Here is what Charley Airesman's prop shaft extension looks like.
All thrust is taken by the soob's internal thrust bearing. The large plain bearing
out
by the prop is pressure fed with engine oil with drain back to the
sump. The prop shaft is carbon fiber layed up at a 45 degree angle
and bonded to the prop hub. The torque isolation looks to be a bit
over kill and some of the six rubber bushings could probably be removed.

The whole idea here is to get the prop as far back as possible and keep
the slope of the cowl at a minimum to keep the air attached.
Usually with an ordinary prop and prop extension the prop on a pusher is 
in danger of contacting the ground. This is not a problem with a direct
drive prop as the diameter is only 54 inches or so.

Paul Lamar
 
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