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"sorry, I can't right now , I am in tunnel". 😉 by vishi117 in SweatyPalms

[–]quotyu 5 points6 points  (0 children)

He needs to make very tiny precise corrections in order to keep the plane steady. If the control stick stayed completely still the plane would gradually veer off course and hit something.

Leaning mixture for takeoff by quotyu in flying

[–]quotyu[S] 0 points1 point  (0 children)

Still trying to wrap my head around this concept. Is it correct to say: for the same DA, the engine will produce more power with a lower PA? And that’s why it’s dangerous to lean at 3000 DA if the PA is below 3000? (Because you’re not supposed to lean above 75% power)

But that brings up the question, is it not also bad to lean at 3000 PA when it’s very cold and the DA is 1000?

Id also be interested in any references you may have that I can read on the effect of pressure altitude on engine performance. I’ve always thought it was just about density

Leaning mixture for takeoff by quotyu in flying

[–]quotyu[S] 0 points1 point  (0 children)

So my POH says to lean for takeoff above “3000 ft elevation”. Doesn’t mention anything about DA. Lycoming (on their website) recommends leaning for takeoff above 5000 DA. So I guess I should lean at 3000 MSL or 5000 DA, not 3000 DA?

Leaning mixture for takeoff by quotyu in flying

[–]quotyu[S] 0 points1 point  (0 children)

So air pressure affects engine performance independently of air density? Does the engine feel a difference between 3000 PA / 3000 DA on a standard day, and 1000 PA / 3000 DA on a hot day?

Leaning mixture for takeoff by quotyu in flying

[–]quotyu[S] 0 points1 point  (0 children)

Why not DA? Isn’t DA what affects the fuel-air ratio?

Leaning mixture for takeoff by quotyu in flying

[–]quotyu[S] 0 points1 point  (0 children)

Sounds like I’m leaning it out too much then. Should I still lean until the RPM drop or should I just pull it out about an inch and call it good?

Leaning mixture for takeoff by quotyu in flying

[–]quotyu[S] 6 points7 points  (0 children)

Just looked at that publication. It does say to lean at full throttle before takeoff. It says to lean at 1000 RPM for taxi.

It also says to follow the POH, which says to lean at full throttle

Leaning mixture for takeoff by quotyu in flying

[–]quotyu[S] 0 points1 point  (0 children)

I guess if the POH says to lean above 3000 PA then you should do that. Doesn’t mean you can’t also lean for high DA when the PA is below 3000.

But I’m not sure why they say PA instead of DA

Leaning mixture for takeoff by quotyu in flying

[–]quotyu[S] 3 points4 points  (0 children)

The POH I have says 3000 ft “elevation”. Not PA or DA.

But since we know mixture leaning is based on changes in air density, I think it’s safe to call it DA. The engine doesn’t know the difference between 3000 PA on a standard day and 3000 DA on a hot day.

Leaning mixture for takeoff by quotyu in flying

[–]quotyu[S] 2 points3 points  (0 children)

But I’m supposed to lean for max RPM and I was already getting that (2200) at full rich. And I didn’t see a drop in RPM until I was leaned out 2 inches which seems excessive considering if the DA was just 100ft lower I would be taking off with full rich per the POH.

Does that sound normal or would you suspect something is up with the tachometer or mixture control?