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RE: Hammock Camping Franken pad and bride of Frankenpad

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  • Ernest Engman
    The pad I use serves a couple of purposes. 1. Wind/air barrier. It is made of aluminum coated close cell foam pad. I can use it alone in cool but not cold
    Message 1 of 18 , Feb 2, 2003
    • 0 Attachment
      Message

      The pad I use serves a couple of purposes.

       

      1. Wind/air barrier. It is made of aluminum coated close cell foam pad. I can use it alone in cool but not cold temps by turning it shiny side down and preventing air circulation.
      2. Since it is also foam, it adds a light and small layer of insulation.
      3. It serves as a ground pad under the hammock when I lay it on the ground to stay warm. It is wide and long enough for that. Often when having to do this, the ground isn’t dry and no sense getting the fabric wet.
      4. Closed cell foam pads work better against a non-breathable barrier than against a breathable material like than hammock. See this excellent post by youngblood: http://hikinghq.net/forum/showthread.php?s=10900e520cfd29662ed8485b43febff2&threadid=359

       

      I say heat reflectors are snake oil, because the science that says they are a radiant heat reflector for someone sleeping in a hammock is highly flawed.

       

      Ernest Engman

      AKA SGT Rock

      sgtrock@...

      http://hikinghq.net

       

       

      -----Original Message-----
      From: David Chinell [mailto:dchinell@...]
      Sent: Thursday, January 30, 2003 9:25 AM
      To: hammockcamping@yahoogroups.com
      Subject: RE: Hammock Camping Franken pad and bride of Frankenpad

       

      Sarge: Thanks for the R&D work. I'm dreaming along the same lines. That's what the evazote "shawl" is about -- extra width between the hips and shoulders.

       

      But I need to make a cloth casing to hold the wings so they're detachable, rather than permanent, so I can roll it all up in a single, 24-inch wide roll. How do you pack the Frankenpad?

       

      And if, as you say, "heat reflectors are snake oil" why do you use a windshield reflector? Why not just another pad?

       

      Bear

       


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      hammockcamping-unsubscribe@yahoogroups.com



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    • starnescr <starnescr@yahoo.com>
      If a reflectic pad is snake oil then why are emergency blankets made of reflective material. Of course you wrap a space blanket around you and are not laying
      Message 2 of 18 , Feb 2, 2003
      • 0 Attachment
        If a reflectic pad is snake oil then why are "emergency blankets
        made of reflective material. Of course you wrap a space blanket
        around you and are not laying on it only. Would a reflective pad be
        more effective (no mater how unpracticle) if it went all the way
        around you. I think the reflective pad is somewhat usefull if you
        are not laying directly on it. From what Tom Hennessy and others
        have said there needs to be a little space between the heat source
        and the reflective surface. Hence my fleece covered reflectic pad.
        A 1/2 inch closed cell foam pad the same size as mine would be
        heavier but I'm not sure how much. I'm not saying a reflective pad
        is the answer either. I just believe given the same R value a
        reflective pad would be slightly warmer.

