Altitude Hold severe jitter



  • Engaging autopilot Alt Hold causes jitter, and the view ahead jitters up and down slightly, several times a second and is hard on the eyes.

    Looking at the trim wheel demonstrates the jitter as the wheel quickly jitters forward and back.

    Disengaging Alt Hold stops the jitter

    I have raised a ticket and supplied a video of the issue.



  • @smoothpp I see it too, and others users i've talked to on Discord as well.



  • I second that... These vibrations start at around 130kt IAS, as long as you keep slower it's fine.
    Totally annoying and should be fixed definitely.



  • I don't understand how you guys can get this plane to 130kt.... have a hard time getting 120 at cruise settings.



  • @theissondergaard Just go lower, at 2000ft you should be easily getting 140kt IAS and this vibration bug.



  • I'm also observing this behavior and it's a rather unpleasent experience.



  • I reported it as a ticket.
    Someone else got the reply from Support to their ticket that this feature is provided as a bonus and thus they don't plan on changing this.
    But this being an advertised feature on the product page is an official feature which of course needs a fix if it behaves erratically especially since it's reproducible.

    I guess it was there from the beginning but with the earlier versions it was much harder to get to these speeds that start causing it. So it's not a regression from other changes but rather an old bug.
    Replacing the ai.cfg for autopilot doesn't solve it, it seems like there is something custom in the way the PA works for altitude hold.



  • The quoted response was slightly misleading, in it's entirity what I said when asked was that I will have a look at the autopilot settings and see if there is something in there which is causing it. However, you have to be aware that the autopilot in the sim uses trim for control, and I will not be altering the trim settings in any way as it works and you are able to trim precisely with it at all speeds. As the altitude hold is there as a 'cheat', I will not prioritise that over fundamental flight dynamics for those who fly the aircraft as it is intended to be flown.

    So let's hope it's something in the autopilot settings!



  • +1 for that. I'm not using altitude hold and find I'm able to trim out the airplane to a very stable hold - and I like the fact that I'll need to keep an eye on my altitude as weather changes or I go from flying over land to water or mountains.



  • @Delta558 said in Altitude Hold severe jitter:

    The quoted response was slightly misleading, in it's entirity what I said when asked was that I will have a look at the autopilot settings and see if there is something in there which is causing it. However, you have to be aware that the autopilot in the sim uses trim for control, and I will not be altering the trim settings in any way as it works and you are able to trim precisely with it at all speeds. As the altitude hold is there as a 'cheat', I will not prioritise that over fundamental flight dynamics for those who fly the aircraft as it is intended to be flown.

    So let's hope it's something in the autopilot settings!

    While I hear you that the plane doesn't have it IRL, the sim version does and was added as a highly desired convienenance, all the AP's (or most?) Use trim in MSFS successfully, so trying to blame it on that is a head scratcher.

    It seems like an easy fix, maybe you're trying to hold too precise of an altitude or you just need to apply smoothing to the AP trim commands to even it out, but I know the community would appreciate it if.you could fix it, especially with the turbo arrow sales probably highly dependant on the state of the standard arrow when the turbo goes live.

    I personally love the Arrow you have built, but the pitch thing is really bad, I wanted the turbo more than anything but AP is very useful if I need to do something real quick like pick up the baby, and the turbo will be even more of a cross country machine.

    Edit: and yes I do want to agree JF arrow trims absolutely beautiful and it's a real treat to fly on my control loaded setup, I've spent considerable hours tuning the control loader for this airframe, aside from the horrendous cross wind takeoff roll problem sometimes I just like to do touch and gos and enjoy the flight dynamics.



  • The following recommended changes to the AI.CFG file will smooth out the Heading Hold and Altitude Hold...

    headingPID = 1.0, 0.01, 1.0, 0.2, 1.0
    verticalSpeedPID = 1.0, 0.05, 0.2, 300.0,1000.0



  • I'm pretty sure it wasn't doing this in the first patch, it seems to have started in the 0.3.0 patch, very annoying. Really hope they can fix this.



  • @Evillian it was there on the first release, that’s when I submitted a ticket about it.



  • Thank you RetiredMan. Unfortunately those changes did not sort out the jitters for me. I'm curious what those changes do but I'll mess with that later.

    Anyway, it did lead me to look into it more. I found this page and pulled up the AP debug in the sim.

