Introduction: DIY Water Rocket Mortar

About: I like to make stuff like bullwhips, crossbows, launchers, and I grow strawberries.

I was walking through a section of woods the other day and I found a bunch of piping that had floated down a nearby stream and washed up onto the bank from a construction site. I knew I could build something with it so I brought it back to my house. I noticed that there was a "Make it Fly" contest and I realized I could make a mortar tube to shoot custom water rockets.

Here is the list of materials:

- 4 by 10 PVC or some other similar material

- Lots of Duct Tape

- A 2 liter plastic seltzer or soda bottle

- A bike valve

- Plastic grocery or sandwich bags

- a nail

- A 4 - 5 inch diameter circular lid

- Dollar store plastic martini cups

- Styrofoam or plastic cups

Step 1: The Pokey Thingy...

Start by drilling a small hole into the end of the martini glass. Then insert a nail into the end and pull the tip through so that it sticks out 2-3 inches. Pour a copious amount of hot glue into the very end and completely cover the nail. After the glue has dried get the circular lid and glue the martini glass/nail onto it. After the glass and lid are firmly held by the glue, tape the whole thing onto the end of the PVC tube.

WARNING: Do not glue the lid to the tube because you might need to access the martini glass and nail later incase something breaks.

Step 2: The Stand

The stand is very simple. Just cut two boards until they are about 14 inches long and screw them together into a V. Then get a piece of PVC and screw the V firmly onto it.

Step 3: Finished Product

To assemble the mortar just put the stand against the mortar tube and tape it firmly together.

Step 4: The Mortar Shell

The mortar shell is just a 2 liter with a bike valve in the bottom and a hollowed out cap as the nozzle to direct the air and water fuel mixture when launched.

Step 5: The Seal

So to make the seal simply cut a 4 by 3 inch piece of thin plastic (i.e.. a grocery bag or sandwich bag) and fold it 2-3 times and place it on the top of the bottle. Then screw the cap down until very tight and you've just finished the perfect seal.

IMPORTANT: The number of times you fold the plastic changes the pressure the seal can handle. 1 to 2 folds can handle 20-30 psi, while 3 folds stays sealed at 40-50 psi.

Step 6: Loading and Firing


To load the shell just fill it with about 1/4 to 1/2 cup of water and place the plastic over the opening of the bottle neck. Then screw the cap down very tightly. Go outside with a bike pump or compressor and fill the shell with 20 - 50 psi. After pressuring the shell place a styrofoam or plastic cup over the bike valve to protect it when the shell hits the ground.


To fire just drop the shell down the tube and onto the nail, which punctures the plastic seal, which in turn launches the shell into the sky. The max range I have tested so far was over 175 feet.

P.S Vote for me in the Make It Fly and First Time Author Contest if you liked my intractable.

First Time Author Contest 2016

Participated in the
First Time Author Contest 2016

Make It Fly Contest 2016

Participated in the
Make It Fly Contest 2016