Autopilot not holding altitude.

[Mav87th]

Using the throttle will control if you will be sinking or climbing respectively. It works fine for me, even as a WSO. If i want to climb and hold to a higher altitude i add the new altitude via UFC in the back, and push throttle forward a bit. Then when the autopilot reaches the altitude i reduce the throttle again, and now it maintains altitude. Vice verca for loosing altitude to a lower level.

[Chops]

On 8/24/2023 at 1:05 AM, Holbeach said:

F15 CBU 97 SA 10 3l.trk 1.15 MB · 2 downloads

You can watch the video, but for basic alt hold it's a 2 button press. Here's what I do.

Press A on keyboard or UFC AP button. This will give pitch hold and heading if you are below 7 deg bank. Then press UFC Alt hold. This will level to maintain current alt.

If over 7 deg, this will give Attitude hold.

I will post a track if you still have trouble.

Press button A at start, then alt hold, the NAV then, steering.

All subsequent alterations are button "A".F15 CBU 97 SA 10 3l.trk

..

 

Thanks guys for the help.  I do know how to operate the autopilot and have read the manual.  However, the Altitude functions do no work consistently.  I will check out your track.

[Holbeach]

57 minutes ago, Chops said:

Thanks guys for the help.  I do know how to operate the autopilot and have read the manual.  However, the Altitude functions do no work consistently.  I will check out your track.

I don't know if it will help at all, but I'm trying to show that it is rock solid down to 50' over the sea, in a turn, whilst inputting data with confidence.

Maybe if you are still having probs, post a track to view.

..

[Chops]

What I have found so far is that Altitude Hold and Altitude Select in climbs and descents works when flying a mission that starts in the air.   When flying a custom mission with a "take off from parking hot" start, the Altitude modes don't work correctly; and yes I am flying the aircraft to the altitude I want and trimming to hold level flight before engaging the autopilot.

I will test a mission starting from "take off from ramp" (cold start) to see if that makes a difference.

[dporter22]

The autopilot simply does not work consistently or reliably at this stage. I've tried different missions, different starts, different configurations, different scenarios, etc. and it just doesn't work well.

Hopefully it's on the short list to be addressed for repair.

[Q3ark]

2 hours ago, dporter22 said:

The autopilot simply does not work consistently or reliably at this stage. I've tried different missions, different starts, different configurations, different scenarios, etc. and it just doesn't work well.

Hopefully it's on the short list to be addressed for repair.

I don’t get why we would have such different experiences of the same thing. I have had no problems with the autopilot at all. Do you guys have any mods installed? They can conflict with stuff in odd ways. 

[dporter22]

Yes, it's very odd that it works for some and not others.

No mods, current beta version.

[Q3ark]

2 minutes ago, dporter22 said:

Yes, it's very odd that it works for some and not others.

No mods, current beta version.

Same as me, I’m stumped. All I can suggest is that you post a track and let us have a look at what you’re seeing. 

[Nealius]

I always fly from cold starts. Have plenty of mods installed. Zero problems with autopilot altitude hold. Level flight, press AP, then press ALT HOLD. Paddle to disconnect, however ALT HOLD retains the * for some reason, so when reengaging the autopilot press AP, press ALT HOLD twice; once to deselect the * and a second time to reselect. 

[Holbeach]

NOTE: the ALT HOLD selection will not disengage on its own and remains selected even if autopilot mode changes. It is therefore a good habit to check its status before switching the autopilot modes.

..

[Holbeach]

14 hours ago, Chops said:

What I have found so far is that Altitude Hold and Altitude Select in climbs and descents works when flying a mission that starts in the air.   When flying a custom mission with a "take off from parking hot" start, the Altitude modes don't work correctly; and yes I am flying the aircraft to the altitude I want and trimming to hold level flight before engaging the autopilot.

I will test a mission starting from "take off from ramp" (cold start) to see if that makes a difference.

I spent some time this morning flying the Caucasus map trying to make the Alt hold not work.

Constantly changing modes, eventually the Alt hold wouldn't hold. Diving would come up to level, but climbing wouldn't come down to level, but I didn't know how I achieved it.

There was always a slight climb. Turns out that Alt hold and Alt select were both on and I didn't have enough power on to increase the climb rate and so didn't recognize it.

Turn off Alt select, (I've never used it before) and it immediately jumped to level.

Might not be your problem, but I learnt something from it.

..

[dporter22]

Have to say, even if it were working properly in the F-15E I much prefer the autopilot in the A-10, F-18, etc.

[Chops]

6 hours ago, Holbeach said:

I spent some time this morning flying the Caucasus map trying to make the Alt hold not work.

