Simple Water Rocket Launcher
This is a simple water rocket launcher that you can have your scouts build. It is easy to operate,
safe and lots of fun. This launcher is based on a design found on Stan Pope's web site (see sources below for URL
of the web site).
||Quantity and Size
||qty one, 18" long
||½ PVC pipe
||½ PVC elbow
||qty one, 4' long
||½ PVC pipe
||½ PVC T-connectors
||qty two, each 6" long
||½ PVC pipe
||qty one, 6" long
||½ PVC pipe
||½ PVC end caps
||qty one, with 9/16" hole
||½ PVC end cap (flat style)
||qty one, 8" CPVC
||½ CPVC pipe
||Tubeless Tire Valve
||½" or thicker board 12"x12"
||qty one, 6" long
- one 8 foot section of ½" PVC (this is white plastic pipe you CAN NOT use for drinking
- one section of ½" CPVC (generally TAN and can be used for drinking water)
- one ½" PVC 90 degree elbow
- three ½" PVC end caps (get the flat ones. Some are rounded. The flat ones are easier
- two ½" PVC T-connectors
- one tubeless tire valve
- two pipe straps and some screws
- one board about 12x12 or 12x8 to mount the launcher on.
- Duct Tape
- CPVC-PVC cleaner and glue (cleaner is generally purple. There is a clear version that looks
- Glue (either PL Premium or Household Goop)
- Tape measure
- Pencil for marking cuts
- Hacksaw for cutting pipe
- File and/or razor knife for removing rough edges/burrs from cuts
- Screw driver
- ½" wood drill bit
- Rag to wipe excess glue from joints
- Have the boys do the measuring and cutting.
- The boy can also glue the parts together with some adult assistance, but remind them that the
glue sets almost instantly. Where a piece needs to be glued in a proper relationship with another piece, it may
be advisable to have an adult put those pieces together.
- Have the drawing of the completed launcher visible so the boys can use it like a blue print.
Have them lay the parts to be assembled on top of the drawing to help them visualize how they are assembled. You
may wish to enlarge the picture some to assist this process.
- The launcher can easily be made in one evening.
- Read the notes on how properly glue PVC below.
- Take one of the ½" PVC end caps and drill a ½" hole in the end. Put
some glue (PL Premium or Household Goop) around the hole inside the cap. Insert the tire valve through the hole
from the inside of the cap and pull through until rubber locking ridge (located toward bottom of valve) snaps through
the hole. You have now assembled part H & J. This activity is best done ahead of time. I don't recommend that
the Scouts drill the hole unless you have a good vise to hold the end cap while drilling.
- Now cut out parts A, C, both E, F, and L from the ½ PVC pipe. Using the file and/or razor
knife, clean the cut edges so any extra material is removed.
- Glue the H&J assembly onto one end of part A. Then glue part B to the other end of part
- Now glue the other end of part B to part C.
- Holding the tire valve pipe assembly so it is pointing straight up(perpendicular to the ground),
glue the first part D (that holds the launch rod) so the top of T-Connector is pointing up (perpendicular to the
- Next glue each part G to one end of each of the two part E's as show in the diagram. Glue the
part E's to the second part D t-connector. Into the top of part D, attach part L. This is the anti-tip assembly.
- Take the anti-tip assembly and glue into the first part D (holding the launch rod) so that the
anti-tip assembly is parallel to the ground and the launch rod/tire value are point straight up, perpendicular
to the ground. (It is more important for the launch rod to be pointing straight up in case the tire valve wasn't
glued quite parallel to the launch rod).
- Cut out part I from the ½" CPVC pipe. Using the file and/or razor knife, clean the
cut edges so any extra material is removed.
- Use the file to slightly round the bottom edges on one end of part I (the ½" CPVC).
Next use the file to slightly widen the opening on one of part F. Now insert the rounded end of the CPVC into the
widen opening of F. Using a hammer, whack F tightly over I (or I tightly into F) as far as possible. The fit will
be so tight you won't need to glue it into place. If desired you may, but you will still have to whack it into
place, so work fast before the glue sets.
- Now glue part F into the top of the first part D t-connector.
- Lay the launcher onto your board. Use the pipe straps to fasten the launcher to the board. Put
a strap over part L and part C. Additional straps, if available, could also go over one of the part E's, and part
C near where the pipe leaves the board.
- Take the Duct tape and wrap it in a band around the bottom of the CPVC launch tube. Form it
so that it is narrow at the top and thick at the bottom of the band. You want to be able to slide a pop bottle
over the launch rod, and have it fit tightly over the duct tape. The duct tape will provide a friction fit, to
hold the bottle into place until the pressure forces it free. You will have to periodically replace the duct tape
as it wears out.
PVC Glue Instructions.
To successfully glue PVC & CPVC follow these simple rules.
- Only glue a few pieces at a time
- Have good ventilation as the glue and cleaner produce fumes and are aromatic. Keep containers
closed when not in immediate use.
- Wipe pieces to be glued so they are free of dirt and grease.
- Apply cleaner only to the surfaces you are working on right then.
- Apply glue to the first part, then the part it goes into, then put glue on the first part again.
- Quickly insert part one into part two, and twist slightly to seat the part (1/4 to ½
twist). Make sure parts end up in correct relationship after the twist. Remember that this glue sets instantly.
- Wipe excess glue from joint.
Using the Launcher
- Take a 2-liter bottle and fill between 1/3 & ½ with water.
- Tip the launcher on its side and slip the bottle over the launch rod, down onto the duct tape.
- Put launcher back flat on the ground and with a twist of the bottle, seat it tightly over the
- Clear the launch area
- Apply air pressure to the launcher using either a hand air pump or a mechanical air compressor.
For safety do not exceed 100PSI.
- When the air pressure exceeds the friction holding the bottle down, it will launch with a whoosh
and streak skyward. If pressure reaches 100psi and the bottle does not launch, remove the air source, then depress
the valve stem and release the pressure in the launcher. Standing next to, but not over, the launcher use a stick
to whack the bottle loose. When loose, re-tighten on launcher and re-apply the air pressure.
- When done, drain the pipe as best you can.
- 2-liter pop bottles can take up to 100-120 PSI of pressure without much problem. The Science
Olympiad uses 75psi for their launches. I use 100psi when I can. Bottles that have been abused, or weakened by
inappropriate adhesives can burst under pressure. It is important to keep people away from the bottles while they
are being launched.
- Bottles leave the launcher at tremendous speeds 30+mph (more like 60-80mph). It doesn't feel
good to get hit by one. So never lean over a bottle on the launch rod. Make sure launch rod is always pointing
up when applying air pressure to a rocket.
- DON'T USE DRY ICE to pressure the water bottle rocket!!!
Dry Ice can pressurize your rocket so fast that the rocket may explode rather than launch. Don't lose fingers for
doing something stupid.
- Bottles that go up, must come down somewhere. Please launch rockets in open areas so they don't
land in streets or on your neighbors car or roof.
- Liquid Nails, Super Glues, and HOT Glue Guns have been known to weaken the plastic used in pop
- PL Premium (a construction adhesive found at Home Depot next to Liquid Nails) and HOUSEHOLD
GOOP work good for making rockets. PL Premium is best for gluing bottles together to make bigger rockets. Household
GOOP is best for gluing fins onto bottles.
The basic design of this launcher was found on the Internet in some scouting web pages created
by Stan Pope. Please visit his site to see the original design and other scouting information. The web page is: