Shell size - Expense vs. Performance gain

[AdmiralDonSnider]

Few weeks ago I did some calculations out of interest. I tried to figure out how the loads (garniture volume) necessary for - in my case - cylinder shells change with the diameter of a shell. The results were quite surprising - at least for me.

 

http://img18.imageshack.us/img18/1183/volumey.jpg

I commented the table on Pyroguide: "When we increase the caliber of a shell, the loading volume increases almost exponentially. That means: to properly fill the case of a 4" shell, it takes almost three times as much material as in case of a 3" shell. In case of a 6" can shell, it takes more than ten times as much; and if we made a single 8" break, the necessary material could fill more than twentyfour 3" shells! The increase in case of the lift charge weights is not as drastic, but still remarkable. Sure, a 4" or even a 6" shell will break more impressively than a 3"; but will it look three times as good as a 3" or ten times as good as a 3"? Will it look as good as three or even ten 3" breaks? ... However, for the sake of fairness it must be noted that some effects (such as comet/crossette breaks or shell of shells) require large shell calibers to operate properly. "

 

Hence, are large shells really worth the effort? What do you think?

[Arthur]

IMO you can get better effects from a bigger shell BUT they need to be so high that the effect is lost on a close audience. The big shells with fancy burst patterns are best viewed from 200m to 2000m they are wasted on close audience.

 

With 8in shells being promoted to 1.1 I'm probably thinking that good 6 or 7inch shells will be good enough for the biggest displays. For small social events possible 3 or 4 inch shells will be adequate. Also there is the UK insurers ruling that the safety distance is the number of meters that the shell diameter is in millimetres so a 150mm shell should be viewed from 150m minimum. -Most UK wedding type venues do not have that sort of safety distance available.

 

I suspect that well filled 3 and 4 in shells will do most jobs.

[Mumbles]

That trend is expected. Volume is related to diameter via a cubed relationship.

 

I think big shells are worth it to an extent. You can do much more with them, they're more impressive. You can fit more in there to fill the sky. I think they're more fun to make too.

[AdmiralDonSnider]

I get the point. However, I personally can´t convince myself that a single 6" break will be as impressive as ten three inchers shot in close intervals or as a finale. With a given (maybe limited) amount of stars and gunpowder I can choose between one of this options - and tend to choose the latter. At the same time I´ll have to admit that I lack the experience of making shells exceeding the 4" diameter.

[qwezxc12]

My $.02,

 

I have the most fun with 4 to 6in shells (ball and can). I've made a few 8in ball shells and at ~7.5-8lbs ea, they consume much more material than a 6in with a less than commensurate increase in 'wow' factor to me. The 6in shells I can make do a great job filling the sky, so I'm not too fired up to go bigger right now. I'd rather spend my effort (and chems) refining the actual shell effects.

 

On the smaller side, the 3in shells that I make are so close in performance to Chinese 2in festival shells, I don't really bother anymore - when we throw parties or bonfires, my friends all want to see the bigger stuff that they can't get.

[Arthur]

The general public seems happy with a show of 19 - 29mm shatter comets called palms in cakes. The cognoscenti want more we want multi petals, multi break, bow tie, hearts, faces, animals, crackling, time rain, we want it all and more than that we want something new and innovational each time- all for £1 a shell.

 

Some of the things we look for are lost on the paying public.

 

We can do effects in a 6 that we couldn't do in a 3 or 4 but does the client value them?

[Seymour]

Ignoring the issues with what sells...

 

I believe that with the largest shells (above 12") you need to be increasingly aware that you need to use what you have to do effects that cannot be done in any other way. If you try to do a standard chrysanthemum shell, it will be impressive, but not so impressive that it is really worth the effort.

 

Here is an example of a shell which is simple, but does something that a small shell cannot do. Make the sky glow deep blue.

http://www.youtube.com/watch?v=wZ-sukZ0mG0...feature=related

 

Here is a shell also based on a simple concept, but that DEFINITELY cannot be done on a small scale. Massive respect to the builder of this one. Yes it is, a five petal chrysanthemum.

