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!

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!

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.

phyrmon5 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 acaron1945 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 acaron1945 years ago
I totally agree with this statement.
kateast phyrmon5 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

rlawrence54 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.
photo.JPGphoto (1).JPGphoto (2).JPG
Byoung4now4 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)  butterflycookies6 years ago
Because it is fun!
mwells44 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!!
xolthrax5 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
xolthrax5 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.

xolthrax5 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)  xolthrax5 years ago
Do you have a picture, I would love to see it.
ROSEH875 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'
piropos5 years ago
I don't think the kid is having any fun, judging by the way he looks.
Macka piropos5 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.
regular pvc is rated to around 100 psi and coke bottles can go to around 100. This would be alot safer if you just added a ball valve to the pipe beneath the neck of the bottle, and opened it to fire.
bigfoose5 years ago
Remember that while soda bottles must pass a pressure test without failure, I beleive it is well over 100psi, that water bottles are not required and will very often explode at a much lower psi. Also I don't beleive most white PVC pipe is rated very high for pressure and a PVC pipe can explode with devastating results.
junits155 years ago
if you heat up the launch tube with a blow torch and apply pressure while it's still hot, it will create a taper that the bottle grips very well. this way you don't have to hold it. When I mine was working that was my method, and the bottle will always launch before it explodes. :)
jjay105 years ago
We made one of these at my house and I invited my friends over and we got to launching them at 80psi , and they would go like 100 feet in the air! but then we decided to try and catch them. When we launched it my friend took off run as fast as he could, but he was watching the bottle not where he was going. He ran straight into a mailbox. The owner of the mailbox came running up to him making sure he didn't have concussion. I was rolling on the ground laughing, but he got up and was fine. Good times.
zappenfusen5 years ago
Hot water increases flight exponentially!
CVC9 years ago
i was wondering, wouldnt the water from teh bottle leak down the pipe?
tristantech CVC5 years ago
nope! The air trapped inside the pipe by the valve keeps the water in the bottle.
if it is perfectly sealed, it wont leak!
Gecko23 CVC9 years ago
I just fill the base with water before putting the bottles on, so it has no-where to leak to. Helps keep it stable too.
i bet the overhead launcher is perfect and fun during summer!
 i made a  more complex desghin and it goes heaps far i MIGHT put it up
kgunmaker5 years ago
how much does it cost to make???
bpwagner (author)  kgunmaker5 years ago
You can make 2 for less than $10 if you already have PVC cement and a bike pump.
lockon5 years ago
sounds like a nice project for a hot friday at work just need to amp up the air supply. wish me luck.
nick2237896 years ago
how fare up does that go? how much was all that stuf
bpwagner (author)  nick2237896 years ago
50 to 75 feet
millster7 years ago
Instead of holding the bottle, try a piece of 1/2 ID plastic tubing on the launch tube. Taper the top so the bottle fits snug. I've gotten over 100 PSI before the bottle lets go. (you still get wet) Also found that a 12 volt air compressor sure beats the hand pump...
Bholoo millster6 years ago
The thing i would do is get a release valve and just turn it to the open position at about 80-100psi
but than it will lose presher
kingsbridge6 years ago
As a former Industrial arts teacher who built water rockets with teachers and students I can't stress how dangerous it is to launch rockets the way you do...If someone didn't get hurt yet they will eventually...First no one should be that close to the rocket as it is being pumped up...second, the little boys should be wearing eye protection...Your launcher is well designed, however, you need a way to let the rocket go by using one of the many safer releases you can find in "Instructables" concerning this topic.
kangelo6 years ago
Excuse me, does this launcher work with the litter soda bottle?
bpwagner (author)  kangelo6 years ago
It should work with any bottle that has a 1/2 inch diameter opening. Be careful about pumping up a large bottle with too much pressure. I never go more than about 80 PSI. BTW, the smaller 10 or 12 oz coke bottles work really well.

