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Big Freaking Water Rocket Launcher

by cgapeart, published

Big Freaking Water Rocket Launcher by cgapeart May 24, 2014
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4487Views 575Downloads Found in Sport & Outdoors


I want to turn a 15 litre water cooler bottle (the non-deposit kind made of of heavy pop bottle plastic) into a big freaking water rocket.

This design is untested, use at your own risk. I for one don't plan on being anywhere near the launcher when I put pressure in.

Just uploading it for comments/ideas.

-Release mechanism (in progress). The base design has spots for o-rings, and could operate by just letting it go whenever the pressure is stronger than the friction. I would like to add arms that lock on to a ring on the bottle later on, after I figure out if it will work at all.


The STL won't print as is: the two parts have to be seperated. I didn't think the hose barb would print well even with support unless it was vertical. It still needs work for overhangs.

Build Thoughts
Probably needs to be printed with 30-60% infill with extra shells/perimeters and I plan on using ABS rather than PLA on this one.

An acetone vapor treatment or a brush with acetone slurry might be a good idea to make sure it's air tight.

The barb end is sized for 1/4" id air hose, but may need to be seperated: it's probably not going to print nicely that way.

The rings on the riser should hold a set of O-Rings. They don't all need to be filled - just the 2 or 3 that the cap of the bottle touch against.

The style of bottle I am using (see pictures) is smaller than the normal cooler bottles, and doesn't have a handle, so it should balance more easily. None the less, the legs of the launcher have holes to peg into the ground or screw onto a larger base.

Potential issues

  • The cap may completely pop off instead of launching from the smaller nozzle. Epoxy might help there.
  • I have no idea what kind of pressure these bottles can take. I plan on using just a little bit of water and building up
  • Balance and aim: the bottle will likely need some fins for stability and a nose cone for aerodynamics.
  • Need lots of space, probably bigger than a back yard. I don't want this thing hitting me or landing on anything I don't want damaged.

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any videos of a launch, I was thinking about this same thing!

Per previous comments, I never got it to work. The launcher leaked air pressure through the plastic. I suspect if I printed it again now, I could probably get better print quality, but I haven't gotten back around to it.

I was looking for something like this for a gravity-fed water system. Thanks.

Did you refine the design ?
I would like to use that building for my 2-Stage Water Rocket.
Do you have ideas how i could improve the launcher ?
Should seal rings improve the launcher ?

Nice design !

I haven't refined the design any. Actually, the tolerances and fit weren't bad, but the plastic layered together just wasn't air tight enough. When I tried to pressurize the water rocket, air and water leaked out through the plastic.

Since I never actually got it running, I really don't know if the release mechanism will be any good.

If you are going to try it, I recommend using 6 or more perimeters and use ABS, so that a vapor smoothing operation can be applied to help seal the air channels. Also, the design was first made for PLA which doesn't shrink much, so you may have to scale it up a bit for ABS. I ran out of time and summer to play with it, but I plan to try again next summer.

Good luck, and I hope you will post back updates or remixes if you get anywhere with it.

I will also try it next summer.
Its freaking cold on my Island....

I will post back my archivements if i shot a Water Rocket with your launcher.
Sorry for my English.

The first print test with PLA had a good fit -- It's not air tight though, so I think ABS with an acetone treatment will be needed. I am going to refine the design with release arms now, and offer a pop-bottle sized head as well.