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Andrew,
all very interesting, What noise do you get
back in the cab? bearable, loud or great? Neil.
Neil, I stumbled on a system that seems to
work quite well. In my head I think it works similar to an
ANR headset where the noise is not muffled as such but
reflected to cancel it out.
Important bit is exhaust enters & exits at
same end. In my case I used a 65mm ss pipe inside a 100mm pipe
about 150mm long, but longer would be better again as outlet
on outer pipe does see some holes on inner pipe so noise has
direct escape path. 65 mm pipe has 10mm holes with about twice
area of pipe to try to minimize back pressure.
Theory is that exhaust pulses are broken into
smaller bits as they see holes in inner pipe, but then hit the
blanked off end and are reflected just like in ANR. Not sure if
this is correct or not, but it seems to work in use quite well.
My exhaust system is quite short as tailpipe exits
just behind prop similar to PT6 turboprop. I made exit pipe from
65mm also but think smaller may be better as I think the exhaust
gas flows much better after the pulses are broken up.
Andrew
Attn
Todd Bartrim,
When in doubt check
the
instruction book!! I finally checked the archives to find
that Todd you
are way in front of me. I am definitely going to put a
turbo on my
renesis, but am still looking for a muffler. Depending on
what Lynn
suggestes, but your experience with the spintech or your
latest version
is appreciated. Do you have any tests with a decibel
meter? My exhaust
noise is just too loud, fine for me but passengers do not
exactly que up
for another ride.
So design starts all over again, but I do have another
engine to play
with to keep mine in the air while I experiment. Here
again Todd you
have the electric water pump --- thoughts?
Neil.
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Regards
Andrew Martin
Martin Ag
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