Build an Overhead Water Rocket Launcher Part 4 seal bump

Part 4 of 7 parts, instructions for building an overhead water rocket launcher, as seen on the Ask This Old House annual kids program.
Links to all 7 steps, as well as other science toy projects are at http://www.sciencetoymaker.org/

Category:

Science & Technology

Tags:

• build
• make
• water rocket
• ask this old house

[hellandlife]

my bottle jsut leaks. like a flood

[sciencetoymaker]

@hellandlife Did you adjust it? It will involve loosening the hose clamp and moving the trigger assembly down so the bottle lip is pressed against the "bump" then tightening again. Rarely, the spout of the bottle will crack, which is the only other thing that causes leaks.

Slater

[sciencetoymaker]

@sciencetoymaker Get some more pipe and make the top part again. Watch the part about making the bump again, and practice on some scrap pipe.

Slater

[nieknikey]

there are some rings you can just roll up your pipe. If it fits on the pipe and I can still move the bottle on the pipe, will that be watertight?

[sciencetoymaker]

O rings don't work that way ("just roll onto a pipe") under pressure. I know you're not a fan of the melted bump, but by the time you work out what O rings involve, it might not seem so bad to look at the video and try the bump method again.

Slater

[nieknikey]

Okay.

This Rocket is very easy to make, the difficult part is the bump. We did alot of time doing that. If someone can't do that using a candle, you might do the other things first. When you did that, you can hold your hand very tight on the end (where the soda bottle is placed) to make it airtight. if you connect the pump to the pipe and you heaten the place where the bump is using a burner (DON'T HEAT IT TOO MUCH!) you can make the bump without pushing.

How can i make it tight with O-rings?

[sciencetoymaker]

O rings invove somehow machining a grove into the PVC to hold it in place and recess it. But that weakens the pipe, so you neet to reinforce it with a smaller pipe inside, possible 1/2" CPVC. Check other sites for ideas.

Slater

[tr0s3ph]

@hellandlife a single layer of duct tape works to seal it better.

[hellandlife]

@sciencetoymaker yes the dam bump wont form it just bend inwards and out so it will never seal

[pyroman675]

@sciencetoymaker make a grove so the O-ring dosen't slide

[nieknikey]

I'll give it another try. If I find out any other ways to make it tight ill post em here.

Thanks for your answers.