Moving Up To 12"

[AzoMittle]

I wasn't sure whether to post this here in Newbie Questions or over in Pyrotechnics. I also did some Google and APCForum searches before typing this but came up dry.

 

Up until now I've been building 6-8" in plastic but someone offered to let me use their WASP at the next event so I am going to build a 12" paper. What should I know going into this?

 

What construction methods are different from smaller shells? Should I add a second spollette? Would it be okay to use 1/4" time fuse inside a tube or should I ram spollettes? How much burst and lift should I expect this to take up? In comparison to a 6" plastic shell how much booster might I need, if any?

 

Looking at sphere calculators a radius of 3 gives a volume of 113, while a radius of 6 gives a volume of 904. Will it then consume roughly 8 times the amount of stars and burst? I normally use 10% of the shell weight for lift, will that work for a 12"?

 

I'm thinking of joining the halfs by putting a garbage bag over one half, putting a piece of plywood or cardboard to hold it flat, flip it over and then slide out the plywood/cardboard. Add a few pieces of 3" reinforced kraft tape to hold it shut and then WASP it. Does this sound correct?

 

What am I forgetting about?

 

Thank you, I know that is a lot of questions.

[dagabu]

Wow! Big step up! First, get a case of tape for that wasp!

 

Yes, a 12" shell can weight a lot depending on the contents. Others will chime in but we didn't use booster in 12s but used BP covered rice hulls, 7:1 and that was a little much. For lift, we used 1 Oz of BP per pound of shell weight up to 10 pounds and 1/2 Oz per pound after that.

 

Nothing smaller than 2FA for lift, more push, less bang.

 

Stars need to be very large, we used 2" pumped comets, D1 glitter.

 

Good luck!

[Niladmirari]

I use 700 grams BP tor lift. This is about 1/13 of the weight of the shall. Grain size 4/4/2 millimeter.

I use 3 kg bursting charge.

 

I wish you good luck.

[MrB]

 

I normally use 10% of the shell weight for lift, will that work for a 12"?

 

 

As indicated by Niladmirari's answer on liftcharge, generally, as the size goes up, you actually need less lift proportionally to shell weight.Honestly tho... I'd much rather over-lift, then under-lift my first 12".

Just saying.

[Mumbles]

You can expect the shell to probably weigh somewhere between 18-25lbs. That mostly depends on what stars you're using (charcoal vs. color), and how fancy you're getting (single petal vs. multi, etc). Total ball park guess here, but I'd estimate 10-12lbs of stars, 6-8lbs of burst, and a pound of paper/tape/etc for something simple like a charcoal streamer or glitter. I agree with Dagabu, no booster should be required. You may also want to consider a larger carrier like cotton seed as opposed to rice hulls if possible. Hopefully XtremePyro will swing by. He'd really be the guy to ask.

 

There is a different method of filling and closing shells, that is particularly well suited to large shells. It's illustrated on page 245 of Shimizu's FAST. It utilizes a top hemisphere with a hole cut into the top to facilitate loading. Using the normal method can become unwieldy with large shells due to the mass, and extra effort to fill them. If you stick with this method ratchet straps can help hold things together while you settle the shell.

[mikeee]

With the amount of burst charge contained in a large diameter shell you will want to use a slower burst charge with no booster at all.

Too hard of a break and you will shatter your stars depending on what composition they are made off.

BP coated rice hulls, BP coated cork, BP coated cotton seed, etc. is best for larger diameter shells.

[Arthur]

First make the change to paper hemis! The break system is different few people make both plastic and paper shells well (basically the break in a plastic hemi depends on the amount of booster, the break on a paper hemi shell depends on the amount and quality of the pasting).

 

Perhaps start with paper 8" to keep the costs down.

[dagabu]

First make the change to paper hemis! The break system is different few people make both plastic and paper shells well (basically the break in a plastic hemi depends on the amount of booster, the break on a paper hemi shell depends on the amount and quality of the pasting).

