Good luck, Mike,
on the absorption muffler with a rotary. I have tried a number of
different approaches including mufflers with ceramic packing that can
withstand 2000F+. The heat is no problem, the problem is the exhaust
shock wave pulverizes the ceramic/fiberglass/stainless steel/etc into
small pieces in a relative short time. Its true they were good in
suppressing sound while they lasted, but two weeks – 1 month was about the
limit.
I still dream of
doing a remake of a muffler design I came up with which had 3” 1/8”
stainless steel discs (about 4-5) in a 36” tube. The disc were
slotted and “blades” bent until the disc looked a bit like a fan.
The blades were bent at an approx 45 deg angle. If you looked down
the tube with the disc in it all you saw was solid metal – however the
blades provide room for exhaust gas to flow around them. The theory
was the shock wave would see basically a solid disc and reflect some/most
of its energy back and forth between discs, whereas the gas could
more or less freely flow around and through the
blades.
The concept
worked well in that my hangar neighbors were all remarking how quite the
engine sounded and I could still get a static rpm of 6000.
The problem was I
am not a welder and while I had the disc clamped with Jam nuts to a SS
thread rod through their center – it was not sufficient to keep the
exhaust from loosening the nuts and causing the discs to spin like a
turbine wheel. IF I could have welded the tips of the blades to the
tube then it may have been viable. But, not a welder and got tire of
messing with exhaust so I hung two Hushpower mufflers and went
flying.
Ed
Ed
Anderson
Rv-6A N494BW
Rotary
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