CoolIP index                                                          Most recent edit: Wednesday October 24, 2012

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Mid-Span Reefing of Megascale Parafoils

Rob Creighton asked how giant soft-wing power-kites could reduce CL (Coefficient of Lift) for stable return-phase reeling.

One well-developed solution is Mid-Span Reefing of giant cargo parafoils. The technique was developed for US Army cargo drops as a means to reduce opening shock of the packed parafoil. Its a standard method closely related to the sliders used in sport parachuting for the same purpose. Such techniques generally will work in reverse (back-drivable) for AWES use in modulating CL.

Cargo Parafoils are a close analog of Power Kites under any Similarity Analysis. They have been proven to scale past 1000 m2 with reefing and steering capabilities. Unlike rigid wings, the ultimate megascale limit of variable CL soft-wing is unknown, with no looming scaling law as a barrier. The mid-span reefing method uses drawlines and rings or grommets across ram-air cells to let them open (or close) controllably. The reefed unit flies stably with a far lower CL.

Unlike reeling AWES with soft-wings, reefing is not the operational basis for direct crosswind or short-stroke AWES generation schemes, but can serve for matching the wing to wind conditions and to facilitate launching/landing operations.

  • CoolIP*                      ~Dave Santos                 5 Oct 2012             AWES7367

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  • Terms and aspects:   
  • Related links and concepts:
    • Variable area
    • Morphing
    • Variable porosity
    • Variable geometry
    • Pinching, gathering, collecting,
    • Segment depowering
    • Shading, hiding
    • Closing
    • Furl, furling
    • Luffing
    • Flagging
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