Mailing List flyrotary@lancaironline.net Message #27430
From: Russell Duffy <13brv3@bellsouth.net>
Subject: RE: [FlyRotary] muffler new info.
Date: Thu, 3 Nov 2005 19:50:23 -0600
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Message
I also had a chance to ring the muffler and see what the resonant frequency of the structure is. As fate would have it, the fundamental is 2400 hz. This is a multiple of the 1200 hz resonant frequency of the cavity of the muffler. So it will self excite when the muffler is really working hard. This explains the horrible screech at 6000-6500 rpm. This is also bad for fatigue life. I should be able to weld a couple of strips of metal to it and fix that problem.
 
 
Sorta gives a new meaning to "tuned exhaust" :-)
 
Cheers,
Rusty (RV-8 and Zenith XL are now neck and neck) 
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