Constantly changing modes, eventually the Alt hold wouldn't hold. Diving would come up to level, but climbing wouldn't come down to level, but I didn't know how I achieved it.

There was always a slight climb. Turns out that Alt hold and Alt select were both on and I didn't have enough power on to increase the climb rate and so didn't recognize it.

Turn off Alt select, (I've never used it before) and it immediately jumped to level.

Might not be your problem, but I learnt something from it.

..

When climbing using ALT Select I increase thrust and maintain an airspeed above the required speed, when descending I reduce thrust and maintain an airspeed below the required speed.  As others have said, sometimes it works and sometimes it doesn't.  Difficult to figure out why.  Hopefully Notso can confirm whether or not this is still a work in progress.

[Holbeach]

I never use Alt select, because Attitude, steer and alt hold are so reliable and simple to use that I don't need anything else.

But I've given Alt select some time today, (it should peg at 6000 fpm in the climb) and decided it's too clunky and unreliable, so I won't be using it again.

Alt hold can even be used when raising and lowering the gear and flaps, keeping alt steady.

Having said that, Alt hold can be engaged at 6000 fpm VVI and the limit should be 2000fpm, with AP auto disengage at 2000 fpm.

Also when flying high, heavy and fast with the airspeed low, the fpm can be slightly above or below 0 deg, giving  slight alt increase or decrease.

This can be cured by manual retrim.

[Holbeach]

On 8/26/2023 at 3:58 PM, Chops said:

When climbing using ALT Select I increase thrust and maintain an airspeed above the required speed, when descending I reduce thrust and maintain an airspeed below the required speed.  As others have said, sometimes it works and sometimes it doesn't.  Difficult to figure out why.  Hopefully Notso can confirm whether or not this is still a work in progress.

OK, I spent more time today with the Alt select mode and now have it working perfectly with 100% reliability.

T/O from ramp or runway makes no difference.

Wheels/flaps up. Engage AP, engage Alt select 31000', climb at 15000fpm full AB and it levelled perfectly at 31000'.

Changing alt up or down repeatedly, up to 50000'. Sometimes it worked, sometimes not.

The reason soon became apparant. Alt select only works below Mach 0.97. It will disengage and re engage at that speed.

Providing you keep below M 0.97 it is flawless. For any speed above this, use Alt hold.

Nothing in either manual states this.

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[Ramstein]

nice video, but I want TRIM help..

[Avio]

I noticed too that the AP doesn’t seem to hold altitude too well at times.

By the way, how does one clear the entered altitude value so as to revert to normal altitude hold?

[razo+r]

2 minutes ago, Avio said:

I noticed too that the AP doesn’t seem to hold altitude too well at times.

By the way, how does one clear the entered altitude value so as to revert to normal altitude hold?

You press the button next to it again.

[Avio]

6 hours ago, razo+r said:

You press the button next to it again.

Ok got it.

 

[flavnet]

The autopilot is automatically disabled when switching from pilot to WSO and vice versa. It would be appropriate if this did not happen. I hope for the next patch.

[Q3ark]

5 hours ago, flavnet said:

The autopilot is automatically disabled when switching from pilot to WSO and vice versa. It would be appropriate if this did not happen. I hope for the next patch.

I don’t think that’s the case, check that you’re not moving the flight controls when you are in the WSO seat, that’ll trip off the autopilot. 

[flavnet]

11 hours ago, Q3ark said:

I don’t think that’s the case, check that you’re not moving the flight controls when you are in the WSO seat, that’ll trip off the autopilot. 

HI. The transition from pilot to WSO only serves me to activate the laser pod, I don't act on the flight controls. When I return to the pilot's seat the plane is losing altitude and the autopilot is disabled.

[Shiroka]

I'm in the same position as the posters above. Cannot for the life of me get alt hold or alt select working. Current OB, multi-core. I've RTFM multiple times.

Here is a track, I can't think what I haven't tried. Any advice appreciated.

 

F-15E Autopilot.trk

[dporter22]

Yep, still doesn't work consistently, and when it does it doesn't work properly.

[Ignition]

8 hours ago, Shiroka said:

I'm in the same position as the posters above. Cannot for the life of me get alt hold or alt select working. Current OB, multi-core. I've RTFM multiple times.

Here is a track, I can't think what I haven't tried. Any advice appreciated.

 

F-15E Autopilot.trk 8.59 MB · 0 downloads

Turn on the AP and THEN turn on the alt hold. I'm not sure it should work like that (I don't think so) but it works

Edited January 24, 2024 by Ignition