PSRU design advantages

"Morgans" wrote in message
...

"ADK" wrote in message
news:X6TXf.28774$%H.11944@clgrps13...
This is probably going to open old wounds. What I would like is
experienced input on the advantages, for economic, efficiency and
longevity etc. of different types of redrives.

I am leaning towards a cog-belt reducer in a 6 cylinder, liquid cooled,
configuration driving a long drive shaft to the prop.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Warning,Warning, Danger, Danger, Will Robinson!

Yep, that is a really big can of worms.

The redrive is not as big a problem as you think. You get into a mess
when you start talking about long drive shafts.

Torsional resonance has brought many of the great minds of the flying
industry to their knees. No joke. I don't have all of the links at hand,
but someone here does. Start by googling torsional resonance.

Then, be afraid. Be very afraid.
I you don't get afraid, keep looking, until you get afraid, because you
need to get afraid, or you don't understand the problem.
--
Jim in NC


The long driveshaft is a problem. Unlike a car, in an aircraft you put the
driveshaft in between the crankshaft and the flywheel. Not the place for a
driveshaft. My recommendation is to couple the driveshaft to the
engine/reduction unit with one of the shot filled fluid couplings. They
kill any feedback and pretty well damp the reinforcement that makes the
driveshaft go totally bonkers. Then use the largest diameter tubular
driveshaft you can fit into the space available. That will tend to put the
resonant frequencies into a range you won't pass through or run in normally.

Highflyer
Highflight Aviation Services
Pinckneyville Airport ( PJY )