I have always wondered this about the corkscrews on Arrow's looping roller coasters. You know how, especially on demon, they drop you into a bank without turning, and then you get thrown to the side? Is that necessary? Couldn't the roller coasters have a drop without a bank, and then go into the corkscrew?
If you don't know what I am talking about, check out this video:
http://www.youtube.com/watch?v=9eCSnxke1oE
It's about at 1:20