Wasn't quite school, buuuut....
In the Scouts, we used to dabble in mildly pyrotechnic things, but after our experiments with the coke can/Pringles tube mortar and the banning of bangers from sale, we turned to less fiery methods of lobbing projectiles. The first attempt was the rubber-band bazooka. A four foot piece of drain pipe, twenty four Royal Mail rubber bands, a tin can and a firing mechanism made of a piece of string with a knot in it and piece of coathanger pushed through a piece of wood. All very good, could fling an egg a respectable forty foot at someone. We did scale it up to a nine-foot, forty-eight-band artillery piece that put a hole through a canoe from fifty foot using a ball of blu-tack as a shot.
Our crowning achievement was the water rocket. We took the basic design and fiddled with it so it went from a paltry thirty foot until we could get over three hundred foot of altitude. The adjustments we made were to add a pebble to the top of the bottle to give it more momentum when the water had gone, to shoot it out of a drain pipe (thus retaining the force of the exhaust) and to add plastic fins that folded down flat against the body of the rocket in the tube, but popped out on exiting, like a smart-bomb. The first test resulted in two smashed roof tiles on a house on the other side of the estate, being considerably more powerful than we had imagined.
When it used to go off, the crew of two would disappear inside of a pearlescent cloud of water droplets and all you would see was a small speck near the top of a very high arc.
Somehow word spread and we ended up giving a demonstration of it to the Chief Scout (back when they were proper Scouts, not just 'pick a celebrity for the week').
Happy days.
( Colonel Boris "...a desperate Buzzfeed imitation...", Tue 18 Aug 2009, 18:43, 1 reply)

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i gurentee more clicks if you post the plans for the artillery piece ...

Clicked
(mediumformat likes cyan, Tue 18 Aug 2009, 20:59, closed)