Hey there Wouter, thanks for the question.
It is quite complex to explain in a few words and without seeing what you are actually doing.
I don’t usually use the terms “kick” or “whip” when it comes to releasing the energy with the tongue. I simply want the tongue (whatever way you are articulating) to move independently of everything else in the system.
Now I MUST CLARIFY for those thinking I am incorrect in saying this. This is a DRILL and not to be confused with a stylistic articulation. Quite often, body and tongue work together in sync to give a particular sound effect. What we are working on here is eliminating the sub-conscious connection between tongue and body.
As far as air direction goes, that is purely based on the SHAPE of the “aaahooooh” lips.