TRIM ISSUE WITH AUTO PILOT

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shermank
Airman
Posts: 43
Joined: 10 Jan 2013, 07:10

TRIM ISSUE WITH AUTO PILOT

Post by shermank »

Hi all,

First the positive....I have 20+ hours real training in a Cessna 152, though never did get my PFL. Still, I think that the A2A 182 comes very close to handling compared to what I remember about real world flying.
But,, there is a serious negative. When I set auto pilot, and then release it for whatever reason, the trim goes crazy. I mean the plane noses almost straight up. The trim wheel shows +100, and I have not touched it since going into AP with level trim.
I have tried to adjust this through FSUIPC without success.
So, flying with AP is virtually impossible (no pun intended). What am I doing wrong, if anything? Is there something in my aircraft.cfg that is out of whack?
Is this relevant from aircraft.cfg
"elevator_trim_effectiveness=0"

I love the plane, but not the trim with AP.

THANKS!
Sherm

Tomas Linnet
Senior Master Sergeant
Posts: 2286
Joined: 05 Nov 2013, 10:48
Location: Oksboel, Denmark

Re: TRIM ISSUE WITH AUTO PILOT

Post by Tomas Linnet »

What do you use to manually trim?
I have a Saitek Cessna trim wheel, and I have the same problem as you. As my trim wheel doesn’t have a motor rotating it it wheel stay in th position I left, most likely set for around 90 kts, when disengaging the auto pilot the PC whil return the trim settings to what ever value the hardware is set to.
Maybe it’s possible to beat this by slowing down the aircraft before disengaging the auto pilot??
Kind Regards
Tomas

Sim: FSX SE
Accu-Sim aircraft in my hangar:
C172, C182, P51 Civ, P51 Mil, B17, Spitfire, P47, B377 COTS,
J3 Cub, T6, Connie, P-40, V35B
A2A Accu-Sim Avro Lancaster Loading:............0.000003% complete, please wait.

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Jacques
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Joined: 26 Jun 2011, 17:54
Location: West Coast, USA

Re: TRIM ISSUE WITH AUTO PILOT

Post by Jacques »

Hi Sherman, in addition to Tomas’ question, and to help paint a more complete picture, which flightsim platform are you using and any other hardware such as yoke and rudder pedals?

shermank
Airman
Posts: 43
Joined: 10 Jan 2013, 07:10

Re: TRIM ISSUE WITH AUTO PILOT

Post by shermank »

Thanks Tomas and Jacques,

I use the Saitek Yoke, left handle wheel for aileron trim up and down as configured through FSUIPC. NY rudder pedals are CH, and controlled independently from the Saitek Yoke and Throttle Trio. I am flying the LM P3D v4.5 with their latest hotfix. I don't recall the number off hand, but it is their last HF since LM has moved on to end support of V4.5 now that V5 is their latest standard.
As for P3D performance, I have it running perfectly without blurries, though there is a momentary freeze from time to time, an issue that has been raised on the P3D as well as Avsim and other forums. I do not think that issue has any connection to this one, especially since I have no trim issues with any other aircraft, freeware or payware.

Again, thanks for your thoughts. I should add that I have the most current A2A Accu Feel software installed, afaik. Now that I think of it, I am wondering whether there may be an issue there. I will check that and disable Accu Feel on my next flight, then report back here.

Sherm

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Nick - A2A
A2A Captain
Posts: 13734
Joined: 06 Jun 2014, 13:06
Location: UK

Re: TRIM ISSUE WITH AUTO PILOT

Post by Nick - A2A »

Hi Sherm,

Sounds like you're using a hardware axis for trim, and in that case you'll run into the issue that Tomas mentions. The autopilot will apply pitch trim inputs when it's engaged, but unlike in the real aircraft, your physical trim control has no way of staying synced with these inputs. The only way this would work would be if your trim wheel was motorized so that it could move like the one in the real plane when the pitch trim servo runs.

The workaround is to be mindful of the position of your physical trim wheel before you disengage the autopilot, and to try and match as closely as possible the current trim position.
However, in your case maybe there's something extra going down if the autopilot is trimming all the way nose up. What sort of airspeed are you typically engaging and disengaging it at?

We did release an update in late 2018 to fix a trim runaway issue if the sim is paused. Please can you just confirm which version of the 182 is installed on your system? (You can check this in the list of installed apps/programs under Windows settings.)

Thanks,
Nick
A2A Simulations Inc.

shermank
Airman
Posts: 43
Joined: 10 Jan 2013, 07:10

Re: TRIM ISSUE WITH AUTO PILOT

Post by shermank »

I may have solved my trim issue. I checked Accu Feel, only to discover that the C182 was not activated. I changed that to active, adjusted a setting or two and now the aircraft flies and trims as it should, with or without AP. Thanks for helping me brainstorm this one....

Sherm

shermank
Airman
Posts: 43
Joined: 10 Jan 2013, 07:10

Re: TRIM ISSUE WITH AUTO PILOT

Post by shermank »

Hi Nick, sorry I did not see your post when I added my latest about engaging Accu Feel. I am flying C 182 20.5.26... btw, AF is 2.1
Hope this info helps and I hope I am flying the most current revision.

Thanks,

Sherm

Tomas Linnet
Senior Master Sergeant
Posts: 2286
Joined: 05 Nov 2013, 10:48
Location: Oksboel, Denmark

Re: TRIM ISSUE WITH AUTO PILOT

Post by Tomas Linnet »

Hmm, if I remember correctly Accu-Feel should be off for an Accu-Sim aircraft. Accu-Feel is a program designed to enhance the experience of flight in all non A2A aircraft. However, I’m not sure if it will cause any problems, but you will not gain anything
Kind Regards
Tomas

Sim: FSX SE
Accu-Sim aircraft in my hangar:
C172, C182, P51 Civ, P51 Mil, B17, Spitfire, P47, B377 COTS,
J3 Cub, T6, Connie, P-40, V35B
A2A Accu-Sim Avro Lancaster Loading:............0.000003% complete, please wait.

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Nick - A2A
A2A Captain
Posts: 13734
Joined: 06 Jun 2014, 13:06
Location: UK

Re: TRIM ISSUE WITH AUTO PILOT

Post by Nick - A2A »

Yes, Accu-Feel should indeed default to 'off' when using an Accu-Sim plane and not having it enabled certainly shouldn't cause this issue Sherm. Anyway, your version of the 182 is the most recent so at least we can rule out the historical bug. If the problem reappears, please let us know.

Thanks
Nick
A2A Simulations Inc.

shermank
Airman
Posts: 43
Joined: 10 Jan 2013, 07:10

Re: TRIM ISSUE WITH AUTO PILOT

Post by shermank »

wilco...thanks

Sherm

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