Make a launchpad that holds the bottle with the neck downwards, lets you attach the pump and stand behind the bottle. One good method is to plant a spade or garden fork in the ground at a low angle ...

The problem with a lot of these water bottle rocket projects is that they leak where the bottle meets the launcher. In most cases this is a good thing as it’s almost impossible to build up ...

SAFETY: This rocket uses air pressure to fling a bottle ... Keep pumping until the cork pops and the bottle flies away. Here's a simpler design using a pump that has a needle for inflating things ...