Splicing Bottles for Water Rockets

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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:

http://wrockets.trib-design.com/index.php?project=nick&page=splicing

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

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31 Comments

ya could just melt it

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

Your best bet is probably Sikaflex 11FC.

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.

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How did you splice your bottles together?

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.