Trim wheel problem

[Jimimac]

I am using the saitek trim wheel the 172 flys great and no problem using the saitek trim until I use the the autopilot, when I turn off the autopilot and trim the aircraft with the trim wheel the 172 goes out of control and I have difficulty try to get it to fly straight and level I don't have any problem using fsx trim buttons so it's got to be the saitek trim wheel that's the problem anyone using the trim wheel have this problem and can it be fixed.

Thanks,jim

[Nick - A2A]

Hello Jim,

Afraid this is an unavoidable limitation of using a trim axis with hardware which isn't isn't motorized to follow what the trim wheel in the sim is doing. In the 172, when the autopilot is engaged (or when you use manual electric trim) the trim wheel will rotate by itself powered by the pitch trim servomotor. However, your Saitek trim wheel doesn't have a motor, so when you disconnect the autopilot, chances are it's in a different position to the trim wheel in the simulator, hence the control issue.

Past discussion of this here if you're interested.

Cheers,
Nick

[Jimimac]

I will just use the saitek trim wheel my 172 flys very stable with minor adjustments at cruise to keep the desired altitude/ heading so I don't use the autopilot very often like to do most of my flying hands on I have used the autopilot to climb so I was wondering if I set the autopilot hold after I was set at cruise altitude then there would be no movement in the trim motor so when I disengaged the autopilot the saitek trim wheel should work ok,I will give this a try tomorrow .

Thanks,jim

[Nick - A2A]

Yeah, if you just use the AP to hold your existing altitude and make sure you're properly trimmed before you engage it, you shouldn't experience much of a 'pitch glitch' when you disconnect it. However, the longer you keep it engaged for, the more fuel you'll burn and the more likely it is to quietly adjust the pitch trim servo.

Nick

[solisto]

Someone wrote a LUA script that works with the FlywithLua plugin for X-plane. This script took over the trimwheel input to the sim. When AP was engaged, moving the real trim wheel would not affect the sim trim wheel. Once AP was disengaged, if you moved the physical trim wheel, the sim trim wheel would not move until the value of the real trim wheel was equal to the sim trim wheel. Additionally if the two were out of synch, an overlay would pop up in the sim to tell you which direction to turn the physical trim wheel to match the sim. Once they match, the overlay goes away and the sim once again takes input from the physical trim wheel. This avoids the sudden pitch up/down when the physical trim wheel is re-engaged after AP is turned off. i've used this in x-plane and it works great. I'm not sure if this is doable in FSX/P3D with perhaps FSUIPC and/or LINDA. I don't possess the expertise and haven't had time to investigate this.

[AKar]

I wonder if it would take a lot of work to create a version of 172 that has an autopilot without automatic trim? That would solve the issues for trim wheel users, and would be preferable simulation for those who fly planes without automatic trim in reality.

-Esa

[Oracle427]

That is a clever solution and it would be good if it could be implemented. I don't know how the FSX API works, but perhaps that is something that A2A could integrate if it made sense to do so. Perhaps include it as an optional function?