Cylinder - Round / Symmetrical Break

[mkn]

Hi all,

Working on my breaks for the cylinders. This is a 2 inch with1/4 to 3/8" round stars

boosted break with 2.2 g flash with 10% Ti sponge 20- 40 mesh.

Spiked with 16 vertical of 20# hemp. 75 # inner wrap 2 layers and 30# outer 3 layers.

 

 

Have a look and let me know what you think.

Thanks Matt

 

 

 

[Mumbles]

Is there a question in there?

 

I hate to say it, but if you have to use that much flash with that kind of casing/reinforcement you need to work on your techniques or your BP.

[mkn]

Hi Mumbles,

 

Yes the question is generally looking for feedback to improve the round symmetrical break of a cylinder.

 

No I don't have to use that much flash, I am just starting to incorporate it in the break as I read that it helps to swell the casing faster for a more round / symmetrical break. I also do not have a reference point for the amount to use. 2.2 g was used instead of 2g as it contains 10% Ti. I read that 1 g per inch of diameter was a guide up to 5", from then on it may not be needed.

 

What are your usage rates from 2" to 5" cylinders?

 

BP seems fine - baseball tests on various batches yields 6.5 to 7.5 sec flights. BP made during some 0 - 10 below weather, which I read is not a good temp, better at 90 + degrees.

 

I had a 2" height of stars inside, possibly decrease that to 1.75" trying to reduce the "flat " sides of the break, any thoughts on that ?

 

anything thoughts on making a more symmetrical round break out of a cylinder?

 

Thanks Matt

[nater]

Cylinder shells typically burst with an oblong break. Depending on the angle you are viewing from and the orientation of the shell when it breaks, it may appear more round to some viewers.

 

Many cylinder shell builders use only BP to break their shells. Small flash bags are used for some effects, but there is a concern about flash breaks reliably passing fire to a second spolette for multiple breaks. Other builders do use some type of booster with good results, so it mostly depends on your preference. In both cases, most of the confinement comes from spiking and pasting. A big round break like you see in Japanese ball shells is not created with a cylinder.

 

For a color star break, make the fill height the same as the OD of your former. IE: fill a 3" shell 2.5" deep in a casing rolled on a 2.5" OD former. Inserts like serpents or small shells might need a taller shell, so this rule is not set in stone.

Edited March 11, 2014 by nater

[mkn]

Hi Nater,

Thanks for the feedback, When this broke, I was under it and it looked more round / symmetrical so I thought I had nailed it ! Then I saw the video which shows the oblong break you mention. I have had some 3 in ball shells break much more round.

Just thought I would work towards a better symmetrical break.

Tonight I built 4 more 1.75 ( I call them 2 ") I filled them to 1.5 " same as former. They are some TT 3/8 "pumped with a home made star press, very nice for the charcoal stars, I rolled TT once, I don't know if I 'll do it again in the near future

I tapered back to 1.8 g of slow flash boost for these, as before the boost is placed center of shell in the canuell with 4fa BP above and below. also am trying 12 , 14, 16 vertical with 10 horizontal. On the 12 I also tried without a cardboard 1.5 inch liner, thinking it may allow the vertical spiking to swell out easier, producing a more round break. time will tell, I'll post vids if anything interesting pops up.

 

Matt

[Mumbles]

I don't usually build that size specifically, but I do build a size below (1.25" ID), and a size above (1.75" ID). The biggest difference is probably the fact that you use a cannula. You also didn't mention that this was slow flash before. I just bulk fill the casing with stars and fill in all the spaces with 4FA sized BP. If I'm looking for a particularly hard break, such as for spider shells, I use between 1-3 grams of 70/30 depending on the size and how hard I want it. The 1.25" shells get 8 verticals, and the 1.75" shells get 12 verticals.

 

In this size of shell particularly, I really consider these inserts. I'm usually going for a splash of color, so I don't bother trying to optimize my break.

[mkn]

Thanks for the feedback Mumbles, I understand this size is an insert for you ! I was working with 3" and a few 4" on rockets, which are great, but..... the chems go fast and I was/ am spending a lot of time milling, rolling, cutting, pumping. I thought I would work these 1.75" for awhile and get some good assembly under my belt, and a touch of inventory. I have gotten better at overall construction and at spiking patterns, canisters are flat on both ends, and the heights are the same !! see pics.

 

Tested one of the TT 16 vertical with slow flash, and you guessed it.....smashed the pumped stars up a bit, I forgot that these charcoal stars are not as hard as the rolled Veline.

 

 

With that finding, I built 4 more last night to test the spiking patterns and NO slow flash , just a 1/2 " cannula, wrapped in tissue ( from Viking Pyro posting ) filled with 4FA. a tiny amount of BPCRH to fill in around the stars a bit.

 

Spiking as follows (8 vertical 6 horizontal) ( 12 vertical 7 horizontal) ( 14 vertical 8 horizontal ) ( 16 vertical 10 horizontal ) the patterns proved to be challenging, quite a lot of un spiking and re spiking. I am more used to the 16 vertical.

 

Should make for an interesting test, BP and stars are the same batch, so the spiking is the only variable.

 

 

I am going to try a few as you build, fill with stars and fill gaps with 4FA, and see the difference. I will put a spoulette to get the fire to center of canister.

 

Matt