[ I call the 57es a five 'winged' propeller ; as these elements are heavier at their leading edges and taper to their trailing edges, in the manner of wings ]

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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 that the base needs to become more slender to avoid excessive drag and turbulence in forward flight ; particularly at speed