A tumble: Fly straight and level at a moderate speed. Quickly hit a right positive snap (full up ele, full right rud, full right ail) As soon as a 1/4 snap, as fast as your fingers can, give full down elevator. Your plane, if the tumbling type, will yaw almost 90* whilst pleasantly rotating about the lateral axis.
Some planes even tumble without giving the quick snap first. I find the quick snap helps less tumbleworthy planes to get into a halfdecent tumble. The cap dosn't need the quick snap before the tumble command, so just put the sticks in the upper corners and have fun.
Can you tell I really like to tumble??
I will try and get a video camera out to my field soon.

Sean