Flash broken shells

[dangerousamateur]

Hi,

 

I mostly do small rocket headers, between 2-3 inch, without to much pasting.

Now when I use Nitrate based Flash, everything works fine, parlonbound color stars primed with perchlorate hotprime and a final layer of green mix allways light.

I just dump the flash in the shell, and only the flash, no BP ect.

 

I know this is not the professional way, but I like it.

 

Now I would like it a little harder. What's the strongest breaking charge a well made parlon star can survive in your opinion?

Do you have any experience with perchlorate?

 

Or just look at it this way, imagine you have a big salute with some stars inside...

 

What kind of flash would you choose?

I was thinking about some compromise, nitrate flash with some percent Perchlorate...

 

[AdmiralDonSnider]

Flashbreaks seem to become increasingly popular even in round shells. This may make sense from an economic standpoint, but also makes the fireworks unnecessarily loud and somewhat destroys the break appearance. This is not to say they can´t be used successfull and can´t be tuned to produce good breaks, but I personally dislike this development.

 

That said many ( if not all) commercial rocket headers I know seem to use flash in one or the other variety, plain 7:3 perchlorate flash or a type also employing fine MgAl in addition to the aluminum. The flash is best used in a flash bag which keeps the small charge centered and prevents it from getting "lost" in the casing. The stars have to be well primed and chosen in order to light and stay lit at high speeds.

[Seymour]

I have quite a bit of experience with flash boosting, and while I've tried a few different things experimenting, I use 70% Potassium perchlorate and 30% Dark Aluminium for all normal use, added to BP on filler, or even just BP screeen (or grater) granulated.

 

My use of flash booster depends a lot on the desired effect of the shell, but as a general rule, one gram of flash per inch of shell diameter is a good place to start if you want 'hard breaks'. I've gone up to 10g of 70/30 in a 4" shell (definitely need the right stars for this), and also made 10" shells with this much booster.

 

I'm happy to add up to 2g of 70/30 to a shell with stars made and primed for black powder lift or burst situations, but if more is used, like AdmiraldonSnider said, the stars must be suited to the job. Often a KP hot prime then greenmix will do the trick, but if your coloured star is prone to blowing blind, you might want to also add a thin layer of charcoal streamer in there too to buy a moments time for the stars to have slowed down a bit more before the colour ignites.

 

Stars do also need to be rather strong. Parlon stars should be fine, as with good Dextrin, though if they are driven in, they'll smash. If it was that batch of soft comets, they'll smash. If they are easy to scratch, they are unlikely to be good enough.

 

As for putting stars in salutes, I've put Barium nitrate green, Parlon bound stars in with the flash in a rocket header. It was not huge, just 5-10g of 70/30 but the stars survived.

 

For best results, use a black powder burst charge and add flash a little at a time until you are happy. I don't see the reason to use anything but perchlorate prime here, since you will just need to use less for the effect, which, along with the cleaner burn of the fine flake Al, reduces the luminosity. I think that some of the more negative aspects of flash boosting are greatly reduced with small quantities if the flash is well distributed, while the performance of a 4" shell is still improved significantly by one gram. Sometimes though, I think there is a time for a smashing hard break.

[dangerousamateur]

The stars have to be well primed and chosen in order to light and stay lit at high speeds.

 

Often a KP hot prime then greenmix will do the trick, but if your coloured star is prone to blowing blind, you might want to also add a thin layer of charcoal streamer in there too to buy a moments time for the stars to have slowed down a bit more before the colour ignites.

 

Can you be more specific what kind of stars are prone to blow out, and respectively what kind of primes?

What attributes make a mixture blowout proof?

 

I would think that fast burning stuff survives better, and charcoal streamers don't burn very fast.

 

Also, how do hot burning metal composions compare to low temperature ones?

[FlaMtnBkr]

Parlon is basically a type of rubber or plastic and if you are making a high Parlon content star they are almost like a hard piece of plastic when dry. These will probably survive a hard break the best. And a rolled or pumped star that is really dense will probably work even better. If you follow Ned Gorski's instructions for screen cut rubber stars with the hot prime he recommends you should be able to break the stars really hard. Using fence post prime instead of green mix as the final layer should also help the stars light at high speeds. The silicon and DE form a molten slag that stays hot after the BP mix stops burning and should light most anything. If you screen cut them, the square stars will be nearly round once you get all the prime on them. This also helps conserve the more expensive star chems as the prime will be burning when the shell initially lights and you can't see the color yet as they are still inside the shell.

 

I assume you just dump the stars in and then put the flash on top to mix in. If you glue the stars to the shell casing and fill the inside with BP you might get fuller breaks. It is fairly common to just dump flash on the BP to boost the break instead of using a flash bag. But if you don't want to use BP you probably can use all flash in smaller shells. This is how bombettes are made. But a gram or 2 of flash does not have much volume so there will be a lot of air space between stars. In bigger shells this is usually looked down upon.

