1569 replies to this topic

[completebeginner]

I made my first shell! i didnt remember to take a pic of it but it was 1 1/4 " wide 1 1/2" long instead of time fuse i use nc coated blackmatch although i should have used more the break was kno3 mg flash (less than a gram) i used chryssanthemum stars but they were made with alder which means that they werent as sparkley as they could have been i used too much lift aswell but im satisfied for my first shell here is the vid
http://www.infernola.../FIRSTSHELL.mpg

Edited by completebeginner, 21 October 2005 - 03:29 AM.

[sizzle]

Wow, that looks quite good, well done completebeginner. I wish I could do shells.

[RegimentalPyro]

Was there only one bang there? on lift? Also the lift flame was very bright, as if there was some Mg in it.

That shell looks as if it flowerpotted in the mortar.

Still nice as a mine though.

[karlfoxman]

Regimenatal is correct, only one bang and also a bright sparkly lift charge so it was a flower pot. Nerver the less that is a good first try and you can learn trom the mistake. You need to work on either the seal around the time fuse and the strength of the shell case. Also make sure your lifting charge is not too much. How much lift and what type was under the shel??

[Rip Rap]

I made my first shell! i didnt remember to take a pic of it but it was 1 1/4 " wide 1 1/2" long instead of time fuse i use nc coated blackmatch although i should have used more the break was kno3 mg flash (less than a gram) i used chryssanthemum stars but they were made with alder which means that they werent as sparkley as they could have been i used too much lift aswell but im satisfied for my first shell here is the vid
http://www.infernola.../FIRSTSHELL.mpg

Hi "completebeginner",
(This is friendly constructive criticism btw)
I watched your vid - your shell didn't work! As regimental said - that flowerpotted (the shell ruptured in the mortar). That is why there is no aerial burst & the stars leave a trail in a vertical direction - after being lit in the mortar & blasted skywards - much like a mine.
Your shell casing failed due to:
* Too much/too powerful lift powder
* Weak/badly constructed shell case
* Combination of above
Another reason, could have been using a sensitive burst mix or star comp (eg a chlorate burst) but you mention kno3 flash & chryssanthemum stars, so that should be OK.
I think the lift flame was so bright because that was your kn03/mg flash igniting in the mortar - confirming that your case burst!
If you can tell us a bit more about how you constructed the shell & what you used in the way of lift powder, we can be more specific in helping you construct a shell.

[paul]

... instead of time fuse i use nc coated blackmatch...

Thats, for sure, the reason your shell flowerpotted, maybe together with factors Rip Rap called

Don?t use blackmatch as an timefuse substitute. You can use thin or thick visco or a pressed spoolette, but blackmatch will burn too long.

[completebeginner]

the reason the lift looked that way is because there is a bit of medium couse aluminum in it im assuming that flowerpotting is exploding in the mortar thats not what went wrong i just didnt use enough fuse im probably going to do another one tomorrow i would use a spollette or visco but when i tried spolettes they would flower potand i dont have access to visco in canada

[karlfoxman]

Mate, what happened is a flower pot. The stars were shot upwards as they were directed by the mortar tube. There was only one audible bang. Even if the fuse is too short when the shell explodes inside the mortar tube its still a flower pot. Spoolettes will fail if the powder is blown through the tube its in, the bp must be rammed or pressed very hard to work. Why did you stick aluminium in the lift charge??? Good luck for the next one, hope it works.....focus on your delays if you believe this is the problem! My advice is also remove aluminium from the lift, it is not needed..

[completebeginner]

the aluminmum was in the lift because i was trying to make some tourbillions with the aluminum effect and ran out of sulfur for my bp so i had to use the left over powder from the tourbillion to make pulverone for lift because the pharmacy was out of sulfur they still dont have any sulfur so thats all that i have and iff you listen there are 2 bangs just relly close together or at least i think o well ill figure out after my next shell

Edited by completebeginner, 21 October 2005 - 06:21 PM.

