From: "Todd Bartrim" <flyrotary@lancaironline.net>
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Date: Fri, 20 Jan 2017 00:27:27 -0800
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Subject: Muffler housing - something else I probably wouldn't do again
To: FlyRotary <flyrotary@lancaironline.net>
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I'm on a bit of a roll here so I might as well cover this one too. This is
more for your entertainment pleasure because I'd be surprised if anybody
else would even consider this...

Back when I began to build and had decided to use the rotary even though I
had never even had a ride in an RX7 (still haven't), but of course I'd
heard all about the terrible bark of the rotary. That didn't dissuade me at
all because as I pointed out, all aircraft engines were loud.
  I was actually surprised by the arrogance of pilots. Whenever I mentioned
mufflers, they would start talking about noise-cancelling headsets, because
hey it's all about him, screw the people on the ground below, you know the
people that fight to have airports shut down because of the noise. The same
people that bought land by the airport because it was cheap, but that's
another topic for some other forum.
   So I was still determined to use a muffler and at the time Tracy was
experimenting with mufflers. The leading contender at that time seemed to
be the SpinTech, but it was also quite draggy, which Tracey did not like,
being an efficiency freak that he is. So after many hours of consideration
(and probably a few beers), the half-baked idea of an enclosed muffler
housing within the fuselage was born!
   There was many considerations involving structural integrity that I had
to address, but the biggest obstacles were weight and loss of leg room. The
leg room I justified by looking at so many high end sports cars that had no
more room than I'd have. It turns out to be just fine for me. Heat was
another consideration so the housing was made from .018 316 SS. I can't
remember exactly but I believe it came in under 5lbs complete. I know I
have it logged somewhere. The back of it has a curved double wall to add
extra heat protection to that area of the wing spar. The cockpit side of
the housing had a firewall blanket insulation over it, but it still kept my
toes warm! It also provided extra exit area for cowl air through a series
of louvers I cut into the bottom skin cover.
   I made my own version of a SpinTech muffler as money was getting tight
as I neared completion. This worked reasonably well and survived for over
100 hours of running with 50 of those in the air. It still looks fine, but
Tracey's success with the Aero exhaust convinced me to buy one of those for
this rebuild. This fits nicely inside my housing, but being more
aerodynamic it would have been ok outside under the belly as well.
  Now this whole half-baked idea actually works pretty well and while I'm
not sorry that I did it, I likely wouldn't do it again, but since it's
there I'm still using it to full advantage. If I didn't then I'd turn it
into a bomb bay :-).Ha!
 Pics for this are at the bottom half of this page of exhaust pics.

https://goo.gl/photos/NvD5YH4jwbktESi88

Next post I'll cover my efforts to duct all the exit air from the rads.
This was advice that Ed Anderson used to expound on all of us. Wish I'd
paid more attention back then as it would have been a better use of my time
than the muffler housing. (Still listening Ed?)

Todd Bartrim

C-FSTB
RV9 13Bturbo

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<div dir=3D"ltr"><div>I&#39;m on a bit of a roll here so I might as well co=
ver this one too. This is more for your entertainment pleasure because I=
9;d be surprised if anybody else would even consider this...</div><div>=C2=
=A0 =C2=A0</div><div>Back when I began to build and had decided to use the =
rotary even though I had never even had a ride in an RX7 (still haven&#39;t=
), but of course I&#39;d heard all about the terrible bark of the rotary. T=
hat didn&#39;t dissuade me at all because as I pointed out, all aircraft en=
gines were loud.=C2=A0</div><div>=C2=A0 I was actually surprised by the arr=
ogance of pilots. Whenever I mentioned mufflers, they would start talking a=
bout noise-cancelling headsets, because hey it&#39;s all about him, screw t=
he people on the ground below, you know the people that fight to have airpo=
rts shut down because of the noise. The same people that bought land by the=
 airport because it was cheap, but that&#39;s another topic for some other =
forum.</div><div>=C2=A0 =C2=A0So I was still determined to use a muffler an=
d at the time Tracy was experimenting with mufflers. The leading contender =
at that time seemed to be the SpinTech, but it was also quite draggy, which=
 Tracey did not like, being an efficiency freak that he is. So after many h=
ours of consideration (and probably a few beers), the half-baked idea of an=
 enclosed muffler housing within the fuselage was born!</div><div>=C2=A0 =
=C2=A0There was many considerations involving structural integrity that I h=
ad to address, but the biggest obstacles were weight and loss of leg room. =
The leg room I justified by looking at so many high end sports cars that ha=
d no more room than I&#39;d have. It turns out to be just fine for me. Heat=
 was another consideration so the housing was made from .018 316 SS. I can&=
#39;t remember exactly but I believe it came in under 5lbs complete. I know=
 I have it logged somewhere. The back of it has a curved double wall to add=
 extra heat protection to that area of the wing spar. The cockpit side of t=
he housing had a firewall blanket insulation over it, but it still kept my =
toes warm! It also provided extra exit area for cowl air through a series o=
f louvers I cut into the bottom skin cover.</div><div>=C2=A0 =C2=A0I made m=
y own version of a SpinTech muffler as money was getting tight as I neared =
completion. This worked reasonably well and survived for over 100 hours of =
running with 50 of those in the air. It still looks fine, but Tracey&#39;s =
success with the Aero exhaust convinced me to buy one of those for this reb=
uild. This fits nicely inside my housing, but being more aerodynamic it wou=
ld have been ok outside under the belly as well.=C2=A0</div><div>=C2=A0 Now=
 this whole half-baked idea actually works pretty well and while I&#39;m no=
t sorry that I did it, I likely wouldn&#39;t do it again, but since it&#39;=
s there I&#39;m still using it to full advantage. If I didn&#39;t then I=
9;d turn it into a bomb bay :-).Ha!</div><div>=C2=A0Pics for this are at th=
e bottom half of this page of exhaust pics.</div><div><br></div><div><a hre=
f=3D"https://goo.gl/photos/NvD5YH4jwbktESi88">https://goo.gl/photos/NvD5YH4=
jwbktESi88</a><br></div><div><br></div><div>Next post I&#39;ll cover my eff=
orts to duct all the exit air from the rads. This was advice that Ed Anders=
on used to expound on all of us. Wish I&#39;d paid more attention back then=
 as it would have been a better use of my time than the muffler housing. (S=
till listening Ed?)</div><div><br></div><div><div class=3D"gmail_signature"=
><div dir=3D"ltr">Todd Bartrim</div><div dir=3D"ltr"><br></div><div>C-FSTB<=
/div><div>RV9 13Bturbo</div></div></div>
</div>

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