Somersault throw?
 

Are somersault throw-ins legal in NFHS? I can't find anything in the book that would suggest otherwise.

Yes, they are. The player simply must land on his/her feet and not end up on his/her backside. The reason is that technically the ball must be released while both feet are on the ground, so releasing while in the middle of the flip isn't allowed by rule, but it gets overlooked by accepted practice if the player ends up on his/her feet as the vast majority of all involved feel that meets the spirit of the rule.

FWIW, every time I've seen a legal flip-throw, both feet have been on the ground when the ball is released. The knees are usually still bent, but there's no rule against that.

Thank you.