Robert Youens
Easy Deploying Water Rocket
The EZD is an easy to build rocket that can be built from materials you might find at any school. The pressure vessel is a one liter soda bottle. The paper tube in the middle is 15 inches long and is made from some paper I purchased thats intended use was stated on the label to cover school books. The paper came in a roll 15 inches wide and 20 feet long for 99 cents. The paper tube is glue together with contact cement and taped to the bottle and cone.

The extra length provided by the paper tube assure good flight and results is a slower transition through apogee which allows the parachute to deploy.
The top of the rocket is made from a second 1 liter bottle. The base of the bottle is cut as short as possible to keep weight down and is taped to the paper tube.

The cone is made form the top of the 1 liter bottle. I simply cut the neck off and glued a piece of plastic over the hole. A piece of paper would probably keep the cone lighter and work just a well.

The chute is made form a garbage bag. The shroud lines are made of nylon thread. The thread is glued to the chute with contact cement and a piece of tape is place over that.

The cone is held to the rocket by a second piece of thread.

The lighter you can keep the top of the rocket the better with this design.

If you are curious why long skinny rockets work the way they do you may want to take a look at my page covering the Backslider Water Rocket.
When prepared for flight, the chute is loosely folded and wrapped by the shroud lines. The cone actually rests on the chute.
Once the rocket takes off the cone is forced down on the chute. As the rocket moves slowly through apogee (due to the rocket design) the chute pushes the cone off the rocket and deployes the chute. There is also a differential in the density off the rocket and the cone with the cone being more dense. This further aids the cone in it's separation from the rocket and deploying the parachute.