I was flying my trusty Stryker, if it's too windy for anything else, or I just want some stick time, it's a good plane.
I didn't put any thing on it I figured I didn't need. That means I have no cowling or center covering of any kind. Double stick the ESC, and double strap the battery with the excess wire underneath.
I tighten the velcro straps over the battery real tight as I do some pretty fast wrenching maneuvers, inside and outside extreme loops at full throttle. The battery has never moved. it sits just forward of CG.
This time I was climbing almost vertical, and I slammed the sticks, I think to right aileron, down and low motor, then pushed the motor to full throttle. The plane went into a flat spin like I have never seen anything do before. I could not even begin to count the turns or even focus on the plane, it looked like the blades of a heli.
Then the battery was thrown out of the plane, so hard I can't believe what I saw. It went about 25 feet before it started dropping. (destroyed the battery when it hit a rock) The weird thing is that as far as I can figure out, the battery left the plane towards the back end. The straps were still tight, and all the wiring was pulled out towards the prop in the back. This does not have thrust vectoring,--yet. Plane came down like a dry leaf, no damage.
I don't know what exactly I did, but I am going to tie the battery down a lot better, and try again. It sure looked crazy for a few seconds.
Back when I started flying, a buddy of mine could get his Superfly into a flat spin. I've tried with mine, but haven't succeeded yet. The one elevon-only plane I ever got to flat spin was this one I built from the wings of a jet my buddy crashed. It had a crazy amount of throw on the elevons.
The only way I could get it out of a flat spin was to let it hit the ground. That stopped it pretty quickly.