Mailing List flyrotary@lancaironline.net Message #40544
From: Russell Duffy <rusty@radrotary.com>
Subject: RE: [FlyRotary] Re: Giving up on single rotor
Date: Sat, 1 Dec 2007 23:34:01 -0600
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Message
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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