2 Liter Bottle Rocket Launcher
- Coated/laminated bookshelf piece, ¾" thick, 1' wide, and at least 18" long
- Steel bar, ¾" wide, 1/8" thick, 27" long
- Drill and various bits
- Wood file or rough sandpaper
- Four wood screws, 1-½" long
- Two 2"x2" wood supports, 18"-24" long (no longer than your bookshelf piece)
- Three ¼" bolts, 2-½" long
- Two pieces of ½" metal pipe, ¾" long (copper flush bushing ¾" x ½")
- Three ¼" flat washers
- Three ¼" wing nuts
- 1- ¾" compression spring
- Two eyebolts (No. 10 x 1-3/8" or bigger)
- String (about 1/8" in diameter, 9" long)
- ½" male PVC elbow (one end is ½" ID, other end fits around ½" pipe, both
ends unthreaded - called Schedule 40 Pressure 90° Street Elbow)
- ¾" inner diameter flexible hose, 4' long
- Two ¾" diameter hose clamps
- Tire stem valve
- 1-½" piece of ½" PVC pipe
- ¾" hose strap
- Two wood screws, ½" long (No. 8 x ½")
- 3" x 3" piece of neoprene (soda can insulator, knee brace, back supporter,
etc. are made of neoprene)
- 3" x 3" piece of flexible rubber
- Contact Cement
- Four spikes (very large nails, about ¼"-3/8" diameter and 6"+ long)
- Empty 2-liter plastic soda bottle(s)
- bicycle pump with pressure gauge
Note: Many measurements are approximate and can be varied. Materials were purchased
from Wal-Mart and Lowes at a total cost of approximately $25 - $30 (tools were
- Use a hacksaw to cut the steel bar into two 1-foot pieces and one three-inch
- Mark the drill holes in the steel and wood as shown in the diagrams above.
Note that the diagram is for a piece of wood that is 1 foot by 2 feet. You
may need to adjust the intervals if your piece is a different size, but keep
the spacing between the center holes the same.
- Drill the holes with the following bit sizes: pivot holes (4) - 1/4", compression
spring holes (2) - 1/4", string attachment holes (2) - 1/8" (note that these
are slightly off-center), anchor holes (4) - 3/8" or other depending on your
spikes, wood screw holes (4) - 1/8" or other depending on your screws, air
inlet hole (1) - 1-1/8". It will probably be difficult to find a drill or
bit big enough to make the air inlet hole. To make the hole without a large
drill bit, trace around the large end of the PVC elbow to make a circle where
the air inlet hole should be. Then drill several holes within this circle
so that most of the wood is removed. Finally, use the file or sandpaper to
make the hole smooth and big enough for the PVC elbow to fit through.
- Use the wood screws to attach the two 2"x2" wood supports to the bottom
of the bookshelf piece as shown in the diagram.
- Place two of the 1/4" bolts into the pivot holes in the wood such that
the threaded ends stick out the top. On top of these threaded ends place the
following items in order: metal pipe piece, steel bars (through the pivot
holes on the bars and with the string attachment holes toward the outside),
washer, and wing nut.
- Place the other 1/4" bolt through the spring compression hole in the wood
so that the threaded end sticks out the top. Place the following items in
order on top of the bolt: compression spring, washer, 3" steel bar, and wing
- Place the eyebolts near the edge of the wood piece so that when the steel
bar is swung outward the string attachment holes are next to the eyebolts.
You may need to use a nail or drill to start the holes.
- Tie one end of the string through the string attachment hole in one of
the steel bars. Thread the string through the closest eyebolt, then the other
eyebolt, then attach the string to the other steel bar through the string
attachment hole, as shown in the picture.
- Put the small end of the PVC elbow into one end of the flexible hose. You
may need to use soap to lubricate the hose or heat to expand it. Secure the
hose with a hose clamp.
- Place the large end of the tire stem valve into the other end of the hose.
Place a hose clamp slightly ahead of the tire valve bulge and tighten it.
- Put the small piece of PVC into the large end of the PVC elbow and push
it in as tightly as possible.
- Place the PVC elbow through the air inlet hole so that the hose is on the
underside of the launcher. Secure the hose to the bottom using the hose strap
and small wood screws. It may be necessary to secure the hose with a second
hose strap directly under the male PVC elbow to prevent high-pressure blowout.
When constructed, the 1/2" PVC pipe that the bottle will fit over should
NOT be able to be pressed downward under the air inlet hole of the main board.
Air inlet hole
- If you do not have a pre-made neoprene washer, cut the piece of neoprene
into a washer with an outer diameter of 2-1/2", and an inner diameter of 5/8".
Do the same with the piece of rubber.
- Check to make sure that washer(s) fit snugly over the PVC piece sticking
out above the air inlet hole. You should have to stretch the washers to get
them around the pipe. Remove the washers.
- Apply contact cement to an area about 2-1/2" around the air inlet hole.
Place the neoprene washer around the PVC pipe and onto the bookshelf piece.
If you have two washers, first put down the neoprene piece, then apply a lot
of contact cement to the neoprene piece and put the rubber washer on top.
Make sure that the washer(s) lie flat and are secure. Let the glue set overnight.
- Put a spike in each of the anchor holes and use the hammer to secure them
into the ground. Attach the bicycle pump to the tire valve stem.
- Check to make sure that the opening of your empty 2-liter soda bottle will
fit over the PVC pipe. It should be a close fit, but some bottles are irregular
and may not work.
- Add varying amounts of water to the bottle (0% to 100% full). Quickly turn
the bottle upside down so that the neck is over the air inlet hole.
- Pivot the 1' steel bars inward so that they go over the bottle lip and
under the 3" steel bar.
- Tighten the wing nut above the compression spring to secure the bottle
and make a tight seal.
- Using the air pump, increase the pressure in the bottle to about 40 psi.
Be sure that nobody is above the bottle, then pull the string to remove the
steel bars and thus launch the rocket.
- Observe the motion and record your results.
Note: The industrial specifications for the pop bottles maintain that the bottles
can withstand 180 psi. For maximum safety, do not exceed 90 psi.