Subject: Sq. muffler
From: ACRE NL
Date: 9/2/2002, 8:07 PM


 > >>  Thanks Lynn,  Paul's Tailwind Motor Mount design is about as good as
 >>  it can get in my opinion.  The same layout works for RV's too.  I
 >>  principle that I am hoping will work in my muffler is that the
 >>  exhaust note will be softened by  turbulence.  The exhaust pipes
 >>  enter the four inch sq pipe perpendicular to the long axis.  The
 >>  exhaust gas, I hope, will  bounce off the far wall of the muffler and
 >>  not get that reorganized as it flows out of the system.   The muffler
 >>  will be in two pieces that bolt together  at the 45º turn down.  If
 >>  version number one is too noisy, then I can make different end
 >>  pieces.   I think a home made version of Spin Tech could be a bolt on
 >>  option.  Issues such as clearing heat from inside the cowl, not
 >>  having the muffler in the air stream, keeping the exhaust system away
 >>  from the radiator and oil pan are all at play in this design.  Lack
 >>  of space forces compromises throughout.   Jerry


 >I think your muffler might work real well. We have never tried a square
 >can. That might break up the sound waves with all sorts of bouncing
 >around in there.
 >
 >BTW does this look about right? I'll add the muffler and rad soon.
 >What size rad are you going to use? Where would you like the inlet
 >and out let?
 >
 >Paul Lamar

 I was just about to ask you to look at my  installation in Rhino if
 you have the time.  My radiator's outside measurements are  13" x 22"
 x 2.75".  (Core size is 594 cu.in.)  The radiator will be displaced
 to the right to get away from the muffler.  Looking at it from the
 front, the Barry Mount centers are 20.5" apart.  The radiator  will
 be 1.5 to 3" inside the right Barry Mount.  Lots of small variables
 that can move it one way or the other within that range.

   The exhaust pipes extend out about 9 inches (this is to the outside
 of the down tube) before doing a 90º straight down.  They go around
 and underneath the frame to connect to the muffler.  Final connection
 is by 4" long flex tubes that will be clamped not welded.    As the
 exhaust pipes come out from the engine they go from 5.5" centers down
 to 4" centers to clear the upper Motor Mount tube.  Four inches is
 maintained all the way to the muffler.   The muffler is 3" or 3.5" sq
 SS.  It is not four inches.  What I wrote above was a mistake.

 Any chance you could portray my PP intake manifold?   I would love to
 see how it will look.  Thanks,   Jerry




Sure I can do a PP manifold. Will do.

This is 45 degrees down right out of the flange and then straight.

If I bring the pipe out straight it runs
into the tube.  I have 45 degree bends and 90 degree bends.
Or I can make anything you want :-) These bends are four inch center
line radius but I can make 5 inch if you think it is important.
It gets expensive if you have to buy them.

What do you want to do?

Now you know why I put my rubber bushings 29 inches
center to center :-)

Paul Lamar


Paul, here is a drawing showing how I plan to use two 45s to jog over
a bit to miss the mm tube.  The distance from the  exhaust flange to
the tube is 6" at the exhaust  pipe  center.  The pipe needs to be
jogged over between 1.5 and 2 inches to clear.   I have made several
drawings that lead me to believe this is possible.  Another option is
to jog the other way and go over the mm tube.  This would add length
to the primaries and is something that needs to be explored.  Can
you look at that in Rhino as well?   Thanks, again      Jerry


OK I will try something like that.

In the mean time the cowl looks good with your rad position of choice.
The rad's left edge is 4 inches left of centerline.
12 inch spinner. Would look even better with a 14 inch spinner.

If you want to use the stock cowl send me a sketch of the
cowl shape 1/3 of the way back from the front (height width and radii
on the corners), the diameter of the spinner and any opening you plan
to use. I can then check and see if the rad fits.


Paul Lamar
 
The AirCraft Rotary Engine NewsLetter.              Powered by Linux.
ACRE NL web site. Copyright 1998-2002 All world wide rights reserved.
http://home.earthlink.net/~rotaryeng/            http://www.linux.org