aerial shell 3" plan

[jukka]

*PHEW*

Damn that aerial shell topic is long.. Finally done.

Kind of odd hobby this is, more U read the more U have quoestions.

Well hopefully U can confirm this "desing" of "mine".

 

I had my hands on on 20+ tubes, cardboard tubes lengt 1070mm, OD 59mm and ID 51mm what leaves on wall thickness 4mm.

Tryed with 100kg weight on them and they didint even bend. Plan is to cut those in to shells with length of 100mm.

First Q, are those too heavy for shell covers and is that length ok?

 

Crappy desing picture (what can u expect with Paint ) is attached on this topic.

 

Hot clue cardboard disks on both end to the shell. Im trying to make those disk as hard as the tube casing. And when spiking add extra rounds around the poles just to make sure maximied even burts.

Those shells seems to be strongs so do I even have a change with spike/clue those to be constant strong?

 

Ill need to add paper around the spiked shell to extend the OD. OD would be 75 (mortar ID) - 10mm for gases = 65mm

Shell OD = 59mm

After spiking = 63mm

2 rounds of craftpaper leaves me with OD of 65mm.

 

Will this be too loose? If it is, then I would have plan B to use HDPE pipes with same preasure value of 10 but ID 63.

5% clearense would give maximum shell OD ~61mm. Thinner spiking and only 1 layer of graft paper I could make it?

What do U think?

 

For timefuse I was plannig to use green visco covered with aluminium tape and timed to 3s.

Hot glued from both sides on the bottom disk.

 

Burst = Paper tube, ID 20mm filled first near visco with small amount of BP covered grass seeds and then the rest of the space with FFg.

With this shell, will I be even near of "clean" burst? grass seeds are there to maximine the burst ignition.

 

Mortars, I have 6m HDPE pipes with preasure value 10, wall 4,7mm. Im guite sure those will make it.

Plan is to cut those to be 450mm long and insert 40mm woodplug which is 1mm wider than the tube. HDPE is flexible so they should fit in there nicely.

Add some extra heavy duty glue and screws with predrilled holes to prevent any chops.

Hopefully I got this rigth.

 

Lift BP would be also FFg with volume of 1/13 from shell weigth.

With this plan, considering the clear space between shell and mortar, is this enough? Of course I will test this with dummyshell, if this even seems possible on the paper.

 

Lift in the blastiback, fired with quick match and e-match. I will be sitting 50m away from the rack behind concrete wall. I realy trust myself

 

The rack will have 6 mortars. May I attach in front of them 6 mine tubes or will I have problems with sparks?

 

Last the stars. I was planning to fill caps between stars with BP covered grass seeds just to make sure that all start will ignite and make the shell full.

For star compositions, I read that TT formula is guite safe and good ones to start. What else would U recomend for newbie stars to start with? D1´s?

Stars in these shells would be (now im not sure of the terminology) pumped and pressed with hydraulic press and finely cutted from the presspipe for length of 9mm. Presspipe ID = 9mm also.

Are those 2 formulas rather safe to create with this method?

 

I dont have yet ballmill, thats why I need to use for new years eve fireworks that FFg. This also causes small problems on choosing the stars. Ill have time to make my own ballmill on January and then have a year time to polish my owns superior BP for next NYE.

 

Ill lean on your knowledge and hope U could give me your toughs on this. I do hope to have this as "should work fine" in the desing phase first rather just purely use trial and error method.

 

Thank you.

Edited December 12, 2009 by jukka

[Pretty green flame]

First Q, are those too heavy for shell covers and is that length ok?

 

These tubes will be too heavy and will not break properly. Your best option is to roll your own casing with as many turns of paper as is the nominal size of the shell. use a 100g/m2 paper. For a 3" shell the paper should go 3 times around the former.

 

Hot clue cardboard disks on both end to the shell. Im trying to make those disk as hard as the tube casing. And when spiking add extra rounds around the poles just to make sure maximied even burts.

Those shells seems to be strongs so do I even have a change with spike/clue those to be constant strong?

