wip AH-64D Attitude Hold

[bradmick]

There is a reason, the stabilator and its interaction with main rotor thrust. As the angle of attack changes on the stab, the nose will naturally pitch up and down with speed changes.

[SloppyDog]

10 hours ago, papaz said:

AH-64D_ATT_hold_test_Dec_25.trk
Uploading a track again, where you can clearly see the issue:

1. Trim for stable flight. 2. Activate ATT hold and ALT hold. 3. SCAS ATT hold commands forward pitch (as to why you can see later). 4. ALT hold tries to compensate with additional collective. 5. This speeds up the nose down command of the SCAS. 6. The feedback loop drives you into the ground.

Near the end of the track I deactivate the FMC and trim for stable flight. What happens is that you get an slight nose bob, up and down, for no reason (FM issue).
That's what I meant for oscillation, not the oscillation on ATT hold activation-deactivation (refered to in the changelog).

I believe the ATT hold tries to compensate for this pitch-up movement where the problem starts.

edit:
With the latest patch it's possible to deactivate only the Pitch channel. This makes the Hold functions actually useable (in cruise, not hover). Still I feel that the FM is the source of these problems.

 I've been experiencing something similar. Once ATT and ALT hold are engaged, the aircraft starts to accelerate or decelerate, and the ALT HOLD can not maintain altitude. 

I'm able to counter the accelerating or decelerating tendencies by re-trimming the aircraft to a position where the speed is maintained constant. No problem there, since it is Attitude hold, after all. Just a slight re-trim, that's it. 

However, even in a constant speed state, the altitude starts to drift slowly, to the point I get a SAS Saturated message and later on a Altitude Drift Warning. I have to retrim, and engage ALT HOLD again.

Another point I noticed is that the SAS Saturated message shows up with the controls at half of their total deflection. At least it is what is shown on the second controls indicator. 

Before, the SAS Saturated would occur only when any of the axis were at its corresponding stop.  

[skypickle]

Half the time, I cannot even get altitude hold to work. Even flying straight and level, trimmed with Attitude hold working. I wish I could post a track but how can I show that I am trying to engage altitude hold in a video? Is there a switch somewhere on the cockpit that moves for this?

[LorenLuke]

11 minutes ago, skypickle said:

Half the time, I cannot even get altitude hold to work. Even flying straight and level, trimmed with Attitude hold working. I wish I could post a track but how can I show that I am trying to engage altitude hold in a video? Is there a switch somewhere on the cockpit that moves for this?

I would imagine from how the track system functions, and the fact they have diagnostic tools that let them take tracks apart in detail, that ED can see what buttons you're inputting, regardless of if they're tied to any controls or not, as well as what buttons you're pressing go to. 

Worst case, you put a track and they say 'sorry, we can't help.'

[admiki]

29 minutes ago, skypickle said:

Half the time, I cannot even get altitude hold to work. Even flying straight and level, trimmed with Attitude hold working. I wish I could post a track but how can I show that I am trying to engage altitude hold in a video? Is there a switch somewhere on the cockpit that moves for this?

4-way hat on cyclic.