Is it normal to have a sexual fantasy about a girl i like?

Usually men have sexual fantasies about their girlfriends, but there's this girl in my class at school. I think she's hot but I only have a crush on her. I don't date her.
Anyway, remember the scene in Return of the Jedi when Princess Leia is taken prisoner by Jabba the Hutt and made into a slave girl? She wore a pretty gold bikini that was very revealing and a collar around her neck that had a chain attached to it to keep her prisoner on Jabba's throne.
I sometimes fantasize about the girl I have a crush on in Leia's position wearing that bikini and chained to Jabba. I like to imagine I'm the hero that rescues her.
Is this fantasy normal? Is it normal to have the fantasy about the girl I like?