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Old 03-09-2019, 04:41 PM   #1
RadialEngine
 
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Default Taper Hub to Tip

Blade axial thickness tapers down from hip to tip.
Some propellers have the leading edge on or nearly on a plane
Some are tapered symmetrically around a central plane
Some have the leading edge receding

Is there a criteria to choose one design versus the other?

Thanks
Mauro
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Old 03-09-2019, 07:38 PM   #2
Dbahnson
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Much of the design was done via experimentation, often following theoretical concerns about blade efficiency, but over time most wooden propellers were manufactured with the same general shape. But in all of them the pitch along the blade length is quite constant, so the angle of the blade decreases along the length of the blade.

"Test club" propellers are different in that the angle of the blade is constant along its whole length. The propeller is designed to provide drag, not designed for efficiency.
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Old 03-09-2019, 11:09 PM   #3
RadialEngine
 
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Yes, understand the thickness is reduced because the angle changes to keep a constant pitch.
My question is about which side of the blade is thinned down.

Suppose to stack up layer for the blank with the leading edge down.
The stack side view may look like a pyramid, an inverted pyramid or two pyramids glued at the base.

All three stack up can be made into a prop of the same diameter and pitch if they start with the same hub thickness.

Are there any mechanical or aerodynamic difference/advantages of one design over the other?
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Old 03-10-2019, 12:15 AM   #4
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Sorry. I really don't understand what you are asking.
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