Draker
Well Known Member
I'm almost embarrassed to ask this, but my private pilot training was done at sea level in Florida and like many flight schools, they pretty much glossed over the mixture knob.
I'm trying to get more methodical and repeatable in my flight testing. One of my goals is to pick a particular fuel economy setting, and hold it constant through a variety of engine power configurations. For example, let's say I'm cruising at 5,000 feet density altitude, 2300 RPM, 23inMP. I lean the mixture to best power with the mixture knob. (Assumption: Fuel injection)
1. Now I change RPM to 2400 without touching the red knob. Am I still at best power?
2. Instead of changing RPM, I change MP to 22in. Am I still at best power?
3. Instead of the above, I descend to 4,000 feet DA. Am I still at best power?
My intuition says 1. Yes, 2. Yes, 3. No, but I have to admit I don't know enough about the mixture control to know for sure. When do you have to re-lean to your desired fuel economy setting? After any change? Only after altitude changes?
Is this also true for other mixture settings? Let's say I lean to 25* LOP. Can I change RPM or MP settings (or altitude) without having to hunt around for 25* again?
This has been an unexpected benefit of taking Phase 1 seriously: It's shaking out and highlighting gaps in my training, which I can correct.
I'm trying to get more methodical and repeatable in my flight testing. One of my goals is to pick a particular fuel economy setting, and hold it constant through a variety of engine power configurations. For example, let's say I'm cruising at 5,000 feet density altitude, 2300 RPM, 23inMP. I lean the mixture to best power with the mixture knob. (Assumption: Fuel injection)
1. Now I change RPM to 2400 without touching the red knob. Am I still at best power?
2. Instead of changing RPM, I change MP to 22in. Am I still at best power?
3. Instead of the above, I descend to 4,000 feet DA. Am I still at best power?
My intuition says 1. Yes, 2. Yes, 3. No, but I have to admit I don't know enough about the mixture control to know for sure. When do you have to re-lean to your desired fuel economy setting? After any change? Only after altitude changes?
Is this also true for other mixture settings? Let's say I lean to 25* LOP. Can I change RPM or MP settings (or altitude) without having to hunt around for 25* again?
This has been an unexpected benefit of taking Phase 1 seriously: It's shaking out and highlighting gaps in my training, which I can correct.
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