Problems combining MechJeb and FAR

[Cairol]

I've MechJeb2 and FAR installed. And since I have FAR, MechJeb is no longer able to get my rockets to space.

They begin to wobble and vibrate like mad at about > 200 m/s until they break into pieces.

When flying manually, it works just fine. No wobbling.

Is it possible to configure MechJeb to do a more "careful" or kind of more optimized ascent, to not break my rockets?

How do you do this? What are the most important parameters to tweak?

FYI: It's not that I use MechJeb extensively. It's just that I can't use it at all for the ascent phase while FAR is installed.

[n0xiety]

Set your AoA in ascent guidence to 3 degrees. If the craft can't take that much turn above prograde set to 2 or 1. The lower you go with this the slower and more stable your turn will be and it will use more fuel. Set the PA to whatever FAR uses. If FAR is using the same pressure values as stock don't touch it tho. Enable corrective steering. %40 turn rate is good and start your turn before 3km.

[cybersol]

One option is to use the Kerbal Joint Reinforcement mod (also by ferram4) if you are not already, which should help with the wobble. Otherwise struts can help, but they can also make things worse depending on placement and amount. Manually tuning the attitude adjustment tab by decreasing Kd and proportionally decreasing Kp can also help with the wobble.

[Cairol]

Thanks.

Limiting AoA to 5° helped a ton. I'm also limiting my LRB thrust to about 60% while my SRB stage is burning to reduce structural stress.

When using "Stock SAS", the rocket tries to roll during ascent. With the MJ controller, it's more stable.

I haven't tweaked the PID settings yet. But I will, to make it even more steady.

Both of your comments really helped.

[monstah]

I once advised someone to mess with the PID settings, to which Sarbian himself immediately replie "don't mess with that unless you really know what you are doing."

So, don't mess with that

[Cairol]

Otherwise struts can help, but they can also make things worse depending on placement and amount. Manually tuning the attitude adjustment tab by decreasing Kd and proportionally decreasing Kp can also help with the wobble.

My rocket is not wobbling in its internal structure. But it's cranking and tries to roll and pitch in growing amplitudes until it reaches a certain altitude.

The MechJeb Controller can barely keep it under control.

But this only happes during a mechjeb ascent. Manual ascent is pretty smooth.

So I guess I have to balace the controller by playing with Kp, Ki and Kd to remove this behavior.

I once advised someone to mess with the PID settings, to which Sarbian himself immediately replie "don't mess with that unless you really know what you are doing."

So, don't mess with that

I'm aware of that. ^^

I sometimes have to mess around with control processes in my real world job too.

So I'll be cautious. I promise.

This is my current rocket (but others behave the same):

The problem arises during the first stage and continues till a certain height.

This is a short video that demonstrates it: