This blog covers the day to day progress of water rocket development by the Air Command Water Rockets team. It is also a facility for people to provide feedback and ask questions.

Friday, February 25, 2011

Bottle Splicing Tutorial

Over the last couple of years we’ve had a number of requests for a tutorial on splicing same sized bottles. We found that the technique we used to use ( ) would work on 1.25L bottles but did not translate well to 2 Liter bottles. No matter how carefully we would do the symmetrical splices on the larger bottles we would often end up with a small leak and the whole splice had to be thrown away. Sleeves larger than 2L bottles which could be shrunk to size were also increasingly difficult to get.

So we developed a modified splicing technique, that we now use for 2L bottles. We posted the technique in outline form here last year, but finally got around to actually finishing the tutorial this week. Talk about dragging our heels.

It’s by no means the only way to splice 2L bottles, but it’s a technique we’ve found reliable and haven’t had a single leak since we started using it. The splices hold up well to repeated launches and non-destructive pressure test cycles to 140psi. We are currently using it on our Acceleron V and Polaron VII rockets.

Here is the full tutorial that also includes a how-to video:

If people do end up using this technique, we would love to get feedback about what worked for you and what didn’t and perhaps ways to improve or even simplify it.


Unknown said...

Hey George,

Thank you for that, i have been wondering how you do those splices for a while now. :)

I will be giving them a go sometime in the future. :)

Regards Doug

George Katz said...

Thanks Doug,

Yes, it's taken us a while to finally put the tut together. :) I think it's only 1 year late. Hopefully the tut is easy to follow, but have spare bottles on hand as some of the steps take a bit of practice.

Anonymous said...

Hi George,

Thank you for this tutorial. Much better way for doing this that you presented in construction_2.htm. I will definitely try this, with better chances than the other one, I believe, for me.

You use the same technique, covered with fiber glass, for G2?

How big bottles do you use? I believe that bigger ones (2l - 2.5l) are thinner (plastic thickness) and unsuitable for bigger pressures.


George Katz said...

Hi Marius,

For the G2 we use 2L bottles. We use the same splicing technique for the fiberglass bottles only up to the Sikaflex glued joint. We don't add the sleeve. The bottles form an air-tight bladder, and most of the strength comes from the fiberglass. Because of how the fiberglass forms a solid shell it stops the two halves from flying apart so the PL premium is not needed.

Yes the 2.5L bottles are made from the same preforms as the 2L ones, so you end up with thinner walls. Though that wouldn't be an issue if they are being reinforced with fiberglass.

Rodrigo said...

Really good tutorial!!
Congratulations George.

Orcslayer said...

Could you make a tutorial of how you make the tornado tubes? Right now I only use Robinson couplings but I would like to try tornado tubes. Thanks!

George Katz said...


You can just buy commercial tornado tubes. There are a number of places that sell them. Here is an example: