SodaJet Rockets




Introduction: SodaJet Rockets

About: I'm a licensed PE with expertise in embedded and RF systems, especially "Internet of Things" product design. I've spent almost 2 decades developing industrial, military, and consumer electronics products, and…

Launch an empty 2 liter bottle 100 feet into the air with this easy-to-build launcher. Get the 3D printed parts, or a full kit, by backing my Kickstarter before December 31, 2014, HERE. After the Kickstarter concludes on January 1, 2015, you can contact me for parts HERE.

Step 1: Collect the Materials

You'll need to purchase the following parts to get started:

  • 2 five foot pieces of 1/2" PVC pipe
  • 4 PVC 1/2" 90 degree elbows
  • 2 PVC 1/2" T fittings - all solvent weld joints
  • 2 PVC 1/2" T fittings - base of T is threaded, 2 ends are solvent weld
  • 1 PVC 1/2" cap
  • 1 PVC 1/2" threaded male adapter
  • 1 PVC 1/2" coupling (optional)
  • 1 pipe clamp, 1-1/4" minimum
  • 1 standard valve stem
  • 15 cable ties - 6" length
  • Teflon pipe sealing tape
  • PVC cement (may also require PVC primer, depending on cement type)
  • soda bottles for launching (2 liter bottles work well, most 1 liter will also work)
  • small candle, and a means by which to ignite it
  • 2 - 6 rubber bands, ponytail holders, or the like
  • 2 #6 machine screws 1" or longer
  • 2 #6 flat washers and nuts (optional)
  • 3D printed latching mechanism (4 pieces) from my Kickstarter, again HERE or HERE
  • 20 - 30 feet of heavy synthetic cord (such as mason's twine)

Step 2: Gather Tools

You'll also need:

  • hacksaw, or miter saw
  • screwdriver
  • drill
  • drill bit - 37/64" preferred, but 9/16" will work, and 1/2" in a pinch
  • channel lock pliers (or gloves and a strong grip)
  • rubber headed mallet

Step 3: Start Assembling the Base

Create 2 identical T assemblies for the base. You need:

  • 6 pieces of pipe, cut to 9"
  • 2 T connectors, both of which have 3 solvent weld connections
  1. Apply PVC cement to one opening of a T connector, and then to one end of a 9" piece of pipe. Press the two glued pieces together with a slight twisting motion. Be sure the pipe is fully seated into the T connector by tapping it with the mallet.
  2. Continue assembly by gluing the remaining 5 pieces into the other openings of the 2 T connectors as in step 1.

Step 4: Complete the Base

Complete assembling the base of the launcher. For this step, you'll need:

  • 1 T connector, which has 3 solvent weld connections
  • 1 T connector, which has a threaded base connection, and 2 solvent weld connections on the "ears"
  • 2 pieces of pipe, cut to 9"
  • 4 elbows
  • EITHER one piece of pipe, cut to 19 1/4" OR 2 pieces of pipe cut to 9 3/8" plus the coupler. It is simpler to use the single longer piece of pipe, but you may need to couple shorter pieces, depending on how you have cut up your pipe so far. Make certain to reserve one section of pipe 18" to 22" long for the launcher tube in a later step. The launcher tube must be constructed of a single length of pipe, with no couplers.
  1. Glue the T connector with the threaded base to the sub-assemblies from the last step, forming a capital "H". The "bases" of the T sub-assemblies should be inserted into the "ears" of the T fitting. Once glued, make sure that both sub-assemblies lie flat (check it on the floor or a table) and that the threaded port of the T connector is pointing directly up. This will ensure that your rockets will be launched directly skyward. For future reference, we'll call this the "H" assembly.
  2. Glue one elbow onto each of the remaining 9" pieces of pipe. Glue the other end of each piece of pipe into the "ears" of the remaining T connector with the 3 solvent weld ports. Once glued, make sure that the elbows lie flat, while the base (unthreaded) port of the T connector is pointing directly up. This port will become the air fill port, in later steps.
  3. Glue the two elbows into the two lower legs of the "H" assembly. Work quickly, ensuring that the entire assembly lies flat once assembled.
  4. Complete the upper legs of the "H" assembly with the remaining 2 elbows, and EITHER one 19 1/4" piece of pipe, OR two 9 3/8" pieces of pipe and the coupler.