 

Don't just glue the dics to the wall, insert the disc so it fits snugly in the casing and push it down a couple of centimeters, cut the overlaping paper into flaps and glue them down with some white glue

 

Ill need to add paper around the spiked shell to extend the OD. OD would be 75 (mortar ID) - 10mm for gases = 65mm

Shell OD = 59mm

After spiking = 63mm

2 rounds of craftpaper leaves me with OD of 65mm.

 

The case former for a 3" shell should be 10mm smaller than the mortar ID, so 65-66mm when the shell is made it will be a few milimeters smaller than the ID of the mortar. Look for 3-4mm clearance on a 3" shell. You need to keep the gasses under the shell so more clearance will mean less height.

 

 

Will this be too loose? If it is, then I would have plan B to use HDPE pipes with same preasure value of 10 but ID 63.

5% clearense would give maximum shell OD ~61mm. Thinner spiking and only 1 layer of graft paper I could make it?

What do U think?

 

10mm is too loose. 3-4mm is good for a 3" shell as stated above.

 

For timefuse I was plannig to use green visco covered with aluminium tape and timed to 3s.

Hot glued from both sides on the bottom disk.

 

Do not use visco in aluminium foil. Make a spolette (thick walled tube with a small ID (6-8mm) that has been rammed with pure black powder. Very reliable when made properly and you can get some serious timing from them. Some testing is neccessary before using it in a shell. Ram them firmly and test them to determine the time it takes to burn through. With nice fast black powder you can tipically get 1sec/cm

 

 

 

 

Burst = Paper tube, ID 20mm filled first near visco with small amount of BP covered grass seeds and then the rest of the space with FFg.

With this shell, will I be even near of "clean" burst? grass seeds are there to maximine the burst ignition.

 

Use only FFg powder, the BP covered grass seeds will not work very well in small canisters.

 

Mortars, I have 6m HDPE pipes with preasure value 10, wall 4,7mm. Im guite sure those will make it.

Plan is to cut those to be 450mm long and insert 40mm woodplug which is 1mm wider than the tube. HDPE is flexible so they should fit in there nicely.

Add some extra heavy duty glue and screws with predrilled holes to prevent any chops.

Hopefully I got this rigth.

 

That's pretty much spot on. Though no need to glue the plug in, just screw it in place with some wood screws.

 

 

Lift BP would be also FFg with volume of 1/13 from shell weigth.

With this plan, considering the clear space between shell and mortar, is this enough? Of course I will test this with dummyshell, if this even seems possible on the paper.

 

Make a dummy shell first to test your lift powder, firing live shell blind with no idea if they will lift properly is not a smart idea. For homemade powder 10% of the shells weight is typical. 1/13 will not be enough if you have 10mm clearance.

 

 

Last the stars. I was planning to fill caps between stars with BP covered grass seeds just to make sure that all start will ignite and make the shell full.

For star compositions, I read that TT formula is guite safe and good ones to start. What else would U recomend for newbie stars to start with? D1´s?

Stars in these shells would be (now im not sure of the terminology) pumped and pressed with hydraulic press and finely cutted from the presspipe for length of 9mm. Presspipe ID = 9mm also.

Are those 2 formulas rather safe to create with this method?

 

TT, D1, C6 are all good for starters. Check out some star meking techniques, you do not need a hydraulic press to make stars.

 

 

I dont have yet ballmill, thats why I need to use for new years eve fireworks that FFg. This also causes small problems on choosing the stars. Ill have time to make my own ballmill on January and then have a year time to polish my owns superior BP for next NYE.

 

You'll need one as soon as possible. Without one you pretty much can't make anything that even comes close to the stuff people here can make. And dissassembling fireworks, no that smart either.

 

PGF

[Arthur]

With cylinder shells the spollette is often at the top! The Leader fuse goes into the spoolette and into the lift cup.

 

This is because the cylinder will weigh more than a ball shell and will need a strong lift that may break the spoolette back into the shell as it lights causing the whole shell to go aff with the lift or just at the muzzle. The longer the shell to more likely it is that the timer is at the top.

