "weird" flight.
                    
                    73 de Mark N9XTN
                    
                    On Tue, Aug 31, 2010 at 18:24, Joe <nss@... <mailto:nss@...>> wrote:
                    
                        I'm thinking myself that with the minimal lift, and the extra rarefied
                        atmosphere, I'm wondering if we had a close,, but not quite good enough
                        Pressurization of the envelope. and the lift was reduced,  but not
                        canceled.  The envelope wasn't strong enough to pressurize enough. To
                        totally cancel the lift  But it did reduce it.
                    
                        What I'm thinking is at 120 K point was where the envelope has hit that
                        cant stretch any more point, And now the pressure differential starts to
                        rise.  But i need accurate numbers to calculate these numbers to see
                        what the actual pressure differential would have had to be to act like this.
                    
                    
                    
                    
                    
                    
                    
                  • L. Paul Verhage
                    Okay, I ll pipe in about the meteor. I ll break them into three groups based on mass. First is the typical meteor we see at night. They are some 60 to 80
                    Message 9 of 24 , Sep 1, 2010
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                      Okay, I'll pipe in about the meteor.  I'll break them into three groups based on mass.
                       
                      First is the typical meteor we see at night.  They are some 60 to 80 miles above the earth.  Most are the size of a grain of sand or smaller and they won't survive their passage.  They end up as some of the dust you sweep out of your house.  The bit of dust that survives floats to the ground over a long period of time as a gentle rain of stony or metallic dust.  
                       
                      By the time larger meteors (less than 60 tons) reach the denser atmopshere, they have aerobraked enough to fall at terminal velocity.  These make it to the ground for collectors and museums to purchase.  Fresh meteorites are actually cold, not glowing hot.  Ablation has melted their surface and as it streamed away, the vaporized melt took heat with it.  Meteoriods have been cold soaking in the space for billions of years and a brief passage through the atmosphere doesn't heat up their interiors greatly (plus they made a passage through an extremely cold stratosphere to reach the ground).  The largest intact meteorites in collections are 60 tons and they land with a thud, producing a minor pit in the ground.  I don't think its likely that a tumbling stone will make a small hole in a balloon upon impact.
                       
                      Meteors more than 60 tons will continue to fall at cosmic velocities because they are too massive for the atmosphere to slow down.  If one of those impacted the balloon, there would be a substantial impact site on the ground below (or if large enough, we'd all be dead).  These meteors are bright, even during the day and the impact site would be destroyed.  Unless I've missed something in the news, that didn't happen.
                       
                      So meteorite impact?  I don't see how.
                       
                      By the way, in space they're called meteoroids. 
                      As the glowing streak across the sky, they're called meteors (the brightest are called bollides). 
                      On the ground they're called meteorites. 
                      If you think you have a meteorite but it turns out to be a plain 'ol earth rock, its called a meteorwrong.
                       
                      Paul
                             

                      On Wed, Sep 1, 2010 at 1:37 PM, Mike Manes <mrmanes@...> wrote:
                      Michael makes an excellent point.  This is perzactly how a super-pressure
                      balloon operates - by holding a fixed volume and floating at an
                      altitude where the mass of the displaced volume of air equals the mass
                      of the balloon + gas + payload.  Normally, the latex would not tolerate
                      that much tension and would burst, but with such a light neck load and
                      at that unusually high altitude, maybe it could?

                      It's also possible that a leak developed at the neck.  The neck on a
                      3000 gm Totex is pretty stiff, and it's nearly impossible to fold it
                      over to tie it off after a fill.  That's why EOSS uses a modified PVC
                      reducer and 1/2" NPT-M plug on 3000's.

                      Another possible causal mechanism is perforation by a meteor. I'll now
                      avert my eyes and plug my ears to escape your jeers and evil laughter.

