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Dynamic Plummet Mode? (Inverted Wind Gradients)

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  • dave santos
    Brian called for a discussion of AWE micrometeorology in the context of Makani s AWT Power Curves and claims of confidence , and lets include similar
    Message 1 of 4 , May 9 7:27 AM
      Brian called for a discussion of AWE micrometeorology in the context of Makani's AWT Power Curves and claims of "confidence", and lets include similar architectures with identical flight patterns. There is too much past consideration for a full review here, but some new twists to note, such as a predicted "Dynamic Plummet" flight mode in inverted wind gradients.
       
      Makani has observed a Dynamic Soaring effect as its AWT loops up and down in the surface wind gradient. They don't call it that, but distinguish in their Power Curve measurements between "wind shear" and no "wind shear", as two crude unquantified windfield states, which we can parse to mean a steeper pronounced gradient v. a less pronounced gradient, as there is usually some amount (greater-than-zero) of increase in windspeed by height. But what about the inverted gradients characteristic of Downbursts, and other wind mechanisms like Katabatic Wind and surface Convective Tails?
       
      We have since the beginning of the AWES Forum known that Downbursts are an occasional but still fairly common event in windfields, a hazard to aviation, but decades of research into this topic has resulted in better safety.  There are several causes and varieties of downburst, but the common reality is a pronounced inverted wind gradient near the surface. This clearly suggests that the Makani AWT and related designs must confront a flight failure mode where the boost effect of Dynamic Soaring is aimed at the ground, a risk of a greatly accelerated plummet to the surface.
       
      Large-scale KiteLab Group AWES architectures depend on an upper layer of pilot-lifter kite(s), which seem favored to support hot looping wings, as a tendency to suddenly plummet in an inverted gradient is progressively resisted. No such passive corrective exists with Makani's AWT, which must depend on better detection and faster actuation within tighter load-limits. Of course, any AWES can be forced down; we are talking about a major relative advantage.
       
      Brian is quite right that this questioning is (partly*) motivated by competitive rivalry between contending architectures, but badly mistaken in thinking it improper to seek to draw out secretive AWE VCs, especially those enjoying exclusive public subsidies, into open technical debate. Makani and ARPA-E may continue to stonewall, but the debates can proceed with Brian playing the valuable role of surrogate debater for Makani's claims v. KiteLab's critiques.
       
       
       
      * Lets get the science right!
    • roderickjosephread
      I ll try a bit of arguing for Makani in their absence. Dude, when scenarios of anomalous vectoring occur, our awesomely sharp computer brain will totally
      Message 2 of 4 , May 9 9:06 AM
        I'll try a bit of arguing for Makani in their absence.

        "Dude, when scenarios of anomalous vectoring occur, our awesomely sharp computer brain will totally notice.
        And it will be all like "hey man totally bogus vectoring, why I aughta pull one of my 15G corners and go into emergency "Don't let my precious wing tips hit the ground mode" " and it'll totally power up out of there like a Phoenix broo. yeah, high five. woooh"

        that was me, being a Makani man, talking about his computer, talking about its recovery mode.

        And really, why not?  If they've got the billions to waste.. might as well do it.
        I suppose apart from the fact that it's the American taxpayers billions.
        So doesn't really bother me.
      • Doug
        Dave S.: Since you (like me - pot calling the kettle black here...) profess to understand exactly what is required for a successful AWE machine, it baffles me
        Message 3 of 4 , May 10 9:31 AM
          Dave S.:
          Since you (like me - pot calling the kettle black here...) profess to understand exactly what is required for a successful AWE machine, it baffles me that you could waste one second of your time fixating on what words some other team uses to describe their effort, especially since you seem convinced that their effort will ultimately fail anyway.

          Why waste a second on someone else's impending failure? Why not stay focused on the performance of your oscillating kite arrays or whatever your certain breakthrough is this week?
          Then again I should take my own advice - I am doing the same thing to you right now. (sigh).

          I had better get back to work and make sure I don't waste valuable time on nothingness...
          :)

