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Old 06-22-2015, 07:29 PM   #4
pmdec
 
Join Date: Nov 2006
Location: France
Posts: 441
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Hi,

IMHO:

On a propeller drawing, the cross sections are "true" cross sections, not viewed from a particular point, but drawn at their true size (prop drawings are 1/1 scaled).
Their trailing edges are not align with anything. They are drawn so that:
- their barycenter (center of mass) is on the neutral axis of the blade,
- their "inclination" is their true inclination ("H/2pi").

Anyway, you can't reduce all the dimensions to obtain a scale working prop, because the air resistance is in relation with the square of the speed (in first approximation).
You have also to consider that a prop is not made for an engine, but for an a/c fitted with an engine
Eventually, test prop are not designed like prop for flying, they have a specific design, and I don't know if any test prop for the Anzani 25HP has survived...

Regards,
PM

The added drawing is from Guéret book page 153 (B&W only original).
Attached Images
File Type: jpg RatmDrawingBench.jpg (85.3 KB, 16 views)

Last edited by pmdec; 06-28-2015 at 09:45 AM. Reason: Add drawing.
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