57es, (external serration), revision #1 : When i posted the 57es, (on 13 July, 2010), i included an earlier version of the [flat plan at top] as an afterthought .

It contained an error ~ the dark green serration, basis for the trailing edge of the model, was not resting on its gray line, (representing the trailing edge of the wing as it would be if it were smooth) .

I had not noticed this ... but this made the wings, or 'blades', (i say 'wings' because they are heavy at their leading edges and taper to their trailing), wider than intended .

This post corrects that, and introduces a longer base taper which is integrated directly with the first, (shallowest), serration .

Revised text, (below), is carried over from the 13th .

Figures are new

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The 57es, (external serration), modifies the 57 horizontal axis wind turbine, (posted on 10 July, 2010), for use as an airplane propeller .

Here, the serration has been made additive to what would otherwise be the smooth surface of the wing, producing a wider, more durable form .

A second change is that the taper point for the base of the wing has been advanced, reducing its width .

Third is the inclusion of a swept-back tip, (based on a continuation of the hyperbolic sine and cosine geometry of the serration, with a shallow end cap), which may help reduce end-noise by rolling off contact with the air .

And a fourth is the reversal of the wing's pitch ; from a passive, power receiving bias for turbine use, to an active, power expending one .

Shown are views, details and close-ups of wing one of five

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Though the wing is both wider and thicker at its tip than the original 57, it is still a noticeably thin wing, (and one long for its width), when compared to most propellers .

This may make it more vulnerable to impact, wear or defects than standard models, (noting, however, that if and as it should be made from composite materials, it is likely to be strong for its size) .

The widening cross-section approaching the base may churn the air more than do most models, (though this can be reduced in design) .

For these reasons, i think that the best use for the 57es, as shown, would be in aft-facing, counterrotating pairs .

This might be particularly important at high speed when transonic flow may be induced

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On the other hand, i think these propellers would be substantially quieter than standard ones, (at low and medium speeds), possibly more fuel efficient ; and capable of broader ranges in speed and altitude .

This belief is due in port to the serration's (expected) :

focusing of airflow into accelerated bands along the wing ;

ability to diffuse its own wakes, and separate and deflect those produced ;

to the shape of the cross-sections ;

width and pitch characteristics intended to produce thrust evenly across the wing ;

and, in part because it's my boy

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I see the possibility of applying this to the purpose of helicopter rotor-sets, but feel the base could be made more slender to reduce drag on, and turbulence behind, the main rotor when traveling at speed