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Marcus,
I am really glad you brought up the Mistral incident, as I
have been meaning to mention it too. For what it's worth, my
experience with mufflers confirms what many other have said.
The exhaust environment in rotary aircraft is very extreme and
component failure can be catastrophic. I have tried several
types of high end packing, and nothing survives more than a
few hours. 300 series stainless tolerates the heat, but any
welds on thin stainless have limited life. I would be very
suspicious of anything with complex innards like the Aero
Turbine 2525. Doing what Jeff Whaley did by adding
perforations should be a must-do in my opinion.
Dave Leonard
Just remember the Mistral muffler event. The
muffler caused the Piper Arrow (?) with their rotary to
crash after the internals blocked the outlet and led to
power loss. It may have partially led to their withdrawal
from the engine/PSRU market. To all our loss.
M
Sent from my iPad
This is the Aero
Exhaust 2525XL diagram. I have one, but left it in
Canada. Will bring it back with me in Jan to try
at taming the exhaust again.
- Matt Boiteau
On
2019-11-19 3:23:50 PM, Charlie England ceengland7@gmail.com
<flyrotary@lancaironline.net>
wrote:
Kelly, I would
if I had some, really did not
expect it to work as I
deviated from the design a
bit. Will be back at airport
on weekend to take photo, too
late for construction photo.
But nothing to it.
I read about
the idea by Gary Schwarz
in this thread,
post #7 , post #58 for his
testing and post #142 sums
up his findings.
Someone on
here may know him as he
was doing it for a rotary.
Mine is much shorter than
his drawing below due to
space constraints but the
theory works.
edit: Ahh!!! deleted
his picture as too big
to post. it is in his
post #7 mentioned above
though.
Andrew
That looks a lot
like a simplified version (one less
turn) of a standard automotive muffler.
The Aeroturbine
tries to achieve similar effect (without
the flow reversals) by using venturi
effect to suck part of the exhaust
around and then back into the central
tube.
Charlie
<2525.JPG>
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The caution about potential blockage is warranted on any engine, but
obviously a greater danger with the rotary's powerful pulses.
It's worth mentioning that the Renesis' exhaust should be
significantly less 'violent' than a 13B, for a couple of reasons.
The exhaust has to take a 'sharp right' as it exits the combustion
chamber, which helps break up the shock wave a bit, but even more
importantly, the exhaust port, instead of 'snapping open' like a
piston ported two stroke, opens more gradually, more like a
conventional poppet valve in a piston engine.
As a FWIW on the Aeroturbine: I don't have a 2525XL to examine, but
the regular 2525 (minus the 1st chamber of the XL) is a 'straight
through' design. That cone on the input end is open. Drawing of the
guts is on the Aeroturbine web site.
https://aeroexhaust.com/i-30497606-aero-exhaust-turbine-at2525-performance-muffler-2-5-inside-diameter-necks-aggressive-sound.html
IIRC, Tracy's been flying one on the 20B powered RV-8 for a number
of years. That's what motivated me to purchase one, but it hasn't
seen any exhaust gas yet.
Charlie
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