 

Then you get shells which definitely do not match what you might expect from a 24" shell. True, it was filmed from two kilometres away, and the burst was probably very large, and no disrespect to the builder who would have put a huge investment of time and materials in to this thing, but I do not consider it worth it.

http://www.youtube.com/watch?v=606zrH4RQRQ...feature=related

 

There is another large shell that I have seen, where the builder filled it with several cases of bought shells. In my opinion, not only was this shell unimpressive, but it achieved skypuke. I've just spent half an hour searching for it on youtube without success. Those of you who have seen it will know what I'm taking about.

 

With these monster shells it is widely known that they will not deliver the intense raw scale that people might expect after comparing them with an eight inch shell. This is why I believe the builders should focus on what they can do within them, that does not need to burst six kilometres across, but does need the huge volume that you have at your disposal.

 

If you are not going to do this, I believe you should stick to the 'smaller' sizes. I believe it is commonly believed that sixteen inch shells give the biggest punch for their size (in the standard chrysanthemum form). I have also heard 12".

 

I get the point. However, I personally can´t convince myself that a single 6" break will be as impressive as ten three inchers shot in close intervals or as a finale. With a given (maybe limited) amount of stars and gunpowder I can choose between one of this options - and tend to choose the latter. At the same time I´ll have to admit that I lack the experience of making shells exceeding the 4" diameter.

 

Of course, when you make a few friends for the friends and family it is quite different.

 

But for us who have ambitions that stretch beyond the limiting factors of the law, our finances and what has been done... Whole new story!

Edited March 30, 2009 by Seymour

[tentacles]

With 8in shells being promoted to 1.1 I'm probably thinking that good 6 or 7inch shells will be good enough for the biggest displays. For small social events possible 3 or 4 inch shells will be adequate. Also there is the UK insurers ruling that the safety distance is the number of meters that the shell diameter is in millimetres so a 150mm shell should be viewed from 150m minimum. -Most UK wedding type venues do not have that sort of safety distance available.

 

I suspect that well filled 3 and 4 in shells will do most jobs.

 

I'd suggest that anyone who has seen a PGI display would disagree - the shows wouldn't be half as good without the big shells! I think part of the problem may be that many display operators buy only the cheapest available large shells. Some of the competition 12's and 16's have ludicrously large breaks, and they're shot halfway to the moon.. yet the stars go out about 50 feet above the audience's heads! You just can't get the sense of wonder and awe like that out of a small shell.

[FrankRizzo]

Then you get shells which definitely do not match what you might expect from a 24" shell. True, it was filmed from two kilometres away, and the burst was probably very large, and no disrespect to the builder who would have put a huge investment of time and materials in to this thing, but I do not consider it worth it.

http://www.youtube.com/watch?v=606zrH4RQRQ...feature=related

 

 

Seymour, that shell was lackluster because the outer petal of comets failed to light. The builder was talking about it the last PGI convention; it was one of his first attempts and he hadn't let the comets dry enough before assembly.

 

Yep Tentacles, I completely agree. You haven't lived until you've been *inside* the burst pattern of a 12" glitter shell and the stars are burning out right before they reach you, or hitting the ground around you..somehow avoiding you like they each have there own radar.

[a_bab]

Hmm; last New Year's Eve (the only time when I use my shells, all built in a week) I thought about going for something bigger next. I had 3" shells two years ago; last year I made some 4" shells and for this year the next step would have to be a 6" shell.

 

But then I noticed the enourmous amount of chems needed for my resources of both time and chems, so I gave up the idea.

 

Instead, I'll go for "minimalism", like perfecting the small shells. The 4" would be the absolute largest, and I'll go for a computer-fired cake with all the possible inserts (shells, comets, mines, etc).

 

I saw last year some very hot rockets able to make a perfect circle on the sky, all at maybe 2 inch diam. the heading (maybe less). Mini-patern shells anyone? I'd rather spend my "pyro" time/life trying to perfect the small items, instead of going for the "bigger". Lots of other people did it. So what?

