FlightDetent: My reference point "0 seconds" doesn't hold any importance. It's just meant as a split between takeoff roll and liftoff for orientation. As you show, the issue starts around 4 seconds before that. Why the rudder was moving this way I don't judge. I haven't read most of the files yet.
An interesting note from me for casual readers:
Wind from clearance was 010/17
A321 has a 25° sweepback wing
The heading change was up to 8° per second
When a swept wing plane is yawing left:
right wing accelerates forward into the wind = lift increase
right wing sweep angle reduces relative to airstream (160kn IAS vs. 010/17) = lift increase
left wing vice versa: ... decelerates ... sweep angle increases out of the airstream = lift decrease
within fast left roll, right wing effectivly faces lower AoA = lift decrease, left wing higher dynamic AoA, lift increase
Now I can't do the math obviously and what dominates over what. Let's not forget, countering aileron input was large. But just not enough obviously. By the way, what's the A321 Flight Law / Aileron Strategy in this takeoff phase?
Any mentioning of gusts in the docket? CVR states a 010/17G23 at landing clearence later.