Pete,
Careful for what you ask. "Snapping" can "take" your model
very quickly.
"If" you want to go in that direction: start (slowly)
increasing control deflection, and (slowly) begin to move the
C.G. to the rear.
You will need: aileron, rudder, and elevator at the same
time to snap. "purists" leave out the ailerons...
Too soon you will have a "snappppa-haaappy" model, that may
well get you into trouble on slow landing approaches, or,
especially "dead-stick" landings....
Regards, Masked Pilot (Robert)...........