Just look at the accident with the poor guy who managed to get toasted while pouring the contents of his huge ball mill (some 10 kgs of BP). He went for large shells too, shells that required lots of BP for break.

 

At an amateur level, one has to have the skill of managing the risks very well. One has to always ask himself:

-what IF my shell goes off while I'm pasting it? Will it kill me? (sensitive chlorate stars)

-what if my ball mill goes off? What will my neigbours say? What would be the damage?

-what if my batch of stars will ignite? Will it create a fire big enough to burn the whole house down? How do I manage the smoke? (neighbours again)

 

But I guess I'm already derailing. The point is, for an amateur, unless having a "factory", or a special remote place (NOT the garage, not close to the house and/or the family) building large shells ain't worth it. It's doable, but it comes with the price:

-expensive

-the "whoah" factor doesn't quite match the invested efforts

-dangeorus

Edited March 31, 2009 by a_bab

[andyboy]

I'm with you on that a_bab, small is beautiful. And if you can perfect something small, you will have the knowledge to go big if and when you want to (even more so since smaller is harder).

 

 

The largest shells I make are 3" and that's quite enough for me, if one of those would go of while pasting it. I would probably lose my hands anyway but the feeling of security over making 6"-12" far outweighs the fact that I won't be making the largest shells in Sweden. (I don't think they can sell any shells over 100mm in Sweden without a license though).

[Arthur]

In the UK the insurers require that the safety distance for shells is the number of metres that the diameter is in millimetres. So for a 50mm shell 50m safety distance, foe a 200mm shell 200m safety distance. For a lot of UK venues 200m is out the back and across someone else's plot.

 

Yes WE PYROS like to be up close to the burst radius BUT commercially it is uninsurable in the UK (likely elsewhere too!)

[Seymour]

Seymour, that shell was lackluster because the outer petal of comets failed to light. The builder was talking about it the last PGI convention; it was one of his first attempts and he hadn't let the comets dry enough before assembly.

 

That would have been gutting... Has he made any twenty fours shells since?

 

Some of the competition 12's and 16's have ludicrously large breaks, and they're shot halfway to the moon.. yet the stars go out about 50 feet above the audience's heads! You just can't get the sense of wonder and awe like that out of a small shell.

--------------------------------

Yep Tentacles, I completely agree. You haven't lived until you've been *inside* the burst pattern of a 12" glitter shell and the stars are burning out right before they reach you, or hitting the ground around you..somehow avoiding you like they each have there own radar. 2smile.gif

 

Perfectly said. Then comes the thought "I made that thing I'm inside!"

Edited April 1, 2009 by Seymour

[Mumbles]

I believe he has made a few 24" last summer. 2-3 perhaps.

 

I have the same outlook as the Japanese or the Maltese. I want every shell I make to be able to stand on it's own in a show. I don't care about combinations. To me a single amazing shell holds far more weight that a dozen mediocre shells. If no one has ever seen a show like this, they are amazing. A real old school pyro show with one or a few shells at a time, set pieces, real thought and care.

 

Sure, 2 and 3" shells are fine. Chemicals arn't that expensive for me, so I try to push the envelope. I don't make many really big shells. Maybe one or two 8" or larger shells a year. For roughly the same time imput I'd prefer to make a bit larger shell. My theory is if I wanted to see 2 or 3" shells I'd buy commercial stuff. I want to see bigger and better stuff though so I stick to 4-6". '

 

Math doesn't play a role as much. I don't care if an 8" shell is 8x as impressive as a 4" shell. I just care that it's more impressive.

 

I've heard the japanese philosophy on big shells. I mean really big 16" plus.

 

"We make 16 inch shell for pretty. We just make 24 inch shell for big"

 

Up to 16 is really all they make with care. The others are just make for publicity, tradition, or for the hell of it. It's very rare I find anything over 16" I find truely an impressive expression of the craft.