wrote:

Even more surprising was the torque specs for wooden props. As I
recall it was on the order of 14 lb-ft.

The torque requirement is very dependent upon the size of the bolt -
3/8" bolts obviously require less torque than 1/2" bolts. The torque
requirement is also dependent upon the hub size - an SAE-1 flange will
require less torque/bolt compressive force to get the same pressure
over the hub face than will an SAE-2 flange.

Finding appropriate bellevilles that can give the right force level at
1/2 compression, along with appropriate compliance to be able to
protect against wood expansion/contraction during temperature/humidity
changes is non-trivial. Doable, but non-trivial.

... Of course, the best joke is
the claims made by 'experts' selling prop hubs with drive lugs :-)

The wood prop MFG's better understand what's going on, and the ones
that I've talked to all do.

--
Marc J. Zeitlin
http://www.cozybuilders.org/
Copyright (c) 2008 http://www.mdzeitlin.com/Marc/