Auto pilot tuning- slip and trim warnings.

[Peterelsea]

I am new to the Dynon system and trying to tune the pitch axis in my auto pilot. During my first attempt, I was getting repeated conflicting prompts to trim up and then trim down with quick changes back-and-forth. I was also getting a trim slip warning. I confirmed that the connections are tight. I also confirmed that the pitch torque is set at 100%.
Not sure what I am missing, any advice?
Also, does the auto pilot have a function for automatic trim adjustment? My friend, who flies Garmin, thinks that it should, but I looked through the sky view set up and did not see a setting for this.

 

[Marc_J._Zeitlin]

It would be extremely useful, when asking for advice, to provide information that might allow folks to know more about your system. Like:

• What airplane?
• Which servo model?
• Do you have the A/P Control Panel?
• Are you in Simple or Expert Mode?

If you're already at 100% torque and it's still slipping and/or asking for trim constantly, you either have the wrong servo installed or you have a lot of friction in your control system. But knowing more about your system would help in diagnosing if something's wrong or what it might be.

And yes - the system can do auto trim. Check Trim Motor Configuration under Hardware Calibration.

 

[Peterelsea]

Thank you, and yes, I should’ve provided more information!
It is a factory assist built Arion lightning, with dynon skyview HDX, autpilot control panel, and standard dynon servos installed by the factory tech.
I am in expert mode as instructed for the tuming procedure, using IAS mode.
There is no tactile restriction in elevator movement on hand flying.

 

[Marc_J._Zeitlin]

It is a factory assist built Arion lightning, with dynon skyview HDX, autpilot control panel, and standard dynon servos installed by the factory tech.
I am in expert mode as instructed for the tuming procedure, using IAS mode.
There is no tactile restriction in elevator movement on hand flying.

So does the A/P work, but just ask for trim a lot? Or does it not engage? Or if engaged (at least per the indications on the screen), does it do anything? Will it hold altitude in altitude mode, even if you perturb it?

If there's no friction in the pitch system and the flight forces can be easily trimmed out with the trim system, then it sounds like you might have a problem with the servo itself...

 

[jakej]

Hi Peter, I’m not sure of the full process you used however I’ve installed a/pilots in 10 Arions & have not had an issue - first steps I use are these -
The basics first —-
Don’t use the a/pilot yet. Make sure the HDX skid ball is centred when at cruise speed. Use a ruder trim tab if you need to achieve that.
Then work on lateral control - you also may need a trim tab on an aileron & another way is to lower 1 x flap very slightly to pick up a ‘heavy’ wing.
After all of that you should be able to fly ‘hands off’ in still air for a while. The idea is to tune the airframe as much as possible to make it easier later for the autopilot. If all is good THEN start the calibration process for the autopilot/trim system.
Do you have electric elevator & aileron trim motors ?
You are using the Dynon manual for the complete calibration process?

 

[Peterelsea]

Thanks so much for the extra info. Yes I have electric aileron and elevator trim motors. There is no Ryter trim and I have noticed. I need a very slight right rudder input at cruise speed to keep the ball centered. The plane does seem to want a little bit of left aileron trim to keep it level, we did try lowering the left flap slightly compared to the right to adjust for this. I’m going to go up tonight and see if the pitch is a little more stable and more quiet air. I am using the most recent dynon auto pilot tuning procedure.
I will let you know how it goes!
Glad to hear you have worked with Arion lightnings! Do you own one?

 

[jakej]

I don’t own 1 but have plenty of working experience with them.
You could also disconnect temporarily the static line (be aware that WILL have some affect on the altimeter etc) to determine if there are errors caused be incorrect placement/style/shape of the ports.
Also - are the servos connected by pushrods or cables. I developed simple pushrod actuation rather than cables (less opportunity for free play) with the Arions, Glastars & a couple of other types.
Btw - I air tuned my aircraft & flew it on a cool clear morning & found that I could make pitch & roll changes ( a/pilot not engaged) just by moving my torso around - I’m sure others have achieved that too. That’s what I meant re ‘airframe tuning’ as mentioned previously.