Easy to Build, Easy to Use, Water Bottle Launcher!

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Introduction: Easy to Build, Easy to Use, Water Bottle Launcher!

About: I am a middle school computer teacher with an EE degree. I do programming to pay for my teaching habit. I am also one of the founders of LVL1 - Louisville's Hackerspace.

Here it is... a simple water bottle rocket launcher that you can build in an evening and play with the very next day. I first saw this design at the Tunnel Mill scout camp in southern Indiana. Kids will have a blast (no pun intended) launching water filled 20oz plastic bottles 50 ft or more into the air, all the while getting their weekly shower!

Step 1: Shopping (enough for 2 Launchers)

Shopping (enough for 2 launchers)
**** PRINT THIS LIST AND TAKE IT WITH YOU ****

Go to the hardware store and buy...

1 - 10 foot piece of 1/2 inch outer diameter PVC pipe.

8 - 1/2 inch PVC T???s

2 - 1/2 inch PVC elbows

6 - 1/2 inch PVC caps (you may want to buy a couple of extra T's, Elbows and Caps in case you mess up drilling or gluing)

1 PVC pipe cutting tool. Your really don't absolutely need this but it sure make cutting this pipe easier. You can use a hacksaw instead.

PVC Glue and cleaner (primer, often purple in color), comes in a two pack. Your neighbor probably has some you can borrow.

Go to the auto parts store and buy...

2 auto tire valves, also called Schrader valves. The end of them should be able to fit inside a 1/2 inch PVC pipe cap.

You will also need...

several 20 oz soda bottles. The ones that have previously held carbonated beverages. Wash them out or you may get ants!

An abundant supply of water. I like to take a 5 gallon bucket of water out to the launch site.

A standup bicycle tire pump.

A supply of neighborhood kids with dreams of becoming Astronauts! They will get wet!

A nice sunny day!

Step 2: Cut the Pipe!

Using the handy PVC pipe cutting tool, cut the pipe into eight (8) one foot sections and four (4) six inch sections. Use a permanent marker and a ruler to measure before you cut. Measure twice, cut once!

Step 3: Drill the Cap.

Put one of the pipe caps into a vice and drill a hole on the top of it that is big enough to fit the tire valve. You will only need two caps with holes in them (one per launcher). Go ahead and insert the valve into the cap from the inside, with the connector facing out.

Step 4: Glue the Contraption Together.

It is now time to take your project outside because PVC pipe glue fumes can knock you out. Lay the pipes out on a drop cloth or newspaper. Read the instruction on the PVC primer and glue! Use the purple primer to clean the ends of the pipes and the insides of the caps, elbows and T's. Carefully apply glue to the pieces and fit them together. You do not have to glue the valve to the cap, air pressure will do that job. This is not rocket surgery (or maybe it is), there really is not much you can mess up. If you do, cut the pipe off and try again. A few inches here and there are not going to hurt your launcher.

Let the glue set overnight. Have a break; drink a 20oz soda or two.

Step 5: Launch Day!

Gather your launcher, kids, 20oz soda bottles, bicycle air pump, a big bucket of water and excitement and take them to the launch area. Your launch area should be an open field, back yard, cul-de-sac but probably not your mother-in-law's living room.

Hook the pump to the tire valve. Fill your 20oz soda bottle 1/4 to 1/3 full of water. Carefully and quickly shove the soda bottle down on the launch pipe. Some bottles will fit on easily; some are going to be much tighter. Hold the soda bottle with your hands and have another person pump air into the launcher. When the air pressure is too great to hold, let go! KEEP YOUR FACE AWAY FROM THE PATH OF THE ROCKET! I told you that you would get wet.

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    105 Comments

    were I can get the valve online in Pakistan please reply with the link

    This is a great idea! One major safety issue is that it is EXTREMELY dangerous to let kids hold the bottle while it is being pressurized. If the bottle hit someone or exploded at high pressures, someone could get seriously injured. I would consider using a release mechanism of some sort and an air hose to stay far away from the rocket. I can tell you it isn't fun to have your rocket explode on the launchpad.

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     PLEASE!!!!  DO NOT LET THE CHILDREN HOLD THE BOTTLE!!!!  I looked these up today after playing with three of them yesterday at a cub scout campout.  They are TONS of fun, but potentially harmful.  Twice, we had the 16 ounce soda bottle explode while still on the launch tube while being pumped up.  The potential energy is TREMENDOUS and capable of damaging hands if a child were holding it and the sound was deafening, much greater than my 12 gauge.  I noticed the PSI reaching 80, 90, and 100 before the bottles would break loose at times.  So PLEASE PLEASE PLEASE don't let the kids hold the bottle on.  Configure another way to secure the bottle and it will be tons of safe ( well, "safer", fun)

    2 replies

    I just wrap some self-adhesive silicon tape around the opening a couple times and then screw the bottle onto that. It holds the bottle on until the pressure is high enough to blast it off.

    I agree....I am a science teacher and use a similar set up with kids at school and summer camp. But DO NOT let them hold the bottles! You can rig up a remote release of some kind. Letting the kids hold the bottle is only asking for trouble - I know from experience it hurts to get hit by a bottle and I can't imagine the potential damage to a child's face!!

    I hate getting wet, so I put on safety gogg

    Has anyone ever tried making a setup with the rocket 'nozzle' smaller?
    In other words not using the full size open soda bottle, but somehow going to a lower dimension?

    Seems to me it might go a lot higher as it would likely propel for longer rather than exploding it all out at the same time.

