Yankies Flash Stars

[dagabu]

I know this is an old thread, I would really like to try these stars, but the formula doesn't add up to 100%? Am I missing something here?

 

Formulas do not add up to 100% many times since they are based on weight and not percentages. Whistle fuel for example: 70:30:1:4 = 105%.

 

-dag

[Mumbles]

Everything adds to 100%, it's just not always out of 100 parts.

[PyroAce]

Thank you for the answers!

What's the properties behind the star flashing several times? It's an interesting "phenomenon" if you like.

[Seymour]

I'm sure it's rather like the Barium nitrate/MgAl/Sulfur strobes.

 

Here is my interpretation of it...

 

The potassium nitrate and sulfur smolder together, possibly with sulfur-Aluminium reactions, until the thermal buildup is sufficient to ignite the second reaction, where in the pre-smoldered zone, Aluminium burns with the Nitrate, and all the sulfur and sulfides in a flash. The composition does not burn stably enough for the reaction to be sustained and consume the whole star (I expect due both to the high sulfur content (ablative cooling a factor?) and the Aluminium particle size. However, in the process of being consumed, it initiates (or does not disturb) the low temperature smolder reaction in the remaining unreacted composition.

 

Repeat.

[PyroAce]

I'm sure it's rather like the Barium nitrate/MgAl/Sulfur strobes.

 

Here is my interpretation of it...

 

The potassium nitrate and sulfur smolder together, possibly with sulfur-Aluminium reactions, until the thermal buildup is sufficient to ignite the second reaction, where in the pre-smoldered zone, Aluminium burns with the Nitrate, and all the sulfur and sulfides in a flash. The composition does not burn stably enough for the reaction to be sustained and consume the whole star (I expect due both to the high sulfur content (ablative cooling a factor?) and the Aluminium particle size. However, in the process of being consumed, it initiates (or does not disturb) the low temperature smolder reaction in the remaining unreacted composition.

 

Repeat.

 

Thanks! So is the burning mixture really just burning in an unstable manner, which gives off the flashes?

[Seymour]

Depending on perspective. It's two quite different reactions, both of which seem fairly stable. Please note that what I'm saying is largely speculating based on observation and the, in my opinion large similarities between this formula and Glitters. While still very much mysterious, due to very low funding for research, and the difficulties of identifying complex chemical mixtures that are created on fire and quickly burn up. There is however, some published glitter research to read if you are interested.

 

If you have ever burned a fairly slow and slaggy glitter star on the ground, you will have seen a build up of semi-molten slag, comprised more or less of the mysterious soup that causes glitter flashes. After a few moments this glowing soup erupts in a fierce flash.

 

While glitter stars contain a different proportion of the core chemicals in the reaction (KNO3, Al and S), as well as extras to promote a streamer star effect, I believe the reactions are quite similar, though the chemical mixtures of the reactive slag will obviously vary. In both cases, once the 'flash' reaction is initiated it consumes the entirety of the slaggy zone without interrupting the separate, slower smolder reaction.

 

Barium nitrate/Sulfur/MgAl strobes I expect fit in this category... there are after all Barium nitrate and MgAl glitters. I'm sure Yankie was far from the first to discover this effect with such easy to get chemicals, and would not be surprised if many decades ago they were the inspiration to the more contemporary Barium nitrate strobes.

 

Ammonium perchlorate strobes definitely have the same system with two different reactions, but with the different chemical makeup, each reaction is very different from the nitrate twinkling phenomenon. Analogous, but more co-evolution in pyrotechnic development.

[PyroAce]

Thanks for the explanation Seymour, appreciate it

[Floydism]

Make sure it is atomized spherical aluminium you are using, flake aluminium will probably give you a sort of silver streamer stars.

 

Yup, since i've not got any decent sperical al at the mo i tried this recipe with 250 flake (figuring the larger particle size would partially compensate).

 

they didn't strobe but were a quite cool looking white/silver with short streamer tails, it's a nice simple comp and great if you can't afford to have a huge range of chems on hand.

[zAZO9a]

im gonna try this today .. been wanting too for awhile now

[jl88]

I know this is a dead thread so sorry but I was looking to try this composition and the video demonstrations seem to have failed. I ended up trying these stars anyway and here is a video of a single star th size of a Panadol tablet. Shell to come.

 

[Col]

not sure how big a panadol tablet is but the ground test looked good.

I use 3/8" dia x 3/8" long pumped stars

ground test

 

in the air

[LambentPyro]

That's more of a strobe effect, hmm...

 

Mine flashes but sprays sparks with the flashes.

 

I made my latest Yankie stars a little unique. Half of the Aluminum parts are Alcoa 120 and the other half is 220 Mesh Atomized Al from gumby96 on eBay.

Edited February 3, 2014 by LambentPyro

[jl88]

Yeah there are only a few smaller particles being thrown off per flash. They are bloody bright though. Probably due to the 400 mesh al. Might try a mix of 200 mesh and 400 mesh as that's what I have (apart from course flake and 600 mesh) Any suggestions or has any one tried using two different meshes? Edited February 3, 2014 by jl88

[DasKapital]

I use 325 mesh al and it flashes much slower than yours. Ill upload a vid of mine too soon so you can see mate. I like yours though

[LambentPyro]

Yeah there are only a few smaller particles being thrown off per flash. They are bloody bright though. Probably due to the 400 mesh al. Might try a mix of 200 mesh and 400 mesh as that's what I have (apart from course flake and 600 mesh) Any suggestions or has any one tried using two different meshes?

That's exactly what I described doing in my last post.

[Col]

I use 325 mesh too, using a mix is worth a go.

[jl88]

Well here is a 2" ball shell. Not quite as impressive as I was hoping.

 

[LambentPyro]

Ehhh, it happens my friend. Try what I suggested, use half 225 Mesh Atomized and the other half Alcoa 120. You can purchase Alcoa 120 from HobbyChemicalSupply.com FYI.

[jaysgoh]

I love it! But sometimes it work.. Maybe my stars haven't fully dry yet

[Zumber]

Well here is a 2" ball shell. Not quite as impressive as I was hoping.

good shell but flashing rate sounds to be too slow.

[jaysgoh]

Stars won't dry man ..been oje day dy. .inner still soft