 

Perhaps start with paper 8" to keep the costs down.

 

The OP already stated he was going to paper:

"Up until now I've been building 6-8" in plastic but someone offered to let me use their WASP at the next event so I am going to build a 12" paper. What should I know going into this? "

[AzoMittle]

I should have clarified that to begin with: I *mostly* make plastic, I have made 6" in paper before, but first time using WASP and first time building 12". I actually got started in pyro via Fulcanelli-esque cylinder shells (shout out to the salami builders, you guys and gals are crazy for how much work goes into building just one, much respect). I already have two 12" shells and a roll of 3" kraft on their way from Cannonfuse.

Edited July 11, 2016 by AzoMittle

[CrossOut]

Expect to dump more money into that shell than you expect.. depended on the effect the cost in chems was about 75 - 150.

 

My wasp in its configuration uses just under 2 rolls of 2" gummed tape per 12. Must be gummed tape not craft.

 

Stars I use are 1 1/4" rolled. I never count how many I use.. can't count that high lol. But if you can fill an entire hemi with stars that should be about enough. Of course Make more just incase.

 

I use home made coarse bp for lift ~1/4" corns as people said much less is needed for larger shells. About 1/13 - 1/15 the weight of the shell. If you don't make your own bp try to get F but Don't go higher that FF.

 

For my burst I use 4:1 rice hulls I get beautiful big breaks with that. I use that on all my shells 3" - 16".. smaller shells I'll add a little booster.

 

I use 2 time fuses (or spooletts) for my shells timing I think was about 8 seconds.. I'd have to check my notes on that one. I always top fuse my shells.

 

I'll show you my method for slapping the two halves together.. main thin is to have them aligned perfectly and do it fast. Make sure your hemi's are as rounds as possible if you get to pick.. elliptical hemis are a pain in the ass. I use fiber reinforced tape and tape them all the way around 8 poles method. Then wasp.

 

Don't worry too much about volume just bring a shit ton more than you expect to use. Last event I bought 2 5gal buckets of burst, 3 gallons of lift and a bucket of stars. If you have extra time and materials you can always build more...

Edited July 23, 2016 by CrossOut

[dagabu]

The last 12" I made (with help) ran about $100.00 in raw materials.

[Xtreme Pyro]

I apologize in advance for reviving an old thread, however I wanted to add a few things since I missed this..

@AzoMittle You say you have some 3" tape for pasting on a WASP? This size tape does not work period on a machine, bring this to the event and you will be greatly disappointed as no one will be able to paste your shell. The tape application wheel is only 1.91" wide so it simply will NOT work. Either find some 1.5" wide tape or cut the rolls you have in half, you will need two 500 foot rolls just in case, do make sure it is not the reinforced paper tape, or your shell will turn into a salute. As for burst, rice hulls will work fine for the carrier. I used 6 pounds of hulls coated 5:1 (BP:Hulls) and they broke nice and big. Booster is not really needed but if you'd like a bit more kick use 6 grams or so of 7/3 with 10890 AL. For stars, you're looking at about 10 pounds worth, I'd use 3/4" - 1" stars max, don't try to cut corners or save time by using larger stars, do it properly and you will be glad you did. Unless that's the effect you're going for..

For lift, I'd go with 2FA, don't use the standard 10% rule on shells of this size, you'll shoot it too the moon and the effect will be GREATLY diminished. I don't generally go by the OZ per LB rule as my lift is a bit hotter than commercial. I use 5% of the shells weight on my 12's and 16's, but if you're using commercial GOEX BP from Craig, use the OZ per lb by all means. I always use a grocery bag over one hemi to close them as earlier stated, it makes things alot easier while you're trying to mate the two hemispheres together. I typically use two 7 second time fuses for a shell this size with great results, and 24 layers of tape (2 layers per inch). If you need help or have any questions come find me in manufacturing at do-it and I'd be happy to help out.

