Splicing Bottles for Water Rockets

Introduction: Splicing Bottles for Water Rockets

Splicing bottles together is technique often employed by water rocketeers to increase the volume of their rockets. Splicing involves gluing sections of bottles together to make a longer pressure vessel.

Because of the forces involved inside a typical rocket, and because PET plastic is very hard to glue, there are only a few existing glues that are suitable for the job. The most commonly used is PL Premium construction adhesive, but VISE and a small number of others can also be used.

Splicing is not as easy as joining bottles using a Robinson coupling, is permanent and is less predictable at which pressure it will fail, but it has the advantages of virtually unrestricted internal flow and potentially long pressure bodies can be made this way.

The technique presented here is based on previous work done by other rocketeers:


In the following video tutorial we present a technique called 'symmetrical splicing' for joining two bottles. The same technique can be used for making much longer bodies. The join is just repeated for each section.

For more water rocket instructions visit: http://www.AirCommandRockets.com



    • Fix It! Contest

      Fix It! Contest
    • Metalworking Contest

      Metalworking Contest
    • Creative Misuse Contest

      Creative Misuse Contest

    31 Discussions

    Hi there, I live in India and pl premium glue and Sika glue in not available here and therefore i am looking for something to splice bottles in order to make a large rocket . Will any one of these work on this webpage - http://www.aliexpress.com/wholesale?catId=10000665... .Please help!!!!

    Very nice explanation. Any idea shich Sika product in AU would be most suitable. There seems to be hundreds.

    15 replies

    Hmmm, no clear available at bun nings. Oh well looks like black splices for me. I am starting to see the benefits of bottles over FTC and pressure pipe. My two stage rocket with drop away boosters is boardering on the same drag co-efficiency as a bottle rocket due to the drop away. I am thinking now a third stage done in bottles would give me a little more bang and air volume.

    If the main stage has a similar burn time to the boosters, then the boosters will not necessarily give you greater altitude, but will be able to lift a heavier weight to the same altitude compared to the main stage alone. This is good for lifting a bigger second stage. -> more volume and more water in your sustainer. Do you have any pictures of your rockets?

    This rocket have a custom quick change mech for the fins. I don't know if you have spotted these little clips/holders in any stationary stores but they make a great fixing method for the fins. They bite onto boards, especially celled boards commonly used for fins very well. It takes a great deal of force to remove the fin but it will pull out at an angle under great physical force.


    That's not a bad idea for attaching fins. Certainly makes it easier to swap fins between rockets or replace damaged ones. I can see transportation of the rocket also being a lot easier if you can remove a fin. Have you tried them with a full open nozzle where acceleration is a maximum? My only concern would be that the high G loads on take off could either move a fin or loose it entirely. Perhaps a safety piece of wire through the fin and the clamp would make sure the fin does not move. Cool stuff though!

    Yes I would definatley think that at a max G launch they would shift. Just looking for a identical fixing method that can replicate. They almost guarantee a perpendicular mount. If your ever in Bunnings they are the holders to the bay item signs. We hit them regularly with machines and the sign always breaks (which is hard plastic) before the clip releases the sign. I still intend on either applying a glue to set the fins or a method like you suggested.

    Not as yet, but i'll post pic of my pressure pipe rocket when it's done. I just finished a 7L spliced rocket body using the Sika 11FC. No neck to necks just straight through mid sections. That black Sika (as you would know) has a great advantage when a light is shown from behind it. You can easily see where you have spread the glue to thin or if you have missed a section... Now to just wait 5 days... hmmpppfffhhh!!!

    Air.command is like the jesus of water rockets, I see he answered your question. I use sika 11FC black.

    Ok great. That's off the shelf stuff. Tops!! Thanks.

    Just as an estimated guess. What would you think this MOSS branded quad garden fitting would rate to? It appears to be cast steel coated in a golden layer. Ball valves look good. I was hoping around the 150PSI-200PSI mark.

    I'm using this unit on this Quad metal launcher


    Hard to tell from the photos. It's unlikely to be steel, perhaps brass? You should be able to contact the manufacturer and ask for the rating. From the looks of it, you should be okay with 150-200psi. But hydro test it first and stay well away while testing.

    Perhaps brass coated, but not solid. Will certainly take your advice, in regards to pressure testing it.

    Any chance I could convince you to do some of your write ups on Instructables?
    The water rocketing community is in need of some good info.
    I am sure everyone would love a write-up on how to build Polaron IV.

    I was actually going to email you to request if I could use a shot of Polaron IV as the picture for my new water rocket group. Water rockets

    I'll consider writing it up, unfortunately I don't have any spare time over the next few months.

    Hmm... I'm getting back into this stuff again. But how can I use this type method with only the same type bottles? I can't find any bottles wider than my 2L bottle.

    1 reply

    You can actually heat shrink the bottles before curling the edge so that you can use the same bottle type for the sleeve. This is best done in a saucepan full of hot water ~70C. Fill it up with enough water to a depth of half the length of the splice. After removing the bottom of the bottle and neatly trimming the edge, submerge it in the saucepan for a few seconds and the bottle will shrink a little. (make sure there is no cap on the bottle) Test fit it into the sleeve, if it still does not fit, repeat the procedure. Don't leave it in there for too long otherwise the bottle will shrink too much. With a little practice you can get a good yield of bottles shrunk the correct size. You can then curl the edge as normal and splice the bottles together. Hope that helps - George