How much lift for the "Yonshakudama" ? hehe

[Pirotecnia]

http://www.gizmotrix.com/uploads/2009/07/48in_Firework_shell_1.jpg

 

[Mumbles]

That certainly is a lot of shell. By the rules of thumb, you'd need about 28lbs (12.75 kg) of BP for lift. However I know of two 36" shells that were build before that used 25lbs of lift, so 28lbs doesn't sound right for a shell that weighs nearly 3x as much. Now, I don't know if those 36" shells were truly over lifted, but when they broke I'd say they were at a comfortable height, nothing extreme. I'd probably be comfortable around 42lbs (19kg) of BP for the lift. This is a total blind guess based upon only a few select bits of previous knowledge.

[psyco_1322]

There is probably 6" of clearance on that shell. I would think it might need a little extra lift to get out of the tube.

[Potassiumchlorate]

Those are giants. I think the biggest ones ever shot in my country were 16" or maybe 24". Anything bigger than 12" is very unusual here. I have seen a 16" mortar IRL but never a 24".

[californiapyro]

i was going to comment on the clearance. I can't tell if there's really that much space, but it would certainly make sense, seeing as that much BP would no doubt destroy a tight-fitting shell. Also, it's curious that the lift isn't attached to the shell. Perhaps it's spread out over the bottom of the mortar? and maybe a 1/2" granulation

[Sideburns]

Yes, I realize this is an old post.... but Ive got some outdated info to add to the old post! Just watched a very interesting video about the Yonshakudama -https://www.youtube.com/watch?v=Txq3NM35_C4. I guess it went off in the tube this last year in September! They claim this is the first failure in 20 years, but a post from apc in 2009 shows a suspiciously blown apart mortar tube!

 

The 400 year old tradition on sept 9-10, the Katakai Matsuri, launches Japan's largest (920lb/420kg) fireworks shell in Katakai, Niigata Prefecture.

 

 

There is probably 6" of clearance on that shell. I would think it might need a little extra lift to get out of the tube.

 

In the video above, it shows the loading and it looks like there may be more than 6 inches clearance!

[SeaMonkey]

Sideburns,

 

What an incredibly informative video. I love these kinds of

documentary videos which go into history, geography and

other relevant details. I was surprised to see women loading

the stars into the shells - is that commonplace in other areas

also?

 

I spent eight years in Japan with the U.S. Navy and sorely miss

being there in my "golden years." Hanabi in the 60s and 70s

were available in many small shops any time of year.

[Sideburns]

Seamonkey

 

Yeah that was pretty decent for a YouTube video. I too like learning about the history and traditions/origins of my hobbies and technical interests.

 

Not sure how common Japanese women are in pyro? I think a lot of their fireworks are made in small family run operations, so I'm sure everyone is involved in those cases. My wife is half Japanese, spent much of the 80s and 90s near Osaka. She says she remembers running around with her sisters unraveling spent fireworks shells to read the newspaper print and try and figure out what city they were from!

[memo]

if the yonshakodama was my shell to launch this shell i would need a tube with 2 inch clearance. have to put a few more wraps on the shell. then i would use 27 lbs of 1 fa and hope

Edited March 2, 2020 by memo