What you need

You’ll be needing: 2l Bottle, bike pump, duct tape, and that’s pretty much it. Take cap off from your bottle and put some duct tape around bike pumps blow hole so when you try to cram it to bottle mouth it’s hard, if the bottles mouth is 1cm your duct tape hose system should be about 1.1 cm, because it should be little flexible. Fill the bottle with 3/4 water before placement the hose. If you’re having troubles my instructions, because I’m using dictionary, I’ll put picture here.

Water rocket: Placement the hose to bottle.

How to use it

Build a launch rack, maybe PVC pipe placed at ground pointing up, and you put a stick to your bottle and duct tape, place the stick to PVC pipe and start pumping with the pump until pressure grows inside the bottle and your hose will get loosed and the bottle will fly, be creative with launch rack.

How it works

Image tells more that 1000 words. Gif image tells more than 10000000 words

if it doesn’t work

The pressure at bottle is building, when it reaches point where the pressure is higher than grip with the hose and bottles mouth it looses and air pressure is still high and air is pushing water out, because of water is so much heavier than air it gets thrust.