Clay plug

[pipiso]

I am using clay from backyard as plug it often blows up .Is kitty litter any better ? Also what are the alternatives for plug ?

[FlaMtnBkr]

Yes kitty litter will likely be significantly better than dirt in your yard.

 

Though you may have something useable. The Chinese have a red clay like dirt that they dig out back and ram into paper tubes for use as mortars in cakes. Not sure even that would work well for everything.

[MadMat]

scoopable kitty litter is made from bentonite clay. Bentonite has a few unusual properties for one, it creates thixotropic suspensions and secondly (for pyro use) it compresses into a very hard plug in a rocket tube. I have heard that Fresh Step is one of the best brands for making rocket nozzles and headers. I have used a number of different brands and they have all worked. Just make sure it is the scoopable kind.

Edited April 20, 2016 by MadMat

[mikeee]

Depending on the application, I have used foam backer rod cut into lengths equal to the diameter

and glued these into tubes. You can easily pierce a hole through the foam backer rod and glue a fuse

in the foam plug to produce a fused pass-through.

 

This does not replace the use of a clay plug, but I use it for several applications where a clay plug can't be used.

[pipiso]

Thank you for answering ,but i have one more problem

I bought kitty litter crushed it into dust then pour it on motor and compressed with hammer.

When i tested out the motor ,it reached about 3 meters then the plug was ejected.

Motor have 32 mm in diameter nozzle have 6 mm in diameter.

 

Is it fault of badly crushed kitty litter or the nozzle is too small ?

Edited April 23, 2016 by pipiso

[OldMarine]

Unless you have nozzle forming rocket tooling,I would drill my nozzle to 1/3 the tube's inside diameter then adjust it from there.

[MadMat]

Was your nozzle plug even with the end of the tube? Did you press your nozzle plug incrementally? You need to put a spacer in the bottom of the tube (about 5-7mm thick). The diameter of the spacer should be a close fit to the inner diameter of the tube. When you ram the nozzle, the tube will expand just a little; having a small length of the tube past the plug that doesn't expand, it holds the plug in tighter. Grinding the kitty litter down to a fine powder is a good thing, but not absolutely necessary. When you ram the nozzle, you need to do it a little at a time. Add a small increment, pound it, add a little more..... Yes, your nozzle was too small. You made it close to 1/6 the inner diameter of your tube, when it should have been closer to 1/3. I will tell you now, these are things you would know if you had looked around the rocket forums, or did some searches on the internet. There is a LOT of information out there, now it is time for you to find a few things out on your own. Do some research, test things out, then if something goes wrong, ask questions here.

Edited April 23, 2016 by MadMat

[Mumbles]

Also, if your nozzle was actually ejected it probably means you're using PVC. Stop using PVC, it's dangerous. It shatters into sharp fragments in the case of an explosion. If you were using cardboard, it means you're not compressing nearly hard enough.

[calebkessinger]

For what it's worth,

I never got a hand rammed endburning plug to stay in without a tube support. Same result you are having, About 20 feet of flight and then bam.. plug ejected.

 

Keep trying, smaller increments, more pressure, and support the tube.

Then they will work.

[Rocketman14]

I've been having the same problem with blow outs. My bulk head usually does fine but nozzle gets blown out. I. Using 3/4" parallel tubes. I think I need to use a spacer as suggested so my nozzle isn't all the way in the end of tube. Good info, thanks guys. I'll try after the shell experiment I'm working on.