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| Bob... |
 Posted: Mon Oct 19, 2009 3:44 pm |
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On Oct 19, 7:36 am, "Lloyd E. Sponenburgh"
<lloydspinsidemindspring.com> wrote:
Quote: This theory explains to me why even a half-shell of stars will give a
round break. I challenged this at one FFFF
Fireworks For Fun Festival? Fla. Fans of Fireworks Fandango?
Quote: We "group-built" a daytime smoke 6" plastic shell. One half - exactly -
was filled with Shimizu's naphtalene black chrysanthemum stars. The
other half was filled with a mixture of 4FA and mealed hulls, with some
4FA sprinkled in among the stars, as well. It was broken with an 8g
flash bag centered in the shell (not centered in the stars).
With observers posted all over the field, the unanimous opinion was that
it gave a perfectly symmetrical, round break. (and I grinningly picked up
about $10 of fun money!<G>)
I do not understand any other mechanism that would allow that, than the
theory I've stated.
I can think of one: that you got lucky and it broke with the star end
facing directly toward or away from you. But if it was lifted only to
such a height that those scattered-over-the-field observers were able
to triangulate on it, then you couldn't've ALL been that lucky.
Otherwise, you're right, I can't think of any, while my intuition &
money would've been saying "sky mine".
So then it's simply the more confinement, for a given speed of burst
charge, the better? Here I was hoping for some complicated material
science whereby the structure inflated to some critical point and then
failed simultaneously all over, too fast for the failure at one point
to relieve the stresses elsewhere -- a kind of bimodal breakage.
Instead it turns out to be the same as for a maroon.
Robert |
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| Lloyd E. Sponenburgh... |
| Posted: Tue Oct 20, 2009 5:57 am |
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Bob <robgood at (no spam) bestweb.net> fired this volley in news:fcd18c97-925e-42cc-
9812-d4cdb7443726 at (no spam) z34g2000vbl.googlegroups.com:
Quote:
I can think of one: that you got lucky and it broke with the star end
facing directly toward or away from you. But if it was lifted only to
such a height that those scattered-over-the-field observers were able
to triangulate on it, then you couldn't've ALL been that lucky.
This wasn't a one-shot event. For over five years, we supplied shells to
a client who demanded bottom-dollar prices, but who wanted nice 6"
shells. We built 6" plastic half-n-half shells for him. They always
broke round, and he loved them. The star patterns were a bit sparse, due
to the small star count, but other than that, they were acceptable. I
know of other manufacturers who have done this with "standard pricing"
shells, including a few Chinese brands.
I couldn't convince the guys at the Florida Fall Fireworks Festival that
it would work, but I already knew it would. I didn't get into taking
bets until a couple of them got strident about it's not possibly working
<G>.
Quote: So then it's simply the more confinement, for a given speed of burst
charge, the better?
Up to a limit, yes, that is correct. When the confinement is increased
to the point where the contents are substantially consumed before the
shell opens, you get a salute, not a color shell.
Quote: Here I was hoping for some complicated material
science
Nah... pretty simple phenomenon, really (if my thought experiment is
correct).
Of course, I can routinely break a slat of wood into three pieces simply
by bending it from the ends, too <G>.
LLoyd |
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| Bob... |
| Posted: Tue Oct 20, 2009 5:34 pm |
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On Oct 20, 7:57 am, "Lloyd E. Sponenburgh"
<lloydspinsidemindspring.com> wrote:
Quote: Of course, I can routinely break a slat of wood into three pieces simply
by bending it from the ends, too <G>.
Do you win bets on that one too?
This is like one of the arguments I use that the mid-air plane wreck
shown on "Lost" must depict the breakup of an internally rigged
airliner, because the initial break into 2 pieces would've relieved
the stress and prevented it from breaking into 3 as shown.
Robert |
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| AdmiralDonSnider... |
| Posted: Wed Oct 21, 2009 5:45 am |
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On 15 Okt., 01:25, "Lloyd E. Sponenburgh"
<lloydspinsidemindspring.com> wrote:
Quote: AdmiralDonSnider <a0403... at (no spam) unet.univie.ac.at> fired this volley innews:0d7ce286-7fe4-47c2-866c-529f97dcafc9 at (no spam) o10g2000yqa.googlegroups.com:
How are these tracer comps attached commercially to work well? Note
that I intend to use comps such as tiger tail, as plain ascending
color doesnīt give the same impressive effect.
Tracers are difficult on small shells, if they're attached externally.
The only good way to do it is with lots of cement (hot-melt doesn't work
very well, but old sodium silicate/carbonate "pyro glue" works pretty
well).
I think there´s been a misunderstanding. I don´t want to attach comets
on the outside of a bombette, as this is impossible (at least in case
of 30mm units), because there is no flat upper side (as in case of can
shells) or a gap between the wall and the mortar (as due to the shape
of round shells). Shimizu describes the process of attaching comets in
detail, so I know about this method.
However, in the case of bombettes the tracer comp mounted (wet) in a
recessed empty portion of the bombette´s casing. The clay plug is not
flush with its lower end and thus leaves to some space for tracer
composition to be applied.
The question is: what is the best way and binder system to apply these
comps and how can they be prevented from separating from the bombette
while it rises?
My autopsies told me that these squat tracer "stars" are applied damp;
but they adhere suprisingly well and I´ve not witnessed a single
separation yet. However, if you try to reproduce these at home, they
are very hard to get right, at least with a dextrin binder. Especially
charcoal comps are very brittle and are easily fragmented or separated
during flight.
Any ideas how to improve that? |
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| Bob... |
| Posted: Wed Oct 21, 2009 10:34 am |
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On Oct 21, 11:45 am, AdmiralDonSnider <a0403... at (no spam) unet.univie.ac.at>
wrote:
Quote: My autopsies told me that these squat tracer "stars" are applied damp;
but they adhere suprisingly well and I´ve not witnessed a single
separation yet. However, if you try to reproduce these at home, they
are very hard to get right, at least with a dextrin binder. Especially
charcoal comps are very brittle and are easily fragmented or separated
during flight.
Any ideas how to improve that?
Are you familiar with how dentists get tooth fillings to stay in
place? Or how some people anchor a wooden magazine to the ground with
cement? |
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| Lloyd E. Sponenburgh... |
| Posted: Wed Oct 21, 2009 10:56 am |
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AdmiralDonSnider <a0403986 at (no spam) unet.univie.ac.at> fired this volley in
news:bdfd4607-8926-4571-b5e6-5e40752c7270 at (no spam) l33g2000vbi.googlegroups.com:
Quote: I think thereīs been a misunderstanding. I donīt want to attach comets
on the outside of a bombette, as this is impossible (at least in case
of 30mm units),
I think we're "out of sync" with our reading and replies. I later addressed
the method you propose as applies to the Spanish RAP bombette cases.
LLoyd |
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