                      73 de Mike W5VSI

                      On 9/1/2010 08:09, Michael Willett wrote:
                      >
                      >
                      >
                      > That presentation was by K5NOT - from ARBONET. The phenomenon of a pressure
                      > increase before burst is documented by ARBONET and the University of
                      > Minnesota, it is really there. I am not sure that it would result in the
                      > decrease in envelope expansion enough to demonstrate the near neutral buoyancy
                      > of the K6RPT-14 flight. But yes, the latex does start resisting continued
                      > expansion at the point I call "mechanical maximum" - where the latex just can
                      > not stretch anymore before tearing. Under ideal conditions, the lack of
                      > increased displacement of the envelope due to reaching the mechanical maximum
                      > would result in a floater, since the balloon envelope would start compressing
                      > the helium, possibly enough to achieve a balance between displacement and
                      > compression, thereby resulting in reduced lift. This is a very fine line
                      > though. We don't normally see this with 1000'ft/minute ascent rates, but at
                      > very low ascent rates like the K6RPT-14 balloon, this profile absolutely could
                      > be an indication that mechanical maximum was reached, the envelope resisted
                      > further expansion due to the lower initial envelope pressure, the very sparse
                      > helium mass started to compress, and the ascent started to level off. However,
                      > in this case, ascent was never fully arrested and the mechanical maximum was
                      > exceeded, resulting in an envelope failure.
                      >
                      > Just one thought among many viable explanations...
                      >
                      > We will never really know, since we don't have a profile of the K6RPT-14
                      > envelope pressure, and no concrete evidence is available to dispute any sound
                      > idea about what happened up there.
                      >
                      > --Michael K5NOT
                      >
                      >
                      >
                      > On 8/31/2010 10:46 PM, Jerry Gable wrote:
                      >> Somebody and I don't remember who presented at GPSL this year about the
                      >> pressure increase in a balloon just before burst.  I found some stuff on
                      >> party balloons describing this effect but nothing on weather balloons.
                      >>
                      >> A few ounces of extra pressure at lower altitudes is going to wash out in
                      >> the noise but at 120K feet where the outside pressure is 0.06 PSI it could
                      >> make a big difference.
                      >>
                      >> ------------------------------------------------------------------------------
                      >> *From:* Mark Conner <mconner1@...>
                      >> *To:* GPSL list <GPSL@yahoogroups.com>
                      >> *Sent:* Tue, August 31, 2010 7:15:55 PM
                      >> *Subject:* Re: [GPSL] CNSP (K6RPT-14) flight ascent profile
                      >>
                      >> I'm still not sure I buy the pressurization theory - I just can't see latex
                      >> stretched that thin suddenly exhibiting a lot more strength.  I don't
                      >> believe we see this with, say, 1500g balloons at around 100 kft.
                      >>
                      >> A pinhole, with a minimal pressure differential behind it, wouldn't seem to
                      >> vent a lot of helium in an hour or two.  I suppose one could do the math
                      >> using a minimal but hopefully realistic pressure differential through a hole
                      >> of various sizes and see just how long it would take, but we are probably
                      >> talking several hundred to a couple thousand cubic feet at least.
                      >>
                      >> I wonder if we have something like the Reynolds number transition that's
                      >> observed at other altitudes with smaller balloons - maybe we get into a flow
                      >> regime that introduces a *lot* more drag.  Or maybe a change in the balloon
                      >> shape (more oblate?) that causes the drag to change due to the balloon's
                      >> manufacturing and different thicknesses of the latex at different points
                      >> around the surface.
                      >>
                      >> It would be interesting to collect the data for all 3000g balloon flights
                      >> exceeding, say, 115 kft with light payloads and relatively low free lift to
                      >> look for some commonality.  I still remember chasing Pete Sias' January 2000
                      >> flight that went from Salina to Ohio, and use it all the time as an example
                      >> of a "weird" flight.
                      >>
                      >> 73 de Mark N9XTN
                      >>
                      >> On Tue, Aug 31, 2010 at 18:24, Joe <nss@... <mailto:nss@...>> wrote:
                      >>
                      >>     I'm thinking myself that with the minimal lift, and the extra rarefied
                      >>     atmosphere, I'm wondering if we had a close,, but not quite good enough
                      >>     Pressurization of the envelope. and the lift was reduced,  but not
                      >>     canceled.  The envelope wasn't strong enough to pressurize enough. To
                      >>     totally cancel the lift  But it did reduce it.
                      >>
                      >>     What I'm thinking is at 120 K point was where the envelope has hit that
                      >>     cant stretch any more point, And now the pressure differential starts to
                      >>     rise.  But i need accurate numbers to calculate these numbers to see
                      >>     what the actual pressure differential would have had to be to act like this.
                      >>
                      >>
                      >
                      >
                      >
                      >

                      --
                      Mike Manes    mrmanes@...     Tel: 303-979-4899
                      "Things should be made as simple as possible, but not more so."
                      A. Einstein


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                      --
                      Onwards and Upwards,
                      Paul
                    • Mike Manes
                      There s the rub. If latex were that strong unconditionally, then all of our flights would be floaters rather than bursters. The hard part of developing a
                      Message 10 of 24 , Sep 1, 2010
                      • 0 Attachment
                        There's the rub. If latex were that strong unconditionally, then all of our
                        flights would be floaters rather than bursters. The hard part of developing
                        a superpressure balloon is finding envelope material that's both light and
                        strong. It can be done easily with ordinary film with 50 gm payloads and
                        float altitudes in the troposphere.

