Autopilot slow to descend on LPV approach?

brennon24

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Jul 18, 2019
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Newton, MS
I have the Dynon autopilot and on approaches I have noticed it does not capture or descend when the glide slope magenta(ILS) or Green (LPV) bar passes the normal point where you should start to descend. I am taking out power and have hit the VNAV. What in the settings will help? Sensitivity...?
 

Dynon

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Are you saying that you have it in a VNAV armed mode - ie, the top bar is displaying ALT>VNAV - but it doesn't transition to VNAV?
 

brennon24

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Newton, MS
It does transition. I should update my question to say it captures but the autopilot is slow to descend. I get 1/2 scale or better before it catches up and then I notice it will start going below a 1/2 scale or better before it reacts. I’m sure it’s just a setting that I need to fine tune, I just would like a good starting point. Thanks
 

brennon24

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Post up your pitch settings, photos are easiest.
Ok, it might be a minute but I’ll grab a picture. I thought each setting was aircraft specific and just thought someone might know by this specific problem if I should start troubleshooting using the gain, torque, or sensitivity settings to help correct. Thanks for any help!
 

jakej

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brennon - if your aircraft was a certified one then, yes, you most likely would have type specific settings however EAB aircraft can be wildly different in how they are built ( don’t ask how I know🙄) with issues like control friction & improper rigging In play here.
Regardless of what you are told you need to have the airframe rigged etc properly & that means making adjustment that will allow it to fly level with hands off for at least a short while, in still air, with the skid ball in the centre. With that done first then you can fine tune the autopilot to suit your aircraft. This will result in a much smoother operation of the autopilot & less work for it to do.
BTW - certified aircraft autopilots quite often need fine tuning as well.
HTH.
 

Solana

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Mar 26, 2017
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I have the Dynon autopilot and on approaches I have noticed it does not capture or descend when the glide slope magenta(ILS) or Green (LPV) bar passes the normal point where you should start to descend. I am taking out power and have hit the VNAV. What in the settings will help? Sensitivity...?
I have the same behavior in myRV10. I did a lot of work and have the autopilot well tuned, but this specific behavior cannot be tuned out. Dynon is supposed to have a fix for this specific behavior in their next software release. I don’t know when that will come out.
 

Dynon

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So this is an issue that we believe our next feature release will address. We don't have a firm date on it yet, but there are a few different AP behavior improvements that we're targetting for v16
 

brennon24

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Jul 18, 2019
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Newton, MS
Thank you all and in the mean time if anyone has cracked the code please do tell! I don’t like de-coupling on a hard IFR day to dive and catch the glide path. Picture of current setting below.
72FA8CF9-799A-45DC-97A4-421623DFF007.jpeg
 

Solana

I love flying!
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Mar 26, 2017
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Those aren’t bad settings. Mine are close and I’ve worked hard on them.

sensitivity 16
o pitch gain 2.0
o altitude gain 0.9
o pull rate 1.2
o VSI gain 1.5
o G error gain 1.0
o G error limit 0.35

I think we all have to wait for the new software.
 
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