h a l f b a k e r yRecalculations place it at 0.4999.
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The idea is to use a variable surface kite (like those used in wind surfing) to generate electricity. The kite, which would be many acres in area, would be located high in the atmosphere where there is a constant source of very powerful winds. The jet stream being a perfect example.
The kite would
be launched into the jet stream. It would be anchored to a base station where the power generation would occur. The cable from the kite would be attached to a long arm. This arm would act as a lever which in turn would be connected to the base station. The kite increases its surface area and creates more force. That force in turn lifts the arm which it turn rotates a large gear which through a series of reductions turns a generator. Once the arm has rotated trough its full swing the kite would decrease its surface area creating less force. The weight of the arm would bring it back down turning the generator again.
The length of the arm as well as the gear reductions would be optimized. The base would be able to rotate to match the direction of the winds. Picture a turret where the arm is the barrel.
Kite Ship website
http://www.kiteship.com/
[MisterQED, Dec 05 2007]
Kite Sail in use article
http://www.networkw...ommunity/node/22225
[MisterQED, Dec 05 2007]
El ingenioso hidalgo don Quijote de la Mancha
http://en.wikipedia...uixote#Plot_summary
read the last part of the third peragraph [BJS, Dec 06 2007]
Kite Power
http://www.guardian...ewableenergy.energy
[imaginality, Aug 16 2008]
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Annotation:
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My first concern would be the cable. At the point just below the attachment to the kite, the cable will need to be strong enough to support the "dead load" of the cable suspended below it, plust the dynamic load of the force exerted by the kite to move the arm. As the cable is going to be 10 -15 km long, it's going to have to be exceptionally strong and lightweight, perhaps beyond existing technologies, since (for instance) sapphire whisker cannot yet be manufactured or woven on an industrial scale. |
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You could do this with an automated steerable kite, where 1 set of strings is fixed so that as the kite rises, the angle of attack is changed and the kite drops. You could possibly also achieve a far more aesthetically pleasing device by linking a number of kites in a chain, kind of like a Chinese dragon kite so that as one kite dips, it affects the next kite and they all move in a wave. |
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Another method would be to have strings at either side like a stunt kite and have a see-saw on the ground. Certain types of kite are auto-recovering so that when they go off to one side, they are steered back across centre to the other side. |
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I saw a project to use a kite-ish device in the jet stream. It was like a gyrocopter with rotors which could be powered to get it up and then provided power once driven by the wind. |
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//The length of the arm as well as the gear reductions would be optimized.// Really? I thought you'd want to have them as inefficient as possiblE. |
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Maybe you don't have to go so high. They are now powering sailing ships with similar kites, so there must be a decent amount of power much lower. |
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The title is confusing. First, it doesn't mention kites. Second, there isn't anything new in this. Various kite-power schemes have been kicked about for decades. |
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Gearing reductions would be stupid. You need gearing increases. |
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Stirngs are not going to do the job - for any useful amount of power you're going to need high-tensile cable. |
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Why even have the arm? You could just unroll or roll-up the cable, that way you probably wouldn't even need gearing. |
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If you have the cable wound round a drunm, then yes, you get rotational power straight out. But you have to put in energy to reel it in again. If I understand the idea correctly , the mass of the "arm" acts as the return mechanism. It makes cable management quite a lot easier, as long as the kite stays aloft. |
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I understand that, and if that is what you want then a torque spring can simulate the same effect of the mass of the "arm". Otherwise I believe the extra energy that would be produced without the resistance to the cable would make up for the energy needed to roll the cable back up. |
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Good point. It rather depends on how the energy would be extrscted from the drum, and the losses inherent in the torque spring. |
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Also, winding the cable round the drum would increase its fatigue stresses. |
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I wonder how distant from a wind farm
turbine a kite could could be to gather
energy at each place |
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If the kite were very light, or computer
controlled it could find the optimal
spaces between or above the turbines
using the siting, permitting, and
structural towers already there
(cheaper, better) |
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I like marklar's seesaw on the ground adaptation. I think changing the configuration of the kite makes the kite too complicated. |
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My only real concern would be finding a cable system that would meet the strength requirements. The arm would act as a counter weight. Place the arm in the xy plane with the z-axis standing vertical. The arm would be able to rotate around the z-axis to match the direction of the wind. The arm would intially lay on the xy plane. It would rise to a position nearly parralel to the z-axis. The force from the kite would be reduced and the arm would pull the kite back down to the xy plane. |
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[Bungston] All of the kites I mentioned exist. AFAIK the variable surface kite does not exist. 'Wind surfers' use a sail, not a kite. All the kites I have seen/used for 'kite surfing' are not variable area, and anyway, there is no description of how the area of the kite is changed or how you tell it when it's time to change. |
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[8th of 7] I call them strings because it's a kite, even if the 'strings' are borrowed from a suspension bridge. |
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As an added attraction, the mechanism should incorporate a large model of a child/clown/Michelin Man which waves as the arm goes up and down. I've often thought that normal wind farms should be decorated to look like the ones you buy at the seaside to decorate your sandcastle. |
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It should look like a ferocious giant. |
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Hmm, I can feel a "make gas platforms look like Godzilla" idea coming on. |
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// the 'strings' are borrowed from a suspension bridge // |
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Better put them back quick, before someone notices. I've tried this sort of thing and for some reason people can get quite amazingly annoyed when you borrow bits of major infrastructure, even if it's in a good cause ... |
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[bigsleep] Oh cool, can it convert mechanical rotation back into JET A kerosene ? |
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You coule vary the kite surface by letting it expand or forcing it to contract. |
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// letting it expand or forcing it to contract // |
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The same effect could no doubt be acheived by forcing it ot expand or letting it contract, shirley ? |
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The airlines might have some cross words to say about this. |
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