----- Original Message -----
Sent: Monday, December 03, 2007 1:19
AM
Subject: [FlyRotary] Re: Giving up on
single rotor
Instead of using durometer in this case. I think
it would be better to measure torque vs. angle of deflection. Using torque
wrench and simple angle measure device. If you graphed this, you would end up
with a chart that defines frequency response of the damper. Goal to have
damper frequency response that's out of phase with the worst torsional pulses.
Once you've measured frequency response, you
could then tune it with durometer tweaks. So you might end up with 2 dampers
at 50 durometer, 2 at 40, to obtain your ideal frequency response of
system.
I've always been drawn to having damper that has
more than one frequency response. You never see designs like that. So with
mild TV, it would respond one way. Suddenly it would have different response
with larger TV. Both responses out of phase. They use this method with
electronics and I've seen a few auto clutch dampers utilizing the concept.
FWIW
al wick
----- Original Message -----
Sent: Saturday, December 01, 2007 10:46
PM
Subject: [FlyRotary] Re: Giving up on
single rotor
Righ-t-o Rusty!
Thanks
George ( down under)
So what durometer is your gut feeling
now that you went this far?
Hi George,
I don't think you can compare the durometer of one
damper to another, because the physical size is as important as the
hardness of the rubber. The Autoflight drive uses a stock Centaflex
coupler that's only available in 50 and 60 durometer. It's a fairly
large diameter, and thick coupler. 50 was better than 60, but two
50's (effectively 25) in series was way too soft. Maybe a 40
would be good, but it doesn't
exist.
Richard seems to be having better luck with
the Hirth drive. Two strokes are rough at low rpms, so perhaps
they already have the right damper for the job. I also suspect
his engine has softer power pulses at low rpms. It's a 12A for one,
and PP for another. PP is great at high rpms, but not know for good
power down low. It's the best theory I
have.
Cheers,
Rusty
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