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George,
With the edges of each cross bar pointed downstream of the exhaust flow, I don't see a problem with the heat attacking them. Also, if one were to somehow break loose, I don't see how it could manage to block the exit, maybe partially, but not totally. The engine should still run at reduced power if that were to happen. I would like to special order one made of 321ss. Also, if you look at the DNA web site, you'll see that they make a Gen 1 and a Gen II. The Gen II is much stronger as the cross bars protrude through the can and are welded from the outside. The Gen I bars are spot welded to the can. The Gen II is also more than twice the price of the Gen I.
Mark S.
On Fri, Jan 16, 2009 at 4:10 PM, George Lendich <lendich@optusnet.com.au> wrote:
Mark,
The heat and pulses attack/ affect the weakest part
of any internal part, a thin edge is the weakest part. You will notice that
I don't expose and edges to the sound wave or hot gases.
George ( down under)
Ed,
That is exactly what I was concerned about too. But if you look
closely, you can see that the bars are made
of 90* angle. That should make them much stronger than
straight bar stock. Not sure what material the cross bars are made
from though. The p/n 1040 is made to weld to a header/collector
and they claim it is good for up to 1000hp.
I have gone ahead and ordered one. I figure it couldn't be
any louder than the Hushpower II whose guts are laying on the hangar
floor in a pile of powder and small pieces. Based on its short
lifespan and the rust-colored debris, I doubt the Hushpower muffler's innards
are made of SS. ;-(
Mark
On Fri, Jan 16, 2009 at 10:08 AM, Ed Anderson <eanderson@carolina.rr.com>
wrote:
Appears somewhat
similar in concept to the SpinTech muffler using baffles/ladders to break up
the sound wave front. The thing I would wonder about is whether those
ladders which appears to stretch across the diameter of the tube could
withstand the pulse pounding from the rotor. My experience with the
turbo 13B (with no exhaust splitters) would indicate it might not long
withstand that pounding. But, I could be wrong about
that.
Guess you're going
to have to buy one and let the rest of us know, Mark.
Ed
From:
Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mark Steitle
Sent: Friday, January 16, 2009 9:05
AM
To: Rotary motors in
aircraft
Subject:
[FlyRotary] DNA Muffler
Does
anyone on the list have any real-life rotary experience
with the DNA Gen II muffler (http://www.dnamufflers.com/DNA/main_DNA.html)? It is an
interesting design in that it has no packing material to burn out.
Instead, it utilizes ladder-rungs, which they call "internal sound
diffusers", which resemble a chain of DNA down through the center of
the muffler body, which is made of 304 SS. Their web site claims that
the racers use them with great success. From speaking with a sales
rep, they claim there the rotary crowd uses them too. I'm considering
purchasing one of their FULL THROTTLE COLLECTOR mufflers (P/N 1040), but
thought I would check to see if anyone else has used this style
muffler. This muffler has a 3" inlet/outlet with a 4" body. So
it is compact enough to fit inside my cowl. My exhaust header has
a 3" swivel joint, so it should be a good fit.
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