    2 replies

    Absolutely smaller nozzle openings can and are being used. I just scrounged from odds & ends I have gathering dust in odd corners of my barn but, in reading around the web I have found a number of references to 8mm & 9mm openings- whatever those may be. I'm an old, unreconstructed "INCH" measure man myself.
    What you are trying to balance is a reduction of thrust to an lengthening of time of thrust. Reduce the outflow too much and you gain nothing or even lose in height. You already know the obverse.

    I agree that children need to have responsibility and be allowed to take certain risks. But there is no sense in pointless and UNnecessary risks when they can be so easily avoided. We would do better to suggest alternatives, which is what I'm doing.
    There is a super simple launch release method employing a lanyard described on Instructables and elsewhere on the web. Simply fasten the end of plastic tie straps- the kind that slip through one end and locks where set, so the the raised portion of the catch end will fit over the flange on a bottle mouth. Have a pvc "coupling" that will slide over them clamping the tie ends tight over the mouth flange holding your bottle on the launch tube. Fasten a string to the pvc coupling hanging it down and turning it horizontal through some device to hold it, a pully or board with a hole, any such thing. When the lanyard is pulled, the tie wraps relax, releasing the bottle and everybody is well out of harms way.
    I know my description is vague but a search will turn up many illustrated and video tutorials.
    Good luck with your project! :)

    I am a teacher and want to use this for a lesson. I've attempted building it with a friend for the past week and CANNOT get it to work. Here's our problem: without any fastener on the open end of the PVC (where the bottle is supposed to go) all of the water drains into the piping (naturally). Did you use any stopper? We tried using a cork then put holes in the cork, but it always managed to find a leak. We tried to seal the leaks with piping glue and then later with duct tape. None of this seemed to work.

    SUGGESTIONS, PLEASE!!! We want to present this lesson in a few days!!!

    2 replies

    I too am a teacher and I used these with 6th graders just the other day. The water from the bottles does flow into the piping as you are firing the rocket. In fact, if you pump on the bike pump with no bottle on top, then water shoots out the center pipe... What you have to do, is fill the 20oz soda bottle (not a water bottle!) about half way. Then flip the bottle over quickly over the pipe end and the have another person pump the bike pump while you are holding the bottle on. During this time water WILL drain out the bottle. Keep pumping until you cannot hold the bottle any more or until there is about an inch of water left. The bottle should fit fairly tight against the outer diameter of the pipe.

    When doing this with kids, be sure to have a safety briefing. I tell them not to go above 60psi, not to run when they want to chase the bottles and also to keep their face away from the bottle. They also wear safety glasses! Even so, I had one girl get a bloody nose from a bottle being launched. USE COMMON SENSE! Keep your face away from the bottle trajectory! If you are still having trouble, keep posting until we figure out your problem! Post a pic of your launcher if you need to.

    Brian

    I am not a teacher, but have a science degree and >15 years of quality control experience. I have been building launchers and rockets for more than 3 years and have never had a failure(explosion). There have been a few "miss-directed" launches, but no injuries. My favorite launcher included a quick connect for water hose and a launch cord so I control when the rocket takes off. I also incorporate a one way valve just below the quick connect that minimizes the amount of water that gets forced into the launcher. To utilize the quick connect I use a little JB Weld to attach a couple of eye-screws and then the launch cord attaches. When I am ready for launch, I just pull the launch cord and the quick connect releases the rocket. Finally, I use an air compressor for this. I have been using pressures from 80-110psi with no problems. Plus with a long launch cord I am out of the way. By using the correct type of PVC cap, the air hose connector can be screwed into it and it will seal great. Always consider who will be in the area when launching. Little kids must be kept in a safe location, but then so should adults. This is one of the funnest pass-times I have found, but we always have to consider the risks and take appropriate measures.

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    Great idea and a lot of fun. Changed the design for mine a little and hooked it to the compressor to make it less work. :-) The valve on the left from the compressor we would turn on and off to charge the base. Then once the bottle was in place the ball valve on the right would launch the bottle. I put a straight connector in launch tube to hold a Lid and some o-rings. this made for a better fit of the bottle and gave the water a little more to push off of. I started with the compressor out put at 60 and gradually bumped it up to 90. Definitely use the stronger soda bottles and not the thin walled water bottles. It blew holes in the sides of the water bottles. Lots of great wet fun. Thanks again for the idea.

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    3 replies

    Hey there, we constructed something similar and ended up using bands of plastic supermarket bags to 'gasket' the bottle on to hold it. It works well but erratically (sometimes 40psi, sometimes 80) before it blasts off. That said it really holds the water in well.

    Can you explain the O-ring idea? I've also heard tale of using cable zip ties to somehow use as a switch, but it doesn't really get past this initial sealing of the bottle/water issue that I would like to fix.

    If I'm right in thinking, you have an outer sleeve over the 1/2" PVC with an O-Ring inside that sleeve that the soda bottle rim can push into? I'm thinking that it would still allow water to seep out between the launch 1/2" PVC and the rim of the bottle.

    Take a look at this instructable
    https://www.instructables.com/id/water-rocket-launcher/step3/step-3/
    Which puts a bulge in the pvc pipe to a more snug fit
    Or like one of the comments on that one You can take a small file and put a groove in the launch tool for the Oring to snap into.
    I used an oring that normally goes on a paintball tank but you can find them in the hardware store.
    If you buy the o-ring from a non-paintball retailer, look for the standard 015 size o-ring - it has an inside diameter of 9/16th of an inch, an outside diameter of 11/16th of an inch and is 1/16th of an inch in diameter.
    HTH

    for a science project , and what bpwagner said

    Because it is fun!

    i am using an air compressor , we tryed a bike pump and it didnt work as well