        Coy Boy

        --- In hammockcamping@yahoogroups.com, "Ernest Engman"
        <ebengman@h...> wrote:
        > The pad I use serves a couple of purposes.
        >
        > 1. Wind/air barrier. It is made of aluminum coated close cell
        foam
        > pad. I can use it alone in cool but not cold temps by turning it
        shiny
        > side down and preventing air circulation.
        > 2. Since it is also foam, it adds a light and small layer of
        > insulation.
        > 3. It serves as a ground pad under the hammock when I lay it on
        the
        > ground to stay warm. It is wide and long enough for that. Often
        when
        > having to do this, the ground isn't dry and no sense getting the
        fabric
        > wet.
        > 4. Closed cell foam pads work better against a non-breathable
        > barrier than against a breathable material like than hammock. See
        this
        > excellent post by youngblood:
        > http://hikinghq.net/forum/showthread.php?
        s=10900e520cfd29662ed8485b43feb
        > ff2
        > <http://hikinghq.net/forum/showthread.php?
        s=10900e520cfd29662ed8485b43fe
        > bff2&threadid=359> &threadid=359
        >
        > I say heat reflectors are snake oil, because the science that says
        they
        > are a radiant heat reflector for someone sleeping in a hammock is
        highly
        > flawed.
        >
        > Ernest Engman
        > AKA SGT Rock
        > sgtrock@h...
        > <http://hikinghq.net/> http://hikinghq.net
        >
        >
        > -----Original Message-----
        > From: David Chinell [mailto:dchinell@m...]
        > Sent: Thursday, January 30, 2003 9:25 AM
        > To: hammockcamping@yahoogroups.com
        > Subject: RE: Hammock Camping Franken pad and bride of Frankenpad
        >
        > Sarge: Thanks for the R&D work. I'm dreaming along the same lines.
        > That's what the evazote "shawl" is about -- extra width between
        the hips
        > and shoulders.
        >
        > But I need to make a cloth casing to hold the wings so they're
        > detachable, rather than permanent, so I can roll it all up in a
        single,
        > 24-inch wide roll. How do you pack the Frankenpad?
        >
        > And if, as you say, "heat reflectors are snake oil" why do you use
        a
        > windshield reflector? Why not just another pad?
        >
        > Bear
        >
        >
        > To unsubscribe from this group, send an email to:
        > hammockcamping-unsubscribe@yahoogroups.com
        >
        >
        >
        > Your use of Yahoo! Groups is subject to the Yahoo!
        > <http://docs.yahoo.com/info/terms/> Terms of Service.
      • Ernest Engman
        If reflective pads are so good, then why not a sleeping bag that is made from them? They aren t. Can a space blanket really work? Somewhat, but I ve never bet
        Message 3 of 18 , Feb 2, 2003
        • 0 Attachment
          If reflective pads are so good, then why not a sleeping bag that is made
          from them? They aren't. Can a space blanket really work? Somewhat, but
          I've never bet my life on one and will never do so because the theory
          that tells you they will is very flawed. But people buy them, so people
          will sell them.

          My position that radiant heat reflectors are snake oil has grown over
          time, and after a couple of debates with some people smarter than I, I'm
          sure of it.

          The science is this, and don't take it is as just me, this is from an
          aerospace engineer working for NASA and another engineer that have both
          convinced me of this:

          Heat isn't as simple as saying 25% of your body heat is lost thru
          radiant heat loss. It is much more complicated than that. On a night
          with high humidity but low temperature, you will be a lot colder than on
          a night with the same temp with lower humidity. Why? Because the
          moisture in the air is conductive, same principle as sleeping in a wet
          bag in a way, but you are loosing more of a percent of heat this way and
          less thru radiant heat. Same thing in high winds. How can higher winds
          make that big a difference if more is lost thru radiant heat loss? It
          couldn't but the real problem is demonstrated by this is convective heat
          loss. I hope this isn't too much of a tangent for the discussion, but it
          just shows how one factor can change the percentages.

          Radiant heat reflectors (actually insulators) were made to work in
          space. In space there isn't any air flow at all to worry about, so
          absolutely no convective heat loss to worry about. In space they not
          only have to protect the person from heat loss, but excessive heat gain
          from solar radiant heat. Ever hear that in space one side will freeze
          while the side facing the sun would burn up?

          So what is heat? Heat is energy, cold isn't the opposite, it is the
          absence of heat. Heat energy, by its nature, will try to equalize the
          energy from places of higher energy to places of lower energy. If your
          body is the point of higher energy (which it normally is at night) then
          your heat energy will attempt to displace outward.

          There are about 4 means of heat loss that you must worry about.

          1. Evaporation. When you sweat or breathe, the water loss from your body
          carries heat energy with it. To prevent this you can wrap yourself in a
          vapor barrier. But to make this work, you will most likely want to be
          totally undressed or you will end up in soggy clothing which is also
          bad. Ed talks about always allowing your breath a way to get out - very
          important!