                        73 de Mike W5VSI

                        On 9/1/2010 13:25, Joe wrote:
                        > Thats what I'm crunching numbers on right now Mike, a low pressure
                        > equivalent of a super pressure system.
                        >
                        > With the giant volume of this balloon. It easily has the volume to be able to
                        > generate quite a LOT of weight differential.
                        >
                        > The question is if the latex has enough tensile strength to hold the pressure in.
                        >
                        > That part I'm working on.
                        >
                        > Joe WB9SBD
                        >
                        > The Original Rolling Ball Clock
                        > Idle Tyme
                        > Idle-Tyme.com
                        > http://www.idle-tyme.com
                        >
                        > On 9/1/2010 1:37 PM, Mike Manes wrote:
                        >> Michael makes an excellent point. This is perzactly how a super-pressure
                        >> balloon operates - by holding a fixed volume and floating at an
                        >> altitude where the mass of the displaced volume of air equals the mass
                        >> of the balloon + gas + payload. Normally, the latex would not tolerate
                        >> that much tension and would burst, but with such a light neck load and
                        >> at that unusually high altitude, maybe it could?
                        >>
                        >> It's also possible that a leak developed at the neck. The neck on a
                        >> 3000 gm Totex is pretty stiff, and it's nearly impossible to fold it
                        >> over to tie it off after a fill. That's why EOSS uses a modified PVC
                        >> reducer and 1/2" NPT-M plug on 3000's.
                        >>
                        >> Another possible causal mechanism is perforation by a meteor. I'll now
                        >> avert my eyes and plug my ears to escape your jeers and evil laughter.
                        >>
                        >> 73 de Mike W5VSI
                        >>
                        >> On 9/1/2010 08:09, Michael Willett wrote:
                        >>>
                        >>>
                        >>> That presentation was by K5NOT - from ARBONET. The phenomenon of a pressure
                        >>> increase before burst is documented by ARBONET and the University of
                        >>> Minnesota, it is really there. I am not sure that it would result in the
                        >>> decrease in envelope expansion enough to demonstrate the near neutral buoyancy
                        >>> of the K6RPT-14 flight. But yes, the latex does start resisting continued
                        >>> expansion at the point I call "mechanical maximum" - where the latex just can
                        >>> not stretch anymore before tearing. Under ideal conditions, the lack of
                        >>> increased displacement of the envelope due to reaching the mechanical maximum
                        >>> would result in a floater, since the balloon envelope would start compressing
                        >>> the helium, possibly enough to achieve a balance between displacement and
                        >>> compression, thereby resulting in reduced lift. This is a very fine line
                        >>> though. We don't normally see this with 1000'ft/minute ascent rates, but at
                        >>> very low ascent rates like the K6RPT-14 balloon, this profile absolutely could
                        >>> be an indication that mechanical maximum was reached, the envelope resisted
                        >>> further expansion due to the lower initial envelope pressure, the very sparse
                        >>> helium mass started to compress, and the ascent started to level off. However,
                        >>> in this case, ascent was never fully arrested and the mechanical maximum was
                        >>> exceeded, resulting in an envelope failure.
                        >>>
                        >>> Just one thought among many viable explanations...
                        >>>
                        >>> We will never really know, since we don't have a profile of the K6RPT-14
                        >>> envelope pressure, and no concrete evidence is available to dispute any sound
