Thanks Ed for the drawing and photos ... you do have some great ideas! I like this one!
The drawing doesn't identify the inside tube as perforated - guess that is for weight savings, as it would be a slip fit into the outer ... a 4 foot long muffler eh? That should get the sound past at least the front seats of most airplanes.
Jeff

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson
Sent: Tuesday, October 06, 2009 8:53 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Photos of Fan muffler

As you can see a couple of the fan blades have been beating off by the exhaust pulse.  I think at least part of the reason is that the tips were unsupported (i.e. not welded to the tube wall) which of course made them very susceptible to fatigue from the pulses.

Also, if I had the time, I would probably have tried to form more of a cone shape with the discs to reduce the surface area of the disc perpendicular to the shock wave.  But, too many projects and not enough time {:>)

Ed    
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