          2. Radiant heat loss (the main topic) which is heat transfer based on
          how IR opaque or transparent barriers between you and the object are. If
          you were to stand naked in a freezer, you would loose a great deal of
          body heat thru radiant heat loss. Wrap yourself in a space blanket, and
          you would reflect about 50% of your heat loss back at yourself because
          the air will still carry away some through convection. But to reduce
          this loss, you can wear clothing. Since the clothing is essentially IR
          opaque, you can reduce this loss of you radiant heat energy down to
          about 5% of your original loss. So if you have a given (which I disagree
          with) of 25% heat loss thru radiant heat, and reduce that to 5% of the
          original loss by wearing clothing, then you are down to less than 2% of
          your total body heat loss. Now use a radiant heat reflector to capture
          50% of that, and it is returning less than 1% of your total body heat
          lost. This 95% (give or take) heat loss prevention occurs for every
          layer of IR opaque material between you, and the colder objects around
          you. So if you wear clothing, then a sleeping bag (inside layer) then
          you already have reduced your IR heat loss to less than 1%.

          For a radiant heat reflector to work (in the atmosphere) you would need
          to be inside it without clothing and not touch it (which is where I'm
          going next) for it to be of any help. Interestingly Stephensons
          Warmlight sleeping bags understands this and explains it quite well for
          someone looking at their bags.

          To prove this, feel free to make a shower curtain of mylar then turn
          your heat off. Stand inside the shower with the curtain nude and see if
          it (the curtain) gets warm. It won't. You are not a big enough an
          emitter of IR to make it work. The sun is a huge IR heat emitter and
          does this quite well, unfortunately our bodies don't come with a huge
          supply of self heating hydrogen.

          3. Convective heat loss. When air passes around your body, it carries
          away heat; this is the biggest problem keeping warm in an atmosphere.
          The trick is to stop air from passing around you and create pockets of
          still air that can be warmed and kept into place. Sleeping bags and pads
          are designed to do this. Again, if radiant heat reflectors were truly
          beneficial, then that is how we should have been staying warm for the
          last 50 years in the hiking world, but so far we all still use sleeping
          bags and pads. Ed has done a great job of figuring out how to make this
          happen with a pea pod. And to make it even better would be to surround
          the pod with a waterproof material that totally stopped any air from
          getting out and totally stopped any moisture from getting out. Foil wrap
          does a great job of this, by the way - that is what a space blanket is
          made from. But it also has a drawback that it traps moisture that
          destroys loft in a down bag. The best solution would be some material
          that could surround your pea pot and prevent air flow in, strip heat on
          the way out for moisture, and wouldn't suffocate you.

          4. Conductive heat loss. This is a problem because some people try
          laying directly on the reflective surfaces which are also excellent
          conductors. Some spots under these conductors are warm because they
          prevent evaporation or convection, but they also conduct heat away. This
          is also how the moisture carries away your body heat.

          So to conclude this lengthy post and spark the debate I don't mean to.
          Radiant heat reflectors are not that inside the atmosphere, they are
          serving as barriers to convective heat and if used right, evaporative
          heat. I've never said that people using a system that involves a "Heat
          Rflector" aren't staying warm (heck I have one) I'm just saying they
          should get smart about why they work and figure the best applications
          for these materials. Aluminized plastic (mylar) is very good at blocking
          moisture, and it is what all really long shelf life packet foods are now
          packed in.

          Ernest Engman
          AKA SGT Rock
          sgtrock@...
          http://hikinghq.net



          -----Original Message-----
          From: starnescr <starnescr@...> [mailto:starnescr@...]
          Sent: Sunday, February 02, 2003 1:37 PM
          To: hammockcamping@yahoogroups.com
          Subject: Re: Hammock Camping Franken pad and bride of Frankenpad

          If a reflectic pad is snake oil then why are "emergency blankets
          made of reflective material. Of course you wrap a space blanket
          around you and are not laying on it only. Would a reflective pad be
          more effective (no mater how unpracticle) if it went all the way
          around you. I think the reflective pad is somewhat usefull if you
          are not laying directly on it. From what Tom Hennessy and others
          have said there needs to be a little space between the heat source
          and the reflective surface. Hence my fleece covered reflectic pad.
          A 1/2 inch closed cell foam pad the same size as mine would be
          heavier but I'm not sure how much. I'm not saying a reflective pad
          is the answer either. I just believe given the same R value a
          reflective pad would be slightly warmer.

