Subaru flywheel pto shaft

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

[Morgans]

> 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.

Look into marine stuff. Inboard/outboard drives have a rubber coupling that
goes on the flywheel, then a splined shaft goes into a metal receiver
mounted in the rubber part.

They need to have the shaft supported by a bearing, very close to the rubber
coupling.

Look into Gates, on the Internet. They have more power transmitting devices
than you ever thought existed.

Caution should be used, if you have an idea of driving a prop from this long
driveshaft. Harmonic vibrations in the shaft can tear apart a drive system
in very short order, and eliminating them is a black science, not to be
taken lightly.
--
Jim in NC

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Do a Google for Molt Taylor and/or Flexadyne. Lots to learn.........
============
Leon McAtee

[Peter Dohm]

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.
>

[Morgans]

"Peter Dohm" > wrote

> 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.

What you say about the shaft extension I don't think is applicable to the
question of a long drive shaft, which is what the post is asking. (I think)

The short extensions you propose (as working for Steve W.) are not long
enough to give a problem with resonance, like a long shaft would have. The
shorter the shaft, the higher the resonant frequency would be.

You are correct about the Soob giving up a lot of power at a 1:1 drive
ratio. It depends if the OP is willing to have that much weight for the
power being produced.
--
Jim in NC

[Peter Dohm]

"Morgans" > wrote in message
...
>
> "Peter Dohm" > wrote
>
> > 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.
>
> What you say about the shaft extension I don't think is applicable to the
> question of a long drive shaft, which is what the post is asking. (I
think)
>
> The short extensions you propose (as working for Steve W.) are not long
> enough to give a problem with resonance, like a long shaft would have.
The
> shorter the shaft, the higher the resonant frequency would be.
>
> You are correct about the Soob giving up a lot of power at a 1:1 drive
> ratio. It depends if the OP is willing to have that much weight for the
> power being produced.
> --
> Jim in NC
>

There is some question in my mind as to "how long is long", and suggest that
Steve Wittman's designs would qualify as long when viewed as prop
extensions.

However, I agree with you that they are short in the context of driveshafts.
With that in mind, a look at Molt Taylor's work (as suggested earlier in
this thread) would be a very sound idea.

I don't think that there is any resonant frequency that would be acceptable
if not damped, although I have been told that any resonant frequency lower
than the frequency of the exciting source is usually trivial. I don't know,
as it is not my field.

Additional sources on information might include any treatise on helicopter
tail rotor drives. And, of course, the original post did not mention what
was to be on the other end of the driveshaft: prop, clutch, fluid coupling,
reduction and/or angle drive, ducted fan, etc...

Peter