1569 replies to this topic

[pyroman89]

Very nice shells sasman. I like the second shell.

[Jerronimo]

Oooh my god!!!
Sasman, those are some awsome shells man!!!
The breaks are huge, how much flash booster are you using in these?

Top job as always.

[maxman]

Just fired THIS 3" ball shell. I wasnt mega impressed as the break was still lobsided. I used 6 gram whistle only to break it with no BP filler! Maybe that was the cause or maybe it was because I used a baggie to house the stars in the shell. The stars were just piled in like on the passfire tutorial. The whistle gives it more kick but something is still wrong!

[sasman]

Yep .., You need to have added some BP burst as well..Also i would think it would help star ignition?..I dont know if Karl videoed his 3" TAPA shell.. but your break should be bigger than that..I think if you had put some BP burst charge + whistle it would have been ok!.

Were you happy with the emerald green stars?....I am about to roll up some Willow Diadem stars and when i build up the test shell i will make up a few of those TAPA shells and see how they perform..

Hi jerronimo...nice to see you back .. I think i used 4g of booster for 4" & the 6" used 2 g? i not sure & cant find my notes at the moment..

Edited by sasman, 02 September 2007 - 01:25 PM.

[maxman]

Sasman, The emerald green are a lovely colour. There were about 60 each of them and Davies white. I could only see about 5 of them in the original video clip!
I think they either didnt light because of me not using BP filler or the whistle pulverised them since they are softer than the Davies white. At the end of the day if I didnt try I wouldnt know and its an interesting learning curve. Next shell will have the stars one layer deep and 3fa filler with the whistle dumped in and then fibreglassed tape too! (something I didnt do this time)

I thought that using a flash bag would be a good idea but the hole in the top of the tapa shell got obstructed and 3/8" stars would not scoop in. 6grams of flash must be less by volume than 6 grams whistle so my coupette was bigger. Probably no problem in a 4" shell but a bit tight in a 3"
Here is a paragraph from the passfire page on making a 4" plastic ball shell


A secondary 4FA "filler" that gets mixed in with the stars is also part of the burst charge. The BP fill is used to create additional gas during the break. Flash powder is almost a 'negative' explosive, in that most of the combustion products (once cooled and condensed) occupy less volume than the original constituents. Flash gives a sharp hammer-blow break of very short duration. Adding a gas producer lengthens the time the stars are propelled, allowing you to use less flash while obtaining a larger break radius.

Anyone know what that means?

[FrankRizzo]

What Lloyd is saying in that article is that when aluminum and potassium perchlorate react, they generate a great deal of heat energy which causes the air around the reaction to expand. The problem with the flash reaction is that it doesn't generate any gasses which continue to expand after the initial reaction (the products of the reaction are all solids at atmospheric temperature and pressure), so a small amount of black powder "filler" (4FA) is added to the stars to create a large ball of expanding gas to help propel the stars further after the flash has ignited everything and given it a "kick".

[maxman]

Thanks FrankRizzo, So would that be the same forWhistle mix to?

[Mumbles]

Well, whistle has some gaseous products, thus why it is good for rockets and such. However, some BP never hurts. I personally skip the 4FA and just use polverone(granulated green meal). No real measured amounts, a handfull here, a handfull there. It seems to work pretty good.

[maxman]

Another two test shells here. I'm still struggling to get decent breaks!

The First shell used conkling blue and Davies white stars. about 50/50 I lined the stars one deep around the inside of the shell hemis and poured 3fa lift powder measured 25g in the middle of the stars. then I dumped 5.6g pink whistle on top. Half that amount in each hemi. I sealed using xylene and fibreglassed taped once around the joint and then four strips vertically and evenly spaced. I don't think I packed the shell full enough as the stars rattled a bit when it was shook! I mean it wasn't half empty or anything but maybe a bit short of what it should have been.


The second shell was about 50/50 improved snowball (using 200 mesh AL in place of I think 12 micron) and emerald greens which were primed with meal containing 10% mgal. The break was 30g 5:1 coated crispies and again 5.6g pink whistle. I know you are thinking why 5.6g? well that was all I had left from the small batch I made and I divided it between the two shells equally. The break was better but nothing special! I have had as good without any whistle added! The emerald greens did not light I don't know if the prime wasn't good enough or if they shattered??

I am using sodium benzoate whistle so I'm not sure it is as fast as it could be. I dried it before making the whistle mix and both that and the perc had been milled for 9 hours (separately) I filmed the whistle mix as soon as it had dried then again after 4 days. The video is from a diferent angle. Can you see any speed difference? I wish I had potassium benzoate instead.

I can only assume that my whistle is still no good.

Sasman HELP! How do I get a break like THIS out of my 3" ers?