Step 5: Build the Launch Tube

Build the vertical launch tube and latch that holds the rocket in place. For this step, you'll need:

  • 1/2" PVC male threaded adapter
  • 18" to 22" section of 1/2" PVC pipe
  • 1-1/4" hose clamp
  • 10 to 15 cable ties, 6" long
  • electrical or other tape (helpful, but not necessary)
  • small candle
  • 1 2-liter soda bottle for test fits
  • Teflon pipe tape
  1. Light the candle, and allow it to pre-heat.
  2. Mark a line around the perimeter of the 1/2" pipe, 11" from one end.
  3. Hold the pipe over the candle, and gently heat the line you just marked. Continuously rotate the pipe, "rotisserie style" so that it doesn't scorch or burn. Continue heating until you feel the pipe start to bend, which means that the area has softened.
  4. Remove the pipe from the heat, and compress the length of the pipe, forcing the heated section to gently bulge outwards. Only a slight bulge is necessary - aim for an increase in diameter of 1/32" to 1/16". Sight down the center of the pipe and ensure that you have not introduced a bend. Allow the pipe to cool until it has hardened.
  5. Test the fit of this tapered bulge by inserting the 11" section into a 2 liter bottle. The opening of the bottle should gently jam against the bulge such that the tip of the pipe is about 1" from the inside bottom of the bottle. This arrangement will allow air to pass into the bottle, but prevent the backflow of water. The jam of the taper against the bottle opening will prevent the water from leaking from the rocket. Make any necessary adjustments by repeating steps 3-5 above.
  6. With the bottle in place, arrange the cable ties such that the heads latch into the rim around the neck of the bottle. Temporarily tape the tips (opposite the heads) of the cable ties in place to hold them.
  7. Install the 1-1/4" hose clamp around the tips of the cable ties, such that it is approximately 15" from the end of the pipe that is inserted in the bottle. Tighten the clamp firmly to secure.
  8. Glue the threaded male adapter onto the pipe on the end opposite the bottle.
  9. After the glue cures, wrap the male threads with 2-3 layers of Teflon tape, and screw it firmly into the threaded T fitting in the center of the launcher base. Use a gloved hand or channel lock pliers to secure the joint, but do not over-tighten. This joint can later be disassembled to make the launcher easier to transport.
  10. Blow out the candle, lest you burn down your abode.

Step 6: Add the Air Port

Add the air port to the base. You'll need:

  • tire valve
  • 4" to 6" piece of 1/2" PVC pipe
  • 1/2" PVC end cap
  1. Drill a hole into the center of the 1/2" end cap with the 37/64" drill bit. It's an odd sized bit, so if you must, drill the hole smaller, and then enlarge it a bit with the tip of a knife or a rotary tool.
  2. Check the fit of the tire valve, by inserting it into the open end of the cap, pulling the stem through the hole. Pull the stem gently until the valve base seats correctly. Make any adjustments to the hole size, as needed.
  3. Remove the tire valve, apply glue to the inside of the hole in the cap, and reinsert the valve.
  4. Cut a piece of 1/2" pipe to a length of 4" to 6". Glue this pipe into the cap.
  5. Glue the air port assembly into the T connector (that has the solvent weld port) on the outer rim of the base. This extra pipe creates an air chamber in the launcher, which will help keep water away from the valve as it occasionally leaks into the base of the launcher.

Step 7: Assemble the Latch

This step adds the latch mechanism, which completes the launcher. You'll need these parts:

