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Re: [AWECS] Automation of AWE [challenges, sensors and crash zones]

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  • Theo Schmidt
    ... As you say, Robert, we now have FOSS and also highly effective hardware, even the beginnings of open source hardware. So, this isn t the problem. The
    Message 1 of 28 , Apr 15, 2011
      Robert Copcutt wrote:
      > ... The explosive growth of the internet and open-source
      > contributions makes a huge difference. Many on this list are
      > resisting computerisation of AWE, in some cases because the
      > technology is not fully understood. It needs to be borne in mind that
      > in an open-source project of any complexity no one person fully
      > understands every element.

      As you say, Robert, we now have FOSS and also highly effective hardware,
      even the beginnings of open source hardware. So, this isn't the problem.
      The challenge is same it ever was: MECHANICS (in a very broad sense of
      the word). Every small project I have ever worked on didn't have
      qualified mechanical engineers or machinists even though most of the
      work to be done was in this direction. It was more sexy to hire
      electronic engineers (like me then) or computer programmers. Who then
      spent most of their time fiddling with nuts and bolts. And even if they
      were skilled (like I am moderately), unless you have a really well
      equipped shop and lots of materials, you spend most of your time
      ordering parts or shopping. The physical world makes for a lot more work
      than cyberspace! And because people are naturally lazy, they will prefer
      to spend hours programming to a fraction of this cutting, filing,
      laminating or sewing.

      ....
      > ... A wing with 4 rotors can be controlled well
      > enough to land in its docking station even in strong gusty winds.

      Good point. I was thinking of a single or twin counterrotating rotor
      job, or twin horizontal savonius rotor (plenty of such toys about, they
      have s-shaped rotating wings), but the antics of the quad-rotor jobs is
      astounding. You could have a quad for starting, steering, lulls and
      landing, attached to a larger twin turbine for generation. Having
      hover-power at any time solves the lull problem.

      I think one of the first group of customers is going to be yacht-owners.
      Either normal sailing yachts who simply want a generator out of the way
      of their normal rigging, or solar-electric yachts for then when it is
      windy with little sun. Yachts don't need a lot of power and their owners
      are required to have lots of money! It would be a cinch to go dead
      upwind with an electric boat and an air-borne generator.

      Cheers, Theo Schmidt
    • Robert Copcutt
      ... If we put forward a coherent and exciting proposal we will get people coming forward with all the skills we need. The boom of rapid prototyping and 3D
      Message 2 of 28 , Apr 15, 2011
        On Fri, 2011-04-15 at 18:06 +0200, Theo Schmidt wrote:
        >

        > The challenge is same it ever was: MECHANICS (in a very broad sense
        > of
        > the word). Every small project I have ever worked on didn't have
        > qualified mechanical engineers or machinists even though most of the
        > work to be done was in this direction. It was more sexy to hire
        > electronic engineers (like me then) or computer programmers. Who then
        > spent most of their time fiddling with nuts and bolts. And even if
        > they
        > were skilled (like I am moderately), unless you have a really well
        > equipped shop and lots of materials, you spend most of your time
        > ordering parts or shopping. The physical world makes for a lot more
        > work
        > than cyberspace!

        If we put forward a coherent and exciting proposal we will get people
        coming forward with all the skills we need. The boom of rapid
        prototyping and 3D printing is something else that could help speed our
        progress.

        > And because people are naturally lazy, they will prefer
        > to spend hours programming to a fraction of this cutting, filing,
        > laminating or sewing.

        Is any of that code available to us to aid our progress? Open source is
        about accepting help from anywhere.

        > > ... A wing with 4 rotors can be controlled well
        > > enough to land in its docking station even in strong gusty winds.
        >
        > Good point. I was thinking of a single or twin counterrotating rotor
        > job, or twin horizontal savonius rotor (plenty of such toys about,
        > they
        > have s-shaped rotating wings), but the antics of the quad-rotor jobs
        > is
        > astounding. You could have a quad for starting, steering, lulls and
        > landing, attached to a larger twin turbine for generation. Having
        > hover-power at any time solves the lull problem.

        I think it is safe to assume that mass in the air will always be more
        expensive than mass on the ground. My inclination is therefore to
        minimize airborne generation potential to nothing more than what is
        required to keep the wing exactly where you want it at all times. The
        rest of the generating power can come from the reel/winch. I notice
        Makani do not seem to use a reel but I think that is a mistake because a
        fixed length tether is limiting. A shock absorber is needed to stop the
        wing bumping against its limits. It also limits altitude control. In low
        winds you want to go high to catch the faster winds. In high winds you
        want to stay low to protect the wing and tethers. Varying the reeling
        out speed as wind speed changes also allows optimizing of power
        generation. Reels also allow you to keep the tether off the ground/sea.
        Since they offer so many advantages I think they are worth the expense.
        They are used all the time in cranes, lifts and other places so the
        technology know-how is there.

