My rocket engine sounds:
You can build a water rocket which can fly.
Rockets Bottle of Water
by Long Valley
In this video you can see the launch of a water rocket.
High Pressure water rocket from AirCommand on Vimeo.
You can find more videos from this group on vimeo
Water Rockets on Vimeo
Younger children can start with the simplest models like this.
Rocket from scribbaloo on Vimeo .
Have a nice flight.