14 replies to this topic

[defective]

Can anyone enlighten me as to how these monstrosities are put into the air so high if at all?

Have seen smaller ones done but surely they're not launched from a mortar tube type thing.

[Creepin_pyro]

Looks like a mortar to me : )



http://japan-firewor...ggestshell.html

[Night Owl]

Good answer lol!

[Mortartube]

Yep they are launched from a mortar.

The time fuse is on the top of the shell (it is covered by a smaller hemi nest to the rising comet tail, shown in the photo for protection) and they take a lot less powder to get them aloft than you might imagine. They are top fused to avoid the risk of driving the time fuse into the shell with the lift and causing a flowerpot. Not good with a 48" shell and all that it entails.

According to Plimpton in his book Fireworks. The Gruccis 48" shell would only need 1lb (454g) of BP to get it high enough, as calculated by the boffins at the Picatinny Arsenal in the USA.

[knackers]

Holey crap dude , thats a bloody monster,

it would be interesting to see an exploded diagram of it,

[Brakkie]

Most of them contain a lot of smaller shells to make up for the "empty" space left inside the shell after the outer petal and burst.

[Spyrotechnics]

And if you notice the list charge is not attached to the actual shell which I have seen a number of times on Japanese displays.

[phildunford]

And the interesting thing is that those who know, tend to say that shells over 12" tend to be a bit of a dissapointment in terms of performance. It's generally done more as a publicity stunt than for it's pyro value...

[pyrotrev]

They're also made by making a one piece spherical casing then loading the goodies in through a little "hatch" in the top half - I guess no one's got big enough hands to allow the normal 2 hemi method of assembly

As to the relative effect, I think it depends on where you are watching from. If you're anywhere sort of underneath, maybe they're relatively not so impressive, as they tend to be fired pretty high - I recall 500m or so. However if you're a mile away they'll look an awful lot better that an 8" I also like the extra burn time from the big stars in a real monster.

[phildunford]

Here a youtube of a 48incher

Click

hmmm - ok...

[Spyrotechnics]

as a feat of "engineering" you have to be impressed

[GZ22]

Holey crap dude , thats a bloody monster,

it would be interesting to see an exploded diagram of it,

No pun intended lol!

[Mumbles]

I got a chance to talk to Devon Dickinson at one point a few years ago. He may not be too well known in the UK, but he's made a couple 36" shells here in the US. He showed us a nice video that shows all the processes and all that fun stuff. They're made and lifted like most any normal shell, just with some proportional modifications. Yes, a hole is cut in the top, and this is how the shells are loaded. I've seen similar small scale casings sold by Plasticos Gamon for multi-petal shells. By proportional modifications I mean stuff like bed sheets in place of tissue paper to separate the burst from the star/shells. A sledge hammer to "tap" the shell and settle the burst. A beach ball as the hemi-former.

I have a hard time believing that 1lb of powder is all that is needed to lift a 48" shell. I could see this for a perfectly machined projectile perhaps, but not a lumpy paper shell. Devon joked that Goex made pre-weighed lift bags for him. IE a 25lb bag of 1FA or 2FA. Most of these big shells use a standoff as well at the bottom to take some of the stress off the shell.

I've seen the mortar too. One guy swore it was a bear trap, and that I didn't know any better.

[italteen3]

I got a chance to talk to Devon Dickinson at one point a few years ago. He may not be too well known in the UK, but he's made a couple 36" shells here in the US. He showed us a nice video that shows all the processes and all that fun stuff. They're made and lifted like most any normal shell, just with some proportional modifications. Yes, a hole is cut in the top, and this is how the shells are loaded. I've seen similar small scale casings sold by Plasticos Gamon for multi-petal shells. By proportional modifications I mean stuff like bed sheets in place of tissue paper to separate the burst from the star/shells. A sledge hammer to "tap" the shell and settle the burst. A beach ball as the hemi-former.

I have a hard time believing that 1lb of powder is all that is needed to lift a 48" shell. I could see this for a perfectly machined projectile perhaps, but not a lumpy paper shell. Devon joked that Goex made pre-weighed lift bags for him. IE a 25lb bag of 1FA or 2FA. Most of these big shells use a standoff as well at the bottom to take some of the stress off the shell.

I've seen the mortar too. One guy swore it was a bear trap, and that I didn't know any better.

Yeah I recall 24" shells using atleast 9-10lbs of lift. Also remember reading on the Grucci website about 24"-ers that were used at the Winter Olympics in Salt Lake City, Utah.

With the meticulous way the Japanese manafacture I'm sure their shells over 12" are definitely not a disappointment in performance. I recall seeing videos somewhere on youtube of a couple Japanese 24" shells being fired, and they were absolutely amazing. How I stumbled across the videos I have no idea.

[Mumbles]

He also visited one of the japanese factories. He said they quoted something along the lines of "We only make 16" for pretty, we just make 36" for big". It's more of a tradition thing than really going for effect. Then again, who wants to practice making 36" shells? I'd imagine the same thing goes with 24" shells. It's the kind of thing where they make half a dozen a year, for the really big festivals. Apparantly there is a factory in Japan that solely makes the big shells. I saw a picture of the entrance, it is lined by the really big guns the shells are fired from.