Lynn is
correct.
In fact the photos I showed of my “Fan”
muffler showed some of the fan blades had been failed due to fatique and the
fact they were unsupported at the tips. That is one of the reasons I had a section
of perforated tube coming out of the back of the muffler. The theory (hope?)
was that if the debris (fan blades) didn’t get blow out the end of the
tube, the perforated tubing would permit exhaust gas to continue to flow. Even
though the design did shed a few blades either they apparently worked there way
through and out.
Ed
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Lynn Hanover
Sent: Thursday, October 08, 2009
6:26 PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: Your
Muffler
Ed,
> Cones are the GO.
>
> Any bare edge will take a battering from the heat and shock waves. Cones
> formed back to back eliminate any edges.
>
> There must be supporting structure for the cones, I've used 1/4"
solid
> round bar welded into the exhaust skin.
> George (down under)
Thought must be applied to the idea that eventually the structure will
decompose, and then the pieces thus liberated, will plug the exit and render
the engine a balance weight. As in the Mistral crash.
Perhaps the back to back cones could be installed over some cooling air
holes in the central pipe.
A solid rod just aft of the cones could support the central pipe and help
prevent such a blockage.
My version would have the entire muffler below the cowl in the
airstream. Maybe there would be room for a collector before the muffler so as
to maintain more engine power.