Dennis,
I have an AVI file of Tracy running his engine at the rotary round up that I
could send you, it is 47 megs worth.  If I knew how to break the file down
and shorten it I would do that.  As it is it would take a week to email it.

Bob Perkinson
Hendersonville, TN.
RV9A
If Nothing Changes
Nothing Changes!


I would expect the Renesis engine with the split/side exhaust is not as
irritating.  What is the experience?  I have not heard either a 13B or
Renesis takeoff or fly-by.
Dennis H.

Charlie England wrote:

Russell Duffy wrote:

So it appears its as much the nature of the Rotary "bark" as it is
the sound level.


I completely agree, and I've tried to get people around the airport
to understand this.  Since the engine doesn't sound like a "normal"
engine, everyone takes note.  Since they noticed it, they assume it's
primarily because it must be louder than other engines.   This isn't
necessarily true of course.
Glad you got your power back.
Rusty (yawn)

This phenomenon is widely understood by audiophiles & (ex)sound
engineers. Certain frequencies, and certain harmonic structures added
to any sound, are much more irritating to the ear than others. The
'bark' or 'edge' in the sound of a 2stroke or rotary is the harmonic
structure of the sound, not the actual level.  I suspect that if you
fed a microphone into an oscilloscope, you'd see something like a sine
or triangle wave from a 4stroke piston engine & something approaching
a square wave from a 2stroke or rotary. We  can run that experiment
here at Slobovia the next time we have a visit from a rotary.

I suspect that's why Paul Conner's exhaust is actually a pleasing
sound while most rotaries 'hurt' your ears. His iron manifold is
probably filtering out the irritating harmonics & 'rounding off' the
waveform.

Charlie

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