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"Highflyer" <john@siu.edu> wrote in message
news:e14pml$1kf$0@pita.alt.net...
>
> "Richard Lamb" <cavelamb@Xearthlink.net> wrote in message
> news:Gb_Xf.2359$i41.1868@newsread1.news.atl.earthlink.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 can't
transmit
> damaging torques from torsional vibration back through the coupling
because
> the output shaft "breaks away" before a crippling torque is reached. You
> do not 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
isn't 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've never personally seem any of Molt Taylor's aircraft, and I do not know
which specific parts he used, but a Dodge Flexidyne brochure is available
at: http://www.dodge-pt.com/pdf/brochures/pt_components/dmr_1513.pdf
Peter
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Re: PSRU design advantages
