2L Bottle Rocket Launcher

This 2L bottle rocket can send a bottle flying over 50 feet in the air. It also has a release mechanism that prevents the bottle from firing until you're at a safe distance away from the rocket.

See the Tutorial on TikTok

Using 1/2" PVC and a few fittings you'll be blasting bottle into space in no time.

• 1/2” Schedule 40 PVC
1/2” 90° Elbows PVC
• 1/2” Slip Tee PVC
• 1/2” End caps PVC
• 1/2” Male Threaded Coupler PVC (optional)
• 1/2” Female Threaded Coupler PVC (optional)
• 1 - 1/4” Coupling PVC
• 0.453” Schrader Valve
• 1/2” Hose Clamp
• 1 - 3/4” Hose Clamp

• 7/16 in. x 1-1/2 in. Extension Spring
• 
PVC Glue/Cement

• Duct Tape
• 8” Standard Outdoor Zip Ties

First measure out each of your pieces. These don't need to be perfect and can be adjusted slightly as you prefer.

For the Base you'll need

• 2 x 11" Cuts (for Base)
• 2 x 6" Cuts (for Base)
• 1 x 4" Cut (for Base)
• 1 x 2" Cut (for Base)
• 1 x 16" Cut (for Nozzle)

Once you've measured them out feel free to cut them all out.
You can use a hack saw, pipe cutter, mitre saw, or anything else that works.

Once you've cut all your pieces clean the cut ends with a knife or sand paper.

Place 1 of your end caps to the side. DO NOT GLUE THIS CAP YET.

Glue the rest of your fittings and pipes with PVC Cement.
When glueing give them a quarter turn to make sure they've had a chance to mate and spread the cement all around inside the joint.

Glue the fittings for both the Base and the Nozzle.

Note
The threaded coupler is optional and make it slightly easier to store. This is completely optional. You could just glue add a 3 inches to your nozzle length and glue it into the elbow if you don't care to split the launcher into 2 parts for storage.

The Schrader Valve will be placed on one end of the base.

Using a 1/2" Drill bit drill a hole through the end cap.
Clean the edges with a knife, sand paper, or a deburring tool.

Pull the Schrader Valve through the cap, make sure it's seated, then glue it on to the base.

Measure your nozzle so the pipe goes to about 3/4 of the way inside the bottle. If you do it too short water will enter the launcher and limit the height of your rocket launch. (water is the main propellant of the bottle, so the more water left in the bottle the higher it should launch)

Make a mark on your nozzle.

Take a lighter or heat gun and warm around your mark on the nozzle.

Once the pipe starts to soften, push both ends of the pipe together to create a subtle bulge on your line.
This doesn't need to be huge, as the 1/2" pipe may already be a snug fit inside the bottle.

This will seal the bottle so water doesn't escape before launching.

The zip ties will act as the locking mechanism to keep the bottle on while pumping.
Measure out the circumference of the pipe and mark it out on your workspace
Place a piece of duct tape sticky side up and evenly space out your zip ties on the tape.

Leave a little space so they don't overlap when they wrap around the pipe.

Place the bottom on your nozzle, and push it down to where it just barely starts touching the bulge we melted into the pipe.

Don't push the bottle down too far or it will take a lot more pressure to release from the launcher.

Once you've found a good place on the pipe, then take your duct tape and wrap it around the bottle so the zip ties rest just above the ledge on the 2L bottle.

Secure your tape/zip tie mechanism with a 1/2" Hose clamp.

If you have a 3D Printer you can print the following part to use as a channel for your trigger:
https://www.thingiverse.com/thing:4911825

Once you have the part, attach the spring to the guide, and then zip tie the guide above your hose clamp on the nozzle.

The arm that connects the 1-1/4" coupler and the spring is just a piece of PVC I cut with a jigsaw. It just needs to be about 8 inches long and thin enough to slight in the 3D Printed guide.

If you don't have a 3D Printer you could easily use a couple zip ties as seen in the other image. If you do this you don't need a spring either. The zip ties are springy enough, but will eventually wear out over time.

If you used Zip ties, connect this string to your collar.

If you 3D Printed the part, tie the string to the arm, which you can connect with the larger hose clamp to the collar. You can also use a bit of glue, or double sided tape to make sure it stays put.

For both, you'll want to add zip ties below the hose clamp at the base so the string pulls downward, not sideways.

Please don't try immediately. The PVC Cement needs time to cure and fully bond, or it may pop apart while you pump.

When you attach your bike pump, you'll want to add 40-60psi before launching the bottle.