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Subject: Re: [FlyRotary] Crickets & progress
From: Ernest Christley <echristley@att.net>
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Date: Sun, 10 Feb 2013 20:05:07 -0500
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To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>


On Feb 9, 2013, at 6:09 PM, Tracy wrote:

> I decided to experiment with a wideband sensor.   They have come down =
in price so even penny pinchers like me can afford them.  $150.00 range. =
 They typically put out a voltage between 0 & 5 volts instead of 0 to 1 =
volt like narrow band does.   The polarity is opposite as well so rich =
mixture is at low end of range instead of high.   With the latest =
version of the software (after Feb 2013) you can now setup the EC3 to =
use either  type sensor.   With the wideband sensor it is much easier to =
target the exact mixture you want and to achieve the best fuel economy =
in closed loop.

The biggest issue I've found in tuning closed loop is that the computer =
I'm using doesn't understand lean surge.=20

The rotary gets into a situation where the mixture is to lean to ignite. =
 The mixture doesn't exhaust as normal (because there is no expansion =
from heat), so a lot of the mixture gets recycled into the next =
combustion event.  The next event fire just fine (because it has double =
the fuel charge).  The O2 sensor sees some combination of the two =
events, and the combination is NOT a useful F/A mixture. =20

Ive found that the most useful way to programmatically tune to a lean =
mixture is to move up to it from the rich side. =20=