 

Added;

 

Those tubes that you have actually would not help your shell building, BUT they would make interesting candidates for mortars! You may get a good three 2" mortars from each tube.

 

They may also make a good former for making the paper casings that a 65mm (2 1/2") would need. Then you need the mortars

Edited December 12, 2009 by Arthur

[dagabu]

Those tubes that you have actually would not help your shell building

 

They would be good for salute canisters though. Spiking them well will increase the report.

 

D

[jukka]

Thank You for your comments!

 

These tubes will be too heavy and will not break properly. Your best option is to roll your own casing with as many turns of paper as is the nominal size of the shell. use a 100g/m2 paper. For a 3" shell the paper should go 3 times around the former.

 

You'll need one as soon as possible. Without one you pretty much can't make anything that even comes close to the stuff people here can make. And dissassembling fireworks, no that smart either.

 

PGF

I was afraid that those bastards where too strong ones. Well at least I can use them now for mines and mayby for mortars on smaller shells.

 

That was good rule of thumb to know "turns of paper as is the nominal size of the shell". With this knowledge of course Im going to make my own sylinder tubes. Excellent!

 

Im not plannig on disamble any commercial fireworks. Those are ready to shoot.

 

 

They would be good for salute canisters though. Spiking them well will increase the report.

 

D

 

well mayby in far future. Ill think Ill focus on first to get nice breaks.

[dagabu]

D

[jukka]

D

Thank You for that. So now I know how to do it.

 

paper weight on 3" shells is recomended by that document to be 30-40lb.

35lb = ~16kg. 16kg/500pcs. = 320g/pcs.

 

mortar ID 75mm - clearance 10mm - spiking and 1round paper over it 4mm- shell wall thickness 3rounds 1mm thick 300g carton 6mm =

shell ID 55mm. Now Ill need to find that diameter pipe/tube start massive rolling

 

Thank You once again!

 

One more question , then I think Im ready to start working/testing.

If I use only for burst that FFg BP, do I need to fill the caps between the stars with that also? So then it would be filled totally (clear space + burst champer diameter 20mm and height 100mm).

Edited December 13, 2009 by jukka

[Pretty green flame]

Thank You for that. So now I know how to do it.

 

paper weight on 3" shells is recomended by that document to be 30-40lb.

35lb = ~16kg. 16kg/500pcs. = 320g/pcs.

 

mortar ID 75mm - clearance 10mm - spiking and 1round paper over it 4mm- shell wall thickness 3rounds 1mm thick 300g carton 6mm =

shell ID 55mm. Now Ill need to find that diameter pipe/tube start massive rolling

 

Thank You once again!

 

One more question , then I think Im ready to start working/testing.

If I use only for burst that FFg BP, do I need to fill the caps between the stars with that also? So then it would be filled totally (clear space + burst champer diameter 20mm and height 100mm).

 

Try this for paper pound to grams conversion, your conversion is way off.

http://www.apcforum.net/forums/index.php?showtopic=302

 

35# is between 50g and 60g per square meter.

 

And your former dimensions are also way off. Get a former that is 65mm DIAMETER. then you take your paper and roll it on the 65mm former.paper you have 10mm clearance for spiking and pasting. The strenght of the casing comes form the spiking, paper only provides fireproofing and a case for the contents. Spike it and paste 3 turns of 35# paper over the spiking, this is it, nothing more needed.

 

The spaces between the stars are usually filled with rough powder, which is a cheap, only screened black powder mix which is granulated, this is then used to fill the gaps inbetween the stars. Using FFg grade powder for this is a waste of good BP.

[jukka]

how did I..? Well

Thank You Pretty !

[scarbelly]

The pound weight system is very weird and complicated, and to convert properly you need many more conversion factors than just "pounds to kilograms". They use a random number of square inches (not meters) and then stack 500 sheets to weigh them.

 

Edit: or you can just use the chart

Edited December 13, 2009 by scarbelly

[Mumbles]

The number of sheets, and size of them, in the stack varies depending on what kind of paper product you are trying to characterize.

[scarbelly]

oh right. I read that, but didn't really connect it