PART 1

ROCKET BASICS

This section takes you through a few straightforward rocket designs and shows you how to build two sorts of launcher: one very simple and one sturdy enough to take even the heaviest and most ambitious models from the second and third sections of the book.

Unless you're already a seasoned rocket engineer, try the most basic rocket first. Not only is it easy and quick to make, but it can also achieve surprisingly impressive results at the firing range. Then build your skills and confidence by adding the features that will make your creations look more like real rockets: fins, nose cones, and even a working parachute.

1.1 A BASIC

ROCKET AND LAUNCHER

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This starter project is made with a simple improvised launcher that guarantees fast and satisfying results. When you have successfully fired your first rocket, you can try a slightly more elaborate setup using the heavy-duty launcher described in project 1.3 (see pages 22–25).

You will need:

• 2-liter plastic soda-pop bottle

• Duct tape

• Scissors

• Pliers

• Inner tube from a bicycle tire

• Cable tie

• Two wire clothes hangers

• Ball of strong string

• Bicycle pump. A pressure gauge is useful but not essential.

1. Cut the valve stem off the inner tube, cutting it as close to the tube as possible. Cut a strip 1 inch (2.5 cm) wide and 24 inches (61 cm) long from the remainder of the inner tube.

2. To make the stopper for the bottle, wrap the strip of rubber from the inner tube tightly around the valve stem until it is the correct size to stop the opening of the soda-pop bottle; it should fit it very snugly. Cut off any excess rubber and secure the rolled stopper with a cable tie. Wrap a layer of duct tape around the stopper. This will improve the seal and make it easier to insert into the bottle opening.

3. Fill the bottle so that it is from one-third to one-half full with water and stop the mouth with the wrapped valve.

4. To make the stand, take a wire clothes hanger and bend it as shown in the diagram. Carefully measure lengths A and B. Length A allows the trigger (see step 5) to fit neatly over the rim of the soda-pop bottle, and length B is the exact distance between the rim of the bottle and the top of the rubber wrapped around the valve. The legs of the stand should about 8 inches (20 cm) long.

5. To make the trigger, straighten out a length of wire approximately 12 inches (30 cm) long from the second clothes hanger and cut it with pliers. Bend it to create a U shape that fits around the neck of the bottle, but under the loops of the stand. Tie a length of string about 13 feet (4 m) long to the center of the trigger's rounded end.

To Set Up the Stand

Push the stand into soft ground. Place the bottle in the stand with the valve pointing downward through the loop in the stand. Hold the bottle steady with one hand, then push the trigger into the stand so that it is wedged between the top of the stand and the rim of the neck of the bottle. This will prevent the rocket from launching prematurely while air is being pumped into it.

To Prepare for Launch

Attach the bicycle pump to the valve and pump air into the rocket. If you have a pressure gauge, a pressure of about 60 psi (pounds per square inch) works well. If you don't have a gauge, you will need to experiment to find the optimum pressure. Keep a record of the number of pumps that were used to pressurize before a flight, and then try repeat flights with more or fewer pumps to find the optimum pressure for each rocket.

To Launch Your Rocket

Now that your bottle is pressurized, you are ready to fire. Stand clear and pull sharply the string that is connected to the trigger to release the rocket. When the trigger is released, the pressure inside the bottle forces the stopper out of the neck of the bottle, leaving the stopper behind as your rocket launches into the air.

1.2 A ROCKET WITH FINS

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Three sleek fins will not only make your rocket look smarter, they will also help to stabilize it in flight. The model shown here has fins of the classic 1950s-style triangular type, but you can modify the designs according to taste–you'll find another variation to inspire you on pages 44–45. We've used the basic rocket described on pages 10–13 as the foundation for this project. You'll find the fin template on page 108.

You will need:

• 2-liter plastic soda-pop bottle

• Epoxy glue

• Heavyweight scissors or craft knife

• Cutting mat

• Soft pencil–2B is ideal

• Tape measure

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

• Sheet of thin, flexible plastic, 11½ × 16½ inches (29 × 42 cm)-you can find this in hobby or craft stores

• Modeling clay (you'll need a piece the size of a golf ball or a little smaller)

• 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.

1. In this project you'll be adding fins to a basic bottle rocket like the one you made in project 1.1. The fins must be added before you fill the rocket and insert its stopper.

2. Enlarge the fin template on page 108 to scale onto the thin cardstock, using a photocopier. 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.

3. Cut around the outlines with scissors or a craft knife. If you are using a craft knife, do your cutting on a cutting mat.

4. Cut the slits on the fins, as shown on the template.

5. Fold three tabs going one way and three going the other on each fin.

6. Make three marks an equal distance apart around the circumference of your bottle, about 2 inches (5 cm) up from the neck where the body of the bottle is straight. Divide the circumference by three and mark it into equal thirds with a pencil.

7. Using epoxy glue,...