Paul,

Thank you for your time this afternoon.  I learned a lot and more importantly, I learned there is a lot more that I don't know. Please put me on your email distribution list for the news letter. Apparently I was on your distribution in the year 2010.

Gary


 Here is that book I mentioned at the hangar.

Scientific Design of Exhaust and Intake Systems. Philip H. Smith
and John C. Morrison Published by Robert Bentley. ISBN 0-8376-0309-9*

http://www.rb.com


 Gary had an idea of connecting the bottom mounted radiator air outlet to the
coaxial muffler. This will work if the outer pipe is large enough.

Try the coax muffler. Less drag for an external muffler
and a lower note tone. The main problem with rotary noise is
the high frequency component.

It works a little bit like a ram jet, ejector or thrust augmenter
 so it does not add too much to the aerodynamic drag.
The tone of the rotary sound is much more pleasant.

Also it can be visually  inspected so it won't plug up if it ever
cracks.


Paul Lamar