"Gunny" wrote

To address an earlier part of the thread, however, I wouldn't count on
friction for a wood-spar attach fitting. The fittings are often made
from thin material. Out-of-plane bending prevents the fitting from
developing much friction away from the bolt holes. And you have
humidity changes constantly modifying your wood dimensions. Tried-and-
true phenolic bushings, match drilled and reamed to the fittings, cost
about a dollar per hole. In the plane I'm building, that is less than
$50, so it was an easy choice to make.


Oh, I've becomne a believer in that part of the tale. It does make perfect
sense that the plates are not ridgid enough to develop any significant
friction.

There are too many conflicts with what I have read from people who's word I
trust, that props are driven mainly from shear loading.

I remember a few months back, that one of the guys on the group
(occasionally) that works at Scaled Composite in an important capacity,
threw the prop on his (vary-easy ?) There were warning signs, as I recall,
that were missed before it flew off.

A top Boeing engineer is not likely to have enough experience with wood
props to make his word more valid than the local guy at the airport that has
been flying wood props all of his life.

I really don't have a dog in this fight. I'll attempt to let it lay, and
let those out there with a dog in the fight make up there own minds. I
could be all wet, but if I am, I have badly misunderstood some reading I
have done.
--
Jim in NC