Paul,

I've continued to tinker with this spreadsheet and make improvements.

Here is the latest version and I am satisfied with this one. This should
give good utility to anyone who is considering a turbo.

I've added a horsepower feature to the altitude section, so you can
easily see what power you want to use for various parts of the flight.

I've also renamed the altitude mass flow "Actual Mass Flow" because
that's what it is. I previously called it "Uncorrected Mass Flow," which
is true too, but not a good description.

I've also added a little note with tips on using it.

You can easily check various power settings and altitudes see where that
puts you on the various compressor maps. Then just choose the sweet
spots where you antiticpate you are going to operate most of the time.


Regards,

Gordon.

Gordon,

Great work.  It keeps getting better and better.  A few points. I noticed
the chart on the right is for STP. I entered 80 degrees for sealevel temp.
and noticed the final figures changed but at 20,000 in step #3, the temp
remained at STP. I believe it should be higher.

Your range didn't let me select a BSFC of 3.6 or anything under 4.0.  Just
kidding here. I know this spread sheet is for turbo normalizing not
turbocompounding:)

For AGE 85 ethanol I just used the stoiometric ratio of 9:1 but  I wonder
about the embedded oxygen content which as I mention as a plus vis-a-vis
100LL over 13K'. That is with NA engines though.  That may be not be a
factor since the manifold pressure is still at sealevel pressure. We may
have to request some more data from  S.D. university to find out about
turbonormalizing at altitude.  Power output will go up a min. of 12% though
and that will effect the BSFC.   Ethanol will again become a bonus when the
plane flies over the altitude the turbo can normalize the engine at.

How about putting the Rotrex supercharger model #32-90 in there for a
comparison?  With a direct traction drive  and belt running at combined
efficiencies of 95% and the sweet spot on the compressor map of 80% it might
be an eye opener to compare it to the Garrett turbochargers.


Last point for Paul to answer.  Doesn't the ability of the heat exchangers
to radiate heat, lose efficiency at a faster rate than the greater Delta T
gains across the heat exchangers?  I believe this is because of lower
pressures and mass of air traveling through the exchangers.  I think we
discussed this a year or so ago.

 I believe this relationship can be proved knowing the volume which is a
constant in this case, and the pressures and temps. Charles law I think. If
so then fuel becomes a cooling factor, and a opened cowl flap perhaps.


Thanks

Doug Fir


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