No Perry, I'm not referring to the AirBus mishap. I
happen to whole heartedly agree with Paul's assesment of
de-lamination/separation of the lay-ups, further
exacerbated by the elements (Moisture) seeping in. I
have personally witnessed this early on the infancy of
Composites, in my brother's Yacht Club.
As far as I'm concerned, the chances of this occurring
in our Prop Blade is zilch to none since it operates as
a HUGE centrifuge.

It's my ignorance of Composite construction
(Epoxies),that makes me very eerie of the bonding
strength of dissimilar materials joints, vs time.......
So Perry, make sure that you OVERKILL the Shank to Blade
Hub joint. I'll take the additional weight even if I
have to fly on an empty stomach to compensate for it ;-)

                                     Butch

Butch,
The only thing that Epoxy sticks better than to itself, is steel,
it loves it ! we have a saying here - you may have heard of it
"Sticks like S... to a blanket"
Paul is right, if done properly there is no problem.

George (down under)

 For primary structure you shouldn't depend on the bond strength
of the resin to the metal, no matter how good it seems to be. In the case
of the LAEV shank to blade joint, the carbon skins will be following the
sinusoidal shape of the outside of the shank and then wrapped with a
substantial circumferential ring or collar of carbon.  In order for the
blade carbon to slide radially outward (towards the tip of the blade)
under centrifugal loads the carbon will have to expand the carbon
ring/collar which will be VERY hard to do.  Alternatively the blade
layup would have to shear away from the collar and slide along the
sinusoidal surface, another very unlikely scenario.  The collar should
lock the blade surface plies solidly to the shank.  At least, that's
the plan.

Take a look at the exterior shape of the blade shanks in Butch's photo
of the prop parts.

Bill Freeman

Here is a drawing. 

Paul Lamar
 
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