Should you lean slightly when taxiing?

Clark1961 said:
So you don't want to stop and think about it. Fine. At least pay attention when you "double check" the manual:
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This is all about setting the idle mixture screw on the carb. It has nothing whatsoever to do with what the pilot does with the mixture control in normal operations.
 
flyingron said:
This is all about setting the idle mixture screw on the carb. It has nothing whatsoever to do with what the pilot does with the mixture control in normal operations.
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Keep up with the thread Ron. I was responding to a poster who claimed the Lycoming didn't expect the idle mixture to be adjusted for sea level operation. Clearly Lycoming does expect the mechanic to account for ground elevation.
 
N801BH said:
If the plane is based at a high altitude airport and not flown to sea level then I would agree to set the idle mixture for local conditions....

The problem is if it is ever taken down lower ( sea level) there is no way to enrichen it without a A&P doing the rework of the carb settings....
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How's the mechanic supposed to know where the pilot is going to fly it? Sounds like one should assume that it may be flown at sea level sooner or later, always.

Hank S said:
When my engine is running and the tires are in contact with Mother Earth, either all knobs are fully forward for takeoff or the red knob is aggressively leaned. Start engine. Scan gages. Lean way back. Begin taxi. Stop at hold short, begin checklist. At "Mixture--Full Rich" it goes forward and stays for takeoff and initial climb.
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Unless you're turbo normalized, that technique won't work well at my home airport and definitely won't work at LXV. You'll be way too rich for takeoff and not producing full available power.
 
True, Nate. But the point was to lean aggressively on the ground.

Question for you high elevation pilots: AWOS at KRAP said something like "density altitude 6600. Consult your POH for proper operation." I know about leaning for takeoff; what do you do when you come down to land and hear this? I don't remember what I did now, I was much more concerned about the wind, 45° to the left and gusting into the mid-20s.
 
Hank S said:
True, Nate. But the point was to lean aggressively on the ground.



Question for you high elevation pilots: AWOS at KRAP said something like "density altitude 6600. Consult your POH for proper operation." I know about leaning for takeoff; what do you do when you come down to land and hear this? I don't remember what I did now, I was much more concerned about the wind, 45° to the left and gusting into the mid-20s.
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I think we have had a number of threads on that but some do full power run-ups and leave the mixture there and others do normal run ups and enrichen slightly from peak RPM at 4000-6000 or so. Above that, almost everyone does the full power run up. Otherwise you're losing power to being too rich.

Of course it depends on your POH but virtually nothing normally aspirated is producing above 65% power at 6000' MSL/DA. You can't really break anything after 45% of the rated power is already gone before you start the takeoff roll. ;)

I'm always blown away at the shove into my seat the O-470 gives at sea level. It doesn't do that up here. And the deck angle to hold Vx is impressive down there.

I'm always amazed that rings even seat properly up here when folks need new engines. I think I'd want that first XC to be to somewhere lower so you wouldn't be inadvertently babying the thing at WOT.

The bigger problem for folks not used to higher DA isn't so much the power loss as in looking up what the high DA does to their ground roll and groundspeed. Everything looks "too fast" and they try to yank the airplane off before it's ready to go flying. On landing they try to make everything look slower and plop it on when it suddenly quits flying.

Simulating it with a 2/3 power takeoff at sea level helps a bit but it doesn't change the groundspeed.
 
Hank S said:
True, Nate. But the point was to lean aggressively on the ground.

Question for you high elevation pilots: AWOS at KRAP said something like "density altitude 6600. Consult your POH for proper operation." I know about leaning for takeoff; what do you do when you come down to land and hear this? I don't remember what I did now, I was much more concerned about the wind, 45° to the left and gusting into the mid-20s.
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Lean for max power on the down wind...
 
Hank S said:
True, Nate. But the point was to lean aggressively on the ground.

Question for you high elevation pilots: AWOS at KRAP said something like "density altitude 6600. Consult your POH for proper operation." I know about leaning for takeoff; what do you do when you come down to land and hear this? I don't remember what I did now, I was much more concerned about the wind, 45° to the left and gusting into the mid-20s.
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I stay leaned on landing at altitude. If I need to go around, I go full throttle then add mixture to add power.
 
My plane does not lean (auto conversion). Buy any time I steal someone else plane, I alway lean it for taxi to prevent plug fouling and cut down on fuel consumption. A friend of mine is an IA and has a few planes he rents out - all have a request to lean in all uses except takeoff unless you know how to do so for takeoff.
 
N517G said:
My plane does not lean (auto conversion). Buy any time I steal someone else plane, I alway lean it for taxi to prevent plug fouling and cut down on fuel consumption. A friend of mine is an IA and has a few planes he rents out - all have a request to lean in all uses except takeoff unless you know how to do so for takeoff.
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First post....

Welcome to POA.... From a fellow auto engine conversion nut case..

