Autopilot question

[swannyuk]

Morning all,

I'm loving this plane but i'm not sure if I'm doing something wrong with the AP.

At cruise alt in nav mode the plane looks like it's hitting heavy turbulance making it pitch up and down quickly. I thought it was active sky being weird but it still does it in clear skies with AS off.

Looking at the yolk it's moving forwards and backwards quickly. When I take it out of AP it shoots for the stars as if the trim was struggling to keep level flight at cruise speed.

I can't remember what speed I was doing but probably 95 on the torque.

I'll try and capture a video next time but wondered if anyone else has had similar?

Cheers

Edited December 23, 2018 by swannyuk

[Mateyhv]

Weird, its not the airplane or the AP. Must be something with the joystick or other setting.

[Bryan @ The Aviation Agenc]

Sounds like you've got some kind of actuator stuck.

Check a couple of things:

1) Still got the TO flaps on after 3K feet? I'm guessing you do... and that this is the problem.

2) Are your controls neutral on take off? (not trying to trim, your joystick isn't going wonko sending signals). This could also be the problem. Some joysticks and controls send "noise" to the computer. There's a sensitivity adjustment in Xplane you can do. If the noise is in your throttle... you can increase the tension knob and reduce the noise going to throttles.

This isn't an AP problem. AP will not override the physical settings of the control surfaces if they're locked, jammed, or being manually actuated (while flying in AP - grab the stick and try and turn... AP will fight you... but you can still maneuver... hence why that big ass red button is on the yoke for AP/TRIM disconnect if the crap hits the fan... you grab the stick... disconnect ... and start aviating. But in a panic... the plane will override the AP controls with your control inputs).  

Sounds like the plane is fighting between something being manually actuated and what the AP profile is for cruise.

My guess... flaps are on after climb. You can keep those flaps on all the way up to 31K... and since the profile for climb is 124 kts... you won't have any issues until the airspeed tries and rip the flaps off.

B

 

[swannyuk]

Cheers for the replies fellas, I'll take a look when I next get chance. Flaps were definitely up, and my joystick and throttle were behaving fine on other planes. Could have been a one off, I'll report back if I find anything.

[shredderguy72]

I had this same issue and spent many hours trying to fix it. Engaging the autopilot caused instability and yoke ocillations. Disengaging caused severe pitch ups and ended in stalls and complete loss of control. I tried everything suggested and even uninstalled and reinstalled the aircraft. I finally realized that I was fighting the controls at anything other than low speeds and tried turning off the “simulate control stiffening” in the airframe manager. This fixed everything, and now I can finally enjoy the airplane. I should add that I just bought the aircraft yesterday, so I’m not sure if this is a bug with a recent version. I only saw two people report this and wanted to share my experience. 

[swannyuk]

Thanks for letting me know, nice to know I wasn't going mad. I've had 3 flights since and didn't have the same issues. I'll turn off control stiffening as reccomended.

Cheers

[Goran_M]

Try increasing flight models per frame by 1 or 2.  So if it's 2, increase it to 3 or 4.

[shredderguy72]

14 hours ago, Goran_M said:

Try increasing flight models per frame by 1 or 2.  So if it's 2, increase it to 3 or 4.

I have tried this, and it has no effect. Turning off the “simulate control stiffening” setting is the only thing that helps. However, the yoke ocillations still occur at higher speeds with the autopilot engaged. The control stiffening setting almost makes the plane unflyable...at least for me.  Hopefully this is a bug that will be addressed.

[Goran_M]

We've seen this happen in some situations.  But not all.  I haven't seen it on my system yet through the tests I've done.  It could depend on certain situations, including weather.  We'll run some more tests and see what we can figure out.

[shredderguy72]

9 hours ago, Goran_M said:

We've seen this happen in some situations.  But not all.  I haven't seen it on my system yet through the tests I've done.  It could depend on certain situations, including weather.  We'll run some more tests and see what we can figure out.

I’ve had clear skies and no winds loaded every time I’ve flown the TBM. I fly in VR with the Oculus Rift without a physical joystick or yoke. I’ve also disabled VR and it still happens. I hope this info helps you a bit. Thank you so much for your replies and help!

[cklaric]

I been having the same problem. It doesn't do this every time but I've noticed my elevator trim has been causing the bobbing so I'm thinking it's the AP. I just havent figured how to fix it. Also I fly VR and when I manually hold my trim the bobbing stops and then when i let go it does it again. Anyone have an idea on how to dampen elevator trim response? I think this might solve the problem.

Edited June 23, 2020 by cklaric

[chuckv]

I have seen this happen. In my case it was caused by my old yoke. When centered, the yoke was not really centered; a noisy sensor was commanding a bit of pitch up or pitch down. The autopilot was fighting this. If you go into the calibration setting for your stick/yoke and click "Add Response Curve" for pitch, you will be able to see if and how much pitch input (a blue x/y plot labelled 'Current') is being commanded while the stick/yoke is in neutral. You can then add a point to the curve just beyond this and set it to zero, effectively creating a null zone to null out the false pitch commands.

Edited July 11, 2020 by chuckv
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