Extreme Soda-Pop Rockets (With Step-By-Step Plans!) - 02

The Pressurized Cluster Rocket

The cluster rocket is a development from project 2.2, the three-bottle rocket, and starts at the point at which that project was completed. The six-bottle addition around its base is adorned with three simple but large fins, giving the cluster rocket a deceptively complicated appearance. Despite its elaborate looks, it’s still very easy to make.

You will need:

• Three-bottle rocket

• Six 2-liter plastic soda-pop bottles

• Duct tape

• Epoxy glue

• Heavyweight scissors and a craft knife

• Cutting mat

• Soft drawing pencil—2B is ideal

• Sheet of thin cardstock, 11 1/2 x 16 1/2 inches (29 x 42 cm)

• Three sheets of thin, flexible plastic, 11 1/2 x 16 1/2 inches (29 x 42 cm)—you can find this in hobby or craft stores

• The launcher from project 1.3 (see pages 22–25) and a bicycle pump, ideally with a pressure gauge. You will also need access to a photocopier

Step 1

Make a three-bottle rocket as described.

Step 2

Using a photocopier, enlarge the fin template on page 111 to scale onto the thin cardstock. Cut out the fin shape carefully with scissors or a craft knife. Draw around the cardstock template on the flexible plastic sheet. Repeat twice so that you have the outlines for three fins. Cut around the outlines with scissors or a craft knife. If you are using a craft knife, do your cutting on a cutting mat.

Step 3

Cut the slits on the fins as shown on the template, then fold two tabs going one way and two going the other way on each fin.

Step 4

Measure the diameter of the rocket and make pencil marks at thirds around the lowest bottle, just above the neck where the bottle body is straight. Glue the fins to the bottle at the marked points using epoxy glue. Add duct tape to strengthen the joints.

Step 5

Prop your rocket in the firing position, and arrange six bottles around its base, two between each fin. Their bases must be aligned slightly above the top of the neck of the central bottle so they won’t interfere with the firing of the rocket. Tape the first bottle in place with duct tape, just above the fin.

Step 6

Continue to tape bottles around the base of the rocket until all six are in place. Run duct tape around the lower parts of the bottles, below the fins, so that the cluster is securely fixed both top and bottom.

To Launch Your Rocket

Fill one and a half bottles with water. Place your rocket on the launcher, secure with the wire trigger, pressurize, and fire.

Firing Report

Although this was not one of the most impressive performers in height terms, due to the weight of the extra bottles, it makes a terrific booming sound at the point of takeoff.