"Meat Thermometer"

Part of a dry-land base for the Melia wind turbine array .

25 August 2011 .

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Essential to an array of turbines rising from a single base is their ability to turn together from that base to face the wind .

These figures provide a more detailed look at a turntable and taproot design, (also shown in the post of 16 August), that may enable this .

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(annotations which accompany lines and arrows to a figure, ''Section view at edge'', follow)

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Part of the upper, weight receiving, surface . Its shape is based on a hyperbolic secant .

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Part of the lower, weight transferring, surface . Its shape is based on an inverted hyperbolic secant .

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Outer drip line :

This would overhang a raised lip on the inner rim of the apron, (not shown), to allow most rainwater, snow and ice to run off .

Both the outer drip line and the apron's lip could have brushes on them to limit the amount of wind-blown water, snow, dirt and debris

which found its way into the turntable enclosure of the base .

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Inner drip line :

A second run-off point for water, if needed .

This area, and the outward wall above it, could have heavier brushes on it for deterring small animals and/or insects which sought entry into the enclosure.

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Groove for rotational position sensor ; (for servo-controlled rotation) :

The structure of the tree, (shown in the post of the 16th), having the core-support bridges extend downwind, should do much to enable it to turn to face the wind naturally .

However, i imagine there may be scales or circumstances where servo-motor assisted turning could be useful or necessary .

One, (and perhaps a better), option would be to integrate the position sensor(s) with the actuating drive motors .

But this relies, (depending on the mechanism used), on drive wheels or belts not slipping, drive gears not stripping, or drive stepper-action not reversing .

Having a ring integral to the turntable which provided positional information to the computer controlling the rotational motors could serve as a fail-safe .

I imagine optical bands, (black/white), to be read by sensors below it anchored to the (non-rotating) base, (not shown), might work well .

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Electrical insulation / shielding .

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Groove for conducting lightning out of the array and into the base .

Lightning strikes, particularly if the array is built to large scales, would be an issue to be handled –– and as well a potential source of harvestable electricity .

Lightning rods could (and should) be added to the tree at various points, passing electricity from a strike down to the turntable by means of high-capacity conductors in the tubing .

The 'bottom' of this groove could hold a high conductivity metal surface on which rode a number of evenly spaced carbon brushes to carry the surge to earth, to capacitor banks in the base enclosure, or both .

If used, the capacitors could then be drained individually into the battery array which i imagine to be an integral part of the system .

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Area for seals to retain grease :

The weight of the entire structure would be borne by the foundation supporting the base of the turntable and, (to a lesser extent), surrounding the taproot .

Between these there would need to be a very heavy grease, akin to that used for the fifth wheel of tractor-trailers .

However, at some point the array would weigh enough so that the grease could be squeezed from between the load surfaces and into the turntable enclosure of the base .

Seals which rode on the turntable wall could help prevent this, depending on their number and qualities . This stretch provides an area for them .

It may take some engineering cleverness to design seals which could be used for the larger expressions of this design .

Redundant layers seem advisable, as would the ability to replace one without disturbing the other(s) .

Automated collection and reuse of what grease did escape primary containment also seems a good idea at large scales .

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Groove for hold-downs :

The taproot and its foundation bear the primary responsibility for keeping the array, (tree), centered in its foundation and vertical to the earth ; (the turntable would also contribute) .

However, in extreme-wind conditions there may be the chance that without hold-down points the tree could be lifted enough to damage or uproot it .

This groove provides a face within the greased zone of the turntable where hold-down points or wheels, (not shown), anchored in the base, could grip the turntable to prevent this .

Such might also be adaptable to the purpose of fine-tuning the verticality of the tree in high-wind conditions ; and of damping harmonic vibration of the tree if this developed .

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Area for the driven gear :

For this purpose, either a spur gear, helical or double-helical might be bolted to, (or molded into), the turntable wall .

The gears(s) would be lubricated by the same grease used in the support of the assembly .

Depending on scale, (which would determine whether the turntable can be delivered to the site as one piece), the gear may need to be assembled from sections.

Using offset layers here, (perhaps 3, not shown), should help compensate for weakness at the butts between segments .

The turntable gear could be driven by gears linked to a number of evenly spaced motors, (perhaps 6, also not shown) .