Mistral autopilot not accurate.

Mistral stays in climb (full fuel, 4x mistral, IR deflector) or descend when using "altitude hold" mode.

Another great report.

No track, no video, nothing to support it.

I didn't think it would be necessary, anyways Mirmidon, here track as proof.

Mistral AltitudeAP.trk

Just tried the Gazelle Mistral, autopilot works as intended for me.

Same here, no problem keeping level flight

Ams999 and Esac. You did try the track?

Daniel. I watched your track but maybe because of never fixed Replay bug issues, what I saw was only a Gazelle was spinning to death towards to up. You extremely zoomed in (to view thorough the windshield) and pointed something with mouse (circle movements etc.) but it was what I saw. I know these were not what you recorded.

You had no forward speed in track. So, I assumed that something wrong with track replay and took control of the Mistral and tried Altitude, Speed and also Hover functions. All working properly.

Maybe you can share a video if the problem will persist.

See you.

I watched the track now. When recording and watching tracks I always disable any mods I have as I found that mods (for whatever reasons) can muck up track recording and playback...

Anyway, my observations:

- unfortunately, you don't show the autopilot switch at all times, so it's hard to guess when you switch it to altitude hold

- however, I see it disengaged when you switch on the UV lights, then you show the VSI with the climb rate (circling you mouse pointer) and shortly afterwards I see the switch on altitude hold

- during that time, the VSI consistently shows a climb rate of at least 1 hm/min, mostly a bit over 2 hm/min

- from my experience, the autopilot won't engage altitude hold at this rate even if you throw the switch to engaged, the climb rate is too high, it won't bring you down to 0 hm/min - it has to be within +/- 0.5 hm/min when engaging, then it will level you to 0 hm/min

- also, if you are on altitude hold and it is on 0 hm/min and you pull or push and force it beyond a certain climb or descend rate, often it won't return to 0 hm/min but disengage - in that case you have to flip the switch back to neutral, go between +/- 0.5 hm/min and reengage

I think this is the desired behavior and in your track you are not within desired limits to successfully engage altitude hold. This should not only go for the Mistral but all Gazelle versions.

Additionally, Chuck's guide mentions that the autopilot will disengage when below 120 km/h. At my test now I could go down to 90 km/h before it warned and then disengaged.

Interesting, iirc in mid-2018 (or early 2018) autopilot would even engage at 2hm/min.

Check first the Gazelle autopilot tolerance margins

It's not in the gazelle manual under autopilot

I didn't think it would be necessary, anyways Mirmidon, here track as proof.

If you don't provide track, it's difficult for the rest of the community and the devs to help!

2 years later, still bugged... wth Polychop??? Short trackfile attached.

After2years,GazelleAutopilotSTILLneedsFixing!.trk

2 years later, still bugged... wth Polychop??? Short trackfile attached.

I don't see any indication in your track that you successfully engaged the SAS altitude sub-mode.

To engage the SAS's altitude sub-mode, you need to fly level with minimal vertical velocity, like auto-hover, it may take several attempts until you get used to it.

You can check if the desired SAS sub-mode has engaged by calling up the controls indicator (RCtrl+Enter).

If there is a bug, I'd say the mode switch should have a magnetic interlock and spring back to the center position if the SAS Alt or Speed sub-modes fail to engage (or when they disengage). Only a RL pilot/SME could say for certain.

You can check if the desired SAS sub-mode has engaged by calling up the controls indicator (RCtrl+Enter).

IRL they don't have sth. like that indicator though afaik....? Sooo...

my vert. vel. was minimal enough, as you can see in trackfile... BELOW 0.5m/s

IRL they don't have sth. like that indicator though afaik....?

IRL the SAS mode switch likely springs back to the center position if it fails to engage.

Without the DCS controls indicator, after engaging the Alt submode - you'll check the VVI and altimeter to see if they are stable, something you'd do IRL regardless of the switch position.

Sooo...

my vert. vel. was minimal enough, as you can see in trackfile... BELOW 0.5m/s

Doesn't change the fact that the SAS Altitude mode didn't engage or that, when I took control of your track, I could engage it.

I could engage it.

You mean the switch was in the OFF-position when you took control??

You mean the switch was in the OFF-position when you took control??

TL;DR:

Yes.

Detail:

To get your track to play correctly I needed to disable force feedback on my system (as I use a MS FFB2), otherwise the helicopter would fail to make the hard LH turn and instead roll inverted and crash.

Note: Disabling FFB to play tracks from users that don't use FFB is normal for the Huey on my system.

When played, your track showed

1. fast takeoff and acceleration to ~160 km/h and 65 m

2. hard LH turn to sea

3. a accelerating descent into the sea starting at -9m/s out of the turn, slowing to -1.0 m/s and hitting the sea at -2.5m/s

4. I didn't see the SAS Alt mode switch change position until you zoomed in on the panel as the helicopter sank (perhaps an animation desync ?).

On another replay I took control after the hard LH turn and before the helicopter hit the sea.

With active pause I checked the SAS mode on the controls indicator and confirmed Altitude mode wasn't engaged (which was fairly clear from the VVI).

It took me a couple of attempts (flicking the the alt mode switch on and off) to engage Altitude mode as it's been a while since I used it and I needed to adjust collective and trim for level flight before it would engage.

Ok then trackfile seems totally broken. just tested again (used autostart), accellerated to 200-205 kph, then had vertical speed of perfectly 0 and flipped up the ALT AP switch (all the way to the right). Seconds later Gazelle started descend......

using latest OpenBeta.