FLC to avoid stalls

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Soareyes
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Re: FLC to avoid stalls

Post by Soareyes »

I did this experiment today in my plane. It behaved exactly as Dave predicted.

FLC Climb:

Starting in level flight at 6,500', 50% power, IAS 130.
Set desired altitude to 7,500' and FLC/IAS to 110 kts - plane starts to climb while decelerating to 110 kts .
Pull power back to 15% - before reaching bugged altitude the plane stops climbing then starts to descend, still holding 110 kts.
A CAS message appears: ALTITUDE SEL - "Descending away from selected altitude"
No stall.
Increase power to 50% - climb resumes.

FLC Descent:

Starting in level flight at 6,500', 50% power, IAS 130.
Set desired altitude to 6,000' and FLC/IAS to 120 kts - plane starts to climb eventually reaching 6,650' while airspeed drops to 120kts.
A CAS message appears: ALTITUDE SEL - "Climbing away from selected altitude"
After achieving 120 kts the plane begins to descend, holding 120kts.
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Re: FLC to avoid stalls

Post by smoss »

Obviously this is software dependent. What version/plane are you in Dan? Your registration shows as a Cirrus.
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Soareyes
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Re: FLC to avoid stalls

Post by Soareyes »

smoss wrote:
Sun May 24, 2020 8:10 pm
Obviously this is software dependent. What version/plane are you in Dan? Your registration shows as a Cirrus.
Still in a Cirrus for another month, they call it "Cirrus Perspective" but basically a G1000.

*Credit to Rob also for predicting the test results.
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Re: FLC to avoid stalls

Post by OriensFlight »

Anyone ever see the little yellow ELE warning?
5CDF694B-3A5E-40FA-B101-2EBEB6BFCD9C.jpeg
Note: This is a decidedly unrecommended attitude!
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Re: FLC to avoid stalls

Post by smoss »

see pic. Never seen the warning though.
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Re: FLC to avoid stalls

Post by Boatguy »

OriensFlight wrote:
Wed Jun 10, 2020 12:02 am
Anyone ever see the little yellow ELE warning?

5CDF694B-3A5E-40FA-B101-2EBEB6BFCD9C.jpeg

Note: This is a decidedly unrecommended attitude!
That's VS, not FLC. I'm not surprised you can induce a stall with VS.

I'm probably a little slow here, but what is the point of VS in a discussion about FLC?
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Re: FLC to avoid stalls

Post by OriensFlight »

Yup, I know my AP is set to VS not FLC in this screenshot. But, it's a warning that I'm assuming you could also get when the AP is set to FLC. I just wanted to know if anyone could explain it, and Steve kindly did. :)
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Re: FLC to avoid stallsF you gave it more power

Post by Soareyes »

“Anyone ever see the little yellow ELE warning?“

Poor autopilot. You’ve commanded a 1,100 rpm VS climb but pulled the power back. The autopilot is trying but it can’t get the nose up high enough. It’s asking for help.

Ordinarily the corrective action for the ELE message with the up arrow would be to give it some up trim so the autopilot doesn’t have to hold constant “sustained force in the indicated direction.” Not the best plan in a stall.

In aircraft with aileron trim it is not unusual to see a similar AIL message with an arrow pointing right or left, for example if you let a bit of fuel imbalance develop. A nudge of the trim in the indicated direction makes the message go away.
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