Altitude hold problem with autopilot

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PurdueKev
Airman Basic
Posts: 9
Joined: 31 Dec 2016, 12:25

Altitude hold problem with autopilot

Post by PurdueKev »

Hello:

First, just want to commend the A2A team for another wonderful aircraft. The T6 is a blast to fly!

ALso, I have been flying A2A aircraft long enough to know that what I think is a bug is USUALLY something modeled accurately but where I am screwing something up or not reading the manual, etc. However, this one has me stumped..

I cannot get the autopilot to hold altitude at all. Quite the opposite - I set everything up, trimmed for level flight, cruise power and rpm, AP master switch on and the Digitrack readout displaying "OFF" with no ALT light. As soon as I hit the center button on the Digitrack, the heading is displayed and activated, but the aircraft dives toward the ground with the elevator trim moving full forward on its own. I have to hold my trim control back full (I have elevator trim mapped to a button on my throttle in FSUIPC, no other axes or buttons assigned to trim in either FSUIPC or the sim itself) just to keep from crashing into the ground. If I let go of trim, I can see the trim wheel turning forward on its own without my input. Mind you, this is BEFORE I hit the ALT button to engage altitude hold - but when I hit the button, I still can't get the system to hold altitude with any amount of trim, the light just keeps flashing. Something in the AP is activating the trim in the aircraft even though I don't even have the ALT hold engaged.

I am running Prepar3D v3.4.9, latest hotfixes, Windows 10 64-bit, latest registered FSUIPC, latest A2A updates, etc. I have controllers disconnected in the sim and only assigned axes through FSUIPC (the usual culprit for these sorts of issues, I have found), I checked and have no other trim axes applied in FSUIPC.

I do understand that this AP is not "hands off" and you need to be trimmed in level flight when AP is engaged, and give trim help along the way when the AP directs. But this happens before I even engage the ALT hold!

I am stumped and would appreciate any help - this is a great aircraft but the inability to get the AP to work properly is bugging me.

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Lewis - A2A
A2A Lieutenant Colonel
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Joined: 06 Nov 2004, 23:22
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Re: Altitude hold problem with autopilot

Post by Lewis - A2A »

Hello,

My first thing to check for you would be to take FSUIPC out of the equation, as from your symptoms it sounds like you have some stray mapping or something causing a trim down command so removing FSUIPC out of the equation can help track things down.

thanks,
Lewis
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Nick - A2A
A2A Captain
Posts: 13728
Joined: 06 Jun 2014, 13:06
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Re: Altitude hold problem with autopilot

Post by Nick - A2A »

Hello Kev - welcome and thanks for the detailed description of your problem! :)

The 'runaway trim' issue has cropped-up before a few times. One potential culprit is the TOGA function in FSX/P3D, but it sounds from your description like you're engaging the Digitrak AP with a mouse click on the "ON / OFF" button rather than with a key or hardware input?

I agree that FSUIPC is often the culprit is situations like this, so I'd advise you to try loading the sim with the FSUIPC4.DLL disabled if possible, to test if this eliminates the issue.

One other question: do you have the T-6 saved as part of your default scenario, or do you load a default aircraft first? (The latter being good practice.)

Cheers,
Nick

... Edit: Lewis was quicker off the mark, but thinking along similar lines! :)

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Lewis - A2A
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Re: Altitude hold problem with autopilot

Post by Lewis - A2A »

Quicker than Nick, wheres my medal! :lol: :mrgreen:
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Nick - A2A
A2A Captain
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Joined: 06 Jun 2014, 13:06
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Re: Altitude hold problem with autopilot

Post by Nick - A2A »

Indeed! Guess I'd better have another coffee! :mrgreen:

Nick

PurdueKev
Airman Basic
Posts: 9
Joined: 31 Dec 2016, 12:25

Re: Altitude hold problem with autopilot

Post by PurdueKev »

Just to let you guys know, I did find that the culprit seemed to be conflicting Control input assignments in P3D (not FSUIPC) - somehow, P3D had annoyingly reassigned controller assignments that I had deleted when I unplugged and replugged some of my controllers (including the TOGA button). :evil: Once I got rid of all those assignments that P3D had so helpfully added :roll: , the problem has gone away.

As usual with A2A stuff, there is almost always some very logical explanation for "unusual" aircraft behavior!

Thanks for the help guys! The Texan is much more enjoyable without the "possessed" autopilot LOL. :P

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Oracle427
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Re: Altitude hold problem with autopilot

Post by Oracle427 »

Ah this is good to know for future reference. This issue seems to crop up from time to time on the forums.

Lewis gets a stale cookie for my belated reward. :)
Flight Simmer since 1983. PP ASEL IR Tailwheel
N28021 1979 Super Viking 17-30A

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Lewis - A2A
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Re: Altitude hold problem with autopilot

Post by Lewis - A2A »

Aha good to hear and thanks for posting to let us know. Thanks for the cookie, I dunked it in tea for breakfast hehe :mrgreen:

cheers,
Lewis
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Nick - A2A
A2A Captain
Posts: 13728
Joined: 06 Jun 2014, 13:06
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Re: Altitude hold problem with autopilot

Post by Nick - A2A »

Darnit! Can't believe I missed out on the stale cookie! :mrgreen:

Seriously though, thanks for the update Kev - glad you resolved the issue. :)

Nick

sixgun
Senior Airman
Posts: 123
Joined: 16 Mar 2005, 18:58

Re: Altitude hold problem with autopilot

Post by sixgun »

Correction, Lewis didn't have a cookie and tea. He had a biscuit and tea or tea and biscuit. lol

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