Autopilot Problems

[Tipspeed]

Is anyone having problems with the autopilot? When I set it on VS, the autopilot hunts too much and can't hold a specific altitude or constant VS.

[Piperflyer777]

I am having the same problem

[lonewulf47]

Did you set up your autopilot as per the procedure in the Bendix/King manual? Altitude hold needs correct handling of the ALT and ARM buttons (to be verified on the display with armed and active mode). The V/S is reacting slow but according to the preset value. Be sure that you engage the autopilot only wenn fully trimmed and only in a shallow climb or descent (or flying level of course). Holding the flight path forcibly with the elevator and then engaging the A/P will of course result in a heavy overshoot of the selected value. This also happens in the real plane - although not so pronounced as in our trainer.

I maybe should add once more that this is a custom coded autopilot. Don't handle it as if it were the default FSX A/P. Read the manual carefully...

[Tipspeed]

lonewulf,

I arm the autopilot the same way I do in the full scale 182. I will be trimmed out for level flight and it seems like the autopilot uses too much trim and overcompensates the climb or descent.

[CodyValkyrie]

I haven't seen this type of issue during testing, so I would be curious what factors can produce it. Can you perhaps give Oskar and myself a scenario that we might be able to replicate?

[Tipspeed]

Okay so if I'm climbing at let's say a rate of 500fpm and arm the autopilot and it goes into VS mode. It will start hunting up and down a few hundred feet and eventually it will get worse and ill dive around 1500fpm and then climb up 1500fpm and then it will go into a steep dive and then a step climb and eventually stall. I thought it might have been my yoke so I changed it to my joystick and still the same results.

[Tipspeed]

Maybe this was a bug? I rebooted FSX and now she's holding perfectly!!

[CodyValkyrie]

Let's keep this discussion open regardless. If it happens again I would like to see resolution if others have issues.

[lonewulf47]

Maybe this was a bug? I rebooted FSX and now she's holding perfectly!!

No, if it were a bug, it would do it again Joke aside, you cannot easily compare autopilots from different installs even if they are of the same type. It always depends on the installation of additional systems. The C172 has no vertical gyro for the autopilot and therefore can maintain altitude or V/S only by using static air pressure. This makes pitch movements very likely to become a bit more unstable than A/P with vertical gyros. The 182 I flew at times hat a vertical gyro for pitch stability and was relying on the slaved KFC200 HSI for heading output. Even it it were the same KAP140 autopilot it would handle completely different.

[Thorsten42]

Hi folks,

I'm seeing the same problem. I will try to reproduce and report back. Seeing the explanation with the static, perhaps something with the weather engine involved? I'm running OpusFSX for example.

Cheers
Thorsten

[lonewulf47]

Hi folks,

I'm seeing the same problem. I will try to reproduce and report back. Seeing the explanation with the static, perhaps something with the weather engine involved? I'm running OpusFSX for example.

Well, unstable westher condition can of course also play havoc on this type of autopilot system. You might need to compare with/without OpusFSX. I for my part regularly use FS Global Real Weather without any issues.

[Thorsten42]

Ok, did some more testing but looks like already noted in the Autopilot FAQ posted in the meantime. It has nothing to do with weather and static. It's a simple aft gc problem. Just load it up with four people and baggage and you will find a Rollercoaster-Autopilot But I don't know if it reacts realistically cause I have flown a c172 only once in reality and this one had no AP. That should be discussed by the pros. But I think we are in excellent hands here

Cheers
Thorsten

[TRBasher]

I to am having a AP issue, I will use this tread as there really isn't a reason to make a new one. The issue I was having last night is the AP kept over trimming the plane. I had a IFR flight set up for 4000, I got the plane to Alt and armed the Alt and then engaged the AP. For about 5-10 minutes it flew just fine holding Alt and course. Then (I had left the room) heard the stall horn going off and I came back in and I was in a dive. I disengaged the Ap and got it back to alt and redid it. Again after a few minutes it did it again. I watched it that time and it started trimming the plane to the maximum nose up trim. When it was in level flight I was cruising at approximately 90 knots and it did this multiple times. I wound up not being able to use the Ap at all as even if I engaged it to just maintain course it still over trimmed the plane. This is the first time it has done this, I have made other flights with it and it flew fine on Ap.


***Edit***
I forgot to mention that with the Ap issue it was also auto setting the VS to - numbers from -300 to -2000 and it would keep it there even if I was trying to change it. When I did change it back to +500 it would change it back to -2000 via a scroll like I was rolling the mouse wheel. The little hand icon was also sticking in the closed fist version at the same time. Never had a issue like that on any plane before.

[N6722c]

Also having Autopilot issues.
Hopefully A2A will address this complex issue in time.

If it is Custom Code, then tuning it is a complex procedure, so I am happy to leave it "INOP" till it is updated to be working correctly.

[some1 - A2A]

I forgot to mention that with the Ap issue it was also auto setting the VS to - numbers from -300 to -2000 and it would keep it there even if I was trying to change it. When I did change it back to +500 it would change it back to -2000 via a scroll like I was rolling the mouse wheel. The little hand icon was also sticking in the closed fist version at the same time. Never had a issue like that on any plane before.

Was the DOWN button also depressed and you were unable to release it?


Also, what is your payload when this loss of control happens?
When such problem with the autopilot occurs, can you make a screenshot so I would know what modes and settings are in the autopilot when this problem occurs?