first ball shells

[TYRONEEZEKIEL]

Well fellas, After the extensive reading done here, and practice, I have finally built my first successful 3" hemi shell. My first 2 attempts were using primed time fuse which didnt work, so I resorted to using visco just to see if I could even break a shell.

 

 

I uploaded the videos here. Please critique and tell me what needs to be done

 

 

I used a 15" i believe hdpe mortar which is side fused, as I dont yet have fuse for top fusing.

These are my first videos of my pyro, and I am proud to share with everyone here.

 

Again, thanks for the vast wealth of knowledge, and I appreciate everyones help

 

 

BTW. If you happen to see the rocket videos, This missile silo style launch technique is the only thing my dad will allow for these bigger rockets since the longer tube really helps stability, and we have never had any incidents, harm, or bad flights because of it.

Edited January 4, 2011 by TYRONEEZEKIEL

[Mumbles]

Time fuse really works best if crossmatched. You can certainly make time fuse work just by priming it, but it does take a little bit of experimentation and dialing in before being as reliable as crossmatched fuse.

 

The shells don't look too bad. They seem to have a bit of a dump break, and uneven pattern. This can be solved, or at least helped, by using similar sized stars and perhaps more pasting. If these are plastic, some pasting over the top or strapping tape or a harder break can all help to improve the pattern. I don't particularly care for plastic as I don't feel one gets as good of results, but it's hard to beat the speed.

 

They get up there just fine, but 3" mortars are normally around 18-24"

[AdmiralDonSnider]

The balance of container and break charge is really critical for good breaks. Stars also; you can´t expect uneven pellets to result in even pattern bursts.

 

Some more info about these variables would be helpful. Forgive me in case I overread them at Youtube.

[TYRONEEZEKIEL]

Alright Ill give the complete lowdown.

 

My stars were rough cut stars. I also use parlon for binder on all my stars atm, and my priming technique is prime the surface i will cut the stars on, form the slab, dust the top with prime, cut all stars, then I adapt the diaper method by putting all my stars and more prime powder until they are evenly coated. I use a KCLO4,Red Gum, Charcoal, prime. I dont remember the ratios off hand. I do notice that since the acetone evaporates so fast, the stars develop serious cracks if I dont baby them.

 

The hemis I used are paper and I used 2 layers of the 3strip method, so 4 layers total, then I spiked the shell with twine. I know Im supposed to use like 14 layers of past IIRC, but my only test was to see if my burst worked, and I could light/ throw the stars. so i know the uneven pattern is most likely from blind stars/ weak burst. I am not going to continue to inadequately paste shells like this. I jsut wanted to see if they worked before spending the time to correctly paste. I also use <1inch gummed paper tape to paste.

 

My burst has been a variety for each of the shells on the video. One shell used meal powder mixed with rice krispies (a sort of coated rice hull experiment). Another shell used straight pulverone. the other was a mix of meal, pulverone, and some left over prime.

 

I did not measure the mass of any of the burst. I simply made a wall of stars around both hemis all the way up to the equator. Added tissue paper layer on each hemi, with a hole cut for fuse, then I filled each hemi to the brim with burst.

 

That was basically all i did to these shells. I plan on having my star roller finished tonight, so I will start making uniform stars, and no longer use acetone/parlon as binder. I will use either alcohol for red gum, or water/alcohol for DX.

[Mumbles]

I'm sure it depends a lot on your burst, but I've been getting pretty good breaks from 7 layers of 35# 3/4" gummed tape using 4:1 BP on puffed rice. I don't make many 3" ball shells, but I sifted the smaller particles out of my normal puffed rice burst. I put it on a 4 mesh screen, and used whatever fell through. I though the majority of my burst was a bit large for 3" shells. If/when I make more, I'll probably just use rice hulls. They probably could have used another layer or two of paper or a small amount of booster, but I was happy with the results.

 

Upping the layers to a higher level will probably solve a lot of your problems. Oddly enough more pasting sometimes improves ignition. Very weak pasting can occasionally result in poor ignition as the casing fails before the fire can really spread evenly and get to the stars.

 

Most of the spiked ball shells I've seen, and there have not been too many, have the spiking on the inside with pasted paper over the top. Having it on the exterior could result in it being burned or damaged by the lift. Internally spiked hemispheres for multi-petal shells only experience the flame for a fraction of a second so as to not be too compromised, but on the exterior it has several seconds to burn and smolder.