Depending on how long of a shaft, Steve Wittman used an extension shaft with
bearing on both his VW (Formula V) racer and the V8 version of the tailwind.
Both had the effect of moving the propeller sufficiently forward of the
engine to significantly improve the aerodynamics of a tractor installation.
I am NOT personally familiar with the VW version and have only looked over
the plans for the V8 version; however I presume that both should have had
the effects of:
1) Isolating the crankshaft from bending moments--including gyroscopic
precession.
2) Isolating the crankshaft from thrust loads.
3) Isolating the crankshaft from any torsional resonance of the
propeller--by being more flexible than either the crankshaft or propeller.

That should have moved any critical speeds to or near the idle range--but I
have no experience and I am sure that any good means to test torsional
resonance between the engine and prop will prove technically "interesting".
Remember that any torsional resonance within the engine, driveshaft, and
propeller of a concentric (planetary or epicyclic) or direct drive
installation will NOT couple to the airframe!

There is also a similar VW conversion in work at FXE in a canard pusher. I
will try to ask the owner about it.

BTW, the plans from Steve Wittman for both the VW and V8 drive systems are
still available and reasonably priced from Aircraft Spruce. You can look
over something that seems to have worked without having to reinvent it.

Peter

P.S.: I really think that you are giving up a lot of your maximum power
in slowing a Soob down enough to drive a propeller at 1:1.


wrote in message
oups.com...
Anyone know suppliers of a device that can take the power off a
flywheel to power a long shaft?
No transmission.