Egypt Silk Mill 62pi wind turbine, revisions 1 ; 4 April 2011 .

These figures revise and extend the post of 22 March ;

showing changes to the core housing, and a variety of ways in which one or more core assemblies,

(shown without wings and mounting brackets),

could be positioned or grouped within a supporting arch, or inverted arch .

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The core housing streamlines are revised to be based on the airfoil curves shown below them,

(at top left and right) .

That at left, derived from the model curve for the wings, is modified for application to the cores' inner ring .

That at right, which is also the model curve for the arch cross-sections, is modified for application to the core housing .

The housing and inner ring hold the wings where their cross-sections are the broadest,

and the air channel through the core, narrowest .

This causes the wind to accelerate past the wings, (by the Venturi effect), increasing lift .

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The supporting arch styles are based on catenaries, applied in two planes .

The arch chosen would stand off-center on a turntable,

allowing the wind to rotate the turbine assembly to its working orientation .

The underside of the clear half of the turntable, (its 'yard'), could be used for counter-weighting .

The arch's cross-sections are modeled with an airfoil geometry,

they should exhibit low drag when facing the wind .

The cores are positioned between the cross-sections' widest points,

which should provide a second Venturi to boost air speed ;

and with it turbine efficiency .

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By its nature, a catenary arch will distribute stress to its feet .

An inverse catenary, supported at center as shown in the top row,

would bring stress to its center .

I like both options, (and both can be improved),

but the arch whose feet rest on the turntable is sounder .

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As shown in the figures with six cores and a skirted turntable,

the footprint for the whole is proportionally much larger,

(for wing area), than that of conventional, towered designs .

However, because a catenary becomes steeper the further it extends,

the ratio of wing area to footprint will improve as more cores are added ;

(six are shown, but i see little reason to limit it here) .

These stacked cores would have the advantage of being able to turn independently –

– with the highest, where the wind blows strongest, turning fastest .

At a given point, the sum of their output should exceed that of a single, larger turbine ;

while using components which may be more deliverable,

(depending on the scale and construction of the arch),

and replaceable should the need arise .

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As an option, the turntable can be surrounded by a skirt based on the secant-h relative of the catenary, (shown) .

This would offer smoother ground-level airflow .

The space beneath the skirt could be used to hold an array of batteries –

– perhaps of the standard, lead-acid type .

By using these as an intermediary between the wind-generated current and the grid or local application,

the variability of this method of power harvesting could be smoothed .

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Among the options for repair and maintenance access :

either or both the skirt and the yard of the turntable could have anchor points

for a service scaffold, bucket or crane, (as appropriate).