Easy to build, easy to use, water bottle launcher!

Picture of Easy to build, easy to use, water bottle launcher!
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!
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Step 1: Shopping (enough for 2 launchers)

Picture of Shopping (enough for 2 launchers)
Shopping (enough for 2 launchers)

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!

Picture of 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!
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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.

phyrmon4 years ago
 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)
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.
your a bloody wimp let your children have some responsibility don't shelter them otherwise they will never learn to be an adult and that accidents do happen. I hate parents like you ruining fun and killing there kids by protecting them.
Jaygo acaron1942 years ago
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! :)
No one is a 'bloody wimp' who keeps a child from being a 'bloody hospital case'. Phyrmon didn't say 'wrap your children in bubble wrap and keep them indoors 24-7. He implied they might lose an eye or be deafened by the blast. Sounds like good sense to me and the warning was wisely stated.
well seeing as phyrmon doesn't realize along with you that children need to suffer to grow up and if they or there parents aren't smart enough to tell there children that they should not have there face directly above the bottle that is going skyward I do agree that safety or sunglasses would be a good idea but not a necessity
Can you say, "child endangerment?"
I built a launcher that can be pumped and launched from 10' away.. it is safe and my son and his friends are learning.. safely. this is not about avoiding suffering, this is about avoiding damage.. suffering is acknowledging pain and working through it for a purpose.. like survival, competition, or some sense of accomplishment. You are correct in that there is much to be learned, builds character, etc. Permanent Damage is something you see every time you brush your teeth, and you learn fear, hate, and distrust. I speak from experience, any knowledge you could gain is NOT worth it. scar your own kids, its your right.
Macka acaron1944 years ago
You don't need to wrap children in bubble wrap to teach them a bit of safety and common sense; it's one thing to "suffer" a from a mistake, it's another thing to lose an eye or to have shrapnel embedded in your cheeks. Safety can be taught to children without them ending up in hospital or seriously injured. Children love water rockets, if every child had to learn not to put their face over the rocket when launching then we would have a lot of injured (possibly blind) children. You don't send an electrician out to do work if they haven't been taught about safety; they may make a mistake and learn not to do something again, but it may be their last lesson. You don't send a civil engineer to build a bridge without first teaching them about construction and what can go wrong. If you don't teach them, accidents will happen and they will learn their lesson, however is it better for them to learn in the classroom or for people to die?
As... Blunt as acaron194 is, I have to agree. The common sense thing here is to not be stupid - a typical soda bottle will reach its bursting point around 110 PSI.. so you should never charge a bottle higher than 80 or maybe 90 psi. Never charge a stressed or damaged bottle (look for white marks in the clear plastic). Eye and ear protection is recommended when working near the launch pad. If you want, you can also rig up a remote launch system like mythbusters in the Bottle Rocket Blastoff episode with little more than some zip ties.
for anyone wondering you can buy special remote bottle releasers made for this specific purpose now if i could only remember where to get them from...........
cdh acaron1944 years ago
I totally agree with this statement.
kateast phyrmon4 years ago
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!!
DanTDM1 year ago

I hate getting wet, so I put on safety gogg

rlawrence53 years ago
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.
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 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!!!
bpwagner (author)  asianpower894 years ago
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.

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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Byoung4now3 years ago
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.
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
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.
Many thanks!
why would u want this
for a science project , and what bpwagner said
bpwagner (author)  butterflycookies5 years ago
Because it is fun!
mwells43 years ago
i am using an air compressor , we tryed a bike pump and it didnt work as well
dude, I built this thing a few years back, and its one of the best things ive ever made off instructables!!
xolthrax4 years ago
here are schematics of my newer designs. One can launch 2 rockets at a time, so I can demonstrate the difference between adding water and not adding water. The other has interchangeable launchers (rocket and balloon).

double water rocket launcher.JPGwater rocket & balloon launcher.JPG
xolthrax4 years ago
Here it is with the ball valve. I have since also added a check valve. The check valve prevents any water from being drawn back into the launcher and therefore into the pump. I had a piston sieze on my pump because of drawing water back in.

I have built some bigger, better designs in the last few days including one that is interchangeable between water rockets and water balloons. I'll try to post them soon.

xolthrax4 years ago
I built 2 of these for under $20. I made one important modification: I added a ball valve to the rocket pipe. It allowed it to be operated by one person. You pump the air into the launcher and then just open the valve. That way no one has to hold on to the rocket. Much to my surprise, I found that they were both easily capable of 150 psi without any problem. You're putting the pressure on the PVC, not the bottle, so no bottle explosions. I agree that you need to make sure you are using pressure rated PVC. You can use 1L or 2L bottles as well. The bottles form a pretty tight seal on the PVC, so you don't need to worry about the seal. I am working on a design that routs the launch tube back towards where the fill valve is and has the ball valve there and then returns the launch tube away from the operator. That way you can launch it without getting soaked or worry about being hit by the bottle. One caveat: if you don't use a ball valve, you are invevitably going to ruin your pump. It is going to invevitably draw water back into the pump which can cause a vacuum that siezes the pump piston. If you use a ball valve and ensure that it is closed prior to mounting the bottle, no worries.
I have been monkeying with a few more designs. As soon as I get a chance to assemble and test them, I'll take some picutures and post them.
bpwagner (author)  xolthrax4 years ago
Do you have a picture, I would love to see it.
ROSEH874 years ago
I agree, there are a lot of pieces that don't seem needed in your list. Either way though, what do you think this project would run price wise, for one launcher?
bigboehmboy9 years ago
Quick question, what is keeping the seal between the lip of the bottle and the pipe, is that done by sipmly holding it in place?
in this design, yes.. but you can heat and compress the pipe lengthwise and it will bulge to create a good seal... there is a MUCH SAFER design, with a reliable release, check my slide show, and the link to the original 'iblr'
piropos4 years ago
I don't think the kid is having any fun, judging by the way he looks.
Macka piropos4 years ago
I'd say he is just bracing himself to get soaked. In my experience, most people pull a face like that when they are about to set off a water rocket, even if they are a short distance away with a remote release mechanism.
This is a cool instructable but a little bit dangerous if you don't use some safety measures. The first being the PVC being used. Is it pressure rated PVC? if not it can shrapnel at a unspecified PSI. Look up potato launchers and all of them stress having PSI rated pipe for a reason. Second, having the child hold the bottle isn't a great idea. It has no reason to shoot straight up vs at an angle into the face. The design I saw had a 2x4 mounted above the long run of pipe with the launch tube through it. A 1 1/2 inch cap was mounted with around the launch tube attached to the 2x4. It has two holes drilled through it and pins put in place that held the top of the 2 liter bottle. A string was attached to the pins which allowed the safety release to be pulled from 5 feet away. You still got wet don't worry. I would also put a air gauge into the pvc so you would know what level you were at and when to pull the pin. Going off how strong you are and what level of psi you can hold it to is just plain moronic and asking for a child to be marred for life. Just my 2 cents as an Eagle scout that played with these, as well as a professional Safety Manager.
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