                        >>> idea about what happened up there.
                        >>>
                        >>> --Michael K5NOT
                        >>>
                        >>>
                        >>>
                        >>> On 8/31/2010 10:46 PM, Jerry Gable wrote:
                        >>>> Somebody and I don't remember who presented at GPSL this year about the
                        >>>> pressure increase in a balloon just before burst. I found some stuff on
                        >>>> party balloons describing this effect but nothing on weather balloons.
                        >>>>
                        >>>> A few ounces of extra pressure at lower altitudes is going to wash out in
                        >>>> the noise but at 120K feet where the outside pressure is 0.06 PSI it could
                        >>>> make a big difference.
                        >>>>
                        >>>> ------------------------------------------------------------------------------
                        >>>> *From:* Mark Conner<mconner1@...>
                        >>>> *To:* GPSL list<GPSL@yahoogroups.com>
                        >>>> *Sent:* Tue, August 31, 2010 7:15:55 PM
                        >>>> *Subject:* Re: [GPSL] CNSP (K6RPT-14) flight ascent profile
                        >>>>
                        >>>> I'm still not sure I buy the pressurization theory - I just can't see latex
                        >>>> stretched that thin suddenly exhibiting a lot more strength. I don't
                        >>>> believe we see this with, say, 1500g balloons at around 100 kft.
                        >>>>
                        >>>> A pinhole, with a minimal pressure differential behind it, wouldn't seem to
                        >>>> vent a lot of helium in an hour or two. I suppose one could do the math
                        >>>> using a minimal but hopefully realistic pressure differential through a hole
                        >>>> of various sizes and see just how long it would take, but we are probably
                        >>>> talking several hundred to a couple thousand cubic feet at least.
                        >>>>
                        >>>> I wonder if we have something like the Reynolds number transition that's
                        >>>> observed at other altitudes with smaller balloons - maybe we get into a flow
                        >>>> regime that introduces a *lot* more drag. Or maybe a change in the balloon
                        >>>> shape (more oblate?) that causes the drag to change due to the balloon's
                        >>>> manufacturing and different thicknesses of the latex at different points
                        >>>> around the surface.
                        >>>>
                        >>>> It would be interesting to collect the data for all 3000g balloon flights
                        >>>> exceeding, say, 115 kft with light payloads and relatively low free lift to
                        >>>> look for some commonality. I still remember chasing Pete Sias' January 2000
                        >>>> flight that went from Salina to Ohio, and use it all the time as an example
                        >>>> of a "weird" flight.
                        >>>>
                        >>>> 73 de Mark N9XTN
                        >>>>
                        >>>> On Tue, Aug 31, 2010 at 18:24, Joe<nss@... <mailto:nss@...>> wrote:
                        >>>>
                        >>>> I'm thinking myself that with the minimal lift, and the extra rarefied
                        >>>> atmosphere, I'm wondering if we had a close,, but not quite good enough
                        >>>> Pressurization of the envelope. and the lift was reduced, but not
                        >>>> canceled. The envelope wasn't strong enough to pressurize enough. To
                        >>>> totally cancel the lift But it did reduce it.
                        >>>>
                        >>>> What I'm thinking is at 120 K point was where the envelope has hit that
                        >>>> cant stretch any more point, And now the pressure differential starts to
                        >>>> rise. But i need accurate numbers to calculate these numbers to see
                        >>>> what the actual pressure differential would have had to be to act like this.
                        >>>>
                        >>>>
                        >>>
                        >>>
                        >>>

