When I was a kid I used to launch water rockets in my backyard. Nothing as elaborate as these, just 2L bottle of soda half filled with water and a compressor. They never went too high, 50 feet if we were lucky, but it was good fun for an afternoon.
These people have decided to science up this little experiment. They added two extra bottles and an elaborate arming system to make a 2 stage rocket.
It’s a neat idea, but I think it’s a bit too much effort and work for me, I like the regular bottle of water and a compressor nothing fancy. The video isn’t bad though.