          Coy Boy

          --- In hammockcamping@yahoogroups.com, "Ernest Engman"
          <ebengman@h...> wrote:
          > The pad I use serves a couple of purposes.
          >
          > 1. Wind/air barrier. It is made of aluminum coated close cell
          foam
          > pad. I can use it alone in cool but not cold temps by turning it
          shiny
          > side down and preventing air circulation.
          > 2. Since it is also foam, it adds a light and small layer of
          > insulation.
          > 3. It serves as a ground pad under the hammock when I lay it on
          the
          > ground to stay warm. It is wide and long enough for that. Often
          when
          > having to do this, the ground isn't dry and no sense getting the
          fabric
          > wet.
          > 4. Closed cell foam pads work better against a non-breathable
          > barrier than against a breathable material like than hammock. See
          this
          > excellent post by youngblood:
          > http://hikinghq.net/forum/showthread.php?
          s=10900e520cfd29662ed8485b43feb
          > ff2
          > <http://hikinghq.net/forum/showthread.php?
          s=10900e520cfd29662ed8485b43fe
          > bff2&threadid=359> &threadid=359
          >
          > I say heat reflectors are snake oil, because the science that says
          they
          > are a radiant heat reflector for someone sleeping in a hammock is
          highly
          > flawed.
          >
          > Ernest Engman
          > AKA SGT Rock
          > sgtrock@h...
          > <http://hikinghq.net/> http://hikinghq.net
          >
          >
          > -----Original Message-----
          > From: David Chinell [mailto:dchinell@m...]
          > Sent: Thursday, January 30, 2003 9:25 AM
          > To: hammockcamping@yahoogroups.com
          > Subject: RE: Hammock Camping Franken pad and bride of Frankenpad
          >
          > Sarge: Thanks for the R&D work. I'm dreaming along the same lines.
          > That's what the evazote "shawl" is about -- extra width between
          the hips
          > and shoulders.
          >
          > But I need to make a cloth casing to hold the wings so they're
          > detachable, rather than permanent, so I can roll it all up in a
          single,
          > 24-inch wide roll. How do you pack the Frankenpad?
          >
          > And if, as you say, "heat reflectors are snake oil" why do you use
          a
          > windshield reflector? Why not just another pad?
          >
          > Bear
          >
          >
          > To unsubscribe from this group, send an email to:
          > hammockcamping-unsubscribe@yahoogroups.com
          >
          >
          >
          > Your use of Yahoo! Groups is subject to the Yahoo!
          > <http://docs.yahoo.com/info/terms/> Terms of Service.


          To unsubscribe from this group, send an email to:
          hammockcamping-unsubscribe@yahoogroups.com



          Your use of Yahoo! Groups is subject to
          http://docs.yahoo.com/info/terms/
        • starnescr <starnescr@yahoo.com>
          That s why I said slightly warmer. I would be interested if anyone has tested how warm a space blanket is compared to say a waterproof silnylon space
          Message 4 of 18 , Feb 2, 2003
          • 0 Attachment
            That's why I said slightly warmer. I would be interested if anyone
            has tested how warm a space blanket is compared to say a waterproof
            silnylon "space" blanket.

            I'll have to admit I'm not as smart as NASA engeniers except for
            maybe Gordo.

