Simplest launcher design

[Jelo]

Hi,

The other day I said I was going to build a new launcher, and I did. I decided to go back to 20mm nozzle for increased stability. The

launcher is basically a rip tie launcher, except with a much easier was to seal the bottle. I basically melted an area of the plastic pipe

(I will tell you the exact type later) using a blowtorch and then pushed on both ends of the pipe to make a little bump. I made sure the

bump was bigger than 20mm and then slid a bottle onto it, and waited for the pipe to solidify. This made a perfect seal between the

pipe and the bottle! I do not remember the type of plastic the pipe was made of but it had a rubberized coating, which made the seal

even better. I'm not sure if this is possible with regular PVC piping. I will upload pictures and possibly a video later on

[Jelo]

The plastic turns out to be PEX, used to carry warm water from heater. Here are some pictures:

[SaskAlex]

Wow, that is a very simple seal. Pretty interesting. What kind of pressures have you had it up to?

[Jelo]

So far I've only tested it to 80 psi, although it showed no sign of leaking or anything. Might try 100 psi if the weather gets better!
Here's a video of the launch:
[youtube][/youtube]

[U.S. Water Rockets1]

The finished product looks really nice. It looks a lot better than it sounded like from the description.

If you have any information about the pipe you used, please post it so that other people can duplicate the launcher.

[Jelo]

Yes I didn't think the seal was going to be very good when i thought of it, but it shows no signs of leakage at 100psi!

As for the pipe, I found it in my garage, the plumber just left it there, he used it to carry the warm water out of the heater.

On it is written that it can withstand 12 bars, which is roughly 180 psi. Considering my pump can only go to 160psi, there's no chance

of it ever bursting because of the pressure. As I said it's a 3/4 inch PEX pipe, which consists of several layers of different plastics.

[tcarnahan]

You can use 1/2 inch PVC schedule 40 pipe which is rated at 240 psi (sorry, I don't know how to convert to bar). Put a wooden dowel rod in the pipe so that it hangs out both ends. Mark the place where you want the "bump" (seal point). Light a candle and hold it under the seal point and slowly rotate. Keep the flame about 1/2 to 1 inch from the pipe. You'll have to experiment on how long to heat it, but at the right time, you push on the pipe from both ends. The dowel rod keeps the pipe straight. Once you achieve the "bump" take the pipe off the flame, but continue to push on both ends until it cools.

It forms a great seal!

[Jelo]

That's pretty much what i did

[U.S. Water Rockets1]

That's pretty much what i did

This idea could be useful to people looking for how to make a launcher for other kind of containers like those water cooler bottles and drink bottles with odd sized necks.