Easy, actually it is easier than inan upright spin. From a vertical line, slow with power on and perform an inverted snap roll(Down elevator)and hold. The plane will fall into an inverted spin, go to opposite aileron to flatten the spin. My Twist likes to fall out of any spin if I use too much rudder or elevator. I have my low rates set for spins so I can use full stick. Play around with your control throws and you will find thisplane loves to spin. If you have enough power and the right prop, you can gain altitude in a flat spin. Enter the spin at about half throttle or so, and whenyou are in a stable flat spin addthe rest of the power. The Ax55 is enough, play with a few props and have fun.