            Coy Boy

            --- In hammockcamping@yahoogroups.com, "Ernest Engman"
            <ebengman@h...> wrote:
            > If reflective pads are so good, then why not a sleeping bag that
            is made
            > from them? They aren't. Can a space blanket really work? Somewhat,
            but
            > I've never bet my life on one and will never do so because the
            theory
            > that tells you they will is very flawed. But people buy them, so
            people
            > will sell them.
            >
            > My position that radiant heat reflectors are snake oil has grown
            over
            > time, and after a couple of debates with some people smarter than
            I, I'm
            > sure of it.
            >
            > The science is this, and don't take it is as just me, this is from
            an
            > aerospace engineer working for NASA and another engineer that have
            both
            > convinced me of this:
            >
            > Heat isn't as simple as saying 25% of your body heat is lost thru
            > radiant heat loss. It is much more complicated than that. On a
            night
            > with high humidity but low temperature, you will be a lot colder
            than on
            > a night with the same temp with lower humidity. Why? Because the
            > moisture in the air is conductive, same principle as sleeping in a
            wet
            > bag in a way, but you are loosing more of a percent of heat this
            way and
            > less thru radiant heat. Same thing in high winds. How can higher
            winds
            > make that big a difference if more is lost thru radiant heat loss?
            It
            > couldn't but the real problem is demonstrated by this is
            convective heat
            > loss. I hope this isn't too much of a tangent for the discussion,
            but it
            > just shows how one factor can change the percentages.
            >
            > Radiant heat reflectors (actually insulators) were made to work in
            > space. In space there isn't any air flow at all to worry about, so
            > absolutely no convective heat loss to worry about. In space they
            not
            > only have to protect the person from heat loss, but excessive heat
            gain
            > from solar radiant heat. Ever hear that in space one side will
            freeze
            > while the side facing the sun would burn up?
            >
            > So what is heat? Heat is energy, cold isn't the opposite, it is the
            > absence of heat. Heat energy, by its nature, will try to equalize
            the
            > energy from places of higher energy to places of lower energy. If
            your
            > body is the point of higher energy (which it normally is at night)
            then
            > your heat energy will attempt to displace outward.
            >
            > There are about 4 means of heat loss that you must worry about.
            >
            > 1. Evaporation. When you sweat or breathe, the water loss from
            your body
            > carries heat energy with it. To prevent this you can wrap yourself
            in a
            > vapor barrier. But to make this work, you will most likely want to
            be
            > totally undressed or you will end up in soggy clothing which is
            also
            > bad. Ed talks about always allowing your breath a way to get out -
            very
            > important!
            >
            > 2. Radiant heat loss (the main topic) which is heat transfer based
            on
            > how IR opaque or transparent barriers between you and the object
            are. If
            > you were to stand naked in a freezer, you would loose a great deal
            of
            > body heat thru radiant heat loss. Wrap yourself in a space
            blanket, and
            > you would reflect about 50% of your heat loss back at yourself
            because
            > the air will still carry away some through convection. But to
            reduce
            > this loss, you can wear clothing. Since the clothing is
            essentially IR
            > opaque, you can reduce this loss of you radiant heat energy down to
            > about 5% of your original loss. So if you have a given (which I
            disagree
            > with) of 25% heat loss thru radiant heat, and reduce that to 5% of
            the
            > original loss by wearing clothing, then you are down to less than
            2% of
            > your total body heat loss. Now use a radiant heat reflector to
            capture
            > 50% of that, and it is returning less than 1% of your total body
            heat
            > lost. This 95% (give or take) heat loss prevention occurs for every
            > layer of IR opaque material between you, and the colder objects