:cheers::cheers:
 
On a 200hp io-360 the difference between leaning and not is 1.3gph vs 2.3gph. It saves a gallon a hour so if your at a busy airport you might save a buck in gas :). As well as prolong your oil change and keep your plugs clean and the piston rings from getting stuck due to sooty deposits. Oh and your exhaust valve guides won't wear as fast and drag all that sooty incomplete combustion up though the guide either and to top it off the engine temps will decrease while taxing. Lean as much as it will take.


Sent from my iPhone using Tapatalk
 
Anybody who does a FULL POWER run up is a fool. That being said, you're not getting FULL POWER in an NA plane at 6000'. Full throttle is a different story.

The one thing that has escaped mention (or at least it escaped my feeble notice), is that if you don't pull the mixture nearly all the way out you're not really doing anything at idle settings. As pointed out, snarkily, the idle mixture is controlled by a setting on the engine NOT the red knob. If you just give it four turns (as we were told to do when I was learning at BJC), you're likely not doing squat.
 
flyingron said:
if you don't pull the mixture nearly all the way out you're not really doing anything at idle settings. As pointed out, snarkily, the idle mixture is controlled by a setting on the engine NOT the red knob. If you just give it four turns (as we were told to do when I was learning at BJC), you're likely not doing squat.
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True, and that's exactly why, if done properly, it'll die as soon as you advance the throttle.

Pull 'till rough, enriched 'till smooth...just like you do in cruise.
 
flyingron said:
Anybody who does a FULL POWER run up is a fool. That being said, you're not getting FULL POWER in an NA plane at 6000'. Full throttle is a different story.
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Don't think anyone here didn't already know that a "full power runup" means a "WOT runup", or "full AVAILABLE power runup".

No need to be calling anyone a fool for that. Which is why I said they should read their POH instead of jumping straight to calling them names.

Plenty of people haven't had that experience at ground level to a point where they understood and applied it to anything but cruise. It doesn't make them fools, it just makes them inexperienced. We see them here visiting every summer.
 
mondtster said:
One thing nobody has mentioned is whether or not the idle mixture has been properly adjusted to begin with. In my limited experience, when the carburetor is adjusted properly you can usually leave the mixture control full rich for ground operations with few problems.
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Apparently you do not know the cruise mixture circuit is not a part of the idle circuit.
The cruise mixture fuel flow is set by fixed sized orifices, and adjusted by the air density passing thru the venturi and delivers fuel at a different place than the idle circuit. The idle circuit fuel flow is set by a max sized orifice, and adjusted by changing the air mixture bleed. the more open the air bleed (big knurled knob on the rear of the MA3/4) is, the less fuel being delivered. this will not change with altitude or air density.
The Cruise circuit mixture is adjusted by the mixture control in the cockpit. it is always richer than needed. Except in extremely cold temps (-40-50)
 
I lean on taxi until she stumbles then advance it a smidge.

There's no way to forget and take off without knowing it.
 
txflyer said:
I lean on taxi until she stumbles then advance it a smidge.
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Leaning on taxi:

IMG_1291.jpg
 
It appears as if...if this was a poll...

It'd be 29,000 for and 1 against.

:goofy:
 
I didn't read this thread. And when I saw it going past 30 posts, knew I made the right decision.

So now, with 137 posts, let me ask - did anyone else immediately think of leaning against the closed door of a 152 to get it to turn?
 
midlifeflyer said:
I didn't read this thread. And when I saw it going past 30 posts, knew I made the right decision.

So now, with 137 posts, let me ask - did anyone else immediately think of leaning against the closed door of a 152 to get it to turn?
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They turn great if you open the door and push out on the one on the side of the direction you want to go.
 
flyingron said:
The one thing that has escaped mention (or at least it escaped my feeble notice), is that if you don't pull the mixture nearly all the way out you're not really doing anything at idle settings. As pointed out, snarkily, the idle mixture is controlled by a setting on the engine NOT the red knob. If you just give it four turns (as we were told to do when I was learning at BJC), you're likely not doing squat.
Click to expand...

I messed with the mixture lever yesterday after landing(this was a rental Archer) and how far to pull it to get the engine to start stuttering. It's pretty far, not too far off from where I had been ground leaning my own airplane, but I realized that I can go a little farther without any negative effects on the idle smoothness.
 
Sam D said:
When they (Lycoming) do talk about keeping plugs clean (in the operating manual and a later SB), they focus on running the engine at 1800 rpm for 15-20 seconds right before shutdown. I'll admit I don't do this.
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This is what I was taught to do in Yaks.
 
flyingron said:
Anybody who does a FULL POWER run up is a fool. That being said, you're not getting FULL POWER in an NA plane at 6000'. Full throttle is a different story.

The one thing that has escaped mention (or at least it escaped my feeble notice), is that if you don't pull the mixture nearly all the way out you're not really doing anything at idle settings. As pointed out, snarkily, the idle mixture is controlled by a setting on the engine NOT the red knob. If you just give it four turns (as we were told to do when I was learning at BJC), you're likely not doing squat.
Click to expand...

Sometimes I'd do them at mountain airports to make sure the turbos would spool up correctly.
 
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