16 replies to this topic

[gandelff]

Sorry if this has already been posted( i have done a basic search
I am wanting the presentation of my rocket payloads to be more visual ally pleasing , I use a varied amount of payload pots ranging from bough paper hemi's and semi spheres to 5/8" inner id tubes,toilet roll tubes,sealed 35mm cartridge cases, the thing i have problems with is, they tend to blasted out from the pots through ruptures in the payload case instead of the join in the hemi/end cap, now am i sealing the whole thing too tight and with too much tape and 3 strip sealer or is there something i'm not doing to the payload pot itself.
As standard i use a 191mm length 4 mm wall thick 3/4"/19mm inner id tube and use the 1lb rocket kit from wolter pyro tubes in the us, this combined with my ball milled bp provides super fast and work horse motors and top fused gets payload ignition 9 times out of ten, its that tidying up that i'm after.
the payloads are normally a fuse through the base ,then coated sugar puffs in bp and then stars on top of the ,then i have a small piece of tissue paper with a couple grams of benzolift and a gram of fp in the middle, wrap it into a ball and make a small hole for the fuse to sit on top, after that i add the second half of my pot which is either stars and filling, when joined i seal the cardboard sphere with masking tape,if theres harder to ignite stars in the pot i tape top and bottom and then 3 strip paste them( i find some green stars are harder to ignite), is it this last process that i'm doing wrong,
do the stars have to be close as they can to the join of the sphere or at opposite ends, ?

[seymour]

I know that you are not getting what you want, but I am slightly confused as for what you are trying to achieve. There are many burst effects, from a sphere, to a bow tie, to a horsetail. With the rockets you are making, the header will be limited by size, but a range of effects are still possible.

By 'pots' do you mean shell hemispheres? http://www.pyrodirec...t/ShellCups.jpg

Is your problem that the burst is not spreading the stars far enough, or that the burst is not spreading them symmetrically?

Is your benzolift powdered or granulated? It will need to be powdered to be an effective booster.

Your green stars, What is the formula, and do you prime them? If so, what do you prime them with?

You asked if the stars should be at the end of the spheres (hemispheres), or around the join. This is important if you are trying to achieve shaped bursts, but you are not. For a spherical flower of stars, they should line the wall of the hemispheres completely, from the bottom right up to the rim. It is the burst, and more importantly the confinement (the pasting) which allows the stars to form the spherical pattern that they are in, once it bursts.

However, if you are happy with a wide, but not perfectly symmetrical burst, it is quite easy to achieve. My method for doing this on small shells, is to completely fill the casing with good stars. I then add rough powder (often called 'pulverone') until the gaps between the stars are filled. Next, a small quantity of flash powder is added. I add up to four grams of 70/30 Potassium perchlorate/dark flake Al to a 2" shell.

To get this shell to burst correctly, it is very important to give it proper confinement. For small canisters, I spike it tightly with good, thin hemp cord which has been soaked in wheat paste. This shrinks a bit as it dries, tightening it further, giving excellent confinement. I have uploaded some photographs of spiked shells here http://pyroguide.com...p?title=Spiking which you can look at if you are unsure of what I mean. You do not need to do it as fancy as them, but you get the idea. I often do this with toilet tube rolls, and have great success. I placed a number of these toilet tube shells in a mine which you can view here The mine is at 58 seconds, and again, at 1.07. Unfortunately I have no video of them on their own, so you have to watch a minute of other things too...

If it is a spherical shell, it is pasted with brown paper and wheat paste. You mentioned that you paste with the three strip method, so you are aware of pasting. However, how many layers do you use? You can almost never paste too much, and if you are unhappy with how your shell is bursting, it sounds like you need to do it more.


My apologies for my messy reply, I hope I have helped, not confused you

[starseeker]

If your 1lb rockets are working well then they will lift a 3" spherical with ease,if not a light 4" shell,so if your shells are well made you should have no problems achieving a decent burst.