[completebeginner]

i used my second shell and karlfoxman you were right it flower potted (it was still pretty) for a spolette should i have a thickly rolled tube? can i use kno3 sucrose as the time delay? can i have the spolette outside of the shell?

[Frozentech]

i used my second shell and karlfoxman you were right it flower potted (it was still pretty) for a spolette should i have a thickly rolled tube? can i use kno3 sucrose as the time delay? can i have the spolette outside of the shell?

Although I have not yet made cannister shells with spolette timing, there seems to be some really good info at Passfire. There is explicit, step by step (with photos) info on how to do damn near anything related to shell building & pyro. You should really think about joining.

excerpts from Passfire:

"Spolettes are usually made from thick walled tubes of strong virgin kraft paper, which are rammed with the appropriate increment of commercial meal powder to give the desired delay. The powder must be rammed tightly into the tube, since there are no clay plugs to hold the charge in place in the presence of high pressures such as those caused by lift or burst activity. Because spolettes must be rammed very hard, thin walled tubes y or tubes made from inferior paper will split open during ramming."

also:

"The fastest burning meal possible is used due to the fact that the delay time is often only three to five seconds, which would result in a very thin charge if slow burning powder were used. Small powder charges present a problem known as "blow through," where the forces from lift or the burst pressure in a multi-break shell can blow the charge out the bottom of the spolette and ignite the shell contents prematurely. The smaller the charge is, the less friction there is between the powder core and the tube walls to hold the core in place while under pressure. Blow-through forces are also reduced by using a smaller I.D. for the spolette tube, which provides less powder surface area for the pressure to act on. Spolette tubes with 1/4" I.D.s are often used for this reason."

Perhaps your spolette blew through from the hard lift ?

[karlfoxman]

Passfire can guide you on making them but the only true way to know is for you to make some, first what type of blackpowder are you using to fill the spoolette? The tube has to be fairly strong and thick walled because when you ram the bp into it will try to split open, the same as loading a bp rocket. Also the tube for a spoolette on a shell the size of yours doesnt need to be very big, i would say 5mm id max. I have always used gummed packing tape to roll my spoolettes as its very very strong and does not take much to make. This shell used 2 spoolettes and then glue soaked string was wound up around the joint between the shell case and fuse. This will reduce flowerpot caused by a weak seal at this point HERE

The ammount of pressure underneath a shell when the lift charge explodes is huge, any gap or weak point in your construction will cause a failure. Try to build your shells making them much stronger than they need to be, this will give you a better chance of a high flying shell.

PS. Test your spoolette timing before you put them in a shell, for a small shell like yours maybe 2-2.5 seconds. Make a note of the length of the powder grain inside the spoolette for the future. When i make them i use my fast willow powder, i get very good results and never had a flowerpot so it must work. God luck and play safe!

[completebeginner]

thanks for the advice i was looking on the net and found a site on making filmcanaster shells and took a look it said that if you take black match and wrap it with taped then it works as well a a timefuse

i launched my third shell that had a spolette delay and it worked magnificently i had a little too much delay and i think im going to stick to spolettes they leave a nice thin trail too heres the clip my gnarly shell

Edited by completebeginner, 23 October 2005 - 04:12 AM.

[alany]

Please don't post that site, gratuitous copyright violation is not funny.

Also, what kind of message is your signature sending?

[paul]

I finishes a small 3" ball shell today.

Its pasted in the 3-strip manner and 8 layers (as describet at passfire, yeeeha, have an account now, too ). Filled with 7mm Ti-spreader cut stars; the burst charge is blackpowder on corn cob mix because i don?t want an very hard break.



and here are some HQ pix:

http://www.kkpaul.rp...pix/3inch_1.jpg
http://www.kkpaul.rp...pix/3inch_2.jpg

greets!

paul

Edited by paul, 24 October 2005 - 06:23 PM.