This rocket launcher is very versatile and can be used in a variety of situations. For example, in a k'nex war, it could be used to destroy bunkers, or fortify positions.
Here is a video of the finished product. As you may notice, it barely leaves the barrel. This is due to the fact that I only used 1 weak rubberband. I have got it to shoot about 80ft, and with the size of the projectile, that is rather formidable.
EDIT: This thing has been rated 3.42?!??!? Are you serious!? Thanks guys :D