Leaning mixture for takeoff, pattern, etc

[Pedals2Paddles]

To date, training has always been "mixture full rich - check". Lean it out as you climb and in cruise. Then obviously bring it back in as you descend. And full rich for landing. This is all in a C150.

I've been reading about folks who say you should lean the mixture to max RPM at any density altitude, not just the arbitrary 3000ft msl that gets thrown around. This seems logical to me. For the same reason we lean during taxi, screaming around the pattern with the mixture full rich isn't necessarily healthy.

Does anyone else have experience with leaning the mixture prior to takeoff? From what I've read, you would make the last step of the runup going full power, lean for max RPM, enrich by a turn or two, and leave that as your mixture setting for takeoff.

What about landing, still leaned for max rpm or full rich?

 

[Jim Logajan]

This is all in a C150.

I think some of the replies missed this, so gave generic "see Operating Handbook" answers. You aren't likely to have EGT or CHT instrumentation in such a plane.

I often fly a C152 from near sea level airports to ones up to 4000 ft. Of course it has a different engine from C150 and I cobbled together my procedures from various flying guides and the POH for the C152. Also, I am a relatively low time pilot so what I say on this should be taken with caution. So far it seems to work:

Before takeoff, apply full throttle and lean to maximum RPM. (The Mountain Flying Bible suggests doing the leaning during the takeoff roll if no suitable place to do it without risk of kicking up debris into the blades!)

When approaching for landing and to set up for possible go-arounds, while nearing pattern altitude and before throttle reduction from cruise, I lean to maximum RPM at that throttle setting. I have not found any great advantage to applying full throttle before leaning - cruise setting seems fine (but I've only checked a couple times.) By the way, I periodically adjust lean on descent - I no longer just shove it to full rich and forget it. (Unless I'm under 3000 MSL.)

It would be interesting to see what others who fly in similar situations think of my procedures, or what they do.

 

[Jim Logajan]

So if you're landing above 3000msl, you leave it at the leaned-for-cruise setting just before pulling the power back?

Yes.

Is that 1000-15000ft difference between that and the runway enough to make a difference if you have to punch it and go around?

There is no doubt some difference - but not enough (I think) for me to fiddle with the mixture on final!

I did use that leaning procedure prior to several go-arounds due to gusty cross-winds at a 4053 ft airport (4S7) last year. Climb was anemic even after flaps retracted, but since I didn't try comparing with several mixture permutations I don't know if it could have been improved.

For landing below 3000msl, are you saying you do go full rich?

In the C152 or C172 I rent - generally yes.