Propeller Experts, Please!

[netjaws]

If you were asked how far forward of the AP a propeller is, what would you say? Would you measure to the longitudinal centroid of the blade's projected area in an elevation view? Would you measure to an imaginary line at the geometric center of the blade tip chord? Would you extend both the leading and the trailing edges to the propeller's axis of rotation, and average the two?

What I am loking for is along the lines of a blade hydrodynamic center (in a side-view) or the dynamic center of mass, or something.

Cheers,
Josh

[mmd]

Measure to the centre of the blade root, which is usually the midpoint of the hub length. All measurements of the propeller (rake, skew, etc.) are taken from this point, as well as measurements for shaft taper.

[netjaws]

Thanks!

To clarify - that is the center of blade root, as it exists on the propeller shaft, and not based on an imaginary extension of the leading/trailing edges to the axis of rotation?

[mmd]

Centre of the blade root where it intersects the surface of the hub. No extended imaginary lines.