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AWE Lightning

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  • Joe Faust
    Following Robert Copcutt, lightning notes are invited in this thread and group folders. sparks with needle gaps And files may also be placed in Files under
    Message 1 of 4 , Mar 18 11:06 AM

      Following  Robert Copcutt,

       lightning notes are invited in this thread and group folders.

        sparks with needle gaps

      And files may also be placed in Files under  Lightning     (files section)

      And links in the Links seciton for similar topic: Lightning     (links section) where already are a couple of links.

      Some investigators of past and some still:  hoping to capture the energy in lightning; will very large ultracapacitors make a difference?

      What hope could there be in staying flying during lightning storms, if any?

      Blue-sky lightning? 

      JoeF  

    • Robert Copcutt
      ... The problem is that lightning is so rare, and so powerful when it comes, that the investment in capture devices cannot be justified. ... Big turbines have
      Message 2 of 4 , Mar 18 12:35 PM
        On Fri, 2011-03-18 at 18:06 +0000, Joe Faust wrote:
        >

        >
        > Some investigators of past and some still: hoping to capture the
        > energy in lightning; will very large ultracapacitors make a
        > difference?

        The problem is that lightning is so rare, and so powerful when it comes,
        that the investment in capture devices cannot be justified.

        >
        > What hope could there be in staying flying during lightning storms, if
        > any?
        >

        Big turbines have steel towers and they run an aluminium lightning
        conductor down their blades. There is a spark gap between the nacel and
        the tower and these usually bear witness to past strikes. The whole
        construction philosophy is about being tough enough to last through
        storms with their high winds and lightning because there is no option of
        pulling the thing down when conditions are bad. That is why they are so
        expensive. The whole idea of AWE is that all the heavy-weight
        construction at high altitude is eliminated. That means it has no chance
        of surviving storms with their high winds and lightning. It is easy
        enough to pull a kite down when conditions are wrong, so why not just do
        it.

        Another reason for retracting the kites is aircraft approaching too
        close. AWEs above a certain altitude will probably need radar so they
        can react before lost pilots get threatened by invisible tethers.

        Robert.
      • Joe Faust
        AWECS * Generator aloft * Tethered flight * Electrically-conductive tethers * Non-electrically conductive tethers; energy gained is transferred in a
        Message 3 of 4 , Mar 18 6:05 PM
          AWECS
          • Generator aloft
            • Tethered flight
              • Electrically-conductive tethers
              • Non-electrically conductive tethers; energy gained is transferred in a non-electric manner.

            • Untethered free-flight
              • Gained energy used aloft only
              • Gained energy sent to ground or other aircraft by some non-tethered means (some of the energy may be used aloft also)

          • Generator on ground with non-electric-conductive tether set   (may have minor for-controls generator aloft)
             The "lost pilot" and "invisible tethers" are interesting talking points.    Maybe aim to have tethers very visible both to the eye and to communication instruments.

          Pre-lightning potential difference shorting by specialized AWECS might reduce lightning-storm impacts. And maybe capture of the pre-lightning potential difference could be more universally a means for gaining useful energy.  The specialized AWECS might lift large-area wide mesh conductor screens and keep a shorting going to captur ultracapacitors; I am wondering what the theoretical limits of such shorting could be during the year. 

          http://en.wikipedia.org/wiki/Atmospheric_electricity#Atmospheric_layers 

        • dave santos
          A simple lightning detector is subject to a prankster with a spark gap or a non-theatening superstrike many miles away downwind, so we need the
          Message 4 of 4 , Mar 19 11:08 AM
            A simple "lightning detector" is subject to a prankster with a spark gap or a non-theatening superstrike many miles away downwind, so we need the fancier lightning mapping detection that comes with aviation radar. The rain returns are constantly refreshed but the radar keeps a memory going of the strikes. You would need to process this data for a smart retract decision.
             
            Aircraft use Static Wicks to keep charge from building too high & there is no reason we can't put little wicks on lines & kites. We could also actively cancel charge so that the semiconductive line remains invisible to the lightning. Similarly the kitefield surface charge could be actively canceled & lightning encouraged to strike elsewhere, but active cancellation is an uncertain trade-off, probably favored in high lightning zones like Florida.
             
            Large meshed arrays of multi-tethered kite elements would tolerate considerable local lightning damage & remain flying. Low mass kites disabled by lightning are far less dangerous in a crash than high mass kite crashes. Whatever the mishap mode, replacement cost is far lower for a cheap rag wing than a fancy composite structure wing. During lightning risk, we might also launch lightning-rod kites on piano-wire to shield nearby arrays of critical kite systems, but this is pretty awkward.
             
            I have experienced electric hail twice while kite flying, experiencing sparking & once even bathed in St. Elmo's fire. The second time a dacron tether long exposed to salt vapor burned thru, but would probably have held if it had been rinsed. An electroscopic charge detector on the kite & line will detect precursor charges before lightning strikes, but also less scary "electric hail" & ionized dust. I made a simple tinfoil-vanes-in-a-jar electroscope & found it sensitive to fluxuating charge on the line as clouds floated by.
             
            coolIP

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