Things You'll Need:
- 2 liter soda bottle Bottle cap Drill or awl Disposable pen Bicycle pump Cork stopper String Bicycle inner tube valve Manila folder/foam core (optional) Modeling clay (optional) Plastic bag (garbage bag or other) Duct tape, epoxy or glue (optional) Air compressor (optional) Wire coat hanger (optional) Paint (optional)
-
Step 1
Build a launcher. The hardest part is building your launcher, but a basic one is very simple. One of the quickest methods is to use a bicycle pump, a disposable pen tube, and the bottle's screw-on cap. Find a disposable pen or cap that will fit into the bicycle pump nozzle. Drill a hole in the cap that will tightly fit the pen cap or tube. The basic launcher is complete. This will last about 20-30 launches before the pen and cap get too loose, so replace with another cap. A sturdier version uses a cork (real not synthetic) microwaved about 20-25 seconds then inserted in to the bottle opening. It will adjust to the size of the bottle opening. Drill a hole for your pen tube or use a Schrader valve from an old bicycle tire inner tube.
-
Step 2
Build your rocket. The basic rocket is a 2-liter soda bottle, turned upside down. For it to fly, fill it about 1/4 full with water and cap it with your launcher cap or cork. Attach your pump to the pen tube or Schrader valve, turn the rocket cap down and propped on its launch trajectory using some objects like bricks or boards. Then start pumping. As the pressure builds inside the bottle, it pushes out in all directions, when the pressure finds a way out---the cap hole or cork---it forces the water out as a jet and it will blast off. You will have to experiment to determine the best amount of water to use.
-
Step 3
Build a more aerodynamic rocket. The basic bottle is rocket-shaped, but it can be made more so. Its fun to watch the bottle twirl around a few times, but adding three or four fins on the bottom will help your rocket achieve straighter flight and go higher. You can use manila folder or cardboard, but foam core or plastic will last longer. A nose cone made out of plastic will make it more aerodynamic and a small weight (ball of clay about golf ball size) added in the nose will help with inertia. Again some experimenting will show how much water to use and the best weight in the nose.
-
Step 4
Build a parachute recovery system. While a permanent nose will help with aerodynamics, a parachute under a removable nose will help keep your rocket intact longer. Cutting a large circle out of a garbage bag or drop cloth is one simple method. Attach four or five pieces of string to the edges of the circle and attach together to the top of the rocket (bottom of bottle) and tuck parachute inside cone. You must tie off your nose cone to the rocket so it stays attached after parachute deployment.
-
Step 5
Build a better rocket. This step is only limited by your imagination. You could cut open a compartment for your action figure or stuffed animal astronaut and see how high they can go.
Merge two bottle top halves together for a bigger rocket using duct tape, epoxy or glue. Custom paint your rocket. Build a more efficient launcher. A small air compressor will get more air in faster (a large compressor can supply too much air causing the bottle to burst). A wire to hold down around the nozzle made out of wire coat hanger can let you delay launch until more pressure is built up, but again be careful of too much pressure.
