A cartwheel executed without touching hands to the floor, to compensate for lack of support from the hands, leg momentum is employed to keep the performer airborne until the leading foot touches down.
Au sem mao or an “aerial” is a foundational skill in the world of gymnastics and tricking. In Capoeira, this movement is literally described as a cartwheel without hands. One leg jumps up, while the other kicks hard to the side, causing the body to rotate over itself. The arms play a vital role in creating power and rotational force. Make sure to punch hard over your head as you jump.
It can be inverted more diagonally to attack in the same way as a butterfly kick, This move doesn't need legs to be perfectly vertical, but the torso should be so you can see your opponent. If your torso is horizontal it's a butterfly kick.