Extreme Soda-Pop Rockets (With Step-By-Step Plans!) - 04

The Finned Floater Rocket

This model, in addition to having fins that will steady its flight on its way up, also has a nose cone containing a parachute that will help it float back down to the ground in elegant style. It’s based on a two-bottle rocket like the one described in project 1.4 (see pages 28–29). The top bottle makes a store for the parachute, while the lower bottle holds the water that will propel the rocket’s flight.

You will need:

• Two 2-liter plastic soda-pop bottles

• Duct tape

• Epoxy glue

• Heavyweight scissors or craft knife

• Cutting mat

• Hole punch

• Soft pencil—2B is ideal

• Measuring tape

• Large black plastic garbage bag

• Ball of thin string

• Sheet of thin cardstock, 8 x 11 inches (20 x 28 cm)

• Sheet 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

• Either the launcher and the bottle stopper from project 1.1 (see pages 10–13) or 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.

• If you wish to add fins, follow steps 2–7 of project 1.2 and add them after step 2

Step 1

Use heavyweight scissors or a craft knife to cut off the top and bottom of one of your bottles. Don’t cut much length off—cut just at the point where the body becomes straight below the neck and above the base, so that you are left with a long cylinder of plastic.

Step 2

Fit one open end of the cut bottle over the base of the second bottle and duct tape the two together neatly. Use two or three layers of tape to ensure that the joint is strong and secure.

Step 3

Make the parachute. Lay the garbage bag out flat on your worktable or on the floor and use scissors to cut off the sealed end, cutting as straight a line as you can. Straighten out the resulting tube and cut down the sides to make two panels of thin plastic. Use one panel to make the parachute and save the other for use in the future.

Step 4

Fold the panel in half lengthwise from left to right, then fold in half again from bottom to top. Fold the left edge to meet the bottom edge and make a small cut in the plastic where the top of the left edge meets the bottom edge. Fold the diagonal edge on the left to meet the bottom, then repeat this again to leave a narrow triangle of plastic with the open edges outer-most. Find the small cut you made earlier, then cut in a slightly circular motion to the top edge. Open up the plastic to reveal the large circle.

Step 5

Mark the plastic circle out in quarters (you can do this by eye or use a measuring tape). Cut a 3-inch (7.5-cm) length of duct tape and stick it at one of the quarter-points of the parachute, wrapping it around both sides of the plastic so that it makes a solid tab at the edge. Mark the other three quarter-points with duct tape in the same way, then add three extra tabs between each quarter-point marker, spacing them as evenly as possible. You should now have 16 tabs around the edge of your plastic circle.

Step 6

Use a hole punch to make a hole through the center of each duct-tape tab.

Step 7

Measure the diameter of your parachute with a measuring tape, and cut 16 lengths of string, each 1 1/2 times the length of the diameter measurement. Use a reef knot to tie one end of each piece of string through one of the punched holes in the edge of the parachute.

Step 8

Knot the loose ends of the 16 strings securely together. Cut a short length of duct tape and tape the knotted ends inside the open end of the top of the rocket.

Step 9

Fold the parachute in quarters and place it neatly into the top bottle, pushing the strings in first, followed by the parachute.

Step 10

Photocopy the pattern for the nose cone of the rocket and its supporting tab to scale onto the sheet of cardstock (see page 108), then cut them out to make a template. Lay the cone template on the plastic sheet and draw around it, then use a craft knife or sharp scissors to cut it out. Draw around the tab three times and cut out the three tab shapes. Fold the tab shapes as shown.

Step 11

Glue the two folded-out edges of each tab at even intervals along the top of the rocket. When glued, the tabs make tiny ledges at a 90-degree angle to the bottle. These will support the cone.

Step 12

Roll the nose cone into shape and tape the tab inside it to hold it together. Cut a length of string 18 inches (46 cm) long and stick one end inside the nose cone with a piece of duct tape. Tie the other end to one of the punched tape ties on the parachute.

To Launch Your Rocket

Fill the rocket with water and, if using the launcher from project 1.1 (see pages 10–13), seal the mouth with the stopper. Place your rocket in the launcher and arrange the nose cone carefully on top of the rocket, balancing it on the tabs. Retreat to a safe distance, pump up the pressure, and fire. As the rocket reaches the top of its trajectory, the nose cone will fall off and the parachute will be pulled out of the top of the bottle. The rocket will drift gently back down to earth.

Firing Report

This isn’t the most reliable model, but although it did suffer from the occasional malfunction, the sense of satisfaction when the parachute deployed successfully was well worth the frustration of the failed attempts.