A while back my friend Dave and I made one of the big ones with the 2 inch diameter.

Wuss!

My friend Joachim told me of the time he and his cousin went out into the German countryside with a 55 gallon drum with the top cut out of it, a coffee can, a grate, and some gasoline.

They built a fire and mounted the grate securely over the fire. They took the coffee can and put a half liter or so of gasoline in it, then sealed it with the very tight-fitting lid. Placing the gasoline-filled coffee can on the grate, they then placed the 55 gallon drum upside down over the coffee can, and stood back.

When the gasoline boiled, it blew the lid off of the coffee can, instantly filling the inside of the drum with well-atomized gasoline vapor. This might have been quite exciting had there been an ignition source nearby. Oh, wait...

Joachim said the drum would launch so high in the air, turning end over end, that it would be just a little speck up in the sky. I imagine it made a pretty satisfactory noise as well.

This is the same fellow who, as a machinest apprentice welded together a box out of 6mm steel plate, the box being about 15 CM on a side. He filled the box with water, welded up the filler hole, and then just before lunch hour tossed it into the annealing oven. The resulting damage when the box exploded was quite extraordinary. Took the door off of the oven, blew out the windows in the shop. Nobody ever found out who did it.

A two inch plastic potato gun? Pah! Kid's stuff!

tanstaafl.