I now can reproduce my "AP confusion" … where I was seeing unexplainable climb activities, even while I did set "VS to 0 ft HOLD".
The key points are (seem to be):
- It only happens on the very first flight after MSFS has been started
- It is related to a "3000 ft minimum radio altimeter" AP target
- … which seems to have priority over the other manual settings
Here is what I do to reproduce it:
- Pick an airport at the ocean … and fly above the ocean at ca 1500 ft … 220 ktas (@ 83% NR)
- Configure AP for … HDG … and VS = 0 ft HOLD
- manually go into a 1000 ft climb
- activate AP … via command binding of CPLD button
- Osprey goes into an even steeper climb … until around 2400 ft radio altimeter … then drops to a 100 ft climb until 3000
- … then it starts to react to the VS set point of the AP panel
If I land … and try the same thing in the same flight or MSFS "session" … it will not happen again.
So it feels like an uninitialized variable somewhere in the AP setup code.
Miltech Simulations @MiltechSimulationsThanks for your deep-dive into this issue. I'll try to reproduce the issue and take appropriate action to fix the issue, based on the findings.
@nenenuiBut it does raise an interesting question … does the real Osprey have a "follow terrain at radio altimeter distance" feature?
At present the documentation only explains how to set when it becomes visible. But the AP being able to maintain such distance would be cool (as it would prevent me on my sightseeing trips to crash into mountains … which did happen during my tea breaks in the past … autsch)
Miltech Simulations @MiltechSimulationsJust had a chance to check this issue again, but I was unable to reproduce. Just to confirm if I followed the steps correctly:
- Flying at 1500ft, manually fo to 1000ft/min climb
- Activate AP: HDG hold and VS = 0 HOLD. No target altitude selected, no ALT hold.
My aircraft just levels off back to VS 0
- @nenenui
I will retry me test run later today with v1.0.1 … and I will report my finings here again.
- In reply toMiltechSimulations⬆:@nenenui
I am no longer able to reproduce this bug in v1.0.2.
It seems to be resolved.
- @nenenui
I had to reopen this topic, because now I have seen (filmed) it in v1.0.2 … so this bug is still present.
What I did here … https://www.objectfarm.org/Public/Misc/2022.11.20-MSFS-MV22B-Bug-AP-3000ft-RadioAltimeter.mp4
- … is just as described in the very first post … but
- all interactions with the AP happened via command bindings (I guess this detail actually does not matter)
- I enforced clear skies weather … to ensure that wind is not a factor
- The initial AP HDG is not perfectly aligned with my manual flight path
- so the aircraft will initially bank noticeably and try to adjust the HDG
The video shows that the VS stays at high levels until the radio altimeter goes above 3000 ft
After that I make some manual adjustments (+500ft … 0 … -500 …) and the AP adjusts swiftly and properly
… so the initial behavior is not (really) a limitation of the AP system … but rather a deliberate action.Besides that I noticed that the HDG is 2 deg off … 114 was set … but the Osprey flies 116. Hmm. In need to watch out for that in the future.
I did read on the H145 forum some time ago that there is issue where the sim does not correctly set up all variables (on the first run after launch)
So perhaps this plays into this bug.- Miltech Simulations @MiltechSimulations
Very interesting, I see the issue now. Let me try a few things.
- Miltech Simulations @MiltechSimulations
Ok, I was able to replicate this issue. Regardless of the selected altitude, it seems that the very first time you engage the autopilot, it always overshoots the selected alt. After the altitude has been overshot by a couple thousand feet, the aircraft reacts and starts descending again to the selected target alt. Any Alt changes after this first event, occur normally and as expected.
EDIT: The source of the issue is very clearly V/S overshooting. V/S is significantly higher than selected (Only on first run, first engage of the autopilot), making ALT Select overshoot. After the aircraft corrects itself, V/S is followed.
Still investigating.
- @nenenui
I am somewhat unsure if the "radio altimeter" is the primary cause here.
I can in 70-90% reproduce this "radio altimeter" issue when I take off from an airport at sea level.
But so far I was not successful to reproduce it if my first departure airport is at high(er) latitudes.
E.g. today I took-off from Zumbo (FLLN) which is at ca 1000 ft … when I activated the AP I was at around 2900 ft (radio altimeter at 1500 ft).This time I did get a different (incorrect) AP behavior:
- I had configured … 0 ft VS Hold
- … but the AP did continue to climb at 200 ft
- I then adjusted to 1000 ft VS … and the AP climbed at 1200 ft
So in this case the AP did follow my input … but the VS was always 200 ft above my target
Here is the video:
https://www.objectfarm.org/Public/Misc/2022.11.22-MSFS-MV22B-Bug-AP-VS_Hold+200ft.mp4
- Miltech Simulations @MiltechSimulations
I don't think it has anything to do with radio altimeter. I'm suspecting it has to do with the PID (control system) behind the V/S, that just overshoots the initial input.
Still investigating and adjusting the PID values.
- Miltech Simulations @MiltechSimulations
Indeed the problem was related to PID. I've been able to fix it. I'm doing some more testing just to make sure it did not affect anything else - if everything looks good, will push the update out this weekend.
- Progresswith handling this problem