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Message-ID: <1ab24f410901061018n7044ec48tc0f7bea5bd0dd304@mail.gmail.com>
Date: Tue, 6 Jan 2009 10:18:10 -0800
From: "Lynn Hanover" <lehanover@gmail.com>
To: flyrotary@lancaironline.net
Subject: Mistral Muffler
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Lynn,

Regarding your statement, "muffler design is serious business".  I couldn't
agree more.  I was amazed when, on my first "spiral-flow" muffler, I found
that the 1/4" bolt that was at the tip of my exhaust downpipe was melted
from the heat of the rotary's exhaust... 3' from the exhaust ports.  Also,
the material around the bolt holes started cracking from the hammering of
the supersonic exhaust pulses.  It's enough to make one stop and think.
Mark S.
I believe that the Supertrap was a spark arrestor, required by the Forrest
Service for diesel engines used in Forrest work. From when diesel fuel would
coke the mufflers and throw off long lasting embers. No longer a factor with
modern (twice as expensive) diesel fuel. Later all off the road stuff in
National forrests had to have such or similar exhaust  many folks used the
cheapest available, so Supertrap became popular, not because it sounded
good, (it doesn't) it is compact, and an idiot can stick one on just about
anything.

When used on piston engine cars, they are good for taking off a few dBs. Not
quite so good on Mazdas, but were very popular for a few years when the
noise requirement dropped to 105 dB. So the 4 packs could take off 2 dB.

Big V-8s could run just the Supertrap with 6 sets of rings (packs). In a
Mazda, with a muffler of some kind, and a 4 pack Supertrap I could make 103
dB. There are still some being used, but more radical muffling is used to
make 103 dB. I think the biggest pipe diameter was 3 1/2" when we needed
4".

I never saw one come apart.

There should be a list of rules for rotary mufflers.

If it has a flat spot on it, it will die. Whatever important part next to
the flat spot will get to be bright orange, for a while. Then it will fail.
If the muffler is flat the flat surfaces have to be supported with a bunch
of struts or rods. It will die anyway, but might last longer.

Distance is your friend. Shock waves loose energy with distance and
temperature.

That fancy metal is probably not stronger than the cheap stuff. It just
retains more strength at temperature than the cheap stuff.

Make test mufflers out of SAE 1010 and try them on the ground. Fly the one
made of the good stuff.

Assume the muffler will fail. (It will) Plan for that failure. Retain all of
the pieces in close proximity. Shield adjacent pieces near the muffler from
high heat.

Keep EGTs as low as possible. Extra rich climb power, and extra lean
cruise.

Rotaries don't like back pressure. They tune like 2 cycle dirt bikes. Even a
small piece of muffler guts stuck
in the outlet or exhaust pipe can remove an amazing amount of power.

Cooling air on a header or muffler makes it last longer. The time period you
are looking for is: I lost my medical.....I can't find my car keys.........I
can't find my car.........I don't remeber having an airplane......

Run the cooling tube all the way through the muffler and into the tail pipe,
or through the side of the tail pipe where it never sees any more fuel.

Make the muffler a round tube. Make the ends out of domes or cones. Apexes
turned into the muffler is best but turned out is second best. Flat ends is
a failure close at hand.

Run a turbo.

Use NA housings with the splitter.

Build a Renesis. Side ports produce a poor shock wave.

 Tap on the muffler and pipes with a piece of broom stick during preflight.
If it rattles, it is broken. Fly commercial.

Sun&Fun is just a few months away.

I live in Zephyrhills through the end of April, so if you need a ride or
help of any kind................

1-813-395-8199 Land line unlimited long distance, so I can call you back at
no cost to me.
Or, 1-614-519-8522 Cell phone.

Lynn E. Hanover

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<div>Lynn, </div>
<div>&nbsp;</div>
<div>Regarding your statement, &quot;muffler design is serious business&quot;.&nbsp; I couldn&#39;t agree more.&nbsp; I was amazed when, on my first &quot;spiral-flow&quot;&nbsp;muffler,&nbsp;I found that the 1/4&quot; bolt that was at the tip of my exhaust downpipe was melted from the heat of the rotary&#39;s exhaust... 3&#39; from the exhaust ports.&nbsp; Also, the material around the bolt holes started cracking from the hammering of the supersonic exhaust pulses.&nbsp; It&#39;s enough to&nbsp;make one stop and think.<br>
</div>
<div>Mark S.<br></div>
<div>I believe that the Supertrap was a spark arrestor, required by the Forrest Service&nbsp;for diesel engines used in Forrest work. From when diesel fuel would coke the mufflers and throw off long lasting embers. No longer a factor with modern (twice as expensive) diesel fuel. Later all off the road stuff in National forrests had to have such or similar exhaust&nbsp; many folks used the cheapest available, so Supertrap became popular, not because it sounded good, (it doesn&#39;t) it is compact, and an idiot can stick one on just about anything. </div>

