help with small homemade mortar

[annihilation18]

Ok so here's what I'm trying. Im trying to make some smaller shells that I can either make for a cake or just something a little quieter that I don't have to go into the middle of nowhere to shoot. The problem is that they aren't working all that well and most of the stars aren't igniting. The stars I'm using worked perfect in my 2" and 3 " shells.

 

Here's what I'm doing. I am making shells by rolling a 2" wide by 24" long piece of kraft paper arounda 3/4" dowel. I'm plugging one side with bentonite, drilling a hole, sticking fuse through and then covering the bentonite with hot glue. Then on the open side I'm first putting in bp hulls then a tad of whistle mix. Then after I put some stars, cover them with a small layer of bp hulls stuff some tissue paper and fill the remaining space with hot glue to plug the other end. Im using a 1" dowel to make the 6" launch tube which is also made of kraft paper.

 

The shell is launching in the air and bursts but almost none of the stars ignite. The stars are tiger tail and zinc cores covered with tiger tail. I didn't prime them cause I didn't think tt needed prime. Help!

Edited November 6, 2013 by annihilation18

[LambentPyro]

How do you dry them?

[annihilation18]

I'mm assuming you're talking about the stars right? I sit them outside to dry. I live in Arizona so not a lot of moisture in the air. After they're dry I put them in a ziplock.

[pyrokid]

What size stars?

[Seymour]

Tigertail is one of the stars that you often can get away without priming them, but I certainly do advise priming. It will give close to 100% ignition, and they will light evenly over the star giving even burn times. this is especially beneficial with colour changing. Often unprimed TT only lights on a few places.

 

However if none of your stars light, I suspect that there is other factors. One possibility is that they have gotten driven in. This is very easy to do with Tigertail if you try to dry them too quickly. For high charcoal stars I like to keep them cool and in the shade for at least a few days before they get in the sun.

 

If you break one open, does it have a hard crust, but is soft underneath?

[Arthur]

Have you recovered any fragments of the casing? If it bursts too easily then the stars may not get fully lit.

[Col]

I would check if the stars ignite with a stargun then you can discount the stars as the issue. I use granulated bp in inserts as it fills the gaps better than hulls. I put a strand of blackmatch in the center of the inserrt so the fire can propogate to the top instantly. In cakes and rocket headers it gives100% ignition with D1, TT and parlon based coloured stars.

[annihilation18]

I appreciate the ideas, looks like I have some narrowing down to do. As far as the stars go I have been able to get them to light just fine from a star gun. They are .25" in diameter. I haven't tried to recover fragments of the casing but I will do that next. The tiger tails are pretty brittle so not drying them slower may be part of the problem too.

[Shadowcat1969]

In small shells like that I use granulated BP rather than hulls. it gets a little more BP in each shell and allows for a hotter fire that burns a little longer.

 

I'd probably urge a test using this method without a booster, just to see if you are maybe pushing the stars out of the flame envelope too fast for them to ignite.

[ice_maniac]

try to mix the stars with rice hulls or bp, and add them on the top of the rice hulls.

I used to make 1'' shells, and to have all the stars ignited, I used to sprinkle bp on them, sometimes spray them with athenol/water solution, (just to make it wet) and give them bp bath ( soak them in bp).

make sure al shell case is thick on all the sides, to have the shell explode with more heat and pressure (similar to pasting at arial shell).

Good luck!

[annihilation18]

Thanks for the help, turns out the hot glue plugs were popping out and the shell wasn't fully exploding. In turn there wasn't enough pressure and heat being built up to fully light the stars. Good to go now!