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 High Altitude Operations notes

As reported previously, after the Leuven conference [May 2011]]we had a group meeting at Moritz's office & discussed the challenges of "perpetual" high altitude operation, particularly large arrays. Moritz presented the basic calculations that predict strict limitations on maximum altitude. Tether weight & wind drag accumulate with altitude & especially when wind slacks one must come down or waste large amounts of power to "reverse pump". Lets review means that ease the constraints. Kites can be put all along a tether (a train) to mitigate increasing weight & drag with altitude. With multiple tethers, some can be leaned into the wind & develop some lift. A tether & kite sequence is progressively tapered, with larger sections lower. The maximum altitude state represents potential energy "in the bank" & AWECS aloft can be driven for while by sink, promoting high capacity factor. In dying wind the heaviest components can be run down promptly on halyards to greatly reduce sink rate & reverse-pumping demand. A remnant structure of aerostat lift can "reserve" a presence in the sky during calm. In rising wind the sequence reverses & added power raises everything nicely. Moritz also explained his intuition that a kite system deployment sequence be naturally reversible to recover from a fault or adapt to any dynamic need. One does not want unrecoverable conditions such as, say, a failed ballistic launch might represent.

CoolIP                       ~Dave Santos           June 3, 2011           M3664

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Terms and aspects:   

  • reversed pumping
  • phased tugging
  • ballistic launch
  • deployment sequence
  • perpetual high altitude operations
  • large arrays
  • maximum altitude calculations  
  • tapered aspects of trains
  • reserve presence in the sky
  • reversible deployment
  • non-reversible deployment

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