          --- In AirborneWindEnergy@yahoogroups.com, dave santos <santos137@...> wrote:
          >
          > Brian called for a�discussion of AWE micrometeorology in the context of Makani's AWT Power Curves and claims of "confidence", and lets include similar architectures with identical flight patterns. There is too much past consideration�for a full review here, but some new twists to note, such as a predicted�"Dynamic Plummet" flight mode in inverted wind gradients.
          > �
          > Makani has�observed a�Dynamic Soaring effect as its AWT loops up and down in the surface wind gradient. They don't call it that, but distinguish in their Power Curve�measurements�between "wind shear" and no "wind shear", as two crude unquantified windfield states, which we can parse to mean a steeper pronounced gradient v. a less pronounced gradient,�as there is�usually some amount (greater-than-zero)�of increase in windspeed by height. But what about the inverted gradients characteristic of Downbursts, and other wind mechanisms like Katabatic Wind and surface Convective Tails?
          > �
          > We have since the beginning of the AWES Forum known that Downbursts are an occasional but still fairly�common event in windfields, a hazard to aviation, but�decades of�research into this topic has�resulted in better safety.� There are several causes and varieties of downburst, but the common reality is�a pronounced inverted wind gradient near the surface. This clearly�suggests that the Makani AWT and related designs must confront a flight failure mode where the boost effect of Dynamic Soaring is aimed at the ground, a risk of a greatly�accelerated plummet to the surface.
          > �
          > Large-scale KiteLab Group AWES�architectures depend on an upper layer of pilot-lifter kite(s), which�seem favored to support hot looping wings, as a tendency to suddenly�plummet in an inverted gradient�is progressively resisted. No such passive corrective exists with Makani's AWT, which�must depend on�better detection�and�faster actuation within tighter load-limits. Of course, any AWES can be forced down; we are talking about a major�relative advantage.
          > �
          > Brian is quite right that�this�questioning is (partly*)�motivated by competitive rivalry between contending�architectures, but badly mistaken in thinking�it improper�to seek to draw out�secretive AWE VCs, especially those enjoying exclusive public subsidies,�into open technical debate. Makani and ARPA-E�may continue to�stonewall, but the debates�can proceed with�Brian playing the valuable role�of surrogate debater for Makani's claims v. KiteLab's critiques.
          > �
          > �
          > Downburst - Wikipedia, the free encyclopedia
          > �
          > *�Lets get the science right!
          >
        • blturner3
          Your suggesting that the Makani wing can t turn fast enough while diving to maintain it s circular path and avoid crashing into the ground if it runs into a
          Message 4 of 4 , May 12 11:12 AM
            Your suggesting that the Makani wing can't turn fast enough while diving to maintain it's circular path and avoid crashing into the ground if it runs into a inverted wind gradient.

            Yes, If a kite does not have enough control authority designed into it that could happen. The same is true of all kites.

            So everyone please note. Design more turning ability than you think you will need and never depend on all of it.

            Get out of the boundary layer and this is one more problem that basically goes away.

            Brian

            --- In AirborneWindEnergy@yahoogroups.com, "Doug" <doug@...> wrote:
            >
            > Dave S.:
            > Since you (like me - pot calling the kettle black here...) profess to understand exactly what is required for a successful AWE machine, it baffles me that you could waste one second of your time fixating on what words some other team uses to describe their effort, especially since you seem convinced that their effort will ultimately fail anyway.
            >
            > Why waste a second on someone else's impending failure? Why not stay focused on the performance of your oscillating kite arrays or whatever your certain breakthrough is this week?
            > Then again I should take my own advice - I am doing the same thing to you right now. (sigh).
            >
            > I had better get back to work and make sure I don't waste valuable time on nothingness...
            > :)
            >
            > --- In AirborneWindEnergy@yahoogroups.com, dave santos <santos137@> wrote:
            > >
            > > Brian called for a�discussion of AWE micrometeorology in the context of Makani's AWT Power Curves and claims of "confidence", and lets include similar architectures with identical flight patterns. There is too much past consideration�for a full review here, but some new twists to note, such as a predicted�"Dynamic Plummet" flight mode in inverted wind gradients.
            > > �
            > > Makani has�observed a�Dynamic Soaring effect as its AWT loops up and down in the surface wind gradient. They don't call it that, but distinguish in their Power Curve�measurements�between "wind shear" and no "wind shear", as two crude unquantified windfield states, which we can parse to mean a steeper pronounced gradient v. a less pronounced gradient,�as there is�usually some amount (greater-than-zero)�of increase in windspeed by height. But what about the inverted gradients characteristic of Downbursts, and other wind mechanisms like Katabatic Wind and surface Convective Tails?
            > > �
            > > We have since the beginning of the AWES Forum known that Downbursts are an occasional but still fairly�common event in windfields, a hazard to aviation, but�decades of�research into this topic has�resulted in better safety.� There are several causes and varieties of downburst, but the common reality is�a pronounced inverted wind gradient near the surface. This clearly�suggests that the Makani AWT and related designs must confront a flight failure mode where the boost effect of Dynamic Soaring is aimed at the ground, a risk of a greatly�accelerated plummet to the surface.
            > > �
            > > Large-scale KiteLab Group AWES�architectures depend on an upper layer of pilot-lifter kite(s), which�seem favored to support hot looping wings, as a tendency to suddenly�plummet in an inverted gradient�is progressively resisted. No such passive corrective exists with Makani's AWT, which�must depend on�better detection�and�faster actuation within tighter load-limits. Of course, any AWES can be forced down; we are talking about a major�relative advantage.
            > > �
            > > Brian is quite right that�this�questioning is (partly*)�motivated by competitive rivalry between contending�architectures, but badly mistaken in thinking�it improper�to seek to draw out�secretive AWE VCs, especially those enjoying exclusive public subsidies,�into open technical debate. Makani and ARPA-E�may continue to�stonewall, but the debates�can proceed with�Brian playing the valuable role�of surrogate debater for Makani's claims v. KiteLab's critiques.
            > > �
            > > �
            > > Downburst - Wikipedia, the free encyclopedia
            > > �
            > > *�Lets get the science right!
            > >
            >
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