Wiring trim to autopilot?

Mark P.

Visit my builders log at www.ZenithOwner.com
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Apr 21, 2017
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38
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Horizon Lakes Airpark, MI
Hi all, I see in the Dynon manual it shows the trim motor and trim switch being wired to the autopilot.

What is the advantage/disadvantage to this? Do I need to include the elevator trim with the autopilot? If I don't, won't the servo just find a new neutral position to hold the plane level?

Wiring the trim motor and switch to the autopilot just adds some complexity to the wiring, and I'm just wondering if there's an advantage to having the autopilot also being able to control the trim.

Thanks!

 

John Bright

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May 4, 2020
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Southeast USA
Auto-trim is a feature that reduces pilot workload because you don't have to respond to the visual prompts on Skyview telling you to trim up or down.

The AC needs to be trimmed because proper trim:
  • Reduces the amount of torque the AP servo needs to apply.
  • Reduces electrical power to the AP servo.
  • Eliminates the possibility of the AP servo being asked for more it can give causing its stepper motor to "slip".
  • Eliminates the out of trim surprise you would otherwise get when you disconnect the autopilot.

As the SkyView User Guide puts it: "The Auto-Trim’s goal is to minimize the stick forces so that the Autopilot servos do not need to apply much force to the control surface to maneuver the aircraft. This allows it to have the ideal amount of control authority over the control surface, while keeping the aircraft in trim continuously. Essentially, Auto-Trim flies the aircraft very similarly to how you do."
 

airguy

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Gods Country - west Texas
And a big safety bonus with that, is that the autopilot will never hand you an aircraft that is significantly out-of-trim and surprise you with high stick forces. Think about having the AP fly an IFR approach down to minimums - then you break out at 200 feet and kill the autopilot to hand-fly the landing. Finding out then that your airplane is significantly out of trim is not a pleasant thing.
 

Mark P.

Visit my builders log at www.ZenithOwner.com
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Apr 21, 2017
Messages
38
Location
Horizon Lakes Airpark, MI
Can anyone make this easy on me-I'm looking for a wiring diagram for connecting the Ray Allen elev trim servo to the AP. I have the trim working by itself, but I'm not sure how to connect any of the wires from AP Panel to the trim system!
 

Rhino

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Jul 20, 2009
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KTHA
 

n28et

I love flying!
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Jul 27, 2013
Messages
25
The installation manual provides a pinout and wiring diagram for connecting the trim motors to the AP-Panel. See Figure 228 – SV-AP-PANEL Trim control wiring diagram.
 
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