Blender
Setup:
Slightly tailheavy ( the less elevator throw you have the more tail heavy you need to be.)
At least 45-70 degrees of elevator throw
High rate aileron
Max rudder deflection

How to:
1.Get the airplane up high maybe 300' to start
2. Chop the throttle and dive the aiplane vertcially, straight down.
3. Immediately give full left aileron input and get several rotations until the plane is rolling fast.
Simultaneously (but ever so slightly lead with full down elevator) feed in full down elevator, full right rudder and half to full throttle. The plane will violently wrap into an inverted flat spin.
4. As it settles into the inverted flat spin, continue to hold full down and full rudder and bring the ailerons back to center. This should level out the flat spin.
5. Adjust the throttle and ailerons to flatten out the spins and slow the descent.

If you get it right the plane will descend vertically flat on its back wrapping tightly around its cg axis.

[link=http://www.youtube.com/watch?v=7n6z-eQUMXo]Blender Video[/link]