JP wrote:
"George" kirjoitti
gy.com...
Richard Lamb wrote:
ADK wrote:

IF you had to design a PSRU, to drive a pusher propellor via shaft, what
would your experience dictate? Thinking along the lines of a gearbelt,
chain or gear. Please, I would appreciate the collective experience
available on this group. I have decided on the aircraft, but want to
make it the most reliable and safest it can be.

"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.



The collective experience is zilch = nada = squat = undefined.

THAT is what everybody had been trying to tell you.

Wait a second. Look around the airport.

How many shaft driven propellers do you see?

Have you ever seen?

If you are heart set on doing it, I sincerely wish you luck.

But I can't offer any further advice - 'cuz they ain't none...



Richard


Richard,

Didn't the military do this once?? Seems there was the P-39 Aircobra,
shaft driven from a rear mounted engine?? Are the gray cells working that
far back??

Not that it would be applicable to an experimental, but at least It was
once done?

George



The P-39/P-63 examples can't probably be compared directly with this matter
in question. These designs both have a large reduction gear casing in front
of the plane. The support structure for this PSRU looks very firm. Perhaps
the safety cage type center fuselage structure has something to do with the
lack of severe resonance problems? Any known resonance problems with these
aircrafts?

JP


I find myself wondering if, even though the P-39/63 can't be directly
applicable to experimental class aircraft, isn't there a lesson to be
learned here.

The primary shart turns at engine speed, the PSRU is located remotely
and the propeller is not transmitting torsional resonant frequency
pulses to the shaft. At least not directly. Would a pulse absorbing
coupling, such as Molt used, totally eliminate the resonant frequencies
in the shaft??

Since the OP was thinking of a remote mounted engine and a long shaft,
is this worth considering, since he seems bent on exploring this
possibility??

Just my mental ruminatings. YMMV