16mm Pumped stars in a 55mm can shell ?

[yvariro]

Hi,

 

I have make some pumpeds stars but I think theres are too big for the size of the shell

 

http://img15.hostingpics.net/pics/293921IMG4111.jpg

 

 

 

 

so i decided to put them on the other side

 

 

http://img15.hostingpics.net/pics/973510IMG4113.jpg

 

 

 

 

 

but do you think it's good to put them like this,the break will be similar ?

Edited July 7, 2012 by yvariro

[Bangkokpyro]

Unless they are fast burning they look to be too big for a shell of that size and your break will look sparse with so few stars in the shell.

The way you had then the first time is the correct way to place them and will give the shell more strength but they are too loose.

You need to put wedges of wood between them to get them to fit tightly around the circumfrence of the casing or roll up a few turns of chipboard and slip it into the casing to make the casing a little smaller and the stars fit in a tight ring

When placing further layers of stars they should be staggered with each one overlapping the bottom ones as in the crosette shell picture below.

You also need to tightly pack those spaces between the stars and the casing with sawdust of rough powder so that when you spike the shell the casing does not buckle. Air pockets inside a shell can cause the shell to malfunction

 

Edited July 7, 2012 by Bangkokpyro

[Arthur]

Until you have done lots of tests you have no confirmed answer to your burn time question.

 

However as above the stars should stand on their ends so that they support the paper casing prior to spiking. IMO the stars that you show are far too big they are likely to be still burning as they hit the ground and there are practical limits to how high you can lift a small shell -more lift powder may not help. IMO start about mortar bore divided by ten for star diameter, experiment with bore over six and bore over eight, see what it looks like.

[yvariro]

Ok,

Yes the first picture was shot just to show the size of the stars,but i dont now if there is no space enough for a good break,

but do you think I Can put the stars like the second picture(mine) and fill them like this ? and after put some granulate powder for fill the space between each others ?

 

My problem is: I dont know if with the good method for place the stars I will have enough place for put a good break,that why i've show in the second picture an others way to place them for have more space for the break

 

 

hope you understand,I have a bad english sorry ^^

 

 

---------------

 

okay so I go buy some pipe in PVC(wich i secure ) for a new mortar i think a 3" will good for my stars

Edited July 7, 2012 by yvariro

[Potassiumchlorate]

You're excused It's actually the first time I see a French pyro on an English-speaking board. I don't know why, because you see people from tiny nations like Lithuania and Slovenia on both this board and others.

 

But yes, the stars seem very big for the shell, unless they contain like 25-30% magnesium.

[yvariro]

thanks you!

 

In france no one practise pyro,there are a lots of laws..... one day i will come to USA !!

 

 

my stars contains 10-15% Al325mesh

but do you think i can place them like the second picture for a good break ?

 

and thanks you all for youre answers!

[Bangkokpyro]

okay so I go buy some pipe in PVC(wich i secure ) for a new mortar i think a 3" will good for my stars ../../public/style_emoticons/default/2smile.gif

 

Your stars realy are much too big for a 2 or 3 inch inch shell . Make some more stars in the 3/8 inch size. The 16 mm ones you could use as headers on your shell.

PVC is not safe for making mortar tubes. If the tube fails it will send sharp fragments of PVC in every direction including yours.

Use HDPE or fibreglass tubes for your own safety and those around you.

[yvariro]

yes i know but i put them in the ground or in a big sand pot,

okay i will crush thems and find how to make them at 3/8"

 

i will shows you the video of the test