                        --
                        Mike Manes mrmanes@... Tel: 303-979-4899
                        "Things should be made as simple as possible, but not more so."
                        A. Einstein
                      • Mike Manes
                        Terminal velocity, given a fixed drag area, varies inversely with the square root of air density. So a meteoroid (thenkyew) will fall ten times as fast at
                        Message 11 of 24 , Sep 1, 2010
                        • 0 Attachment
                          Terminal velocity, given a fixed drag area, varies inversely with the square
                          root of air density. So a meteoroid (thenkyew) will fall ten times as fast
                          at 100K' (10 mbar) than it will at sea level. Now, kinetic energy varies as
                          the square of velocity, yielding 100x the energy at 100K' vs the deck.

                          So an object in free fall thru the atmosphere will carry kinetic energy
                          inversely proportional to air density.

                          Enough to puncture a latex envelope? Beats me, but not out of the question.

                          Ain't physics wunnerful?

                          73 de Mike W5VSI

                          On 9/1/2010 13:41, L. Paul Verhage wrote:
                          >
                          >
                          > Okay, I'll pipe in about the meteor. I'll break them into three groups based
                          > on mass.
                          > First is the typical meteor we see at night. They are some 60 to 80 miles
                          > above the earth. Most are the size of a grain of sand or smaller and they
                          > won't survive their passage. They end up as some of the dust you sweep out of
                          > your house. The bit of dust that survives floats to the ground over a long
                          > period of time as a gentle rain of stony or metallic dust.
                          > By the time larger meteors (less than 60 tons) reach the denser atmopshere,
                          > they have aerobraked enough to fall at terminal velocity. These make it to
                          > the ground for collectors and museums to purchase. Fresh meteorites are
                          > actually cold, not glowing hot. Ablation has melted their surface and as it
                          > streamed away, the vaporized melt took heat with it. Meteoriods have been
                          > cold soaking in the space for billions of years and a brief passage through
                          > the atmosphere doesn't heat up their interiors greatly (plus they made a
                          > passage through an extremely cold stratosphere to reach the ground). The
                          > largest intact meteorites in collections are 60 tons and they land with a
                          > thud, producing a minor pit in the ground. I don't think its likely that a
                          > tumbling stone will make a small hole in a balloon upon impact.
                          > Meteors more than 60 tons will continue to fall at cosmic velocities
                          > because they are too massive for the atmosphere to slow down. If one of those
                          > impacted the balloon, there would be a substantial impact site on the ground
                          > below (or if large enough, we'd all be dead). These meteors are bright, even
                          > during the day and the impact site would be destroyed. Unless I've missed
                          > something in the news, that didn't happen.
                          > So meteorite impact? I don't see how.
                          > By the way, in space they're called meteoroids.
                          > As the glowing streak across the sky, they're called meteors (the brightest
                          > are called bollides).
                          > On the ground they're called meteorites.
                          > If you think you have a meteorite but it turns out to be a plain 'ol earth
                          > rock, its called a meteorwrong.
                          > Paul
                          >
                          >
                          > On Wed, Sep 1, 2010 at 1:37 PM, Mike Manes <mrmanes@...
                          > <mailto:mrmanes@...>> wrote:
                          >
                          > Michael makes an excellent point. This is perzactly how a super-pressure
                          > balloon operates - by holding a fixed volume and floating at an
                          > altitude where the mass of the displaced volume of air equals the mass
                          > of the balloon + gas + payload. Normally, the latex would not tolerate
                          > that much tension and would burst, but with such a light neck load and
                          > at that unusually high altitude, maybe it could?
                          >
                          > It's also possible that a leak developed at the neck. The neck on a
                          > 3000 gm Totex is pretty stiff, and it's nearly impossible to fold it
                          > over to tie it off after a fill. That's why EOSS uses a modified PVC
                          > reducer and 1/2" NPT-M plug on 3000's.
                          >
                          > Another possible causal mechanism is perforation by a meteor. I'll now
                          > avert my eyes and plug my ears to escape your jeers and evil laughter.
                          >
                          > 73 de Mike W5VSI
                          >
                          > On 9/1/2010 08:09, Michael Willett wrote:
                          > >
                          > >
                          > >
                          > > That presentation was by K5NOT - from ARBONET. The phenomenon of a pressure
                          > > increase before burst is documented by ARBONET and the University of
                          > > Minnesota, it is really there. I am not sure that it would result in the
                          > > decrease in envelope expansion enough to demonstrate the near neutral
                          > buoyancy
                          > > of the K6RPT-14 flight. But yes, the latex does start resisting continued
                          > > expansion at the point I call "mechanical maximum" - where the latex
                          > just can
                          > > not stretch anymore before tearing. Under ideal conditions, the lack of
                          > > increased displacement of the envelope due to reaching the mechanical
                          > maximum
                          > > would result in a floater, since the balloon envelope would start
                          > compressing
                          > > the helium, possibly enough to achieve a balance between displacement and
                          > > compression, thereby resulting in reduced lift. This is a very fine line
                          > > though. We don't normally see this with 1000'ft/minute ascent rates, but at
