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Re: [AWES] Flygen vs Groundgen

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  • dave santos
    Brian,   This issue has been a top topic on the forum: Safety under existing aviation regulations (and the underlying physical basis for the regs), and
    Message 1 of 48 , Mar 17, 2012
      This issue has been a top topic on the forum: Safety under existing aviation regulations (and the underlying physical basis for the regs), and therefore liability insurability, seems like the early decisive utility-scale factor in favor of GroundGens. Small Flygens avoid excessive cubic-mass scaling penalties and do not invoke high-consequence safety concerns like large Flygens do. The safety concerns are quantified into aviation regulations that place strict requirements on aircraft based on mass and velocity. Thus a flygen of a given mass generates less power-to-weight than a bare kite, and its larger free-fall terminal-velocity creates a more substantial hazard. Many such quantifiables are highly success-predictive of GroundGens in the short term.
      You missed a long list of FlyGen players like Altaeros, Sky Windpower, Honeywell, and many small AWECS developers. KiteLab Group embraces both Flygens and Groundgens, depending on scale and operational needs, and forsees that giant superconducting generators could in fact someday, decades from now, be lifted by large array formations, mainly for reasons of farm self-mobility (ferrying) or even for high operational independence from the surface (airborne architecture).
      The reason for the Cult of Lowest Mass-Aloft is not just for low wind generation; weight is simply toxic to a good kite, the lightest practical kite wins operationally by many virtues, especially by better general flight performance and especially critical flight stability. In special conditions where more mass is desired, water-ballast is an option (just as high-performance gliders take on water ballast at times).
      You seem to think long reeling cycles, and therefore "intermittent power production" is an inherent flaw to ground gens. In fact, on this Forum, its well known that high-frequency short-stroke pumping and continuous-loop rope-driving are quite practical. Long-cycle reeling is mostly just an early historic phase, much as early biplanes were, and the tether fatigue problems of reeling will mostly go away. On the other hand, composite conductive/strucutural cables have severe inherent problems that simple tethers avoid.
      It would be nice if someone formally explained and proved what is widely believed, that groundgens are generally superior, but this involves a fundamental quantum physics comparison of tug v. electrical efficiency. There is ongoing informal study behind the scenes, with help from Dr. Jeremy Rutman and Dave Lang, with some exciting results due soon,
      PS Ribbed wings are so bad as you suggest, usually provided the ribs run streamwise. Ribs can even act as part of a turbulation mechanism to maintain attached flow in turbulent conditions. One sees ribbed wings everywhere in nature, from insects to birds and bats and fish fins. Its wonderful to see how stone-age aerodynamicists figured out how to use *transverse* ribs as turbulators on items like throwing sticks, enhancing performance. Modern toys like Frisbees and Aerobies rely on ribs in just this way. Ribs is therefore just a tool in our wing-design toolkit.
      Yes, there are lots of acronyms used in professional aviation, and engineering generally, to keep communication concise, and they do require learning them to serve as aids. The AWE Forum is billed as a professional-level venue, so acronyms come with the territory. LEI stands for "Leading Edge Inflatable" (Kite), the technology invented by the Legaignoux brothers enabling kitesurfing to become popular by a kite that will not sink or take on water.

    • Joe Faust
      Hybrid winch/tow (or both at once) options: == Winch positively and tow simultaneously. Pay-in-winching during being towed by vehicle.== Winch negatively and
      Message 48 of 48 , Mar 26, 2012
        Hybrid winch/tow (or both at once) options: 
        == Winch positively and tow simultaneously. Pay-in-winching during being towed by vehicle.
        == Winch negatively and tow simultaneously. Pay-out-winching during being towed by vehicle
        == Let a robot decide during towing just how much winching occurs in order to maintain tensions wanted.
        == As mentioned: Fixed-anchor winching-in. 
        === Fixed-anchor pay-out with clutched device or controllable winch (using ambient wind to fly the wing set and pull out)
        == As mentioned: Static-line-length towing by ground or water-surface vehicle. 

        The line does not care much about the source of its tension:
        "Just do do not overload me!" :)
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