Cylindrical Shells
#976
Posted 28 January 2007 - 11:25 AM
Hope this is of some use.
#977
Posted 28 January 2007 - 11:47 AM
#978
Posted 28 January 2007 - 03:03 PM
Is the same true of Kevlar?Do not put carbon fibre into anything that burns: it is far more dangerous than asbestos when allowed to burn. Its one of the main problems we encounter with aircraft fires and modern man made fibres.
#979
Posted 28 January 2007 - 08:40 PM
Aquamarine stars sound cool! and would make a nice pistil for the yellow glitter (if you've seen the Kimbolton Turquoise and Yellow glitter shells you'll know what I mean) - but the problem with "inbetween" colours is that it's then difficult to find really contrasting colours for 2nd break, which looks better IMHO; however a violet/white quadrant or violet with silver rays ought to be pretty stunning.
BTW, GRP = Glass Reinforced Polyester, GRE = Glass Reinforced Epoxy - I will send an email or two and see if I can find you some high strength tubes. If my databook is to be believed, top notch GRP/GRE has an ultimate tensile strength approaching that of good steel, and at < 1/3 of the weight - just need something a bit thicker that the usual tubes (which are obviously made to a price) and with a better bonded on plug at the bottom. Like you say, it's only the bottom 1/3 that needs the extra strength with this shell construction since all the lift is burnt before the shell really starts to move. Hence a good strapping with heavy glass fibre mat under and around the base of a regular tube might do it - maybe bond a plate on the bottom to spread the load and stop it burying itself as well??
If you want to get something ready made, these guys do heavy duty mortars - http://www.pyro-art....-abschuss01.htm, and I think there's someone in the UK who may have some too - I'll let you know when I get confirmation.
Edited by pyrotrev, 28 January 2007 - 08:41 PM.
#980
Posted 29 January 2007 - 08:04 AM
Those tubes sound good, ill pm you with my email and see what you can find me. They need to be very strong tubes because at some point ill be wanting to fire a true 3 break with bottom shot but only until I have mastered the 2 break. Not forgetting the end plug is going to be the possible weak point for the tube, deppends how its attached to the tube.
Thanks for your help Trev, be my dream to use them in displays one day. When its fully leagal of course.
#981
Posted 29 January 2007 - 08:41 AM
its all about the shells baby
what would we do without black powder
#982
Posted 29 January 2007 - 11:54 AM
#983
Posted 30 January 2007 - 12:26 AM
For canister shells, I think an extra turn of paper, a chipboard liner, or a few extra spikes would work better than dipping in wood hardener. It'd be more economical and faster as well. A lot of people dry roll the inner can actually, Pasting or gluing this would provide some extra containment. I glue mine to provide better fireblocking. If I remember right, in the first fulcanelli paper, they don't glue the can or the inner most disks at all. The process is completely dry until spiking and outer wrap. You'd have to check, but I don't remember them wet rolling their cans, or gluing them to the first end disks.
#984
Posted 30 January 2007 - 03:21 AM
its all about the shells baby
what would we do without black powder
#985
Posted 30 January 2007 - 04:15 AM
I've heard of using wood hardener in rocket and mortar tubes, but never on shells. I use gummed tape on ball shells anyway, 13 layers on 5" and 15 on 6". I am a firm believer in a proper burst for a symetrical burst.
For canister shells, I think an extra turn of paper, a chipboard liner, or a few extra spikes would work better than dipping in wood hardener. It'd be more economical and faster as well. A lot of people dry roll the inner can actually, Pasting or gluing this would provide some extra containment. I glue mine to provide better fireblocking. If I remember right, in the first fulcanelli paper, they don't glue the can or the inner most disks at all. The process is completely dry until spiking and outer wrap. You'd have to check, but I don't remember them wet rolling their cans, or gluing them to the first end disks.
That's correct, Mumbles. The Fulcanelli articles ( well worth the cost! ) have a dry rolled case of kraft paper, usually 70#, the number of turns = the diamter of shell in inches, with a rolled chipboard liner inserted (dry) inside that. The ends of the paper are pasted and pleated down over the inner end disks, though, and then an additional end disk glued on over that. After spiking, the string and the paper is rubbed well with wheat paste, and 2 turns more of kraft wrapped on, ends pleated, and smoothed down. That dries to a very hard, almost plastic-like texture, before a couple more wraps of thin kraft is glued on ( just as a liner, to hold the lift charge, passfire, and cover the top fuse ).
I have had good results dipping cheap Chinese shell hemi's in Minwax wood hardener and letting it soak in and dry. Not positive it makes a *whole* lot of difference, but it sure didn't hurt.
KAABLAAAMMM!!!
"OK... that shows you what could potentially happen."
--Homer Simpson
#986
Posted 01 February 2007 - 07:00 AM
Reguardless of what Fulcanelli says, I glue the casing sides and glue down my pleats. With an inner liner, you might not have to wait for the shell to dry to fill it. It is also useful for making small adjustments to the ID of your can for comet filling. If you want the full 3.5" you can roll your liner directly onto the former before the rest of the can. I've been rolling my cans the night before to let them dry. I paste the full length, but have been thinking about experimenting a bit. Pasting so that the end that the shell is filled from remains primarily unpasted. It may provide a better seal instead of having to rewet the ends to paste.
Rodney, it's good to see you doing a lot of research before making shells. You might not get a good result right away, but the research will pay off quickly in tuning and correcting your shells. Remember not to get discouraged, everyone had to start somewhere. I can almost guarantee that Shimizu's, or Lancaster's shells wern't perfect when they first started. We're always here to help as well. The gummed tape you envision is indeed what I use(1" wide 40lb paper). It's a relatively new technology in the amateur world, so you will probably be able to get a lot more help for the traditional method. It also doesn't work well with smaller shells that you will most likely be making. 4" is rather shakey when using it if you're very experienced. 5"+ works great though.
For whistle, I suggest 70/30 Perc/Benzoate or Salicyliate. Another possibility is KP 70:18:12 Perc:Charcoal:Sulfur. Be sure to use a high quality charcoal. Commercial airfloat leave something to be desired. You might not even need whistle to boost that. It's all part of the experimental process.
#987
Posted 02 February 2007 - 05:30 PM
2 break 6" to bottom shot -
Break 1: Yellow and Lavendar half and half with willow pistil
Break 2: Yellow and Lavendar half and half with willow pistil
Break 3: Bottom shot
2 break 6" to bottom shot - Thanks Pyrotrev im using your design!
Break 1: 3 quadrants red/green/blue with glitter pistil
Break 2: Yellow glitter with lilac pistil (Might need to change the yellow glitter to gold glitter as have no Antimony chinese needle)
Break 3: Bottom shot
Also making a 6" Beraq shell -
Break 1: Red beraq - Green beraq rings
Break 2: Bottom shot
Im starting on making 62 Beraq cases!!
Ill post pictures of the constructions on each shell as I go. Any special requests on pics/vids?
Karl
#988
Posted 02 February 2007 - 07:15 PM
#989
Posted 02 February 2007 - 07:28 PM
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