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| AdmiralDonSnider... |
 Posted: Sun Oct 11, 2009 8:22 am |
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First I´d like to say hello everybody! Glad to be here!
I´ve experimented with 30mm bombettes for quite a while and had good
results in case of colored star breaks. On the other hand, it seems
that breaks of tailed stars, at least if you expect them to be both
even and large, are much harder to get right.
I currently use cut stars in all my bombettes (although I try to
switch to the round variety soon) and - due to the higher burn rate of
e.g. charcoal tailed stars, glitter stars etc- have to use stars
larger than in case of chlorate or perchlorate color.
When I use 8mm tailed stars, e.g. of TT or Winokur 31, the burst is
large but very uneven; I figured this comes from the size of the
stars. The 8mm size is quite large for a 25mm I.D. casing, and there
are only about 15-20 of these stars. Anyway, large stars seem to make
uneven bombette breaks....
The logical consequence is to reduce the star size, so I tried 5mm TT
and Winokurs. Unfortunately, in this case the stars burn out too early
and the flower has no chance to develop, even if the burst would be
quite symmetric...
Given the fact that some of the best bombette effects are tailed star
breaks, this is a dilemma.
I´m still looking for a solution. Maybe my charcoal (commercial beech)
burns too fast, or I´m using the wrong type of stars (cut ones). Don´t
know how to go on, please help! Thanks a lot! |
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| Lloyd E. Sponenburgh... |
| Posted: Sun Oct 11, 2009 5:26 pm |
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AdmiralDonSnider <a0403986 at (no spam) unet.univie.ac.at> fired this volley in
news:9916397d-6103-4c89-9d49-f8a29ce2abb6 at (no spam) j4g2000yqa.googlegroups.com:
Quote:
The logical consequence is to reduce the star size, so I tried 5mm TT
and Winokurs. Unfortunately, in this case the stars burn out too early
and the flower has no chance to develop, even if the burst would be
quite symmetric...
Given the fact that some of the best bombette effects are tailed star
breaks, this is a dilemma.
Given that we manufacture tens of thousands of 30mm bombettes per year,
I'd suggest slower-burning compositions in 4mm rolled stars.
Just sayin'...
LLoyd |
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| rbirch... |
| Posted: Mon Oct 12, 2009 5:44 am |
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Lloyd's answer is indeed correct, but for some additional insight, I
offer this: Comp burning rate, or speed, is impacted greatly by its
density when made into stars or rammed into a tube. Cut stars have the
lowest density, followed by rolled stars, and then by (hydraulic)
pressed stars. Unless you are capable of rolling coreless stars, the
best bet for small scale production will be a 5mm plate and a
hydraulic press. This will give you a dense, coreless star which uses
less moisture to make. The edges on a pumped star take fire better
than a round star, too.
Water, when finally gone from a star after its dried leaves a void
where it once was.(They also shrink a bit) Rolled stars contain
somewhere around 25% water weight when they are rolled. Pressed stars
contain maybe 6 to 8%. I wonder if the packing density in the casing
is slightly improved by using a 5mm cylindrical star over a round star
who's packing density is around 62% to 74% by volume. Any
mathematicians?
Also, you can slow down your favorite glitter comp to meet your needs,
For instance, with Win 39, change the 12 micron aluminum to 18 micron,
add 1% additional magnesium carbonate and make sure you use "chinese
needles" not "fine pyro" antimony. Lastly, dissolve 1/2 teaspoon
bentonite clay and 2 teaspoons gum arabic powder in a liter of
distilled water and use that to moisten your comp. Let the comp sit,
covered, for an hour before pressing. I drop my pressed stars right
out of the plate onto a tray with ball milled BP. The small amount
picked up on the stars helps them take fire when used in flash broke
shellettes.
Russ
Quote: Given that we manufacture tens of thousands of 30mm bombettes per year,
I'd suggest slower-burning compositions in 4mm rolled stars.
Just sayin'...
LLoyd |
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| Bob... |
| Posted: Mon Oct 12, 2009 7:59 am |
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On Oct 11, 7:26 pm, "Lloyd E. Sponenburgh"
<lloydspinsidemindspring.com> wrote:
Quote: Given that we manufacture tens of thousands of 30mm bombettes per year,
I'd suggest slower-burning compositions in 4mm rolled stars.