                          > > very low ascent rates like the K6RPT-14 balloon, this profile
                          > absolutely could
                          > > be an indication that mechanical maximum was reached, the envelope resisted
                          > > further expansion due to the lower initial envelope pressure, the very
                          > sparse
                          > > helium mass started to compress, and the ascent started to level off.
                          > However,
                          > > in this case, ascent was never fully arrested and the mechanical
                          > maximum was
                          > > exceeded, resulting in an envelope failure.
                          > >
                          > > Just one thought among many viable explanations...
                          > >
                          > > We will never really know, since we don't have a profile of the K6RPT-14
                          > > envelope pressure, and no concrete evidence is available to dispute any
                          > sound
                          > > idea about what happened up there.
                          > >
                          > > --Michael K5NOT
                          > >
                          > >
                          > >
                          > > On 8/31/2010 10:46 PM, Jerry Gable wrote:
                          > >> Somebody and I don't remember who presented at GPSL this year about the
                          > >> pressure increase in a balloon just before burst. I found some stuff on
                          > >> party balloons describing this effect but nothing on weather balloons.
                          > >>
                          > >> A few ounces of extra pressure at lower altitudes is going to wash out in
                          > >> the noise but at 120K feet where the outside pressure is 0.06 PSI it could
                          > >> make a big difference.
                          > >>
                          > >>
                          > ------------------------------------------------------------------------------
                          > >> *From:* Mark Conner <mconner1@... <mailto:mconner1@...>>
                          > >> *To:* GPSL list <GPSL@yahoogroups.com <mailto:GPSL@yahoogroups.com>>
                          > >> *Sent:* Tue, August 31, 2010 7:15:55 PM
                          > >> *Subject:* Re: [GPSL] CNSP (K6RPT-14) flight ascent profile
                          > >>
                          > >> I'm still not sure I buy the pressurization theory - I just can't see
                          > latex
                          > >> stretched that thin suddenly exhibiting a lot more strength. I don't
                          > >> believe we see this with, say, 1500g balloons at around 100 kft.
                          > >>
                          > >> A pinhole, with a minimal pressure differential behind it, wouldn't
                          > seem to
                          > >> vent a lot of helium in an hour or two. I suppose one could do the math
                          > >> using a minimal but hopefully realistic pressure differential through
                          > a hole
                          > >> of various sizes and see just how long it would take, but we are probably
                          > >> talking several hundred to a couple thousand cubic feet at least.
                          > >>
                          > >> I wonder if we have something like the Reynolds number transition that's
                          > >> observed at other altitudes with smaller balloons - maybe we get into
                          > a flow
                          > >> regime that introduces a *lot* more drag. Or maybe a change in the
                          > balloon
                          > >> shape (more oblate?) that causes the drag to change due to the balloon's
                          > >> manufacturing and different thicknesses of the latex at different points
                          > >> around the surface.
                          > >>
                          > >> It would be interesting to collect the data for all 3000g balloon flights
                          > >> exceeding, say, 115 kft with light payloads and relatively low free
                          > lift to
                          > >> look for some commonality. I still remember chasing Pete Sias'
                          > January 2000
                          > >> flight that went from Salina to Ohio, and use it all the time as an
                          > example
                          > >> of a "weird" flight.
                          > >>
                          > >> 73 de Mark N9XTN
                          > >>
                          > >> On Tue, Aug 31, 2010 at 18:24, Joe <nss@... <mailto:nss@...>
                          > <mailto:nss@... <mailto:nss@...>>> wrote:
                          > >>
                          > >> I'm thinking myself that with the minimal lift, and the extra rarefied
                          > >> atmosphere, I'm wondering if we had a close,, but not quite good
                          > enough
                          > >> Pressurization of the envelope. and the lift was reduced, but not
                          > >> canceled. The envelope wasn't strong enough to pressurize enough. To
                          > >> totally cancel the lift But it did reduce it.
                          > >>
                          > >> What I'm thinking is at 120 K point was where the envelope has hit
                          > that
                          > >> cant stretch any more point, And now the pressure differential
                          > starts to
                          > >> rise. But i need accurate numbers to calculate these numbers to see
                          > >> what the actual pressure differential would have had to be to act
                          > like this.
                          > >>
                          > >>
                          > >
                          > >
                          > >
                          > >
                          >
                          > --
                          > Mike Manes mrmanes@... <mailto:mrmanes@...> Tel: 303-979-4899
                          > "Things should be made as simple as possible, but not more so."
                          > A. Einstein
                          >
                          >
                          > ------------------------------------
                          >
                          > Yahoo! Groups Links
                          >
                          >
                          >
                          >
                          >
                          >
                          > --
                          > Onwards and Upwards,
                          > Paul
                          >
                          >
                          >

                          --
                          Mike Manes mrmanes@... Tel: 303-979-4899
                          "Things should be made as simple as possible, but not more so."
                          A. Einstein
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