Long story short. I am looking for the way to rigidly insert battery into the cage somehere between roll and yaw motors - so to get yaw rotatating freedom. Currently im holding on the LiPo using magic strips (picture -http://i59.tinypic.com/10eompx.jpg ) but it's not tighten it well - so any vibrations may cause battery movement - and "perfect balance" will be lost.
I guess the best way this porblem was solved - by guys from besteady. They use cylinder battery to insert into the cage-tube. I wonder where can i order (with international delivery) such custom shape battery.