[chris17]

I find it hard to confine plastic shells well enough to provide a hard break without using flash. Generally, I believe it's recommended to use flash as booster with plastic shells, since where pasted paper shells provide the structural strength to build up pressure before bursting appart, plastic will shatter give up more easily. When a paper shell breaks, the stars are carried away by gases escaping while the casing ruptures. With plastic however, it's indicated(at passfire for example) that the stars need to be struck out with a fast burst compensating for the lack of pressure built up inside the shell before breaking appart. Flash breaks are usually pretty hard, and there is a chance of stars blowing blind. Here are two shells I fired last NYE. They have exactly similar construction, but the other one does contain flash while the other doesn't.

http://www.apcforum....les/3inRed1.wmv

http://www.apcforum....WhitePeony1.wmv


What I've done is that I've started to paste a few layers of paper on top of my plastic shells. The more layers I use, the better breaks I get without using a booster. Also, you can try sealing your shells with polystyrene glue. A litle expensive, but works better than Xylene imo. Adding flash is a third option.

[Wyvern]

Sasman HELP! How do I get a break like THIS out of my 3" ers?

And anyone know what they used for the Tail comet the effect is fantastic

[sasman]

Well maxman those rack of 3" shells are commercial not home made.. but you should be able to get that performance in break size ...And wyvern yes i agree those silver tailed comets are great....

If you used 5.6 g of whistle then all i can say is use more? ....I know 5 g flash works very well on 3 " plastic so if whistle is not as strong as Flash maybe you need to increase the amount...or if the booster is not strong enough then confinement is an issue?.. i really dont know what to suggest .. other than start from scratch?..I would use a charcoal streamer star.. they light easy and dry rock hard so wont shatter from too strong a burst..

Ask karl to see if he videoed his 3" TAPA shells... see what they look like? Do you think that the large hole at the top of the shell is a weak spot?..

good luck

[maxman]

Sasman, possibly my whistle is not as fast as it should be. I dont know because I have no videos of what it should be like! Since I made it the wet way it is lots faster than when I just screened the dry powder together. I was just cheking out some of my older vids and found that an improved snowball 3" ball shell seemed a better break without any whistle compare these Latest shell with 5.6g whistle added and Just 20g 3FA for burst

Do you paste tour plastic shells? Can you post or mail me 1g of your flash to compare? or anyone able to post a vid of 1g whistle please??

[Mumbles]

1g of Whistle should burn in an instant, in a little flash.

I noticed two things you are possibly doing wrong. You seem to be somewhat following Lloyd sponnenburg's tutorial on plastic shells on passfire. I think the most important thing you're missing is that it's a poka shell, not one where stars are lining the hemispheres. You line the hemisphere with a plastic bag, I use the kind that you get when purchasing fruit and produce at the supermarket. Very thin, cheap, and I eat more fruit than I make shells. The flash, or in your case whistle, is in a burst bag in the center of the shell. Fill the bottom hemi with stars, and add half your BP. Then add some more stars, and the other half of your BP. Twist off the bag, and place the other hemi over the bag. It shouldn't fit together, this is key. Tap it with a wooden dowel to try to fit it together. If it just wont go, remove a few stars and try again, if it goes too easily, add a few more. It's a process.

None of your stars should be loose. If you're going to line the outer walls with stars, you have to completely fill the center with BP/BP on hulls/etc and flash/whistle. I think the looseness may be inhibiting your break strength a bit. If not doing it poka style, you want the stars to stay at the edge of the shell, so the burst is concentrated from the center. Mixing into the burst will make a weaker burst, with or without the whistle.

I recently broke some 4" plastic shells with 5g of flash, and just polverone instead of BP. The stars were too big for the shell, but they really flew. I confused people with the description. I meant to say willow stars, not willow effect. They were expecting a nice dropping shell, but got a huge chrysanthemum break that burnt out while still traveling out.

The shell should look something like this http://www.passfire...._ball_title.jpg

[al93535]

I just finished my latest shell and thought I would share here with you guys.

It is a 6" cylindrical farfalle shell. I have 38 1/2" x 2-1/2" farfalle that will burn for 4 seconds. I also have red -200 mesh mgal fueled stars that will burn for 3 seconds inside the farfalle circles. Then at last the bottom shot ignites at 4.25-4.5 seconds after the break.

There are three crackling rising comets with -100 feti for a tail, and one glittering dense tail comet.

It weighs in at 2132 grams, and is lifted by 135 grams of my BP.

Construction pics:

http://img.photobuck...5/farImage2.jpg

http://img.photobuck...5/farImage3.jpg

http://img.photobuck...5/farImage4.jpg

http://img.photobuck...5/farImage5.jpg

http://img.photobuck...5/farImage6.jpg

http://img.photobuck...5/farImage7.jpg

http://img.photobuck...5/farImage8.jpg

http://img.photobuck...5/farImage9.jpg

http://img.photobuck.../farImage10.jpg

http://img.photobuck.../farImage11.jpg

http://img.photobuck.../farImage12.jpg

http://img.photobuck.../farImage13.jpg

http://img.photobuck.../farImage14.jpg

http://img.photobuck...3535/arbors.jpg