Mxsmanic wrote:
Robert M. Gary writes:
How do I know when the engine is potentially being stressed based on
the instruments? Low manifold pressure?

You use your POH book. If it says that 75% power at 10,000 feet
requires 22" of manifold pressure and 2400 RPM , that's what you run.
As a pilot you decide what power (percent) you want to run and how fast
you want to get there. From there the POH will give you some choices of
MP/RPM. Faster flying, quickly burns more fuel.


You can't set the propeller pitch but you can adjust the propeller RPM.

On the A36 and B58 I've been trying to fly, there's a lever that says
pitch next to the throttle, and it has a feather setting (which I have
never used), so I presume it's pitch of the propeller blades.

Indirectly. The label is poor. The lever controls the RPM. The actualy
pitch is controlled automatically. You set the RPM you want, the plane
continuously adjusts the pitch to meet that. A typical training plane
would not have this control.

Is that just for reasons of economy, or does a rich mixture damage
something in the engine?

Leaning is also based on the power % you selected in the book.

You car does the same. For the same RPM your car will set a
higher mixture during acceleration vs. in freeway driving. Most planes
have a EGT (exhaust temp ) to measure mixture, but you can do it just
by sound in a more basic plane.

Higher EGT = rich mixture?

Higher EGT = peak temperature. So we speak of mixture in terms of peak.
I might say "I run my plane 50 degrees rich of peak, but Bill runs his
25 lean of peak. Bob likes to run his at peak".

Understood. My main concern is whether or not I'll get into trouble
if I fail to do all the tweaking of engine parameters while flying.

This is really more of a sim question. In real life when you transition
a student to more complex aircraft (with all the controls you are
speaking of) you discuss operations. Its much easier to understand from
a practical point of view. You're approaching it academically which is
harder to understand, especially w/o sitting one-on-one with a CFI.

-Robert, CFI