 

- XP

Edited August 25, 2016 by Xtreme Pyro

[AzoMittle]

I apologize in advance for reviving an old thread, however I wanted to add a few things since I missed this..

 

@AzoMittle You say you have some 3" tape for pasting on a WASP? This size tape does not work period on a machine, bring this to the event and you will be greatly disappointed as no one will be able to paste your shell. The tape application wheel is only 1.91" wide so it simply will NOT work. Either find some 1.5" wide tape or cut the rolls you have in half, you will need two 500 foot rolls just in case, do make sure it is not the reinforced paper tape, or your shell will turn into a salute. As for burst, rice hulls will work fine for the carrier. I used 6 pounds of hulls coated 5:1 (BP:Hulls) and they broke nice and big. Booster is not really needed but if you'd like a bit more kick use 6 grams or so of 7/3 with 10890 AL. For stars, you're looking at about 10 pounds worth, I'd use 3/4" - 1" stars max, don't try to cut corners or save time by using larger stars, do it properly and you will be glad you did. Unless that's the effect you're going for..

 

 

For lift, I'd go with 2FA, don't use the standard 10% rule on shells of this size, you'll shoot it too the moon and the effect will be GREATLY diminished. I don't generally go by the OZ per LB rule as my lift is a bit hotter than commercial. I use 5% of the shells weight on my 12's and 16's, but if you're using commercial GOEX BP from Craig, use the OZ per lb by all means. I always use a grocery bag over one hemi to close them as earlier stated, it makes things alot easier while you're trying to mate the two hemispheres together. I typically use two 7 second time fuses for a shell this size with great results, and 24 layers of tape (2 layers per inch). If you need help or have any questions come find me in manufacturing at do-it and I'd be happy to help out.

 

 

- XP

 

Okay, cool, thanks for the tips and offer to help, it is greatly appreciated and I expect I'll be taking you guys up on the offer. Weighed on a bathroom scale (which is dubious accuracy) I have 2x 12 pound (so 24 pounds total) batches of 3/4" stars, I tried lining a hemi with them and it should be enough for 1-2 full 12's. I will definitely need to make more stars and coat more hulls in this case, for the usual 6 and 8 inch shells I build. The hemi's are slightly elliptical (supplier was Cannonfuse) but not an easter egg profile so I think they can be beaten to shape.

 

I need to get more charcoal (anyone know of a good bulk supplier ie 25 or 50 pound lots?) and pick up a drum of that perch from CrossOut. 1.5" tape is also on the list I wasn't aware of what size so went with what Cannonfuse carries, oh well, still works good for pasting comets.

[Xtreme Pyro]

 

Okay, cool, thanks for the tips and offer to help, it is greatly appreciated and I expect I'll be taking you guys up on the offer. Weighed on a bathroom scale (which is dubious accuracy) I have 2x 12 pound (so 24 pounds total) batches of 3/4" stars, I tried lining a hemi with them and it should be enough for 1-2 full 12's. I will definitely need to make more stars and coat more hulls in this case, for the usual 6 and 8 inch shells I build. The hemi's are slightly elliptical (supplier was Cannonfuse) but not an easter egg profile so I think they can be beaten to shape.

 

I need to get more charcoal (anyone know of a good bulk supplier ie 25 or 50 pound lots?) and pick up a drum of that perch from CrossOut. 1.5" tape is also on the list I wasn't aware of what size so went with what Cannonfuse carries, oh well, still works good for pasting comets.

Stack the hemispheres so the egg shapes are opposite of each other (90 degrees or so, whatever rounds them out best), and leave them that way until the event. They will round out by then no problem, 24 pounds of stars will defiantly make two 12's, or one 16

 

As for the charcoal, a few suppliers sell larger quantities of charcoal.. Check here

 

http://www.lazzari.com/

Edited August 25, 2016 by Xtreme Pyro