On Fri, 14 Oct 2005 21:45:42 GMT, "xerj" wrote:

For example, for the same MP/RPM settings on my Lycoming IO-360, bhp will
be less at best economy vs best power.

That's what my original understanding was, and why I was confused by the
presentation of the power setting table I linked to.

You can prove it simply by leaving the prop and throttle where they are, and
moving the mixture in between best econ and best power. At best econ, you
will be slower than best power. Slower = less power being produced.

If you actually could just get the same power at a lesser fuel flow without
adjusting MP and RPM, putting aside CHT considerations for the moment,
there'd never be a reason to run at best power. It'd just be burning more
fuel for the same result.



Your understanding is correct. The older a/c power charts only showed best
power MP/RPM settings.

One method:

1. Decide on your power setting -- e.g. 65%
2. Set MP/RPM appropriately per POH with adjustments for altitude,
temperature.
3. Set mixture to best power.
4. Note IAS.
5. Set mixture to best economy.
6. Increase MP to regain lost airspeed.

You will now be at 65% power, but with best economy setting, and burning
less fuel for the same airspeed.

It's hard to apply this method unless air is calm.

You might want to obtain the Operator's Manual for the -360- series of
engines from Lycoming. It has a wealth of charts that are much more
detailed than that in the older Mooney's, and might be interesting reading
for you.



Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)