I captured this shot at WashJam 2012 where they were letting the boys build some 2 Liter Bottle Rockets and launch them themselves. I wanted to capture this for an idea on how to build my own set of launchers.
At the base of the top section is an o-ring next to the coupling. I recall seeing somewhere else another setup using a larger coupling with a slice in to to place a pull-pin with to secure the rocket.
With this setup, the boys fill the bottle up with about 1 cup of water then quickly turn it upside-down over the pvc pipe. One boy holds the rocket in place while another boy pumps the air pump. Once a desired amount of air pressure is realized the do a quick countdown and the boy releases the bottle.
These dudes fly pretty good. Due to the water involved, it is certainly recommended for summer-time launches.
As I discover additional tips and tricks for such a launcher I’ll post them.