Bill Jepson wrote:

Paul, The attached jpeg is a variation on the tangental muffler theme.
The intent is to cool the exhaust system using the exhaust energy. A
outside air source is provided near the front. The design could also be
inverted, (exhaust inside the the can), if the inside tube wouldn't
provide enough cooling. The tail pipe mixing should also make it a bit
quieter.  comments? Bill Jepson

That is a really great idea Bill. I really like it. I think it is
THE soluttion.

Do you mind if I have someone build one?

I'll test it on the dyno.

Ed Klepis,

Can you build a two rotor version of one of these out of .049 316SS ?

How much?

Paul Lamar

If you invert it the air drawn in will cool the outside skin and cut down
on the radiant heating in the engine room.  It will make it a bit bigger
diameter.  A half inch or so between the muffler and the shell?

Or, just add the additional outside shell with the opening to the rear so
that engine compartment air will be drawn along the outside of the muffler
then turned down the centerline to the eductor nozzle.

Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR
13B in gestation mode

That will surely work but one of the principles of any muffler is the friction
of the hot gases rubbing on the skin of the muffler and tail pipe reduces the noise
energy. That is partially how a tangential muffler works in the first place.
That and the fact the pressure pulses spin around inside the muffler and 
interfere and homogenize themselves in the process.

This design almost doubles the skin area the gases can rub on while still
cooling that additional skin. I like it. It might not work so well in a 
pusher where you don't have a prop slip stream to help it along.

Paul Lamar
 
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