Make a Manilla Folder Propeller for Physics Project

[physics999help]

I have a physics project where I am supposed to make a car from index cards, manilla folders, paper clips, drinking straws, glue, tape, rubber bands, etc. I am attaching a propeller to the back, but I need a decent design i can make by cutting and bending a manilla folder. It should not be more than 3 inches across. Pretty, much, i need someone to give me dimensions for a workable propeller.

 

[berkeman]

Why do you want to use a propeller to move a car? Seems pretty inefficient to me. And unless you are going to spin that propeller extremely fast, you don't need an airfoil design for it. Just bend the blades at a flat angle.