1569 replies to this topic

[italteen3]

Heinz AMAZING shells! Keep up the excellent work, hope to see more videos soon. By the way you said there where 150 pumped stars in the second spherical shell, what size were they?

[heinz]

Jerronimo - I?ve just finished a chrysanthemum 8 composition, ready for rolling stars.
I wonder if that gold willow formular works with chrys. 8 too. I?ll give it a try.
Oh, by the way, my Al isn?t spherical. Let?s see...

italteen3, the size of those pumped stars was d = 10mm and h = 11mm.

[Jerronimo]

Yes it would probably work with crysantium 8, but what mesh size is that flake AL?

[Chaz]

I'm a bit of a shell newb, I just made and launched my second and third shells. They went pretty well, except the stars I used didnt ignite so well. I put about 30 in each shell, and only around 10 of them ignited. I'll have to give them another prime before using them again. Still, everything else went pretty well, except the wind blew the first shell towards me, and I almost missed it as it exploded right above me.

VIDEO: http://www.infernola...Shells2and3.wmv

A few seconds after the second shell, stuff started falling back to earth. A hemi landed about a foot away from me, so I retreived it, and here it is:



I had 'pasted' it with many layers of duct tape, not sure what happened to it all. I wouldent have pasted it at all if the mortar I was using wasn't too big for the shell hemi's I've got. It looks like the two hemi's were just blown apart rather having the whole shell blown to bits. It could have been the glue I used - I used Poly Cement, the stuff you glue model aeroplanes together with, thinking it was the same stuff as PVC cement, one of the recommended glues for this plastic.

[ProfHawking]

all of the problems might be related. I think that if the glue wasnt strong enough, then the shell would pop too easily apart, and A not shatter, and B not have a high enoough pressure inside to produce the heat to ignite the stars.
Does anybody know if that would be the case?

[RegimentalPyro]

Sounds like it could be the case. Does your glue permamently mark the shell hemi's plastic if it is spilt on it. If not then it probably isn't strong enough.

What you should really use is something that softens the plastic enough so that the hemi's "melt" together and form a good tight bond. I use "Rustins Cellulose thinners" which is available from Wilkinson's

[Jerronimo]

xylene and methylene chloride are the number one choices for a good strong bond.
Also a good stong breakcharge is needed certainly for shells with a small diameter of 1? inch.
I would suggest a wistle composition as it doesn't produce a blinding flash like the kno3/Mg flash u use and still has enough power to fragment the shellcasing.
Flash will diminish the effect of the star, certainly when using a low light output blue composition.

Edited by Jerronimo, 21 February 2005 - 12:19 PM.

[ProfHawking]

What you should really use is something that softens the plastic enough so that the hemi's "melt" together and form a good tight bond. I use "Rustins Cellulose thinners" which is available from Wilkinson's

Or you could use a blowtorch to melt the plastic together


jokn! obviously DONT ACTUALLY DO THAT

[Nova]

had 'pasted' it with many layers of duct tape, not sure what happened to it all. I wouldent have pasted it at all if the mortar I was using wasn't too big for the shell hemi's I've got.

I think that the use of ducktape can cause some problems as well. Ducktape is extremely strong and doesn't 'shatter' easily. Perhaps you should try regular masking tape.

Or you could use a blowtorch to melt the plastic together 

jokn! obviously DONT ACTUALLY DO THAT

Lol, setting a >1000? C blowtorch on a thin plastic shell, filled with lots and lots of highly flammable pyrotechnic composition.

[PyroKid]

Although not all the stars ignited, i still have to congratulate you on producing such a nice blue colour, which is probably one of the hardest colors to perfect due to the low burning temperature required to produce such a colour.

[adamw]

As mentioned by others, you should'nt use any 'glue', rather let a solvent 'melt' the two halves and form a sort of 'glue' of its own.

Try getting some mono (or multiple) -filament strapping tape (the clear tape with glassfibres woven in it) and attatch strips of it from the top to the bottom of the shell (about 6 strips should do). This will serve to cause tension on the shell body and re-enforce the case.

[karlfoxman]

hello everyone

right i am making a 4inch willow shell and some palm tree shells with tails, how many layers of gummed kraft shall i use? i was thinking 15 for the willow and 12 for the palm? my burst is fast willow bp on rice crispies. and paper hemis. no flash or booster.

[al93535]

I make my 4" paper shells with 3 layers of 70lb kraft to form the hemi's. I then use only 4 layers of pasting and I get wonderful results. But I also use thinned wood glue, which makes them pretty strong. I always get nice big round flowers.

[Kembang Api]

al93535: What kind of bursting charge did you used and what is the ratio against rice hulls? Thxs

[karlfoxman]

surely you must be using a booster with bp carrier. i am using only a bp charge made with willow charcoal so i think to get a decent burst i will need a very strong case.