 

I would say if you are already making Parlon stars just start by using a different flash or increasing what you are currently using. I bet you can break them as hard as you want to by just changing the flash type or amount used. The only thing I might do in this case is make sure you are using a hot prime and to use fence post prime. Fence post is a fairly cheap prime too if you use pool grade DE and works really well. Food grade DE doesn't seem to work well so search out the stuff for pools which should be available locally and cheap.

[Potassiumchlorate]

You can use 5 grams of 70:30 to break a 3". No problem. Just have a good prime. The report will be heard several kilometers away

[Mumbles]

Other may feel free to disagree, but I've gotten better breaks from a mixture of flash and BP as opposed to just flash bags. Even a normal flashbag broken shell will have plenty of polverone or other cheap flammable fillers in there. Flashbags were primarily developed an economics thing due to the cheaper materials and reduced processing time. It wouldn't make sense to offset the cost savings by packing a shell full of expensive stars.

 

To me, the BP/polverone with the flash helps to generate a lot more pressure, which leads to better breaks. Purely flash broken shells and inserts IMO look cheap and shitty. The higher quality commercial shells (excalibur types, etc) and inserts are typically a BP/flash break mix.

 

There is also the added concern of stars rubbing against each other with flash in between them that makes me sort of uneasy. If I am boosting shells, I almost always pack them and add the flash/whistle at the end and rely on the finishing and handling to distribute throughout the shell. I've taken a few apart later on and did see pretty good distribution.

[pyrojig]

I have to agree with mumbles on this. I too find flash bags not necessarily the best answer. I have had perfectly nice/balanced breaks from flash or whistle coated bp hulls ,or riced powder.

 

One way to get around the flash migrating around the stars is to line the stars in the shell with tissue paper. The burst is separated (by tissue)and safer w/o contact with the stars.

Edited July 31, 2012 by pyrojig

[Zingy]

I have found KNO3 and 10890 Aluminum, as about the hottest flash suitable, for flash bags. However, the KNO3 must be ball milled, separately, not just using the using granulated stuff. Paper coin tubes from the bank, have been convenient for flash bags, in cylinder shells, 4 inch to 6 inch.. I use 'Saran Wrap', to contain the burst, for ball shells. For 3 inch shells, I plan on trying the vinyl caps, described elsewhere for "Timed Rocket Headings", as a flash booster container, probably with a hotter flash, and 2Fa, as the secondary inner core burst charge.. I always use a lot of polverone, to fill up space, in all star, comet, or insert shells.. Edited July 31, 2012 by Zingy

[owenmill]

Whats the best way incorporate a burst charge in a round shell? Is it simply mixed in with the MCRH's or perhaps put in the end of a spolette tube?

[nater]

Boosters are commonly added one of three ways:

 

1. Coat the BP coated hulls with the booster as the final layer.

2. Sprinkle the booster on each filled hemi before the shell is closed.

3. A small flash bag attached to the fuse before the shell is filled as normal.

 

 

[flying fish]

When making ball shells I use method 2 as per Nater's post, using 7/3 made with bright flake aluminum. It is slightly less violent than flash made with dark aluminum and still makes a nice pop.

[owenmill]

As a personal opinion, if a fairly small shell (1.75 inches or so and fewer) is well pasted and strong, does it need a booster? And do you think shells of this size even benefit from MCRH's, or does granulated BP do the job well enough without being to heavy or too strong?

[Seymour]

Need, not necessarily. You'll get a nice effect, but without a booster for sure it will not burst as wide. Often that is a good thing.

 

Especially for shells/bombettes of this size I like to use them as inserts in larger shells or starmines. With some effects, for example colour bombettes, I quite like the splash of colour to be quite intense and no too spread out. I want each burst to be a distinct expression of the desired colour and I would rather they did not mix because of overlapping. In this case I simply fill the case with stars, then the gaps with black powder grains. Sometimes I don't add this much Black powder and I'll add a measured burst charge of only a gram to a couple of grams.

 

When you want a spider type burst from your shell, which also works well en mass due to the overlap causing the sky to be cris-crossed, you definitely have a better result using a booster, or just breaking it with hot stuff.

 

Other than my few examples there are of course nearly infinite other effects that could be desired, which would cover a wide spectrum of burst mixes and the resulting effects.

 

Granulated burst is generally stronger than MCRH's or other filler coated burst systems. With these shells being small, and having a lot less volume of burst per volume of effect (for most shell loading techniques) the tenancy it towards wanting a more dense burst. While good results have been had in small shells with coated hulls and so on, space is at premium so I don't think it's the right time to have any inert fillers in the shell.