Re: Carbohydrate fueled stars


Mike Swisher wrote:
> Consider a 2:1 mixture of potassium chlorate and fine flake
> aluminum. It is, in effect, a flash powder. Now add to that mixture 5 - 8% red
> gum or shellac, and you have a much slower burning composition suitable for a
> waterfall or a silver tailed star.

Does not the reduction of burn rate in this case have more to do with
lowered flame temperature due to the addition of gaseous reaction
products, rather than the change in stoichiometry?

> Shidlovskii's observations don't apply in the same way to the design of
> compositions having no metallic fuel.

While Shidlovkiy's observations may not apply in the same degree to
organic fueled mixtures as they do in metallic ones, I think they still
do apply to some extent. Maybe I should have used these comments from
Shimizu (F.A.S.T., pages 112-115) to explain the basis of my ideas:

(in regard to shellac); "The quite remarkable character of shellac is
that the carbon content is smaller, and the hydrogen content is larger
than that of other fuels, e.g. rosin. Apart form the the 4 H2O which
should be formed at burning, it contains a further 9 H2; consequently
when it is burnt in combination with an oxidizer, lack of oxygen in the
flame does not cause the generation of carbon particles.......It burns
in combination with ammonium perchlorate at F/O=2:10 creating a slight
reddish orange flame."

(in regard to Wood rosin FF); "In comparison with shellac, it has more
carbon and less oxygen. The excess carbon produces a very bright white
flame which disturbs the production of color. For example, it burns in
combination with ammonium perchlorate at F/O=2:10 producing a bright
white flame. Accordingly, this is used only as a partial substitute for
shellac."

(in regard to Combustion agent BL); "It burns in combination with with
ammonium perchlorate at F/O=2:10 producing a brilliant white flame.
This shows that it contains a large amount of carbon."

It is pretty clear (in Shimizu's view) that larger carbon content
results in less flame purity. These comments seem to indicate that
shellac is a superior fuel for color mixtures due to lower carbon
content. (It seems to me that these statements concur to some extent
with Shidlovskiy's observations.) My idea was to try taking this idea a
step further by using fuels with even lower carbon content.
(As a side note, excess carbon can play a BENIFICIAL role in magnesium
fueled color mixtures, where it reduces MgO to Mg vapor at high
temperatures, thus greatly reducing continouos spectra. On page 58 of
F.A.S.T. Shimizu recommends the addition of up to 15-20% "organic
material to such compositions.)

>You probably don't need so much strontium
> carbonate in your lactose red. At 18% there is enough to choke the burning. Cut
> it back - see the Denisse lactose red composition I posted in the
> chlorate/lactose thread. You might also perk it up by adding 1 to 2% air float
> charcoal. You've already noticed one problem with your dextrine composition.
> Dextrine is more hygroscopic than lactose, which will pose another problem with
> the composition for storage. There's a reason why the industry has gravitated
> towards red gum, shellac, and rosin as fuels for the typical non-metallic color
> star.

Mike, I agree completely with your suggestions about how to improve the
lactose mix. I should not have used such a large percentage of
strontium carbonate. Reducing the carbonate, adding some fine charcoal,
and adjusting the proportions accordingly would result in a useable
star, if rather an unconventional one at this time in history.
I also agree that the dextrin mix is not practical due the hygroscopic
nature of dextrin.
In addition, I concur with your statements in regard to the greater
suitibility of resin fuels due to their oxygen demand (in the
chlorate/lactose thread). I am not trying to claim that resin fuels
should be replaced with carbohydrates. (I would have to use a heck of
a lot of lactose or dextrin to get the same oxygen balance as in my
favorite chlorate/shellac red star mix: it has quite a negative oxygen
balance.) Personally, I feel that shellac is the best fuel for most
color stars. This whole experiment was intended to be an academic
exercise. I feel that the experiment was a sucess: I got great colors!
Thank you for your knowledgeable replies to my semi-knowledgeable
ramblings.

Matthew C.

.

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