SAU in STAB mode: FFB effects (stick deflection) miscalculated

[Flagrum]

Fly level, engage SAU in stabilization mode. Bank left or right, the AP immediately tries to stabilizes the attitude and compensates for any banking.

 

First the AP counters your banking input gently, but when the a/c is almost leveled again, it gets violent. The AP knocks the stick hard(!) into the opposite direction, several times. In a real 21 you would probably end with broken hands ... (and it is not really healthy for a plastic G940 as well, I suppose).

 

It seems, as if the dimishing inputs of the AP are getting somewhat chaotic when the stick position is getting nearer to the neutral position. Instead of smooth counter inputs, the AP suddenly "jumps" to an off-center position.

 

In the attached track I give full deflection to either right or left, then I re-center the stick in an instant. The AP then adds a good amount of input, counter input, etc. until the stick is almost centered. Then the jumping occurs.

 

Joystick: G940

 

edit:

interestingly, this behaviour seems to be more pronounced if the stick is initially deflected to the left ...?

sau stab ffb.trk

Edited September 25, 2014 by Flagrum

[iFoxRomeo]

Same Joystick. Same Problem.

 

Even decoupling the Stab and engaging again doesn't clear the Problem. Going from Stab-Mode to Recovery during this oszillation prevents the Recovery from leveling the wings.

 

Fox

[eyusuf]

Mmm ... time to bail out?

[Flagrum]

Seems to be fixed with 1.2.10u3.

 

Stab mode now dampens the actuation of the control surfaces in case of sudden stick movements by the pilot. Nice!

 

Personally - just a totally subjective layman opinion - I would not mind if this dampening would be a bit more pronounced. Had to watch closely to notice the difference between STAB on or off (but it gets clear when you watch the controls indicator).

 

But I leave that to the experts. The bug at least ist fixed and it works. Thanks LNS!