To reiterate jkpolegirl….
To get full splits in the air (unassisted by the sheer force of your body weight against the floor or your arms pulling your legs into the split), you'll need an oversplit. And as you start getting your legs closer and closer, kick your core into high gear to force yourself to stay there against its will.
But, are you trying to achieve full splits in the air or the floor splits like this video? http://youtu.be/pO1FGo6gPDw
FYI — you'll have to bring your leg slightly to the side of your face to get to the ground. If you go directly in front of your face, your body is usually in the way.
Hopefully that helps a bit!