  • 2 3D printed stopper clamp pieces (bottom right of photo)
  • 1 3D printed cable tie retainer tube (left of photo)
  • 1 3D printed firing chock (top of photo)
  • #6 fasteners
  • rubber bands or ponytail holders
  • pull string
  1. Remove the bottle from the launcher.
  2. Using the #6 screws, attach the 2 stopper clamp pieces around the base of the cable ties, just above the hose clamp. The screws will thread into the holes of the stopper clamps, but you may wish to supplement this connection with the optional washers and nuts.
  3. Slip the cable tie retainer tube over the top of the launcher, and over the heads of the cable ties. The 4 square projections should be pointing upward.
  4. Reinstall the bottle on the top of the launcher. Make any necessary adjustment to the position of the cable ties such that they engage the rim of the bottle, while the bottle is wedged on the tapered section of the launcher tube.
  5. Slide the retainer tube upward so that it neatly collects the heads of the cable ties around the upper opening. The 4 square protrusions on the top of the retainer tube should gently touch the curved top of the bottle.
  6. Any time a new bottle is used, steps 4 and 5 must be repeated to re-calibrate the latching mechanism.
  7. Stretch the rubber bands or ponytail holders around the ears of the stopper clamp, and up to the ears on the retainer tube. Use one or more bands on each side, as needed, to ensure the retainer tube is reliably retracted away from the bottle.
  8. Thread one end of the pull string through the hole in the firing chock, and tie it firmly. Use several knots to ensure the line is firmly fixed.
  9. Insert the firing chock between the stopper clamps and the retaining tube so that the tube is held upward against the bottle. If necessary, adjust the position of the stopper clamps so that there is a total of about 1/16" play between the 3 pieces.
  10. Test the latching mechanism before pressurizing the system. Quickly tug the pull string so that the firing chock is completely removed from the launch tube. The retainer tube should then drop downwards (assisted by the rubber bands) and allow the cable ties to open freely.

Step 8: Wait

Allow the entire assembly to cure for a minimum of 24 hours before pressurizing. If you do not, joints are likely to blow apart, ruining your assembly, and possibly injuring someone.

Step 9: Check for Leaks

  1. Install the bottle and set up the latch mechanism by installing the firing chock as was done during the previous steps.
  2. Attach the bicycle pump to the tire valve and inflate to a pressure of 20 PSI. Remove the pump, and listen carefully for any air leaks. Watch the pressure gauge on the bicycle pump for 5-10 minutes to verify that there is no loss in pressure. Remember - your system is pressurized - treat it with the full respect of a loaded weapon, and do not leave it unattended.
  3. If any pipe joints leak, repair them immediately, and do not pressurize the system further until the repair is verified with another leak test.
  4. If air is leaking around the base of the bottle, gently depressurize the system, make the necessary adjustments to the latch mechanism, and then retest.
  5. Once a pressure test is completed successfully, gently depressurize the system and prepare for the launch...

Step 10: T Minus 9...8...

  1. Fill the soda bottle about 1/3 full with water.
  2. Lean the entire launcher to one side, so that you can insert the bottle over the launch tube, without spilling much of it.
  3. Set the latching mechanism and insert the firing chock so that the bottle is latched in place.
  4. Set the launcher upright, and be certain that the rocket is pointing directly skyward. Consider the direction of the wind, your immediate surroundings, and likely locations where the rocket could get stuck in a tree, break a window, or injure someone. Plan accordingly.
  5. Place the pull string in a location where it will not be accidentally triggered.
  6. Place 10 - 20 pounds of weight around the base of the launcher so that it does not tip over when the pull string is activated. Sandbags are the optimal choice, but large logs or large flat rocks will also work. Place these weights gently, so as not to damage the pipe around the base of the structure.
  7. Attach the bicycle pump, and begin pressurizing the system. Eye and face protection are strongly advised.
  8. It is recommended to begin with modest pressures of around 20 PSI until you are confident with the system, and you know what to do if and when a jam occurs.
  9. Gently stretch the string until all of the slack is removed.
  10. Begin your count down - the big moment is now here!
  11. Tug the string sharply to remove the firing chock, but not with excessive force. A quick snap of the wrist is all that is needed. Do not pull too slowly, or the launcher may begin to lean towards you. A misfire at this point could send a rocket directly at you.
  12. Have fun, and don't get cocky. 60 PSI is more than enough pressure to create an impressive launch. Work up to this pressure slowly to be sure your launcher is working well. Use extra caution as pressures increase, as the potential for a mishap increases dramatically.
  13. Seriously, DO NOT GO OVER 60 PSI, or you're risking life and limb. It's all fun and games until someone loses an eye. Or kidney.

Step 11: Rocket Level: Expert

Add a nose cone, parachute container, or stabilizer fins by helping me reach my stretch goals. Once more, that Kickstarter project is here: SHAMELESS PLUG

Good luck with your build!

