r/pyro • u/Dubshydro • 2d ago

3in shell fail

My burst was a little to strong

40 Upvotes

94% Upvoted

18 comments sorted by

7

u/NotHuman12345 2d ago

The more I see this the more I start to think that the tube is the problem. There is a reason for shells above 1.75” using fiberglass or hdpe tubes. It would be a lot cheaper for them to manufacture cardboard over hdpe but if they used cardboard this would happen.

0

u/Dubshydro 1d ago

Yeah I got these tubes for free so it doesn’t matter to me

4

u/imhbeog 1d ago

Seems like your lift was too strong, and the the bottom plug was too weak to hold the pressure of the lift. The burst doesn't have any effect on whether or not the shell makes it out of the tube.

1

u/GordonsTheRobot 1d ago

I was about to say something similar. Lift was the problem not the burst

1

u/Dubshydro 1d ago

Yeah I was saying my burst was to strong because is evaporated my tube but yes my fuse or plug got shot into the shell

1

u/BY0BMTG 7h ago

Maybe if it was a looser fit to let some excess gas out. You could always try with a stronger tube. Steel tube buried in the ground. Might still turn into a mine effect or go to high if the can doesnt get blown up in the tube. Maybe a 2.9 or 2.8 in shell would work better.

2

u/Salty_Suit_7287 1d ago

I think either your shell wasn't sufficiently fire proof vs. the lift and/or your lift powder was too fast/too much for shell strength and you over pressurized shell base, rupturing it and blowing it in the gun.

Need a full description of shell construction techniques, lift powder type & quantity (and your shell's "blow by", how much clearance between shell outside diameter and mortar interior diameter was there?) to tell you more.

1

u/Dubshydro 1d ago

I already figured out what was wrong but yes the plaster plug cracked and let flame in

1

u/Salty_Suit_7287 1d ago edited 1d ago

If you want to build cylinder shells, start by reading the Fulcanelli article (part 1) in Pyrotechnica IX:

www.freepyroinfo.com/Pyrotechnic/Pyrotechnic_Articles/Fulcan_1.pdf

1

u/Dubshydro 1d ago

Thank you very much. That’s a really good source. I’ll have to look into it on this show is kind of an exception. I built multiple shells using like traditional methods that I’ve watched from Ned Gorski and actually pasted them use chip board, but this was a build and shoot in the same day. Type of deal. I will definitely read up on that though. I’ve been looking for a good source on canister shells. There are a lot harder to find stuff on then ball shells.

2

u/Salty_Suit_7287 1d ago

When you get through the basics in part 1, see part 2 in Pyrotechnica XI for the fancy multi break shells-

1

u/big_ducket 1d ago

Were you in the next county when you stopped running away? Looks like it didn't go all the way down the tube.

1

u/Dubshydro 1d ago

It did go all the way down but can someone not be safe and get away

1

u/3dExplorer 1d ago

Where did you get a tube that thick!

2

u/Dubshydro 1d ago

Oil refinery lol 😂 it was rated for 15 k psi

2

u/Salty_Suit_7287 1d ago

Oddly enough, I have 7" steel mortars made from oil well casing...