resetting mixture

[xerj]

Generally speaking, when making power changes in the cruise once leaned, do
you just adjust your throttle and/or RPM and THEN adjust mixture? I imagine
you wouldn't push mixture to full rich before making power changes at
altitude. Is this the case?

Further question: when going from, say, 24 inches and 2500 RPM leaned to 21
inches and 2500 RPM, would you generally need to adjust mixture at all?

Thanks in advance.

[Michael 182]

"xerj" > wrote in message
...
> Generally speaking, when making power changes in the cruise once leaned,
do
> you just adjust your throttle and/or RPM and THEN adjust mixture? I
imagine
> you wouldn't push mixture to full rich before making power changes at
> altitude. Is this the case?
>
> Further question: when going from, say, 24 inches and 2500 RPM leaned to
21
> inches and 2500 RPM, would you generally need to adjust mixture at all?
>
> Thanks in advance.

Do you have an EGT? Try making the changes and see if you are still running
the same degrees rich or lean of peak - whatever your engine requires.

>
>

[Peter Duniho]

"xerj" > wrote in message
...
> Generally speaking, when making power changes in the cruise once leaned,
do
> you just adjust your throttle and/or RPM and THEN adjust mixture? I
imagine
> you wouldn't push mixture to full rich before making power changes at
> altitude. Is this the case?

It's not really going to be an either/or situation, not necessarily.

First, it depends somewhat on how exactly I'm changing the power setting,
and what sort of airplane I'm in. My airplane is turbocharged, so if I push
the power to full, I'm going to push the mixture to full as well, and I'll
do so before changing the power setting. At low-altitude cruise in a
non-turbo aircraft, a similar procedure would apply.

If I'm making a minor adjustment to the power, I won't worry about the
mixture at all. If there's an EGT or TIT gauge, I'll keep an eye on that,
but otherwise I don't sweat it. By "minor" I mean something around 1" on
the MP gauge, or 100 RPM or less if it's a fixed-pitch prop.

For larger adjustments, I will adjust the power and then adjust the mixture.
This may, however, affect the power setting, which then may need tweaking
again (though probably to a small enough degree that I won't mess with the
mixture again).

> Further question: when going from, say, 24 inches and 2500 RPM leaned to
21
> inches and 2500 RPM, would you generally need to adjust mixture at all?

One thing I left out of the above description is that I generally don't
bother touching the mixture at all on a power reduction, including for
descents. An exception would be if I were reducing the power to extend my
range, since obviously you'd want the most optimum mixture setting for that
power setting. Another exception would be if I'd descended to a new
altitude at which I expected to stay for some time at the new, lower power
setting. This would normally only happen if the new altitude turned out to
be bumpy, requiring a slower airspeed, or if I was flying IFR and ATC issued
a hold instruction or asked me to reduce my speed.

In the example you gave, without knowing anything else, I'd say I probably
wouldn't bother adjusting the mixture, but I might if I was going to remain
in cruise at that power setting for an extended length of time.

Pete

[tony]

>
>Generally speaking, when making power changes in the cruise once leaned, do
>you just adjust your throttle and/or RPM and THEN adjust mixture? I imagine
>you wouldn't push mixture to full rich before making power changes at
>altitude. Is this the case?
>
>Further question: when going from, say, 24 inches and 2500 RPM leaned to 21
>inches and 2500 RPM, would you generally need to adjust mixture at all?
>
>Thanks in advance.
>
>
In general, if you're increasing RPM, I'd recommend prop then throttle then
mixture.

If you're decreasing, consider throttle, then prop, then mixture.

In all cases, your egt is your best friend. Besides all of your other best
friends, of course.

AJW

[Robert M. Gary]

"xerj" > wrote in message >...
> Generally speaking, when making power changes in the cruise once leaned, do
> you just adjust your throttle and/or RPM and THEN adjust mixture? I imagine
> you wouldn't push mixture to full rich before making power changes at
> altitude. Is this the case?

If I'm adding power, I enriching the mixture, add the power and then
relean. Some engines (Cont.'s) will not provide much power at altitude
if you go full rich.

>
> Further question: when going from, say, 24 inches and 2500 RPM leaned to 21
> inches and 2500 RPM, would you generally need to adjust mixture at all?

If you're going to stay at that power setting for awhile, it would be
a good idea. However, its not critical. The important thing is that
when you add power, you need to enrichen.

-Robert