    Long story short I made a change that has removed the jitters. I'll post the whole section, but it's the same as the G36, with a change from

    pitchPID = 2.0, 0.1, 5.0, 1.0, 100.0 to
    pitchPID = 2.0, 0.1, 2.0, 1.0, 100.0

    [STICKANDRUDDER]
    rudderGroundPID = 0.015, 0.001, 0.001, 1.0, 1.0 ; Pk,Ik,Dk,I boundary, D boundary
    throttleGroundPID = 1.0,0.10,10.0,10.0,20.0
    brakeDifferentialPID = 0.0, 0.0,0.0,0.0, 0.0
    throttleDifferentialPID = 0.0 ,0.0,0.0,0.0,0.0
    throttlePID = 20.0,0.50,20.0,20.0,500.0
    pitchPID = 2.0, 0.1, 2.0, 1.0, 100.0
    rollPID = 1.2, 0.1, 0.6, 8.0, 100.0
    headingPID = 2.0, 0.01, 1.2, 0.2, 1.0
    verticalSpeedPID = 0.5, 0.01, 0.35, 300.0,1000.0
    nav_ex1PID = 3.5, 0.1, 10.0, 0.035, 50.0
    nav_yawPID = 0.015, 0.005, 0.001, 1.0, 360
    glideSlopePID = 4.12, 0.05, 4.5, 2.0, 60.0
    flightLevelPID = 100.0, 1.0, 10.0, 100.0, 1000.0



  • So after lots of testing and trial and error, I've got a pretty descent AP now. No swaying, no jittering, not overshooting the turns... not too badly anyway 😉

    ai.cfg

    [STICKANDRUDDER]
    rudderGroundPID = 0.015, 0.001, 0.001, 1.0, 1.0 ; Pk,Ik,Dk,I boundary, D boundary
    throttleGroundPID = 1.0,0.10,10.0,10.0,20.0
    brakeDifferentialPID = 1.0, 0.001,10.0,1.0, 5.0
    throttleDifferentialPID = 15.0 ,0.001,25.0,10.0,40.0
    throttlePID = 20.0,0.50,20.0,20.0,500.0
    pitchPID = 2.0, 0.1, 2.0, 1.0, 100.0
    rollPID = 2.4, 0.3, 1.1, 8.0, 100.0
    headingPID = 1.0, 0.01, 1.0, 0.2, 1.0
    verticalSpeedPID = 1.0, 0.05, 0.2, 300.0,1000.0
    nav_ex1PID = 4.50, 0.1, 10.0, 0.03, 50.0
    nav_yawPID = 0.015, 0.01, 0.001, 1.0, 360
    glideSlopePID = 4.12, 0.05, 4.5, 2.0, 60.0
    flightLevelPID = 100.0, 1.0, 10.0, 100.0, 1000.0

    systems.cfg

    [AUTOPILOT]
    autopilot_available = 1
    flight_director_available = 1
    default_vertical_speed = 700.0
    autothrottle_available = 0
    pitch_takeoff_ga = 8.0
    max_pitch = 15.0
    max_pitch_acceleration = 0.5
    max_pitch_velocity_lo_alt = 1.0
    max_pitch_velocity_hi_alt = 0.8
    max_pitch_velocity_lo_alt_breakpoint = 4000.0
    max_pitch_velocity_hi_alt_breakpoint = 8000.0
    max_bank = 20.0
    max_bank_acceleration = 5
    max_bank_velocity = 10
    max_throttle_rate = 0.1
    yaw_damper_gain = 1.5
    pitch_use_trim = 1
    altimeter_indicator = 2
    default_pitch_mode = 0
    default_bank_mode = 3
    alt_mode_slot_index = 2
    max_IAS_ref=185
    min_IAS_ref=60



  • @weptburrito So far so good here, tried a few different cruise speeds at 7,000 MSL and looking significantly better. Do all the ai.cfg changes only change when computer is flying? any chance it can affect hand flight?



  • @sluflyer06 to the best of my knowledge no, it shouldn’t affect hand flight. Just AP and I assume AI “copilot” flight is tied in there also.

    I did do a test flight with the AI flying just to see what would happen. I was quite surprised it landed the plane. A little rough, but it was ok.



  • @weptburrito said in Altitude Hold severe jitter:

    @sluflyer06 to the best of my knowledge no, it shouldn’t affect hand flight. Just AP and I assume AI “copilot” flight is tied in there also.

    I did do a test flight with the AI flying just to see what would happen. I was quite surprised it landed the plane. A little rough, but it was ok.

    Thanks for posting this, your solution will be the necessary one for anyone wanting to fix the AP as JF has said they will not being looking into it, so it is what it is.



  • @sluflyer06 said in Altitude Hold severe jitter:

    JF has said they will not being looking into it, so it is what it is.

    Not the case, if you'd actually read my post further up this thread in its entirety.



  • @Delta558 said in Altitude Hold severe jitter:

    @sluflyer06 said in Altitude Hold severe jitter:

    JF has said they will not being looking into it, so it is what it is.

    Not the case, if you'd actually read my post further up this thread in its entirety.

    The response to my ticket from JF from a developer on your team said this issue is not being considered.