[gandelff]

wow,amazing answers,i think i asked more than one question and will `upload an image later on to show you what and where my casings are rupturing, anyway it is the symmetry of the stars that i am at the stage off now, i use loads of differant types, the greens in question were

metallic green hardt green star #1
Barium nitrate 39
Barium chlorate 27
Potassium chlorate 16
Red gum 13
Dextrin 5,

if i test them on a flat surface they take some going to get started,though once fired they cook nice and bright, but do find the heat has to be long and intense which leads back to the confinement theory as posted by seymour,i will have to leave it there as due in work in a mo but will add more and the photo this evening and hopefully explain it better then.thanks guys

[Arthur Brown]

Star comps rarely work as well as desired until they are flying through the air.

[seymour]

Are those stars primed at all?

I would suggest a coating with something like the H3 burst composition at the very least. Chlorate stars tend to light fairly easily, but if they are blowing blind, perhaps not easily enough to go un-primed. Good luck.

[Mumbles]

I prime absolutely everything now, even if it is just a light dusting of green meal. Don't ask me how, but I've even managed to blow spider stars blind with a relatively traditional KP analogue burst. After that I take nothing for granted that it will light.

[gandelff]

sorry for the delay , am mad busy at work and never stop, i do prime all my stars, even tiger tail which ignite at the mear mention of flame, some of the chlorate comps i use a thermite coat but it depends on how hard they are to ignite, anyway back to my original post,i think i am getting the confinment factor ok, as the stars are getting thrown out from the rupture blast and they are igniting, its just not clean at the half sphere where ive taped, i was wondering when making my pots and closing the 2 halves together and taping or glueing(depending on the pot in question) wether i should prick small holes in the joining tape( knid of a serrated line) then do the confinement 3 strip paste, so when the break charge ignites all the coated filling and stars and starts to expand it finds this as a sort of weak point and ruptures more cleanly? what do you reckon? worth a try, or is there a more suitable method such as not over sealing the pots?

[seymour]

I still do not really get what you want to do. It would help if you explained what effect you want in the air.

If you get a wide, and somewhat symmetrical spread of stars, then your casing will be broke in to many pieces. In this situation the "pots" that you talk about, are only there to make assembling easier. The many layers of pasted paper are what gives it strength and confinement. For example, in an ordinary chrysanthemum shell, we use thick chipboard hemispheres to line with stars, and fill with burst before losing and pasting over. While these hemispheres are sturdy and would seem to be substantial enough to affect the shape of the burst, in reality the pasted paper is so much stronger, and the burst charge is powerful enough that it may as well not be there, as far as the symmetry of the flower is concerned.

If you do not want a wide and symmetrical burst, then I see no difference between the stars cleanly coming out after the 'pots' separate, or coming out from a random hole.

If the 'pots' are the same as Shell hemispheres, it would be great to know.

[Potassium chlorate]

I'm still to make my first stars. What do you guys think about the 90:10 barium chlorate/shellac composition used for green Bengals and H3 as a burst charge? Since I haven't got any pulverized shellac, I can't make rolled stars, which I intended to do at first but have to use the wet method used for the Bengal and then make cut or rolled stars.

I do have a ball mill now, but I'm not very found of the idea of milling shellac that is going to be mixed with chlorate in a drum where it has been sulfur, no matter how well cleaned it is.

Edited by Pyroswede, 09 October 2009 - 12:24 PM.

[Pretty green flames]

I'm still to make my first stars. What do you guys think about the 90:10 barium chlorate/shellac composition used for green Bengals and H3 as a burst charge? Since I haven't got any pulverized shellac, I can't make rolled stars, which I intended to do at first but have to use the wet method used for the Bengal and then make cut or rolled stars.

I do have a ball mill now, but I'm not very found of the idea of milling shellac that is going to be mixed with chlorate in a drum where it has been sulfur, no matter how well cleaned it is.

