Small wind turbine: mast question

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Obamot
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by Obamot » 02/07/12, 22:34

plasmanu wrote:Halfway up there is the first set of guy lines: 4 hooks.
At 4/5 of the height the second set of 4 hooks.
4 + 4 = 8.


In this case, it does not seem to me that you can count that they will redistribute the forces in a way equivalent to their expected tensile strength!

Furthermore, for them to hold 8 tonnes, they would all have to be on the same side ... Then there is a considerable loss due to the angle of the cables in relation to the mast (they would actually only be 1 tonne if they were perpendicular to the axis of the mast) finally, your wind turbine will rotate according to the wind direction, at best there will be only one cable which will take all the efforts (but on a few hundred kilos) , at worst, the wind turbine will be between two and then it will do very little!

It's just a modest opinion. And the more I brainstorm, the more I tell myself that as long as we don't know the resistance to the constraints of the mat, we talk a little in a vacuum.
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Last edited by Obamot the 02 / 07 / 12, 22: 43, 1 edited once.
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plasmanu
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by plasmanu » 02/07/12, 22:41

It seems fair to me.
Cables limit twisting and retain vibration.
Bolting allows me to have 8 different directions.
The tension prevents an amplification of the vibration.
Whatever the direction in which the mast wants to go: it will have 3 cables which will fight in opposite direction.
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by Obamot » 02/07/12, 22:44

I edited.
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by plasmanu » 02/07/12, 22:52

I have no doc on the mat.
I would put more detail.
Seen from the nose a trunk of a third is borderline portable alone.
A violent blow of mass would make fart of rabbit.
It is oversized for a 500w wind turbine.
The fixation at the top is too wide.
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by Obamot » 02/07/12, 23:05

I see where you're coming from.

But that cannot behave in hyperstatic structure, quite simply because the cables can redistribute the loads only in traction (and absolutely not in compression ...). So you can't rely too much on the script you describe amha. Because don't forget that while cables are pulling in the “right direction”, others are pulling in the “wrong direction”, which increases the push and lever effect in the direction unfavorable and most powerfully ... So the counter effect is more than canceled out. He cannot play his role ...
Okay here, in the state, everything has been said no? I believe on my side, having toured what was accessible to the small neurophilic computer that serves as my brain :-)
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by manitou22 » 02/07/12, 23:30

Hello,
It is also possible to take inspiration from boat masts, with struts (spreader bar) that work in traction and compression on the mast; another advantage, the cables do not eat too much ground surface
http://t1.gstatic.com/images?q=tbn:ANd9GcSLPcTxydHMfDubGwpC4n6glYaTEYLo3R6DBxD80iGpWiC1xCN_
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by plasmanu » 03/07/12, 06:12

Nice boat mast.
I am against a rot-proof acacia tree to fall (not yet dead), against the 50cm diameter wall at the bottom. 10m high.
I can make the foundation against this one, use it to hoist the mast high, keep half of it to make a strut on half the height. And I am against the basalt / limestone wall of the barn about 3m high.
I could even test the wind turbine on it without anything more by bolting the fixing directly into the cut flat trunk: say cut to 5 / 6m.
By providing a passage for electrical cables.
It will have a natural elastic bending: it is wood.
This tree did not move during the 1999 storm.
I would make a ball joint with 4 flap hinges and a large axis: because I need something to hold the mat in a fixed position when lifting
Unless the tree serves me as a crane and takes off the mast from the ground to overlap the 2 axes to be fixed to the foundation.
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by Obamot » 03/07/12, 07:26

manitou22 wrote:Hello,
It is also possible to take inspiration from boat masts, with struts (spreader bar) that work in traction and compression on the mast; another advantage, the cables do not eat too much ground surface
http://t1.gstatic.com/images?q=tbn:ANd9GcSLPcTxydHMfDubGwpC4n6glYaTEYLo3R6DBxD80iGpWiC1xCN_


There is no miracle ! A boat directs its sails facing the wind and the keel acts as a counterweight, the captain plays the balancing act according to the force of the wind, he adapts the sails, almost all the force of the wind is used / dissipated to make advance the boat. In heavy weather it can put it facing the wind to reduce its grip ... None of that on the ground. Except for the breaking strength of the mat, and its elastic limit (as said above, missing data). The rest is very different! A boat can avoid heavy weather. Not a wind turbine.
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by manitou22 » 04/07/12, 00:03

Hi,
I doubt that a wind turbine of the Plasmanu type generates as many constraints as a wing mast over 30 meters high will suffer on a trimaran whose surface is barely larger than its garden. Current rigging technologies tend towards a maximum of "canvas stiffness". A boat that jumps several meters with swerves, a mast-wing head supporting a sails of several hundred kilos, shrouds stretched like piano ropes are among the constraints accepted and mastered so that the boat heels less possible, a guarantee of speed gain. Their construction is designed in a sense of maximum weight saving, always at the limit of undersizing. The plasmanu mast is heavier and has much less surface area to the wind than that of a racing tri. And yet, they face weather conditions rarely experienced in our regions and most often return safely.
To better understand:
http://www.fralo.info/jv2012/bp5/caracteristiques.html
http://www.voile.banquepopulaire.fr/Maxi-Trimaran-Banque-Populaire-V/default.html
http://www.youtube.com/watch?feature=player_detailpage&v=85mIDnNRptg
http://www.youtube.com/watch?feature=player_detailpage&v=ZkptbTOz7Ko
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by Obamot » 04/07/12, 05:20

I was just wondering about the breaking strength of the mat, and its elastic limit ...

When I don't know, I stay cautious ... That must be why : Lol:

And then also, a boat is made in a shipyard and it is calculated with small onions (as mentioned above, the sail is always presented in a more or less optimal way against the wind: precisely, the wind turbine too.

And then I would be remiss if something happened to 'our clairvoyant-droid' : Lol:
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