            around
            > you. So if you wear clothing, then a sleeping bag (inside layer)
            then
            > you already have reduced your IR heat loss to less than 1%.
            >
            > For a radiant heat reflector to work (in the atmosphere) you would
            need
            > to be inside it without clothing and not touch it (which is where
            I'm
            > going next) for it to be of any help. Interestingly Stephensons
            > Warmlight sleeping bags understands this and explains it quite
            well for
            > someone looking at their bags.
            >
            > To prove this, feel free to make a shower curtain of mylar then
            turn
            > your heat off. Stand inside the shower with the curtain nude and
            see if
            > it (the curtain) gets warm. It won't. You are not a big enough an
            > emitter of IR to make it work. The sun is a huge IR heat emitter
            and
            > does this quite well, unfortunately our bodies don't come with a
            huge
            > supply of self heating hydrogen.
            >
            > 3. Convective heat loss. When air passes around your body, it
            carries
            > away heat; this is the biggest problem keeping warm in an
            atmosphere.
            > The trick is to stop air from passing around you and create
            pockets of
            > still air that can be warmed and kept into place. Sleeping bags
            and pads
            > are designed to do this. Again, if radiant heat reflectors were
            truly
            > beneficial, then that is how we should have been staying warm for
            the
            > last 50 years in the hiking world, but so far we all still use
            sleeping
            > bags and pads. Ed has done a great job of figuring out how to make
            this
            > happen with a pea pod. And to make it even better would be to
            surround
            > the pod with a waterproof material that totally stopped any air
            from
            > getting out and totally stopped any moisture from getting out.
            Foil wrap
            > does a great job of this, by the way - that is what a space
            blanket is
            > made from. But it also has a drawback that it traps moisture that
            > destroys loft in a down bag. The best solution would be some
            material
            > that could surround your pea pot and prevent air flow in, strip
            heat on
            > the way out for moisture, and wouldn't suffocate you.
            >
            > 4. Conductive heat loss. This is a problem because some people try
            > laying directly on the reflective surfaces which are also excellent
            > conductors. Some spots under these conductors are warm because they
            > prevent evaporation or convection, but they also conduct heat
            away. This
            > is also how the moisture carries away your body heat.
            >
            > So to conclude this lengthy post and spark the debate I don't mean
            to.
            > Radiant heat reflectors are not that inside the atmosphere, they
            are
            > serving as barriers to convective heat and if used right,
            evaporative
            > heat. I've never said that people using a system that involves
            a "Heat
            > Rflector" aren't staying warm (heck I have one) I'm just saying
            they
            > should get smart about why they work and figure the best
            applications
            > for these materials. Aluminized plastic (mylar) is very good at
            blocking
            > moisture, and it is what all really long shelf life packet foods
            are now
            > packed in.
            >
            > Ernest Engman
            > AKA SGT Rock
            > sgtrock@h...
            > http://hikinghq.net
            >
            >
            >
            > -----Original Message-----
            > From: starnescr <starnescr@y...> [mailto:starnescr@y...]
            > Sent: Sunday, February 02, 2003 1:37 PM
            > To: hammockcamping@yahoogroups.com
            > Subject: Re: Hammock Camping Franken pad and bride of Frankenpad
            >
            > If a reflectic pad is snake oil then why are "emergency blankets
            > made of reflective material. Of course you wrap a space blanket
            > around you and are not laying on it only. Would a reflective pad
            be
            > more effective (no mater how unpracticle) if it went all the way
            > around you. I think the reflective pad is somewhat usefull if you
            > are not laying directly on it. From what Tom Hennessy and others
            > have said there needs to be a little space between the heat source
            > and the reflective surface. Hence my fleece covered reflectic
