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  1. #1
    Senior Member Bradley's Avatar
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    Essay/Thoughts: Insulators such as down vs. air-mattresses.

    I have been thinking for some time now about the UQ and winter camping issues.
    Insulators such as down vs. air-mattresses.
    And how they compare.

    About heat loss, and heat retention, and such like things.

    I have read about radiation vs. convection . . . and try to wrap my mind around it all.

    I tend to . . . in my limited way . . . think microscopic . . .

    What follows are some of my thoughts . . . all be it, not so scientific; yet more layman:

    The bodies feeling of cold or warmth is a function of: artificial/generated heat or bodily/internally generated heat.

    When in a hammock we rely on the latter,
    and how cold or warm we feel is basically dependent on
    heat retention, or a lessoning of heat loss.

    In relation to this or a way I understand heat exchange is like the oceans or air,
    And being that air is the understood/agreed insulator
    it could/would be advantageous to understand how it all works.

    First the oceans are heated by the sun
    and are hottest at the suns apex on the earth
    and coldest at the poles.
    Heat causes currents, and the result is ocean currents.
    The concept is basically the same with air.

    OK . . . next I want to think of the down/thinsulite UQ or pad/air-mattress

    If it is the air inside that is the actual insulator why is one system better that the next.
    I think it is how the system traps the air and what it does with or to the air that makes the difference.

    First Going back to the thought that the human body is the heat generator,
    And it is the free outside ambient air that is the heat robber,
    By wicking the heat away so to speak,
    We need something between the two, to lessen the heat wick action.

    Air . . .

    By capturing the air in an air mattress (AM) we create a barrier between the free air and our body.
    Our body generates the heat and raises the temp in the AM
    Inside the AM there is a closed system of air that is much like the oceans,
    Where as, the heat next to our body is setting up currents in that system.
    The out side free air, which there is so much more of,
    is wicking away heat from the distal side (far side/outside)
    of the AM cooling that portion of trapped air.
    This sets up currents or even a direct heat-loss flow in the AM,
    From the proximal to the distal parts of the AM,
    And with no resistance within the AM’s structure,
    The flow is quite rapid . . . convection.

    Solution:
    Slow down the rate of flow of the heated air from the proximal
    to the cool/distal area of the system.

    Enter, goose down, thinsulite, Climashield, or any other, such as quilt batting.

    The solids in the enclosed area slow the movement of air from proximal (close to you) to the distal (far from you).
    Some actually trap the air in segmented areas so that airflow is restricted, maximally.
    Now the transfer of heat is more in the way of radiant heat loss.
    The transfer of heat from solid to solid . . . so to speak.
    This is a much slower process.

    So as you lay there in your hammock your body is producing heat . . . infinitum.
    Or at least while you’re alive.
    Your body heat warms the fabric next to you and the conveyance of heat starts.

    The more partials and the type of material used,
    in the enclosed area, to slow air movement,
    To, retain heat,
    is all what matters in staying warm.

    Some stuffing’s are just better than others at doing the job.
    I think the take home here is Air mattresses are for comfort,
    Not insulating . . .

    And blue pads are a good barrier, but have little air . . .
    Little air = little insulating value.
    Kinda like sleeping on a 2x4 as far as R-value goes.

    Just me thinking, I hope that helps
    and sorry if some of my words might not seam to work.



    O . . . O
    Now I need to commit to submit
    Last edited by Bradley; 12-11-2010 at 14:09. Reason: Spelling
    Bradley SaintJohn
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  2. #2
    Senior Member Just Jeff's Avatar
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    Sounds like you understand the convection and radiation sides of it. Blue pads are excellent insulators though...they completely stop convective transfer from the proximal to distal sides and greatly reduce conductive transfer. (You can't stop convective transfer AT the distal side.)
    “Republics are created by the virtue, public spirit, and intelligence of the citizens. They fall when the wise are banished from the public councils because they dare to be honest, and the profligate are rewarded because they flatter the people, in order to betray them.” ~Judge Joseph Story

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  3. #3
    mbiraman's Avatar
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    Give me a blue pad over 2x4's any day.
    " The mind creates the abyss, the heart crosses it."

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  4. #4
    Senior Member Danalex's Avatar
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    Good thoughts .... but .... what's the conclusion??

  5. #5
    Senior Member XexorZ's Avatar
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    Quote Originally Posted by Danalex View Post
    Good thoughts .... but .... what's the conclusion??
    Entropy Rules?

    (well... it does...)
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  6. #6
    Senior Member Bradley's Avatar
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    Quote Originally Posted by XexorZ View Post
    Entropy Rules?

    (well... it does...)
    In thermodynamics or information theory . . .


    . . . or both . . .
    Bradley SaintJohn
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    The Transition from Ground Sleeping to Hammocks
    is the Conversion from Agony To Ecstasy,
    and Curing Ground-In-somnia.

    "Call unto me, and I will answer thee, and show you great and mighty things . . ." Jeremiah 33:3
    ΙΧΘΥΣ

  7. #7
    Senior Member Just Jeff's Avatar
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    Or parenting.
    “Republics are created by the virtue, public spirit, and intelligence of the citizens. They fall when the wise are banished from the public councils because they dare to be honest, and the profligate are rewarded because they flatter the people, in order to betray them.” ~Judge Joseph Story

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  8. #8
    Senior Member Mustardman's Avatar
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    Air is but one good insulator - there are many others that do NOT rely on trapped air - they would also suck for backpacking because the whole point is to have something that is light.

    And blue foam pads have a lot more air trapped in them than you think.

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