C182/FSX/SAITEK/SPAD.NEXT

[CessnaSkypilotN7365W]

Not sure where this fits in so my apologies up front if this needs moved. But this is all hangar talk, right?

I fly a 182 with FSX using, for this discussion, a Saitek Cessna Trim Wheel. I works great in all aspects until I disable the AP in APR mode. While doing my approach I slow the plane to 90kt while still on AP following the GS down to DH. After turning off the autopilot, the first time I touch the trim wheel the nose gets yanked up quite dramatically! So much for being on the glideslope! I work around it by being prepared to push the yoke forward and readjusting the trim wheel but it gets old. I have no idea who's at fault here.

I know this is an A2A forum but thought I might find someone who might be able to help.

Thanks
Roger

[Nick - A2A]

Hello Roger,

I'm afraid you've discovered the one major downside of using a hardware axis for elevator trim whilst using an autopilot which has the capability to control the elevator trim too.

In the real aircraft, the autopilot adjusts the elevator trim position using a servomotor, so the trim wheel in the cockpit will move too. The same thing happens if you use the manual electric trim switches on the yoke.

However, because your Saitek trim wheel isn't motorised, it can't match what the autopilot is doing to the elevator trim when it's engaged. Therefore the two are likely to get out of sync which is why the nose get yanked up (or down) when you disengage the autopilot. The bigger the changes to speed and configuration you make between engaging and disengaging the autopilot, the bigger this mismatch will be.

That's one reason why the S-TEC 30 autopilot in the Pipers is so great in this context. It can't trim the aircraft, so you have to do this yourself.

Cheers,
Nick

[CamAir]

Hi,

Long time ago I recall seeing this problem. Not quite remembering the solution, hence to the best of my tired memory cell I believe that to avoid the mismatch between your plane and your Saitek, you have to manipulate the trim wheel, either before you engage the AP or during (forgive me...) or just before dis-engaging the AP.

I might be wrong but I don't have the same problem. I use A2A GAs with all of Saitek gear (except for FIPs) and Logitech drivers v.8.xx

I hope this help.

[CessnaSkypilotN7365W]

I have exercised the trim wheel before disengaging the AP but it doesn't always work. Sometimes yes but not always.