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Date: Mon, 06 Feb 2006 11:18:51 -0500
From: Ernest Christley <echristley@nc.rr.com>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Single rotor smooth as silk now
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Richard Sohn wrote:

>
>     Hi Rusty,
>      
>     let me throw something in here on the dampener. Tracy's dampener
>     is not built to take up a lot of torque vibration at low rpm. What
>     we need on the single is having the soft elements closer to the
>     center line of the e-shaft, allowing more movement in them, eg.
>     having a softer coupling = lower resonant frequency, and at the
>     same time utilizing some of the dampening characteristics
>     inherrent in the rubber. The closest to that requrement I could
>     come up with, is the do-nut shaped coupler used on Rotax and Hirth
>     engines. They are also available in different Shore values. I have
>     not found a US source yet.
>     I have not demonstrated yet if this solution is sufficient, but
>     analysis indicates that, if the idle speed is 1500rpm or above, it
>     should be ok.
>     All this does not eliminate the careful selction of a sufficient
>     fly wheel.
>      
>     Richard Sohn
>     N-2071U
>      
>
There are two ways to avoid resonance.  Drive out all the play in the 
system, putting the resonant frequency above the operating range, or add 
a lot of play, putting resonance below idle.  The Powersport guys tried 
the former, driving the redrive cost beyond resonable.  But that was 
with a two rotor.  Would a single with no dampers put the resonance 
beyond the useful range?

-- 
         ,|"|"|,               Ernest Christley     |
----===<{{(oQo)}}>===----     Dyke Delta Builder    |
        o|  d  |o          www.ernest.isa-geek.org  |