I'm amazed. 4 mm is about the smallest I can even SEE stars coming
out of 1/2" ID mini-shells of my own, lifted 30-50' and broken with
home meal. |
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| AdmiralDonSnider... |
| Posted: Mon Oct 12, 2009 9:19 am |
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On Oct 12, 7:59 pm, Bob <robg... at (no spam) bestweb.net> wrote:
Quote: On Oct 11, 7:26 pm, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com> wrote:
Given that we manufacture tens of thousands of 30mm bombettes per year,
I'd suggest slower-burning compositions in 4mm rolled stars.
I'm amazed. 4 mm is about the smallest I can even SEE stars coming
out of 1/2" ID mini-shells of my own, lifted 30-50' and broken with
home meal.
Very useful info, thanks everybody!
I know cut stars are the least dense, but will rolling exactly the
same comp
to exactly the same size (or even 1mm less, as Lloyd mentioned 4mm)
really make the stars burn that much longer?
Lloyd, you suggested using slower comps... I always thought that TT in
fact is a slow burning
tailed comp? Can you specify your statement, or - still better - can
you post a formula for reference?
I don´t want to use brocade stars every time I want a tail...
P.S. In how far does chinese needle change the properties of a burning
star? Anyway, I guess
in Europe it is almost impossible to get chinese needle. |
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| AdmiralDonSnider... |
| Posted: Mon Oct 12, 2009 9:47 am |
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On Oct 12, 9:23 pm, "Lloyd E. Sponenburgh"
<lloydspinsidemindspring.com> wrote:
Quote: AdmiralDonSnider <a0403... at (no spam) unet.univie.ac.at> fired this volley innews:931945b4-2bc2-4fbe-b26f-3e4481ce2736 at (no spam) v36g2000yqv.googlegroups.com:
Rolling will slow a comp some. Tiger-tail can be very vigorous when
moving through the air. My "buttered popcorn glitter" on the Passfire
database works very nicely in 3/16".
Good to hear, I´ll give it a try; and I´ll definately give rolled
stars a try as soon as I built my roller.
Would you mind if I asked for a charcoal comp you use as 6mm round
stars?
What is more, I still wonder if the appearance of bombette breaks is
contingent on a correct relation break charge - wall thickness, as in
case of e.g. round shells? I.e. can you change the appearance tuning
the casing, or is "a something that merely contains the contents" all
that is needed? Given the breaks are contingent on a special relation,
I wonder if it just takes too long for the units to break. If so, my
stars are basically consumed while still in the casing... Forgive me
in case I´m reflecting about stupid things.
Here is an example for tailed stars used in 30mm units: I would be
satisfied if I realized something alike...
http://www.youtube.com/watch?v=Jyec2vnIB1Q
Thank you for taking the time to answer, Lloyd. By the way, I really
liked your book...and the mill rattles just fine! |
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| AdmiralDonSnider... |
| Posted: Mon Oct 12, 2009 10:24 am |
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On Oct 12, 10:08 pm, "Lloyd E. Sponenburgh"
<lloydspinsidemindspring.com> wrote:
Quote: I don't mine if you ask, but I'll not quote ours. Willow effects in
stars that small take continual tuning. They change with the season,
with the batch of charcoal, with the nitrate... you just have to tune
basic rough powder with excess charcoal until you get the tail you want
and the burn rate. Light on oxidizer, heavy on coal, about normal
sulfur-to-oxidizer ratio.
I see, thanks! I guess I´ll start experimenting with these soon.
Quote: Nope... tuning the burst to the container is about the most important
thing you can do to maximize symmetry and burst size. And it's a bit
touchy. I will say, we burst ours with a mixture of 4FA grain powder and
7:3 flash. That gives you a starting place.
This is the second time someone mentions the combined use of grain
gunpowder and flash in bombettes. The first time it was a chinese
technician who said it, but he mentioned MgAl based flash...
Anyway, can you tell me in how far the use of the (otherwise pricey)
commercial grain makes sense? Adding it, do you cut the amount of
flash? And what about the ratio of the two?
Admiral |
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| Lloyd E. Sponenburgh... |
| Posted: Mon Oct 12, 2009 1:20 pm |
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Bob <robgood at (no spam) bestweb.net> fired this volley in news:ec6c7342-26a1-40dd-
b755-5b1aca1b69ab at (no spam) g23g2000vbr.googlegroups.com:
Quote: I'm amazed. 4 mm is about the smallest I can even SEE stars coming
out of 1/2" ID mini-shells of my own, lifted 30-50' and broken with
home meal.
