"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