            pad.
            > A 1/2 inch closed cell foam pad the same size as mine would be
            > heavier but I'm not sure how much. I'm not saying a reflective
            pad
            > is the answer either. I just believe given the same R value a
            > reflective pad would be slightly warmer.
            >
            > Coy Boy
            >
            > --- In hammockcamping@yahoogroups.com, "Ernest Engman"
            > <ebengman@h...> wrote:
            > > The pad I use serves a couple of purposes.
            > >
            > > 1. Wind/air barrier. It is made of aluminum coated close cell
            > foam
            > > pad. I can use it alone in cool but not cold temps by turning it
            > shiny
            > > side down and preventing air circulation.
            > > 2. Since it is also foam, it adds a light and small layer of
            > > insulation.
            > > 3. It serves as a ground pad under the hammock when I lay it on
            > the
            > > ground to stay warm. It is wide and long enough for that. Often
            > when
            > > having to do this, the ground isn't dry and no sense getting the
            > fabric
            > > wet.
            > > 4. Closed cell foam pads work better against a non-breathable
            > > barrier than against a breathable material like than hammock.
            See
            > this
            > > excellent post by youngblood:
            > > http://hikinghq.net/forum/showthread.php?
            > s=10900e520cfd29662ed8485b43feb
            > > ff2
            > > <http://hikinghq.net/forum/showthread.php?
            > s=10900e520cfd29662ed8485b43fe
            > > bff2&threadid=359> &threadid=359
            > >
            > > I say heat reflectors are snake oil, because the science that
            says
            > they
            > > are a radiant heat reflector for someone sleeping in a hammock
            is
            > highly
            > > flawed.
            > >
            > > Ernest Engman
            > > AKA SGT Rock
            > > sgtrock@h...
            > > <http://hikinghq.net/> http://hikinghq.net
            > >
            > >
            > > -----Original Message-----
            > > From: David Chinell [mailto:dchinell@m...]
            > > Sent: Thursday, January 30, 2003 9:25 AM
            > > To: hammockcamping@yahoogroups.com
            > > Subject: RE: Hammock Camping Franken pad and bride of Frankenpad
            > >
            > > Sarge: Thanks for the R&D work. I'm dreaming along the same
            lines.
            > > That's what the evazote "shawl" is about -- extra width between
            > the hips
            > > and shoulders.
            > >
            > > But I need to make a cloth casing to hold the wings so they're
            > > detachable, rather than permanent, so I can roll it all up in a
            > single,
            > > 24-inch wide roll. How do you pack the Frankenpad?
            > >
            > > And if, as you say, "heat reflectors are snake oil" why do you
            use
            > a
            > > windshield reflector? Why not just another pad?
            > >
            > > Bear
            > >
            > >
            > > To unsubscribe from this group, send an email to:
            > > hammockcamping-unsubscribe@yahoogroups.com
            > >
            > >
            > >
            > > Your use of Yahoo! Groups is subject to the Yahoo!
            > > <http://docs.yahoo.com/info/terms/> Terms of Service.
            >
            >
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            > hammockcamping-unsubscribe@yahoogroups.com
            >
            >
            >
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          • Ed Speer
            Good discussion on heat loss Ernest. I think we all agree that the major body heat loss is from conduction, convection, evaporation & respiration. So unless
            Message 5 of 18 , Feb 2, 2003
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              Message
              Good discussion on heat loss Ernest.  I think we all agree that the major body heat loss is from conduction, convection, evaporation & respiration.  So unless one has conquered these, it's pretty pointless to worry about radiant heat loss.  I gather you feel that the warming benefit from reflective fabrics is due to their vapor-barrier properties, not their radiant properties; or at least the radiant advantages are overshadowed by the vapor-barrier advantages.  A good point indeed.  Maybe we like using the Aluminum-coated Mylar emergency blankets because they are so light weight--even lighter than plastic sheeting.  However, I often use my plastic sheet ground cloth as a vapor barrier on the bottom outside of my hammock--does it work as well as the emergency blanket?  Of course, I don't know--they both work well enough to keep using them!
               
