PSRU design advantages

"Richard Lamb" wrote in message
ink.net...
Big John wrote:

ADK

Look up Molt Taylor and his Aerocar system. He used a pusher
arrangement and seemed to have most of the problems solved with long
shaft back to prop.

His bird may still be flying some place to exhibitions?

Am sure someone will jump in here and give data on his bird and how he
coupled shaft to engine with a "power glide" clutch or some such. It
allowed a small amount of slippage at each power stroke to prevent the
pulse being transmitted to drive shaft and prop as I recall.

Best of luck with a difficult problem.

Big John

Ok,

I think it's also used on the Imp and Mini-Imp.


The "clutch" consists of two (wavy surfaced) plates with lead shot
loaded between them.

As the thing spun up, centrifugal force packed the shot solid, but
there was enough "give" with the shot to absorb the "jerk" (4th
derivative?).


Richard

no idea why that came out in past tense...


It is indeed used on the Imp and the MiniImp. Molt used it on most of his
designs and spent quite a few years getting the bugs worked out of it. It
is NOT "two wavy surfaced plates" but just a little different.

The driven part is a cylindrical case with a charge of shot in it. When the
case is driven the "fluid" shop is packed tightly against the outer diameter
of the spinning cylinder. The output shaft has a single "wavy" plate on the
end of it. This plate is enclosed in the cylinder with the shot. As the
shot gets packed into the rim of the case it grips the plate and transmits
the power to the output shaft. If you try to drive it backwards all the
plate does it turn in the loose shot and warm it up a bit. Like a "sprague
clutch" from a helicopter, it only transmits power in one direction. By
varying the load of shot in the cylinder you can vary the coupling
coefficient and "set" the breakaway torque for the unit. It cannot transmit
damaging torques from torsional vibration back through the coupling because
the output shaft "breaks away" before a crippling torque is reached. You
don't want it to break away at too low a torque either, or you will
basically have a "slipping" clutch in your drive train.

Highflyer
Highflight Aviation Services
Pinckneyville Airport ( PJY )

"Highflyer" wrote in message
...

"Richard Lamb" wrote in message
ink.net...
Big John wrote:

ADK

Look up Molt Taylor and his Aerocar system. He used a pusher
arrangement and seemed to have most of the problems solved with long
shaft back to prop.

His bird may still be flying some place to exhibitions?

Am sure someone will jump in here and give data on his bird and how he
coupled shaft to engine with a "power glide" clutch or some such. It
allowed a small amount of slippage at each power stroke to prevent the
pulse being transmitted to drive shaft and prop as I recall.

Best of luck with a difficult problem.

Big John

Ok,

I think it's also used on the Imp and Mini-Imp.


The "clutch" consists of two (wavy surfaced) plates with lead shot
loaded between them.

As the thing spun up, centrifugal force packed the shot solid, but
there was enough "give" with the shot to absorb the "jerk" (4th
derivative?).


Richard

no idea why that came out in past tense...


It is indeed used on the Imp and the MiniImp. Molt used it on most of his
designs and spent quite a few years getting the bugs worked out of it. It
is NOT "two wavy surfaced plates" but just a little different.

The driven part is a cylindrical case with a charge of shot in it. When
the
case is driven the "fluid" shop is packed tightly against the outer
diameter
of the spinning cylinder. The output shaft has a single "wavy" plate on
the
end of it. This plate is enclosed in the cylinder with the shot. As the
shot gets packed into the rim of the case it grips the plate and transmits
the power to the output shaft. If you try to drive it backwards all the
plate does it turn in the loose shot and warm it up a bit. Like a
"sprague
clutch" from a helicopter, it only transmits power in one direction. By
varying the load of shot in the cylinder you can vary the coupling
coefficient and "set" the breakaway torque for the unit. It cannot
transmit
damaging torques from torsional vibration back through the coupling
because
the output shaft "breaks away" before a crippling torque is reached. You
don't want it to break away at too low a torque either, or you will
basically have a "slipping" clutch in your drive train.

Highflyer
Highflight Aviation Services
Pinckneyville Airport ( PJY )



I can really only agree with part of that. I did not reread the entire
brochure, but the clutch itself does not appear to be unidirectional, and it
is not intended to be a torsional dampener. However, the soft start
certainly would have eliminated resonance at srating motor speed, which
proved to be the most vexing problem in the Contact! article regarding the
BD-5. It could have made that other problems a lot easier to solve as well.

I have never personally seem any of Molt Taylor's aircraft, and I don't know
which specific parts he used, but a Dodge Flexidyne brochure is available
at: http://www.dodge-pt.com/pdf/brochure...s/dmr_1513.pdf

Peter