Why not stars with some safe and simple compositions, Chrysanthemum 6 or Tiger tail for example. Just ball mill and make stars. Barium chlorate is just to dangerous to make your first stars out of it.

[gandelff]

the effect/spread of stars i really want to achieve is a nice symmetrical ring,i use the hard cardboard hemisphere,i also use the hemisphere pots also made out of cardboard, i also use toilet roll tubes, etc., and then i string them and 3 strip paste them really well and leave to dry,
when they ignite in the sky there not coming out in the circle formation that there in the shell in, upon retrieval of the spent shell and rocket(sometimes a tough job on a wet and muddy farmers field) the shell header/payload casing isn't clean blown into the original 2 halves, more blown apart like a fragmentation grenade, so thus i know that my burst charge is strong enough to break the casing and fling the stars out its trying to find the art/skill in making them make come out to make a ring of stars if that makes more sense, i know if i for example stacked stars ontop of each other in a long tube(1/2" x 4") and had a lift charge at the fused based and taped and strung and 3 stripped etc the chances of all the stars getting fired out from the casing from the end of the tube is high, the effect i imagine will be similar to a shot gun spread,but with my round shells they also come out in this manner, i want to wooo the spectators /family members with these nice circles/lines etc as described by seymur

[seymour]

If you use the toilet paper roll, you will need to use very different techniques to if you make a round shell. They will need to be spiked well using a strong, but thin (it's only a 50mm shell), string made of non-stretching natural fibres (hemp, jute, but not cotton)

For the ball shells it sounds like you are doing it mostly right, but you will need some tweaking. Perhaps your booster is not very good (What Aluminium do you use in flash, how do you make your whistle, and how much of this booster do you add?)

The other thing, is perhaps you need to paste more layers of paper over it. I paste my three inch shells with ten layers of brown grocery bag paper. Because ten layers using the three strip method would drive anyone completely mad, you might want to use a new method. For three inch shells I use a 'tennis ball method". Two pieces of paper per layer, like a tennis ball. You just need to let the paste soak in to the paper and soften it up, and it will become much more flexible.

I also boost them with two grams of flash using Potassium perchlorate and Indian dark Aluminium.

[gandelff]

I use a 3 gram flash/break charge made up of 50/50 mix kno3 and german dark aluminium sometimes,

and others i use a 70 /30 whistle mix potassium perchlorate and sodium benzonate
prepared by hand grinding both chems seperate in a mortar and pestle then diapering them together, and then make a 70/30 mix of whistle mix with ball milled bp, though i dont mix it if that makes sense,

i prepare my break charge by placing the 3g of whistle in a small heap in the centre of a single piece of tissue paper(andrex am posh) and add just under a gram of bp on top of this and wrap the mix up and hole it and place the wrap ontop of the fuse. now should i be diapering the bp in with the whistle mix or is my comp not fast enough for a break charge, i like using this mix as it gives tremendous heat as well as fast, maybe if what your saying is that it isnt fast enough

as for confinement wow 10 sheets thats alot, i get bored after 2, though i do use natural twine and when dry it is solid, i will make another tonight and stick with the paper strip method and add the extra layers, before i do should i increase the size of the break charge or change it, the filling will be coated sugar puffs and the stars will be 1/2" chrysantyhm 8's so not too much heat is required to get them firing, just this breaking of the shell that i have to focus on at the mo

[seymour]

You should definitely give it more layers. We have a labour intensive hobby.

You keep referring to the flash/whistle as a "burst" and the BP on puffed rice as a "filler". Generally, the black powder coated filler (the filler being the puffed rice) is the actual burst. The flash or whistle is a 'booster', in that it 'supercharges' the main burst.

Personally, in such small shells I do not use a filler, and just burst the shells with black powder granulated through a screen. Shells 3" and smaller are so tiny that no filler is really needed. I still boost them with the 2g of KP/Al flash.