Heh! Did you try lighting the stars? They're more visible at night if
they've been ignited. <G>
Seriously... some of our glitter and charcoal comps must be rolled into
6mm, but the metal-fueled color comps show up just fine at 4mm.
LLoyd |
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| Lloyd E. Sponenburgh... |
| Posted: Mon Oct 12, 2009 1:23 pm |
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AdmiralDonSnider <a0403986 at (no spam) unet.univie.ac.at> fired this volley in
news:931945b4-2bc2-4fbe-b26f-3e4481ce2736 at (no spam) v36g2000yqv.googlegroups.com:
Rolling will slow a comp some. Tiger-tail can be very vigorous when
moving through the air. My "buttered popcorn glitter" on the Passfire
database works very nicely in 3/16".
Quote: P.S. In how far does chinese needle change the properties of a burning
star? Anyway, I guess
If you must, you can melt, recrystallize, crush, and re-classify your
Sb2S3. Larger particle size makes for a slower burn.
LLoyd |
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| Lloyd E. Sponenburgh... |
| Posted: Mon Oct 12, 2009 2:08 pm |
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Guest
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AdmiralDonSnider <a0403986 at (no spam) unet.univie.ac.at> fired this volley in
news:1f35a7e7-ec5c-4c8b-8a2c-2151e94f8578 at (no spam) m11g2000yqf.googlegroups.com:
Quote: Would you mind if I asked for a charcoal comp you use as 6mm round
stars?
I don't mine if you ask, but I'll not quote ours. Willow effects in
stars that small take continual tuning. They change with the season,
with the batch of charcoal, with the nitrate... you just have to tune
basic rough powder with excess charcoal until you get the tail you want
and the burn rate. Light on oxidizer, heavy on coal, about normal
sulfur-to-oxidizer ratio.
Quote:
What is more, I still wonder if the appearance of bombette breaks is
contingent on a correct relation break charge - wall thickness, as in
case of e.g. round shells? I.e. can you change the appearance tuning
the casing, or is "a something that merely contains the contents" all
that is needed? Given the breaks are contingent on a special relation,
I wonder if it just takes too long for the units to break. If so, my
stars are basically consumed while still in the casing... Forgive me
in case Iïm reflecting about stupid things.
Nope... tuning the burst to the container is about the most important
thing you can do to maximize symmetry and burst size. And it's a bit
touchy. I will say, we burst ours with a mixture of 4FA grain powder and
7:3 flash. That gives you a starting place.
Those are pleasing (really, not bad, at all), but burst a bit small, if
the height is similar to most Class-C cakes in that size. On the other
hand, they have very nice effects with stars fairly well scaled to the
break size. (but not very many stars, except on the crackling brocade
breaks).
Quote:
Thank you for taking the time to answer, Lloyd. By the way, I really
liked your book...and the mill rattles just fine!
I'm glad it helped.
LLoyd |
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| Lloyd E. Sponenburgh... |
| Posted: Mon Oct 12, 2009 4:26 pm |
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Guest
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AdmiralDonSnider <a0403986 at (no spam) unet.univie.ac.at> fired this volley in
news:dcc541ce-e79d-4b9e-916c-1491979efbaf at (no spam) 11g2000yqp.googlegroups.com:
Quote: Anyway, can you tell me in how far the use of the (otherwise pricey)
commercial grain makes sense? Adding it, do you cut the amount of
flash? And what about the ratio of the two?
It's not essential that it be _commercial_ grain powder. Even corned and
screened "clumps" from your mill will work.
The purposes of the grain powder are two:
One: it increases gas output. Flash is a not a powerful propelling
(heaving) explosive. The volume of the cooled combustion products are
all solids, and are about the same or less than the volume of the
mixture. Thus, it creates heat and shock/impetus, but has less
propulsive force than a gas-producing explosive. Black powder has
prodigious gas output, so it helps "heave" the stars into their flights.
Two: it provides "flame paths" through the burst mix, allowing the flame
to propagate more rapidly, increasing the rapidity of combustion. This
allows a lesser amount of burst to serve where more of a slower nature
might be necessary. It also allows a weaker shell casing, since the gas
pressure rises more rapidly, allowing the shell to develop pressure
before the casing fails.
