Aerial Shells

[Mumbles]

I think you're thinking about this conceptually not quite right. A double petal shell doesn't break twice. It's not like the inner petal goes off inside the shell to then set off the outer petal as a separate shell entity. It breaks the same way as a single petal shell. It builds up pressure inside and bursts. In the case of a double petal, there just happens to be other stars than the outer most layer. The stars are propelled proportionally to the distance from the center of the shell. A star in the exact center, in a perfect world, would only be affected by gravity. If you placed a line of stars across the shell to cut the circle exactly in half, you would still get a line in the sky. The internal hemi isn't even needed technically. It's often used to make things simpler and keep things from shifting. If you made a bowl impression in the lift, you could line it with stars and make it into a double petal. Trust me, the burst forces will not just vent and leave you with a wiffle ball of stars.

 

I agree with the drilling holes in the hemi. It is very common practice. You probably don't even need to seal it shut. I've also mentioned this elsewhere, but it is very important here. You absolutely must have a passfire from the fuse to the center of the shell. If you don't, it will not work correctly.

 

Now, Two stars of different sizes in a ring around a shell will travel at the same rate of speed. Or at least it will be close enough you wont be able to tell. I was thinking of some mathematical based explanation, but I'm not sure if it would make sense, or if it's even true. In all honesty, most rings arn't perfect anyway, small variations in position will seem normal. Besides, theres only a 90% chance of the electron being where you think it will be, and then you can't know it's velocity.

 

Two stars the same size can absolutely appear to be different sizes from the ground. Chances are it wont be too noticeable though. The key term here is "flame envelope". Hexamine does a great job at increasing this. What I would probably do though is make a pillbox star. These have very large flames, and would definitely be noticeable. Using a metal fueled star with rings of organic may give the impression it is bigger because it is brighter.

 

Also, I've actually heard that pattern shells are better burst on the softer side of things. It makes any star shifts, and imperfections less noticeable.

[justanotherpyro]

You beat me to it with the hexamine flame envelope idea. It really does make a difference in stars. QM was definitely not up there in my list of favorite classes. The only thing that that I can think of that would affect the way stars fly is the air resistance. If you have a heavier star it would fly faster (theoretically) because it wouldn't be affected by air resistance as much as lighter star. Although generally a heavier star is bigger which has more air resistance so I'm not sure the difference would be to noticeably because the air resistance counters the heavier (larger) star.

 

Like mumbles said, these things are only really for a perfect situation. There are some many other variables that these are kind of trivial.

[ST1DinOH]

thanks to both of you for bringing me back down to earth on this.

 

i have a bad habbit of overanalysing things, this is clearly the case here.

 

i have bulk stars in route and 3's and 6's hanging onthe wall taunting me...

 

i hope to have this sucker in the air and producing color on the 4th.

 

thanks again for all the clarifications.

 

oops...almost forgot.

 

any specific danger of reactions in lining up metal fueled stars and organic stars touching each other in the same shell/ring.

 

anything specific i should avoid?

[TheSidewinder]

"anything specific i should avoid? "

 

Smoking.

 

M

[ST1DinOH]

"anything specific i should avoid? "

 

Smoking.

 

M

damn...so i should be smoking cigars whiel shell building?

 

what the hell, next thing you'll tell me is i can't use candle light or operate my tesla coil for inspiration whiel i tinker...

 

[TheSidewinder]

Of course you can.

 

 

May I have your stereo after you're..... well... you know.

[ST1DinOH]

Of course you can.

 

 

May I have your stereo after you're..... well... you know.

lol

 

well i'm all jazzed up after reading my new books, i can't wait to try some stuff out.

 

got me a nice 1000 gram cap digi scale for 12 bucks shipped off e-bay. hope thats enough to weigh a 6

[justanotherpyro]

I hate to ruin it for you but mine usually pop out at around 1100-1300g. AS far as things to avoid, its basically just the regulars. You wouldn't load an unprimed Chlorate star with a bp primed star etc..dibs on that scale after you're done being inspired by your tesla coil

[TheSidewinder]

1000 gram scale?

 

You can weigh the ingredients with it, but the finished shell? Hmm... not sure, if it's a ball shell. I've only done cans so far.

 

EDIT: Bah, that'll teach me to walk away with the editor open. jap beat me to the dibs.

[ST1DinOH]

I hate to ruin it for you but mine usually pop out at around 1100-1300g. AS far as things to avoid, its basically just the regulars. You wouldn't load an unprimed Chlorate star with a bp primed star etc..dibs on that scale after you're done being inspired by your tesla coil

*runs away and cries in the corner

 

oh well, it's a sweet little digi, i'm sure i'll find a use for it.

[TheSidewinder]

Don't despair.

 

A kilogram scale is a good "starter".

 

You'll know within a few grams what is the final weight, if you weigh all the ingredients and write them down as you go.

[qwezxc12]

I hate to ruin it for you but mine usually pop out at around 1100-1300g. AS far as things to avoid, its basically just the regulars. You wouldn't load an unprimed Chlorate star with a bp primed star etc..dibs on that scale after you're done being inspired by your tesla coil 

*runs away and cries in the corner

 

oh well, it's a sweet little digi, i'm sure i'll find a use for it.

