What Are the Best Creative Designs for a Water Balloon Launcher Project?

[ƒ(x)]

My teacher assigned a project in which we have to build a device that will launch a water balloon at least 200 yards, the only restriction being that the use of compressed air is prohibited.

I have already thought of several designs using a slingshot or catapult. It would be wonderful to be able to use a coil gun or a Gauss rifle, but I believe that I will not be able to make one large enough to launch a water balloon.

I was wondering if any of you have any more...creative, or destructive, ideas and would be willing to let me use them.

 

[ƒ(x)]

Another idea would be using a vacuum spring, but I don't know if it would generate enough force.

 

[JohnnyBones]

a slingshot type idea would probably work:

http://www.frattoys.com/water-balloon-launcher.html"