              I'd be interested in seeing dependable numbers on actual body heat loss by the various processes.   I have found the following, but its' incomplete for our purposes:
               
              "The human body at rest losses 76% of it's heat due to conduction, convection and radiation; the remaining 24% is lost through evaporation, insensible perspiration and respiration".
               
              It would perhaps be useful if we knew exactly how much each process contributes.  Then again, nature is never a constant--like you said, things like wind and humidity greatly change the rules.  So maybe exact numbers are impossible to determine.
               
              Thanks for your reasoned discussion...Ed
               

               
            • Ernest Engman
              Thanks Ed. I think the two strongest sections of your book are the part on cold weather and building a hammock IMHO. And again, I hope everyone doesn t think
              Message 6 of 18 , Feb 2, 2003
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                Thanks Ed. I think the two strongest sections of your book are the part on cold weather and building a hammock IMHO.

                 

                And again, I hope everyone doesn’t think I’m putting them down for using a heat reflector or thinking the reason that they are staying warm is radiant heat reflection. I’m just certain now more than ever that there isn’t the science to support that. BUT, people using them are staying warm. If that is true, then how? If we can figure that out, then maybe more efficient systems can be found to make it work.

                 

                Ernest Engman

                AKA SGT Rock

                sgtrock@...

                http://hikinghq.net

                 

                 

                -----Original Message-----
                From: Ed Speer [mailto:info@...]
                Sent:
                Sunday, February 02, 2003 6:31 PM
                To: hammockcamping@yahoogroups.com
                Subject: Hammock Camping RE: Radiant Heat Reflectors

                 

                Good discussion on heat loss Ernest.  I think we all agree that the major body heat loss is from conduction, convection, evaporation & respiration.  So unless one has conquered these, it's pretty pointless to worry about radiant heat loss.  I gather you feel that the warming benefit from reflective fabrics is due to their vapor-barrier properties, not their radiant properties; or at least the radiant advantages are overshadowed by the vapor-barrier advantages.  A good point indeed.  Maybe we like using the Aluminum-coated Mylar emergency blankets because they are so light weight--even lighter than plastic sheeting.  However, I often use my plastic sheet ground cloth as a vapor barrier on the bottom outside of my hammock--does it work as well as the emergency blanket?  Of course, I don't know--they both work well enough to keep using them!

                 

                I'd be interested in seeing dependable numbers on actual body heat loss by the various processes.   I have found the following, but its' incomplete for our purposes:

                 

                "The human body at rest losses 76% of it's heat due to conduction, convection and radiation; the remaining 24% is lost through evaporation, insensible perspiration and respiration".

                 

                It would perhaps be useful if we knew exactly how much each process contributes.  Then again, nature is never a constant--like you said, things like wind and humidity greatly change the rules.  So maybe exact numbers are impossible to determine.

                 

                Thanks for your reasoned discussion...Ed

                 


                 


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              • David Chinell
                MessageSarge: Didn t mean to get you side-tracked on the reflective heat issue (though I am glad to have someone more credible than me weigh in on it). You
                Message 7 of 18 , Feb 3, 2003
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                  Message
                  Sarge:
                   
                  Didn't mean to get you side-tracked on the reflective heat issue (though I am glad to have someone more credible than me weigh in on it). You didn't answer my other question... How do you pack your super-wide closed-cell foam pad?
                   
                  Bear
                   
                • Ernest Engman <ebengman@hikinghq.net>
                  Doh, Sorry. I use a Moonbow Gearskin, so I don t roll up my pad. Instead I put the two layer part against my back and pack it like a Taco, compression straps
                  Message 8 of 18 , Feb 3, 2003
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                    Doh,

                    Sorry. I use a Moonbow Gearskin, so I don't roll up my pad. Instead I
                    put the two layer part against my back and pack it like a Taco,
                    compression straps on the side close the wings like side panels. You
                    can see the pics of my gearskin and get the idea at:
                    http://hikinghq.net/gear/moonbow_gearskin.html

                    SGT Rock

                    --- In hammockcamping@yahoogroups.com, "David Chinell"
                    <dchinell@m...> wrote:
                    > MessageSarge:
                    >
                    > Didn't mean to get you side-tracked on the reflective heat issue
                    (though I
                    > am glad to have someone more credible than me weigh in on it). You
                    didn't
                    > answer my other question... How do you pack your super-wide closed-
                    cell foam
                    > pad?
                    >
                    > Bear
                  • David Chinell
                    Neeeeet. Bear ... From: Ernest Engman [mailto:ebengman@hikinghq.net] Sent: Monday, February 03, 2003 02:40 PM To:
                    Message 9 of 18 , Feb 3, 2003
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                      Neeeeet.

                      Bear


                      -----Original Message-----
                      From: Ernest Engman <ebengman@...>
                      [mailto:ebengman@...]
                      Sent: Monday, February 03, 2003 02:40 PM
                      To: hammockcamping@yahoogroups.com
                      Subject: Re: Hammock Camping Franken pad and bride of
                      Frankenpad


                      Doh,

                      Sorry. I use a Moonbow Gearskin, so I don't roll up my pad.
                      Instead I
                      put the two layer part against my back and pack it like a
                      Taco,
                      compression straps on the side close the wings like side
                      panels. You
                      can see the pics of my gearskin and get the idea at:
                      http://hikinghq.net/gear/moonbow_gearskin.html

                      SGT Rock
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