A nice solution for really rapid pressure rise is to center a "coupette"
(flash bag) in the shell, and fill the interstices among the stars with
grain powder. The coupette contains the flash until it explodes
forcibly, and the powder creates the gas necessary for large, symmetrical
breaks.
Done well ("balanced" or tuned) it allows a forceful break without an
annoying white flash.
LLoyd
LLoyd |
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| Bob... |
| Posted: Mon Oct 12, 2009 8:17 pm |
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On Oct 12, 3:20 pm, "Lloyd E. Sponenburgh"
<lloydspinsidemindspring.com> wrote:
Quote: Bob <robg... at (no spam) bestweb.net> fired this volley in news:ec6c7342-26a1-40dd-
b755-5b1aca1b6... at (no spam) g23g2000vbr.googlegroups.com:
I'm amazed. 4 mm is about the smallest I can even SEE stars coming
out of 1/2" ID mini-shells of my own, lifted 30-50' and broken with
home meal.
Heh! Did you try lighting the stars? They're more visible at night if
they've been ignited. <G
You jest, but I think ignition problems may be a limiting factor for
me. I've tried using unprimed crumbs from color star making in these,
and maybe they weren't lighting. So I tried making micro-stars by
sieving damp compo onto rough powder, which didn't get much primer
onto them, and I still usually don't see anything. I don't know
whether it's because they burn up too fast, or because the dwell time
in such a small projectile is too short to ignite them. I had the
same problem attempting micro mines. Charcoal or "granite" stars OK,
but others work only if they're rolled or pumped to a size that I can
fit only very few of into such a small dia. cylinder. In my hands
smaller stars of most kinds than 4 mm seem fit only for prismatic
fountains. Maybe I should attempt micro candles!
Robert |
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| Bob... |
| Posted: Mon Oct 12, 2009 8:32 pm |
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On Oct 12, 6:26 pm, "Lloyd E. Sponenburgh"
<lloydspinsidemindspring.com> wrote:
Quote: A nice solution for really rapid pressure rise is to center a "coupette"
(flash bag) in the shell, and fill the interstices among the stars with
grain powder. The coupette contains the flash until it explodes
forcibly, and the powder creates the gas necessary for large, symmetrical
breaks.
That's the 1st time I've seen an explanation for why we were making
them that way at the shell tutorial at Weedsport in 1993. Bill Ofca
et al. didn't know, just said the grain powder made the break "nicer"
or something to that effect.
For film canister shells, approximately the same as 30 mm, I usually
use loose whistle mix. For the 5/8" mini-shells I've found that
sharper burst compos make the breaks LOUDER than triple sieved dry BP
mix or polverone, but make little or no increase in spread of the
break.
Robert |
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| AdmiralDonSnider... |
| Posted: Tue Oct 13, 2009 1:21 am |
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Quote: You jest, but I think ignition problems may be a limiting factor for
me. I've tried using unprimed crumbs from color star making in these,
and maybe they weren't lighting.
Well-primed stars is all that is required, I wouldn´t experiment with
fragments personally, but these can work fine too. Although round
stars would indeed be better, I had very nice results with 4 and 5mm
cut superprimed Veline´s. |
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| AdmiralDonSnider... |
| Posted: Tue Oct 13, 2009 1:29 am |
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Quote:
A nice solution for really rapid pressure rise is to center a "coupette"
(flash bag) in the shell, and fill the interstices among the stars with
grain powder. The coupette contains the flash until it explodes
forcibly, and the powder creates the gas necessary for large, symmetrical
breaks.
Very good explanation. I´m currently using Shimizu Flash Thunder #2,
which is a perc based flash with greasy Al and sulphur. A sulphur
containing flash also seems to produce more gaseous products.
Concerning the flash bag, I imagine it very hard to realize in such a
small casing. Now should these bags resemble their larger relatives in
can shells, or does kind of a newspaper "canulle" work well too (I
remember a video by Tony Petro who used such nitrate flash filled
canulles to break his cylindrical rocket headings...)?
In my autopsies of commercial bombettes I realized that all of them
use a 2mm thick waste paper casing. I currently make use of the same
material, but only roll them 1mm thick. Would switching to 2mm give
any improvement, or why is this 2mm casing so "standard" at all? I
assume it´s used because you don´t necessarily need a mold to press
the clay in...
Admiral |
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