Actually John, I would have to take some issue with a few of your
points.
Lets first come to a common understanding of what I mean by a flash
salute, and what you mean by a "flash salute". I suspect that we're
both on the same wavelength here, e.g., a flash salute is not a
firecracker like an M80, but a device 2 or more inches in O.D. and
designed to be used either as an aerial report or a ground bomb.
While there is little doubt that a hot flash mixture can produce a
significant report when essentially unconfined (Gabe Morte's
demonstrate this fact), still the performance of say a 3" aerial flash
salute (charged with from 1-1/2 to 3-Oz of quality flash is directly
dependent on the confinement provided, at least in my opinion.
I must take exception to your contention that the strong physical
construction of flash salutes has anything at all to do with their
ability to withstand the lifting forces experienced when being fired
from a mortar. Weakly constructed and well constructed flash salutes
experience the mortar lift forces nearly equally (withing limits), but
do not perform equally when charged with the same amoung and quality of
flash powder. Generally speaking, the construction of a bottom shot of
a multi-break is also identical to any well made flash salute, and that
has to withstand the dynamic forces associated with lifting the breaks
sitting on top of it. Also, good ground bombs are made identically with
those intended for aerial use, with the exception of a lifting charge
and timer.
Also, it has been my experience that a well confined and spiked 2-1/2
in salute can easily outperform a 3" or 4" salute made using shabby
construction. The difference in performance is easily noted, since a
cheaply made 3" salute can sound very impressive to spectators within
the confines of a football stadium, but with the proper containment
that same device can be heard for many miles (many here translating to
maybe 5), and thump chests and rattle windows within the first mile or
two.
With insufficient confinement, even using the best possible flash mix
spiked with sulfur and antimony trisulfide, even with significantly
increased quantities of flash mix (say 2 to 4-lbs), you achieve a very
different effect. These are the ultimate chest thumpers at relatively
close range, but are barely audible at ranges of 2-miles and over.
To illustrate, when I has a fireworks business in Trenton, NJ and where
we shot the annual July 4th show at the Trenton Fair Grounds (now the
Trenton Speedway), every hour or so from noon on and up to the time of
the display, we fired two of our very best 3" salutes to remind
everyone that there would be "Fireworks Tonight" -- of course this was
to "Test the Wind". Reports indicated that these salutes were heard as
far away as Bordentown (7 miles), Ewing (5 miles), and even downtown
Princeton (close to 9 miles).
This is why all the labor and extra confinement went into their
manufacture. This is why we bothered to do more than the absolute
minimum...and arguably why we aren't in the fireworks business anymore.
:-)
Today, other than a few small Italian fireworks firms (the mom and dad
firms that do primarily saints festivals), and work done by some of the
PGI masters, you don't often hear salutes of this quality today. Where
you run across them, expect to see large multibreak salami shells there
too.
Harry C.
p.s., As an afterthought, with thick, heavy walled containment, why is
spiking so importan?. My simple-minded explanation is that the spiking
is what contributes to keeping the end disks on a salute from being
blown off prior to a significant percentage of the flash powder
undergoing ignition. This is related to the same reason that we use
bulking agents (bran, etc.) in making flash powder, or half-fill the
volume of a flash salute with flash. The longer the integrity of the
containment remains, the more of the flash mix is combusted, and the
greater the report.
Post by John ReillyPost by yuvFlash powder requires some confinement in order to go bang.
Once we have satisfactory confinement, is there an advantage to
strengthen the confinement? Specificaly thickening the walls of the
salute/cracker.
In slow compositions like black powder, it's definitely so. But is it
SIGNIFICANTLY so for flash?
Many flash powders need no more confinement than the ambient air (1
atmosphere) at sea level provides (no container at all). In a typical
3.5 gm. m-80 salute, the thin walled casing and paper end caps needed
only provide momentary compression to move the mix to a low velocity
"detonation". Even this light casing was unnecessary and you can wrap
the same small charge in a layer of tissue wrapping paper and achive
the same result. Some magnesium flash powders will "detonate"
unconfined at less than 1 gram.
Heavy casings on large aerial salutes are used to protect the flash
inside from the crushing forces of lift and or burst to scatter them in
the sky. The cheaper and coarser aluminum powders with sulfur used by
many makers worldwide explode with a thunderous report using KClO3 or
KClO4, but require more confinement for small quantities. Black
powder is a different animal and can behave more like a mechanical
steam explosion. It requires heavy confinement to give a good report.