        >
        > I think one of the first group of customers is going to be
        > yacht-owners.
        > Either normal sailing yachts who simply want a generator out of the
        > way
        > of their normal rigging, or solar-electric yachts for then when it is
        > windy with little sun. Yachts don't need a lot of power and their
        > owners
        > are required to have lots of money! It would be a cinch to go dead
        > upwind with an electric boat and an air-borne generator.

        Yes, yacht owners should be valuable early adopters. It was quite a
        revelation for me when I first realised that a flying wing could pull
        faster than the wind. Once you are doing that you can pull in any
        direction, as you say. Saul Griffith (CEO of Makani at the time) gave a
        talk in Cambridge 2 years ago and he was dismissive of Skysails. He said
        the ships had to slow down to get the full advantage of the tug from the
        sail. He did not seem to appreciate that if they used a stiff wing the
        Cl/Cd ratio would improve dramatically and that would allow them to tug
        the ships at many times the wind speed in any direction. Cl/Cd for a
        soft kite is apparently about 4 or 5 so tether tension starts dropping
        before you get to wind velocity. A stiff wing can be 10 times better.


        I foresee AWE generators having a selection of wings to suit wind speed.
        For low winds you need large but light wings with strong tethers. They
        will maybe be made using air inflated structural beams tensioning a
        light fabric. For strong wind a much smaller wing that flies at much
        higher speed is needed. Its surface therefore needs to be much stiffer
        so it would be built more like an aircraft. The tethers will be lighter
        but maybe longer to allow for the greater reel speed.

        Robert.
      • Bob Stuart
        ... There might be a good argument for just keeping the sweep frequency constant, to keep the strain on the parts and the power output fairly constant despite
        Message 3 of 28 , Apr 15, 2011

          On 15-Apr-11, at 12:05 PM, Robert Copcutt wrote:

          I foresee AWE generators having a selection of wings to suit wind speed.
          For low winds you need large but light wings with strong tethers. They
          will maybe be made using air inflated structural beams tensioning a
          light fabric. For strong wind a much smaller wing that flies at much
          higher speed is needed. Its surface therefore needs to be much stiffer
          so it would be built more like an aircraft. The tethers will be lighter
          but maybe longer to allow for the greater reel speed. 

          Robert.

          There might be a good argument for just keeping the sweep frequency constant, to keep the strain on the parts and the power output fairly constant despite varying wind velocities.  That way, two or three kites could cover a very wide variety of wind conditions, keeping a generator busy.  When the wind is strong, the price is very low, due to lack of storage.

          Bob Stuart

        • Robert Copcutt
          Bob, Storing the low wind wings could be an issue which is why I suggested using an air beam structure so that they can be collapsed when the winds get too
          Message 4 of 28 , Apr 15, 2011
            Bob,

            Storing the low wind wings could be an issue which is why I suggested
            using an air beam structure so that they can be collapsed when the winds
            get too high for them, even when docked on the ground.

            I am not sure it wise to try to keep anything constant because the power
            of the wind can change many thousand fold in a few minutes. A wing
            designed to generate in 3 m/s winds would break in 12 m/s winds (64
            times more powerful) no matter how you try to protect it in flight.
            Something designed for 20 m/s would drop out of the sky at 5 m/s. As
            with wind turbines we will just have to forget about generating power at
            low and high wind speeds, but the range over which we operate could be a
            bit wider.

            Robert.


            On Fri, 2011-04-15 at 12:40 -0600, Bob Stuart wrote:
            >
            >
            > On 15-Apr-11, at 12:05 PM, Robert Copcutt wrote:
            > > I foresee AWE generators having a selection of wings to suit wind
            > > speed.
            > > For low winds you need large but light wings with strong tethers.
            > > They
            > > will maybe be made using air inflated structural beams tensioning a
            > > light fabric. For strong wind a much smaller wing that flies at much
            > > higher speed is needed. Its surface therefore needs to be much
            > > stiffer
            > > so it would be built more like an aircraft. The tethers will be
            > > lighter
            > > but maybe longer to allow for the greater reel speed.
            > >
            > > Robert.
            > >
            > >
            > There might be a good argument for just keeping the sweep frequency
            > constant, to keep the strain on the parts and the power output fairly
            > constant despite varying wind velocities. That way, two or three
            > kites could cover a very wide variety of wind conditions, keeping a
            > generator busy. When the wind is strong, the price is very low, due
            > to lack of storage.
            >
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