TRY the link for my instructable its like this but you shoot it off your shoulder and it has a pressure release valve.
my little bro is in cub scouts and they do this all the time. When my friends and I step in, we fill the little bottles of water to the top with water. We calculated that the average height for one of these is around 110, and 140 feet. We hit a max of I think 172 feet.
bpwagner (author)  Thelonelysandwitch6 years ago
There are online calculators that can predict the height based upon PSI and water level.
MindEddy6 years ago
This is a neat idea, but very 'over engineered' in my view and not a great project for young kids as it excludes them during more dangerous (cutting, glue, etc) portions of the project. Simple answer. A few bottle corks, air pump with needle valve (like for balls), and 2 litre plastic Coke bottle. Cork in bottle with different levels of water, stick needle through cork, pump until it taks off. Kids could help entire process and screamed with joy each time it launched and soaked us all. Took turns shooting it over the house. 40-80 feet each shot. Experimented with different water levels to balance pressure with water weight. Found perfect "distance" combo was filling about 2 inches above the bottom of coke label. Next weekend we might buy/find a launch tube (like 6" white PVC maybe?) and build some fins to see if we can get more height. Use your imagination but don't over complicate this. Have fun!! Chaz.
bpwagner (author)  MindEddy6 years ago
I would love to see this... Do you have any pictures?
I guess I should have had some pictures before I opened my mouth, since now I realized the entire point of this site is 'show' and tell.....not just 'tell'. (lol) I just had a 'brain rush' one day (and remembered a friends story) so grabbed a two litre coke bottle out of the recycle bin, shaved to fit and inserted a wine bottle cork(after filling about 30% with water) then put the basketball needle on my bike tire pump - pushed through cork, and started pumping. I had one of the kids lay-low and hold the bottle so it pointed up--and WHOOSH! Maybe later this week I can figure out how to add a few pictures. CC
I like the idea, but the last picture looks like when the kid lets go, it is going to hit him directly in the face. A release connected to a string to launch the bottle would be much safer...just an idea. Good job, tho!
bpwagner (author)  robert.a.scheffler7 years ago
I have had hundreds of kids play with these and have yet to have one hit someone in the face when it is being launched. The real danger happens when kids chase flying bottles while trying to catch it without watching. Kids can smack into each other if they are not watching. Lay out some ground rules before playing. Have fun.
Cybrjinx7 years ago
I saw a kit similar to this that used one of those black pvc with threads on both ends used for sprinkler heads. Use a balloon to make the sides of the pipe thicker and it will hold and release without a person's head near the launch site. Cut the tip off of the balloon though.
Ankush7 years ago
what if ur launchers r long?, how will u prevent all the water from flowing out of the bottle?.
thegunthing8 years ago
hey thats a good idea! i already made a pvc cannon, i just never thought of making it indo a bottle rocket!!
I did. lol thats why i made mine the th right size!!!
O nice instructable
rroll7 years ago
What seals the water in the bottle when you place it on the pvc?
bpwagner (author)  rroll7 years ago
Nothing, it leaks out of the bottle, but by the time the rocket is launched, there is plenty of water left. Go ahead, build one this weekend!
I`ve a funny video! (the first is instructions)

the effect:

DON'T go over 80PSI it WILL blow up in your hand me and my friend almost lost our hearing after it
bpwagner (author)  waterbottledestroyer8 years ago
I believe the rating on a soda PET bottle is over 150psi. It looks like the bottle you used is a water bottle that does not have to normally contain CO2 pressure. As with anything like this, use your COMMON SENSE. I personally cannot hold the bottle on the launcher in this instructable more than about 60 PSI. Be careful and use soda bottles.
Heres a picture
Photo 10.jpg
like you made one!
What do you mean look at the picture
he? sorry.. I cant find `look at the picture` )
if you do it with no water, it makes a huge bang, sounds like a gunshot.
Well I also have a bottle launcher. The diffrence is mine have an almost perfect seal and doesn't lock in place with the thread because The thread will probably wear out when you launch it at about 8-10 bar repeatedly. One problem of mine is it as no valves so your source of pressure must stay connected.
I have got to make somthing like this! Just mine's going to be shoulder mounted, so I can shoot my friends (hee hee hee hee). Trust me, if I really hurt someone badly, I will not -in any way- blame the creater of this "Instructable".
future gun maker if u use vinigar and baking soda don't make it shoulder mounted. I made a shoulder mounted one with vinigar and baking soda and the vinigar spat out on to me. I was not a happy kid.
Great,now make it shoulder mounted.
zachninme8 years ago
I had to build one for school that was much more complicated. It allowed for ajustible angle, 3 rockets at a time, and had latches to hold down the rocket, so you picked when to launch.
bpwagner (author) 8 years ago
I am so glad everyone is enjoying this instructable. Part of the fun is in the reengineering. I like the endcap idea. Recently, I had 70 or so 6th graders playing with a couple of these launchers. I had to tell them to limit theirselves to 60psi. We had one smaller (12oz) coke bottle that flew extremely high. One more thing...these launchers make great gifts. I like to bring them to summer parties and then give it to the host as I leave.
lots of ideas flowing here I think I'll make a turret version that shoots four at a time. Im sure ill find some intresting uses for that.
mobri2a9 years ago
These are great plans. I made one change to the basic laucher: used 45 degree elbows to lay the legs out at an angle, which seems to make it more stable. I also added a simple release mechanism. I used a 3/4 x 1 adapter, threaded on the 3/4 side with a slip fitting on the 1 inch side (fits nicely around the bottle). Use a dremel to grind the inside of the fitting until it fits over the 1/2" PVC pipe. Drill parallel 3/16" holes on each side of the top of the fitting about 1/8" from the top (test location with a bottle inserted into the fitting). The holes need to be space far enough apart to fit over the collar of the bottle without rubbing against it. Slide the completed piece onto the launch tube and glue it in place with PVC cement or epoxy. Use a u-shaped bail made of stiff (1/8") wire tied to a string. Fill the rocket, place it on the launcher, and use the wire bail to hold it in the launcher while you pump it up. To launch, one lucky person has to hold the launcher down while the other pulls the string, pulling out the bail and releasing the rocket. The only down side to this design (besides 20 minutes of grinding with a Dremel) is that the fitting will leak pressure around the mouth of the bottle. I'm considering putting an o-ring in the bottom or using silicone caulk to form a thin "gasket".
mobri2a mobri2a9 years ago
UPDATE: I added an o-ring and the launcher will hold 25 PSI with no problem. We've tested this launcher to 100 PSI. Also, I modified the launch release: drill a 1/8" hole in the side of the release mechanism just above where the ring on the neck of the bottle when pushed down slightly (so it forms a tight seal with the o-ring). Use a piece of stiff wire with a loop on one end for a release pin. Tie a long string to the release pin loop. Fill bottle, place on launcher, push down slightly, insert pin, add air, pull string...go "ooooo....ahhhhh" :-)
Austinisi9 years ago
I saw this and built one for myself. Holding down the bottle was not the limiting factor on how much p.s.i. I could put in it. I liked using an end cap better. I recommend putting an extra end cap where the bottle should go. The cap can go much higher if you push it down the right amount. Obviously, don't hold the cap down wth your hand. The cap works great until it busts. Still fun, though.
bpwagner (author) 9 years ago
Yes it does, but by the time the bottle is launched, there is still plenty of water left in the bottle. The bottle fits pretty tightly on the pvc pipe.
bpwagner (author) 9 years ago
I like your design and the way it is hand held. I will look into the connector. Looks cool. My advice to anyone interested in building water rockets is to just do it. There are so many designs out there, but there are no rules. Just go to Home Depot, buy a bunch of stuff and have fun! These things are a blast!
modnar9 years ago
The shopping list seems to me to be a little more than is needed. Surely for 2 launchers you only need 4 T join pieces (not 8). Looks fun though - might put one together with my young'uns and as you say - get wet.
Hmm, the gif isn't gifing. Direct link >
A good quick release for waterrockets you can get at Walmart for a couple bucks, it's called a "hose coupler". The threads don't match exactly, so you have to either epoxy it to the lid (like in my first one below) or a female connector with plumbers tape. I'll post picks of that later, if anyone cares. Mine is pretty small, so you can pump it up, detach the pump, then carry it around and aim it.
Angry J9 years ago
That makes perfect sense. Thanks for your reply!
bpwagner (author) 9 years ago
I have seen those type of launch mechanisms, one of the most clever being one that used zip ties and a pvc sleeve to hold the bottle on (http://www.smoke.com.au/~ic/cable-tie.html). The reason I like my design is that the bottle is smaller (not 2 liter) and the kid gets to hold the bottle on. The boy above is my son and he has held the bottle for hundreds of launches with no injuries. Ultimatly it gets next to impossible to hold it on past 50psi or so. When it launches, the kid can get wet so that also adds to the summer fun. It is more likely that he would get hurt running to catch a bottle and run into another kid or a parked car or something.
Angry J9 years ago
I really like your design. I helped build a water bottle rocket launcher a couple of summers ago that was much more over-engineered. What it did have however, was a quick-release system so that the bottle stayed on the stand as air was pumped into it. Then, when it was holding about 40 or so lbs, we pulled a string from a safe distance to watch the bottle fly. Do you have any ideas on how to build a similar quick-release system in order to safely add more pressure to the bottle? Again, great design!