Assisted son Ian with a science project over the weekend, that the whole family got a kick out of. Who doesn't get a kick out of firing home made rockets? Empty plastic soda bottle, stopper made from a cut up bike tube, crude wooden launcher, bike pump - you're in business.
Fill bottle half way with water, attach pump, balance in crude stand and pump away. At around 50 psi it would blow out the stopper and head for the stars - well, almost. Still, some pretty impressive heights and good cheap fun.
Video taken from local school yard. First few test launches from our back yard resulted in a lost bottle that sailed over the neighbors house, so we had to move to a larger test facility. Even so, we eventually lost this bottle on the school roof.
NASA has nothing to worry about.....