Use it to weigh the filled hemis, add them together, then estimate the additional pasting/rising comets/etc. You'll be close enough.

[justanotherpyro]

Or ask the chem prof. to let you use the ultimate kickass scale in the quantitative analysis lab. But yeah both methods are good

[oskarchem]

Well those kickass scales are very precise, but cannot hold more than maybe a 100g (I'm talking about the 0.0001g precisoin)

[psyco_1322]

I checked my hemis and they fell right under 2 5/8" by about a 1/16th, the plastic ones where right at 2 5/8". I also looked at my 4s and the paper ones I got from the guy on Passfire are suppoded Lidu but do not fit into the black plastic ones I got at the convension last year. They do fit right into the inner lip though.

 

ST1DinOH if your not a passfire member you should be. The site has a good article on building a 6" atomic pattern shell. It doesnt have the free roming electrons but it has the 3 rings and center nucli. The innner petal is usually full of holes of some kind to allow for flame passage. See:

http://pyrobin.com/files/hpim0818.jpg

 

http://www.pyrobin.com/files/building%2024...nch%20shell.jpg

[justanotherpyro]

Well those kickass scales are very precise, but cannot hold more than maybe a 100g (I'm talking about the 0.0001g precisoin)

There are a wide range of scales including the ones that you refer to. The one in particular that I use in the lab for my 6" shells has a 2000g capacity accurate to .01g.

[flying fish]

While we are on the subject of scales, my parents just bought me one for my birthday.... 200g limit/ .01g precision ("AWS Scale mate"). Not anything fancy, but still much nicer than the $10 jewelry scales I typically buy off ebay when the last one broke! And plenty for the small scale experiments I do, with various small batches of experimental glitter formulations and small shells that never weigh more than 100g anyway.

 

I don't have it with me now (I wish I could get a picture), but my last scale, when I turn it on, curses at me instead of going to 0. It actually reads "f--k" (I'm not trying to censor it for the forum, it actually does read "f--k" with the dashes).

[psyco_1322]

lol. Yah I had a cd player that did that once. It used to be real great and would play the most scratched up cds I could throw at it just fine, where others would just say error. Though when it had not disk it would simple say "no disk" but one day it stopped reading disk and when I put one in it would always read "no f disk" I thought it was mad at me for making it play all those bad cds. If you just left one out it would still read the original no disk.

[marks265]

Still being a novice I have built and fired 7 each 6" ball shells now. The little tid bit I want to share is that with MY LIFT POWDER I use 8.5% of shell weight. I know there are some magic numbers out there but I wanted to come up with standard for myself that was easy to remember and not have to use a lot of calculation. These shells weighed 900 grams to 1450 grams.

I've had positive feed back on my lift so I thought I would post this. Now I just gotta get my break figured out!

When I get to 8" 'ers it will be interesting to see if that number still works.

[Mumbles]

I think the 1/16th weight of the shell is more just a convenient rule of thumb rather than a set guideline for optimum preformance. It will work, but I always end up using more. 1/16 is a very convenient way to convert pounds to ounces. Weigh your shell at 7.5lbs, bam use 7.5oz of lift. These guidelines were made far before the majority of the world converted to the metric system.

 

It should be noted that the 1/16th rule of thumb really only applies to big shells(a couple pounds) lifted with 2FA. Using a finer granulation, good home made powder, or a lighter shell would tend to skew the ratio.

 

I can't remember which hemis fit into my plastic shells. I think it was the cheap-o chinese ones from cannonfuse. I doubt my good Vulcan hemis would do it. Vulcan hemispheres are much thicker than normal and break excellently. I got them from Flashing Thunder at the 2006 PGI trade show.

[psyco_1322]

Is Flashing Thunder that company that only uses like 7" and under for their shows?

[hashashan]

Sorry, stupid question...

...erased...

[Xtreme Pyro]

I have a question, im going to start expiermenting with aerial shell's starting off with 1 inch shell's and then going bigger as i progress. I was wondering what kind of commerical grade blackpowder would be best. At the moment i have pyrodex FFG but i am unsure if this will work because i have heard numerous amounts of time's that pyrodex is not good for lifting aerial shells. Thanks.

[Mumbles]

2Fg black powder is probably best. It will work well for lifting and breaking canister shells up to 4 or 5". It can get a bit dicy above that, but if you have good construction techniques, you'll be fine. With ball shells, I've heard reports of shooting shells upwards of 8" with 2Fg equivalent. It may not be smart or advisable, but with good technique again, it will be fine, though a very hard lift with large shells.

[aa92td]

I need a suggestion from you guys, i am planing to make 5" shell with 2" inner petal and i am not sure what mixture i should use as burst i was thinking about put in the inner petal shell small stars and fill it up with flash only and to put in the bigger shell coated rice hulls and stars only that mean that the whole power of the burst will come from the inner petal.

what do you think guys? any suggestions will be welcome.

 

 

Sorry about my English , AgwA.