REFLECTOR:TUNE, STRAIGHT EXHAUST PIPES

Jim Sower reflector@tvbf.org
Thu, 05 Feb 2004 22:24:00 -0600


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Tom,
By straight "tuned" exhaust pipes do you mean sticking straight
out the cowl?  I saw pictures of a Velocity with what appeared
to be a pipe from a 3-into-1 header sticking straight out of the
cowl.  I would NEVER do that.  Exhaust exiting the airplane that
way creates "rooster tail" drag that is the rough equivalent of
having the pipe sticking out a foot or two from the airplane.
That's a LOT of drag.  I would be inclined to find out if the
guy who made the 3-into-1 pipes that went out the back still had
his jigs and get some of those.  Shirl Dickey went NUTS for over
a year trying to track down some hideous vibration in his
E-Racer and found out it was exhaust pulses from the stub pipes
from his V-8 routed straight through the cowl going through the
prop.

Tom Martino wrote:

> I ordered and received six straight, 12-inch, tuned exhaust
> pipes – stainless, with a generous flange and a reinforced
> collar. I have talked to a few structural welders for ideas of
> brackets to tie them to the engine. Each one of them examined
> the installation and told me they wouldn’t do anything. They
> said I should just let them hang (with the exception of a
> safety cable on each, in case they broke away.
>
> Their reasoning is this:The exhaust tubes become part of the
> engine.They will move and vibrate with the engine and a 12”
> extension does not hang down far enough to create a mechanical
> “disadvantage”.They say if I tie them to the engine, I could
> actually create a weak spot, causing it to stress at that
> point.
>
> I am not a welder, nor have I had personal experience with
> straight pipes hanging 12 inches off of an engine.Can I get
> some feedback?
>
> I plan on using a safety cable but should I go further?
>
--
Jim Sower ... Destiny's Plaything
Crossville, TN; Chapter 5
Long-EZ N83RT, Velocity N4095T


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Tom,
<br>By straight "tuned" exhaust pipes do you mean sticking straight out
the cowl?&nbsp; I saw pictures of a Velocity with what appeared to be a
pipe from a 3-into-1 header sticking straight out of the cowl.&nbsp; I
would NEVER do that.&nbsp; Exhaust exiting the airplane that way creates
"rooster tail" drag that is the rough equivalent of having the pipe sticking
out a foot or two from the airplane.&nbsp; That's a LOT of drag.&nbsp;
I would be inclined to find out if the guy who made the 3-into-1 pipes
that went out the back still had his jigs and get some of those.&nbsp;
Shirl Dickey went NUTS for over a year trying to track down some hideous
vibration in his E-Racer and found out it was exhaust pulses from the stub
pipes from his V-8 routed straight through the cowl going through the prop.
<p>Tom Martino wrote:
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<div class=Section1>
<div class="MsoNormal"><span style='font-size:10.0pt;
font-family:Arial'><font face="Arial"><font size=-1>I
ordered and received six straight, 12-inch, tuned exhaust pipes – stainless,
with a generous flange and a reinforced collar.&nbsp;<span 
style='mso-spacerun:yes'></span>I
have talked to a few structural welders for ideas of brackets to tie them
to the engine.&nbsp;<span 
style='mso-spacerun:yes'></span>Each one of
them examined the installation and told me they wouldn’t do anything.&nbsp;<span 
style='mso-spacerun:yes'></span>They
said I should just let them hang (with the exception of a safety cable
on each, in case they broke away.</font></font><o:p></o:p></span></div>


<p class="MsoNormal"><span style='font-size:10.0pt;
font-family:Arial'><o:p></o:p></span>

<p class="MsoNormal"><span style='font-size:10.0pt;
font-family:Arial'><font face="Arial"><font size=-1>Their
reasoning is this:<span style='mso-spacerun:yes'></span>The exhaust tubes
become part of the engine.<span 
style='mso-spacerun:yes'></span>They will
move and vibrate with the engine and a 12” extension does not hang down
far enough to create a mechanical “disadvantage”.<span 
style='mso-spacerun:yes'></span>They
say if I tie them to the engine, I could actually create a weak spot, causing
it to stress at that point.</font></font><o:p></o:p></span>

<p class="MsoNormal"><span style='font-size:10.0pt;
font-family:Arial'><o:p></o:p></span>

<p class="MsoNormal"><span style='font-size:10.0pt;
font-family:Arial'><font face="Arial"><font size=-1>I
am not a welder, nor have I had personal experience with straight pipes
hanging 12 inches off of an engine.<span 
style='mso-spacerun:yes'></span>Can
I get some feedback?&nbsp;</font></font><o:p></o:p></span>

<p class="MsoNormal"><span style='font-size:
12.0pt;mso-no-proof:yes'></span><o:p></o:p>

<p class="MsoNormal"><span style='font-size:
12.0pt'><font face="Times New Roman"><font size=+0>I
plan on using a safety cable but should I go further?</font></font><o:p></o:p></span></div>
</blockquote>

<p>--
<br>Jim Sower ... Destiny's Plaything
<br>Crossville, TN; Chapter 5
<br>Long-EZ N83RT, Velocity N4095T
<br>&nbsp;
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