Or do this.
When you you stretch out making it hard to tuck your legs real quickly to land on your feet, in order to fix this try this simple moderation.
First, when you jump forward you stretch your body out. After you reach full extension tuck your legs in the air (like your about to do a hand stand before you extend your legs and your not all the way up or vertical). Basically dive and tuck really close.
Next, when you put your hands down or even when they are almost touching the object your feet and legs should be tucked in and your head should be angled closer to the ground than the sky. This gives you more power with your upper body to whip your legs under faster. When your hands touch you whip your head up including your upper torso and push up and farward with your arms.
Next, you also have to whip your legs forward so your knees are tucked on your stomach instead of behind you.
Finally, after you have giving the push of your whole body to basically whiplash you backwards, you must lean back and and stick your legs out in front of your body. You must also nearly have your legs straight or slightly bent. When you lean back it should feel as if you are going to land on your butt but the momentum from your speed when your legs are planted you should be pushed up vertical.
If you do this right and as hard as you can you should be able to do an intire backflip from pushing backwards so hard, or at least land on your stomach close to a whole flip so don't push as hard as you can because it will hurt. Just figure out how much force you should need.
One more thing make sure you keep your legs close together when you dive, this is not necessary but you will go mush further.
Ill post the video in a bit, if you don't see the link it isn't there yet OK.
Heres a video of me last year, or maybe this summer don't remember. lol
BTW: it's 12 feet from the leg of the chair to the opposing edge of the box therefore making it a 12 foot long object being 3 1/2 feet tall. Yey I did it I did it.
http://s10.yousendit.com/d.aspx?id=1Q3J3C4VNBMUQ2NSNY7RBP1680