<div>&nbsp;</div>
<div>When used on piston engine cars, they are good for taking off a few dBs. Not quite so good on Mazdas, but were very popular for a few years when the noise requirement dropped to 105 dB. So the 4 packs could take off 2 dB.</div>

<div>&nbsp;</div>
<div>Big V-8s could run just the Supertrap with&nbsp;6 sets of rings (packs). In a Mazda, with a muffler of some kind, and a 4 pack Supertrap I could make 103 dB. There are still some being used, but more radical muffling is used to make 103 dB. I think the biggest pipe diameter was 3 1/2&quot; when we needed 4&quot;.&nbsp;</div>

<div>&nbsp;</div>
<div>I never saw one come apart.&nbsp;&nbsp;</div>
<div>&nbsp;</div>
<div>There should be a list of rules for rotary mufflers. </div>
<div>&nbsp;</div>
<div>If it has a flat spot on it, it will die. Whatever important part next to the flat spot will get to be bright orange, for a while. Then it will fail. If&nbsp;the muffler&nbsp;is flat the flat surfaces have to be supported with a bunch of struts or rods. It will die anyway, but might last longer. </div>

<div>&nbsp;</div>
<div>Distance is your friend. Shock waves loose energy with distance and temperature. </div>
<div>&nbsp;</div>
<div>That fancy metal is probably not stronger than the cheap stuff. It just retains more strength at temperature than the cheap stuff. </div>
<div>&nbsp;</div>
<div>Make test mufflers out of SAE 1010 and try them on the ground. Fly the one made of the good stuff. </div>
<div>&nbsp;</div>
<div>Assume the muffler will fail. (It will) Plan for that failure. Retain all of the pieces in close proximity. Shield adjacent pieces near the muffler from high heat.</div>
<div>&nbsp;</div>
<div>Keep EGTs as low as possible. Extra rich climb power, and extra lean cruise.&nbsp;</div>
<div>&nbsp;</div>
<div>Rotaries don&#39;t like back pressure. They tune like 2 cycle dirt bikes. Even a small piece of muffler guts stuck</div>
<div>in the outlet or exhaust pipe can remove an amazing amount of power. </div>
<div>&nbsp;</div>
<div>Cooling air on a header or muffler makes it last longer. The time period you are looking for is: I lost my medical.....I can&#39;t find my car keys.........I can&#39;t find my car.........I don&#39;t remeber having an airplane......</div>

<div>&nbsp;</div>
<div>Run the cooling tube all the way through the muffler and into the tail pipe, or through the side of the tail pipe where it never sees any more fuel. </div>
<div>&nbsp;</div>
<div>Make the muffler a round tube. Make the ends out of domes or cones. Apexes turned into the muffler is best but turned out is second best. Flat ends is a failure close at hand. </div>
<div>&nbsp;</div>
<div>Run a turbo.</div>
<div>&nbsp;</div>
<div>Use NA housings with the splitter.</div>
<div>&nbsp;</div>
<div>Build a Renesis. Side ports produce a poor shock wave.</div>
<div>&nbsp;</div>
<div>&nbsp;Tap on the muffler and pipes with a piece of broom stick during preflight. If it rattles, it is broken. Fly commercial.</div>
<div>&nbsp;</div>
<div>Sun&amp;Fun is just a few months away.</div>
<div>&nbsp;</div>
<div>I live in Zephyrhills through the end of April, so if you need a ride or help of any kind................</div>
<div>&nbsp;</div>
<div>1-813-395-8199 Land line unlimited long distance, so I can call you back at no cost to me.</div>
<div>Or, 1-614-519-8522 Cell phone.</div>
<div>&nbsp;</div>
<div>Lynn E. Hanover&nbsp;</div>
<div>&nbsp;</div>
<div>&nbsp;</div>

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