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    7 years ago on Introduction

    I always used vinegar and baking soda, never bothered to see how high they shot but half the time I couldn't find the bottles afterwards


    Kudos on the project. I really like the idea. The steps are well documented. The end product is whimsical, educational, and fun for the kids. What I'm not happy with though is that this is only a giant plug for your Kickstarter campaign. There is no way to use this Instructable without waiting 2-5 months to receive a latching mechanism from your Kickstarter. Suggestion: Post your STL files so that people can use this Instructable rather than just read it. If your Kickstarter provides sufficient value add, people will still fund it.


    Reply 7 years ago on Introduction

    There's no secret that I'm trying to promote my Kickstarter - it's the first thing mentioned in the project. However, I have decided to make the STL files available through the Kickstarter, to help those with printers while still supporting the project goals. Thanks for the feedback!


    Reply 7 years ago on Introduction

    Luckily there are other Instructables about latching mechanisms if you can't wait, this one looks pretty similar:

    The old water rocket launcher I used slipped a U shaped metal piece through some holes in PVC around the collar of the bottle and could be yanked out causing launch.


    Reply 7 years ago

    that's a good solution. better than the one I used:


    7 years ago

    I appreciate the feedback, but I thought I was being helpful by providing the instructions for free. My goal with the Kickstarter is to provide injection molded parts if I reach the stretch goal. I may post the files if the project is funded, but posting them now would undermine the project. Most folks seem to be understandable.


    Reply 7 years ago on Introduction

    Brilliant launch mechanism invention!

    That said, without the parts, the Instructable is clearly not"helpful". :-(

    Litmus test: read this instructable to my 8-year old daughter, and watch the sadness on her face when I say, "Sorry, hon, this does look awesome, but we can't build the launcher unless this guy gets way more money, and then we'll have to wait another month or more for him to print all the parts he's promised, and he might never actually print the parts... so Daddy isn't going to give him $25."

    $25 to print, mail parts, pay fees/taxes, isn't unreasonable, but it also isn't scalable, creates four low-quality parts that are super expensive... especially for the handful of people who own a 3D printer, or know a buddy eager to print anything on his for the joy of justifying the printer to his Wife!

    Suggestion: convert that small group of people into advocates for your campaign by posting the STL files now... and if you can, mod the KickStarter so $5.00 (early birds) and $7.50 (later birds, to test pricing elasticity) nabs an Injection MoldedLaunch Mechanism.

    After my buddy prints one and we try it out, we'll both happily throw $10 bucks each at you for some pro-quality injection molded versions that slide better.

    Otherwise, I'm confident somebody else will create a similar mechanism and post the STL files.


    Reply 7 years ago on Introduction

    Thanks for the feedback, and suggestion. I wasn't considering the folks with their own printers when I created the project. I've made my STL files available as a reward on my Kickstarter. Hopefully, that will help those with their own printers to get started building a little faster.


    7 years ago on Introduction

    Why don't you post the .dwg for the release mechanism? That way your instructable would be reproducible, and everyone in the DIY community that you piggie-backed off of to build your rocket in the first place would be happy, because you gave back to the community rather than trying to sell your small contribution to their ongoing work back to them! That would be nice :)


    7 years ago on Introduction

    This is a bold faced AD. You are the epitome of the American way just in the wrong place.


    7 years ago

    I like it. Barbie goes to outer space. Maybe take that cheating Ken with her !


    7 years ago

    Been doing soda bottle rockets for years as a kids program. You have inspired me to post the build of my launcher also.

    How well does the latch work in practice compared with other types of designs? I'm currently using the NERDS launcher with the pneumatic actuator but I've built three or four other launchers.

    Nice write up and great pics.

    Also if you don't 3d print the fins you can make them from cardboard, foam, or corrugated plastic signboard


    Reply 7 years ago

    I tried a few spring based designs, and they jammed often. Sometimes, the spring got weak, and the launcher fired early. That's what led to the rubber bans based design, with the chock that gets removed. It provides a mechanical advantage vs. compressing a spring.


    7 years ago

    PVC under air pressure is subject to catastrophic failure from shock/impact. When it fails it shatters into extremely lethal pointy bits. I would not proceed with this project without armour plating my children


    Reply 7 years ago

    Thus my warnings to not exceed 60 psi, and to keep kids well away when launching. Thanks for the feedback.


    7 years ago on Introduction

    Best of all ... the girl has clearly discovered
    that rockets are way cooler than dolls and is sending her Barbie on a one-way
    trip to the moon.