Power setting table and best economy/best power...

On Wed, 19 Oct 2005 00:31:26 -0700, "Peter Duniho"
wrote:

"Friedrich Ostertag" wrote in message
...
On a turbocharged engine egt affects the enthalpy delivered to the
turbocharger turbine and in turn the power deliverd to the compressor.
This will result in a slight change in boost pressure and therefore MP for
a given throttle setting.

Whether this will be a big enough change to be noticed under typical
operating conditions of an airplane engine I don't know.

Thank you for trying to save me. However, I have to admit a couple of
things: I wasn't meaning to restrict my (erroneous) comments to turbocharged
engines; and your point, while an interesting take on the question, is
probably only valid for turbocharged engines with manual wastegates.

Of course, that second point requires qualification too: I have noticed in
my own airplane (turbocharged engine, with an automatic wastegate) that at
high altitudes, above the critical altitude for the turbo, RPM becomes the
primary power control. It's as if at lower RPM, there just isn't enough
energy in the exhaust to keep the turbo working effectively. Throttle at
full, then adjust RPM. Small adjustments to RPM can make significant (1" or
more) changes in MP.

The RPM thing isn't really what you were talking about, but it seems related
in context.

Anyway, thanks for posting more to think about.

Pete


I notice that on my turbo-normalized, manually waste-gated engine, too. As
a matter of fact, if I'm climbing into the low teens, and maintaining say
25/2500 during the climb, at my target altitude, decreasing RPM to 2400 RPM
will usually drop my MP by 2-3" or so.


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