Hi doc,

    Here is some stuff from the Heisler book.

    --
    Paul Lamar ...No rotor no motor.


That's really excellent Paul.  Thanks for sending this out.  Two notes:

1.  This is very similar chemistry to a fuel cell.  O2
concentration/reaction with a fuel source generates electricity when in
the presence of a platinum catylist.

2.  (more importantly) With the high EGT on a rotary, it's important to
mount any O2 sensor quite a bit of distance from the exhaust port.  The
forwarded text says the O2 sensor suffers from advanced aging if exposed
to extremely high temps.  I wonder how near to the end of the exhaust
stack the sensor can be mounted and not have its readings altered by
reversion of clean atmosphere in the exhaust stream caused by organ pipe
effects.  On a turbo engine, the sensor could be mounted anywhere after
the turbo - damped organ pipe effects and the turbo takes the brunt of
the high EGT stream.


Matt-

There is another point about this. IMHO the wide band uses the distorted
narrow band S curve and feeds it into an A to d. Linearizes the data
and displays it as a mixture ratio between ten and twenty to one.
As such the extensions  of the S have a very low slope so this is
fraught with problems. One would need a 10 bit A to D minimum.

Doc is attempting to use this in a feed back system.
However we need an auto lean system that holds the mixture
at 16:1 to 18:1 for best BSFC and not stoichiometric or 14.7 to one
during cruise only.

Therein lies the problem. Your idea using just the O2 sensor to
tell if you are on the lean or rich side and the EGT data to tell
how much is a good one. However for an aircraft it is over kill
since you sit there for hours at one load, one altitude and one RPM.
The pilot can adjust the mixture. You would need three feedback loops
one for take off, one for climb and one for cruise. Maybe one could
get away with just two. Max power and max cruise.

Paul Lamar ...No rotor no motor.

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