You don't have to mess with explosives to launch a rocket. If you put air under pressure, like in a tire, you can use it to propel an object upwards. Add water to the mix, and your rocket will go far above the trees. This rocket is made from simple PVC plumbing pipe and some plastic soda bottles. Put this rocket together in just one afternoon, and get ready to supervise its first flight.
For full step-by-step instructions, see How to Build a Water Rocket
—and make sure you watch the How to Build a Water Rocket