1569 replies to this topic

[barra69]

Hi Karlfoxman, you have to be extremely careful with MMF's (man made fibres). There is very little in the way of warnings in the general population about possible health risks, however as an airport firefighter there is a great deal of training done to ensure that people do not get exposed to MMF particles(most modern aircraft are now build with MMF's). Current evidence shows that when the material is cut, burned or aggresively abraded, needle like particles of carbon are cast off. These can remain airborne for many days in a still air environment and, if inhaled the particles behave like hypodermic needles penetrating into the cell walls. This is pretty well what asbestos did, however because of the size of the carbon particles it is supposed to be much more dangerous.
Hope this is of some use.

[karlfoxman]

Thats very useful, I will take your advice and stay away from the carbon fiber idea in that case. Ill think ill just stick to the steel seamless idea. Or bury the tubes so the earth adds some strength.

[pyrotrev]

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.

Is the same true of Kevlar?

[pyrotrev]

Karl. sorry I didn't realise the 1st break was ont' way up having never been to Malta (yet) - the only multibreaks I've seen were "top down" - but then that's only a matter of the delay fuse on the 1st break right??
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.

[karlfoxman]

I have seen those shells, im a fan of the more exotic colours. Those colours violet and silver should be nice too, one design I have chosen is the yellow and lavendar colour. Slightly moddified version of my 1 1/4" crossettes used in a roman candle I made. I think in most cases you have to keep both breaks the same effect or you run the risk of making a mess of the first one. I think it would look better using the same colours but either switching them or making them come out as opposite patterns.

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.

[rodney]

well i have been told to use wood hardner for my casings both cyl. and round its a liqued hardner for streathining wood just go to the hardware stare and dip your casings in it and let dry also apply some on the finished shell before pasteing in the lift bag and leader and it will bond and streathen the wood fibers in the paper. it should make for more sym. breaks its just a tip i have heard rodney

[karlfoxman]

I find you dont need it, but I do something similar to my Maltese stuff. The glue used is flour and water paste sometimes with Copper carbonate added to keep mice away. For ball shells I always add lots of strips of gummed tape for a 5" around 12 layers.

[Mumbles]

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.

[rodney]

the wood hardener was jst what i was told awhile back im still pretty young compared to must shell builders im only 24 and i think im the only one who has a interest in making shells and whats weird is im in the same state that firefox is in idaho so i try to get all the chems. i can from there so i can just pick it up when i got towards that way. i havent built a shell yet but im doing alot of research so i can get it as close to right the first time i relize i will have to tune it but thats part of the game. i want to make sure my stars and lift and burst are all up to par before making the shell. also what whistle mix formula do you guys recomend for shells to help with burst. also when i hear gum tape i think of the packing tape thats kraft with the gum side you wet with a sponge is this right or am i wrong. its what i used for making small rocket casings. if im wrong with the gum tape someone please tell me what it is so i get it right. i dont want to use the wrong materials and pos. hurt myself or others. i will either use quickmatch or just e-match igniters. i have a small 6 channel capacitor discharge system i se to fire with. i just hope im on the right track. my ignitors are nicrome with cat 5 and a bp /mag. base bonded with nc laq. there very hot and fire every time i use them for high power rocketry. i got cert. finally. well i hope this site can guide me and help me become a very good shell builder. and if anyone is in idaho usa please get in contact with me i would love to have a mentor that knows what hes doing. well so far this site is great and alot of info. i spent 3 hours just reading this 66 pages of this thread and it was well worth it. anyone recomend a first shell size to build im thinking a round shell and 3 or 4 inch to start with once im there and all my lift,stars and burst are up to par. thanks to all who respond and be safe rodney

[Frozentech]

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.

[Mumbles]

I'll have to go reread it. I learn something new everytime. I just had a quick look and no mention of any paste when pleating down the end disks anywhere I see. They paste the edge of the last turn of the side of the can to hold it down. All it mentions in keeping the pleats in place is to hammer it down until it cooperates.

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.

[karlfoxman]

I've chosen what shells im going to build, they are as follows:

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

[sizzle]

Could you do some pics/videos of the Beraq making process Karl?

[karlfoxman]

Yeah sure, im building them now so ill do a video.

[karlfoxman]

Here ya go,

Must appologise for Eastenders in background and my girlfriend shouting as she was playing a game on her mobile!

Video