Kitfox Aircraft Stick and Rudder Stein Air Grove Aircraft TCW Technologies Dynon Avionics AeroLED MGL Avionics Leading Edge Airfoils Desser EarthX Batteries Garmin G3X Touch
Page 1 of 4 1234 LastLast
Results 1 to 10 of 37

Thread: Trim with the Garmin G3x

  1. #1
    Senior Member
    Join Date
    Dec 2017
    Location
    Canada
    Posts
    308

    Default Trim with the Garmin G3x

    I'm still trying to fully figure this one out. Everytime I think I have it figured more information comes to me that changes everything.

    The G3X can control trim. But it's not as easy as connecting it up I thought.

    As it stands my understanding is that it would need something like the safteytrim system to correctly control the actuator due to amperage. Now, what I'm still not sure of is how does the G3X know the current position? Is that baked into the safety trim? Do i need another position sensor? The actuator is only 2 wire so I can't see it returning any analog info on it's position. And so unless the safety trim using timing to guesstimate, I don't see how it would either. And how much does it really matter if I know the exact trim position? I'm going to know by the feel of the controls. Or would i in KF?

  2. #2
    Senior Member efwd's Avatar
    Join Date
    Jun 2015
    Location
    Yorba Linda, CA
    Posts
    2,817

    Default Re: Trim with the Garmin G3x

    I believe the servos have the means of detecting the pressures and energy being applied to the controls.
    Eddie Forward
    Flying
    SS7, 912iS, Garmin G3X

  3. #3
    Senior Member aviator79's Avatar
    Join Date
    Dec 2016
    Location
    Los Alamos, NM
    Posts
    913

    Default Re: Trim with the Garmin G3x

    I'm not familiar with the G3X, so I don't know anything about its integrated trim controller. However, for smart trim control, you don't really need position feedback. It will adjust the rate based on your airspeed.

    If you want trim position indication on your G3X, you will need to install a trim position sensor. Kitfox sells a kit for this. It's easy to install. I installed it because I wanted to be able to set takeoff trim easily.

    I think what Eddie is talking about is letting the Autopilot auto-trim. For this, he's right, the autopilot servos do have torque feedback, and can trim control forces out so that the autopilot servos aren't loaded too heavily and so that when you turn the autopilot off, the airplane is already trimmed. I don't know if your G3X has this built in. Dynon Skyview can do this if you have the optional AP panel.
    --Brian
    Flying - S7SS

  4. #4
    Senior Member efwd's Avatar
    Join Date
    Jun 2015
    Location
    Yorba Linda, CA
    Posts
    2,817

    Default Re: Trim with the Garmin G3x

    Thanks Brian. I think I prematurely jumped to the AP functioning and trim with the G3X. Since I have the professionally assembled harnesses I do have wires to hook up a trim position sensor installed. I even have the trim LED bar from Ray Allen but I would need a sensor. I don't aim to install it. Trim is felt in your hand with the exception of setting trim for departure. I can count to three or whatever it takes to set the trim just as I did during the transition training at Stick and Rudder. While speaking of the Safety Trim, be sure you are getting the "Safety Trim Booster". I got mine from Kitfox. I have looked at the TCW website after the fact and note that the Safety Trim "Booster" is not listed on their site. They do have a Safety Trim. I have no idea what the difference is but I have had John McBean specifically ask if I had the "Booster" back when I was having auto pilot servo trouble.
    Eddie Forward
    Flying
    SS7, 912iS, Garmin G3X

  5. #5
    Senior Member
    Join Date
    Dec 2017
    Location
    Canada
    Posts
    308

    Default Re: Trim with the Garmin G3x

    Hmm, booster eh... i'll have to find out about that.

    I've decided to pass on the AP right now.

    But sounds like a trim position sensor - if not too expensive - is what's needed here too. So many things.

  6. #6
    Senior Member efwd's Avatar
    Join Date
    Jun 2015
    Location
    Yorba Linda, CA
    Posts
    2,817

    Default Re: Trim with the Garmin G3x

    Just kinda reviewing this post.
    I see we have two aspects that we are discussing. The G3X will adjust the rate at which the trim will move and its based on the airspeeds that you program in as when to move fast and when to move slow when you hit the switch. The G3X wont actually auto trim unless you have the AP as I believe Brian states how Dynon works. What the Garmin lacks is the amperage needed to drive our Pitch servo motor hence the Safety Trim Booster.
    FWIW the Vertical Power unit also has the "trim rate" function for low and fast air speeds.
    Eddie Forward
    Flying
    SS7, 912iS, Garmin G3X

  7. #7
    Senior Member aviator79's Avatar
    Join Date
    Dec 2016
    Location
    Los Alamos, NM
    Posts
    913

    Default Re: Trim with the Garmin G3x

    Quote Originally Posted by efwd View Post
    The G3X wont actually auto trim unless you have the AP as I believe Brian states how Dynon works.
    "Auto trim" is a deceiving term. One might think that the airplane will keep itself in trim while you're flying it. It won't. It allows the autopilot to operate the trim to alleviate the load on the AP pitch servo, just like the pilot would.

    Quote Originally Posted by efwd View Post
    What the Garmin lacks is the amperage needed to drive our Pitch servo motor hence the Safety Trim Booster.
    Just to clarify, by Pitch servo motor, you mean the trim motor, not autopilot servo correct? The Vertical Power and Advanced Control Module both have "smart trim" built in, and can supply the trim motor with adequate current. It might be something to consider when deciding to spend the $$$ on one of these systems. They incorporate a lot of functionality into a single red box.
    --Brian
    Flying - S7SS

  8. #8
    Senior Member
    Join Date
    Dec 2017
    Location
    Canada
    Posts
    308

    Default Re: Trim with the Garmin G3x

    Quote Originally Posted by efwd View Post
    Just kinda reviewing this post.
    I see we have two aspects that we are discussing. The G3X will adjust the rate at which the trim will move and its based on the airspeeds that you program in as when to move fast and when to move slow when you hit the switch. The G3X wont actually auto trim unless you have the AP as I believe Brian states how Dynon works. What the Garmin lacks is the amperage needed to drive our Pitch servo motor hence the Safety Trim Booster.
    FWIW the Vertical Power unit also has the "trim rate" function for low and fast air speeds.
    Right. I was just reviewing the VPX docs as I am planning on using it. The trim is locked at 1 amp, so no good either.

  9. #9
    Senior Member efwd's Avatar
    Join Date
    Jun 2015
    Location
    Yorba Linda, CA
    Posts
    2,817

    Default Re: Trim with the Garmin G3x

    yes, pitch trim motor not the AP servo.
    Eddie Forward
    Flying
    SS7, 912iS, Garmin G3X

  10. #10
    patrick.hvac's Avatar
    Join Date
    Jul 2018
    Location
    Ottawa
    Posts
    104

    Default Re: Trim with the Garmin G3x

    Sorry to bring back an old thread. Been searching on the trim motor issue.
    Is the current solution still to install the booster module?
    Currently drafting wiring diagrams for VPX GSA28 integration and it looks like regardless of configuration the GSA will supply the trim motor and require a boost.
    Confirmation would be excellent.
    TIA!
    Pat.
    🇨🇦CANADA
    Flying | SS7 | G3X | Edge 912

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •