-- 
Paul Lamar ...No rotor no motor.


STRAIGHT.  Anything resistance whatsoever in the exhaust flow will
affect tuning. In fact, putting even a straight tube will affect tuning,
compared to just letting it blast out unconfined.

However, the Wankel gives a much smoother exhaust flow in the first
place, so there's room to play.  You might make a water stack and try
some flex tubing and see where you start getting some back pressure.

I think the reason for the 2.5 bends is that the benders most people use
were made for thicker steel pipe, and 2.5 is about as small as those are
bent.  If they need a tighter bend, they just use an elbow.

Keith W




I agree that straight headers would be the ideal, but I don't know that
I agree that, "blast out" is better.  My understanding is that for ideal
tuning you are trying to set up a situation where the exhaust reaches
ambient air just slightly before the valve opens to give another exhaust
pulse.  This creates a pull that helps the exhaust stroke out.

For 5400 RPM at 3 pulses/shaft rotation? 16200 pulses/min=270/sec
Speed of sound @ 1080fps/270pps=4ft. Answer is ft./pulse.

So if I have my pulses/RPM right then ideally one would need just short
of 4 feet to set up the tune.

Be gentle folks.

Decker, Michael

Michael,
You have to change the pulses per rotor to 1 pulse per shaft rev
(remember,
the rotor turns at 1/3 shaft speed).
Tuning rotary exhaust in an aircraft could be difficult. Years ago, we
played with different lengths of primary tubes before the collector, and
the
best setup had the collector just in front of the rear axle on a RX3.
Not
going to fit in any cowl that I know of.
Larry



So the real answer to my hypothetical is 12ft.?  I agree, that wouldn't
fit in a cowl.

Decker, Michael


These things tend to repeat at harmonics. Also the speed of sound varies with
the temperature of the exhaust gases.

Everett Hatch felt that 32 inches was a good compromise for 6000 RPM.
I also think Racing Beat built a bunch at 32 inches as I recall.
We used the RB header when we tested the p-port engine on the dyno.

Here is a picture.

-- 
Paul Lamar ...No rotor no motor.

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