Energetic materials are not my cup of tea, but I have stumbled upon an excellent paper that describes the evolution of the process of black powder
manufacture.
I used the search engine and the paper was apparently unknow here.
Black Powder Manufacture
R. A. Howard
Journal of the Society for Industrial Archeology 1 (1975) 13
An interesting read indeed, even on just a quick perusal ─ as a foil to it, here's Dan Williams excellent piece on home manufacture of black powder!
bbartlog - 19-10-2012 at 17:42
Never heard of that journal before... and it looks really cool. Thanks!Swede - 25-10-2012 at 08:35
Many of us here on SM were drawn simultaneously or sequentially into amateur pyrotechnics.
No, not kewl bomzz dood, but legitimate display fireworks. The kind that make pretty colors, although loud noises usually accompany them!
Anyway, the pyrotechnics crowd have taken BP manufacture to a well-honed art. To get anywhere in pyrotechnics, one must make decent BP for lift and
burst. And the way to do that on the amateur level is with a ball mill. A well-charged jar with lead or brass media, and the classic 75:15:10
mixture, correctly milled, will make BP as good as or better than Goex or elephant sporting powders, and where you pay $20 U.S. per pound for the
commercial variety, homemade BP can be produced for less than a buck a pound if you buy the KNO3 in bulk.
The real secret is the charcoal. The correct wood makes all the difference, with balsa charcoal being king, and woods like paulownia, alder, willow,
soft white pine, also right up there.
Processing the talc-fine ball mill product into a useful product is also an interesting process. Most people simply moisten, sometimes add a binder
like dextrin, then screen. The density of such a powder is not high but it works well and is easy. Others press the BP into cakes which are then
broken up and screened for size.
It's a lot of fun and very interesting, with obviously a lot of history behind it.caterpillar - 25-10-2012 at 14:54
When I was young, BP was the first of energetic materials, what I was working with. I found, that gun powder and BP as a solid rocket propellant must
be different. The classic BP (75:15:10) provides smaller thrust then 72:27:12, been used in home made rocket's engines. hyfalcon - 25-10-2012 at 14:57
When I was young, BP was the first of energetic materials, what I was working with. I found, that gun powder and BP as a solid rocket propellant must
be different. The classic BP (75:15:10) provides smaller thrust then 72:27:12, been used in home made rocket's engines.
Shouldn't that have been 70:17:13? Yours adds up to 111%.caterpillar - 26-10-2012 at 00:17
When I was young, BP was the first of energetic materials, what I was working with. I found, that gun powder and BP as a solid rocket propellant must
be different. The classic BP (75:15:10) provides smaller thrust then 72:27:12, been used in home made rocket's engines.
Shouldn't that have been 70:17:13? Yours adds up to 111%.
I meant grams, of course. Original mixture, which I found in an magazine was 72 gr KNO3+ 35 gr of charcoal +12 gr sulfur, but I quickly found that one
must decrease quantity of charcoal.Swede - 26-10-2012 at 05:37
Most of the BP rocket guys have formulas that are higher in charcoal and lower in oxidizer... Too energetic a mix causes the dreaded boom on takeoff
rather than a nice lofting of the payload. And the boom from even a small BP rocket is pretty impressive.hyfalcon - 26-10-2012 at 07:50
This I know. First 2 or 3 times I built a BP rocket I used about 4 times as much clay for the nozzle. The KATO that resulted had all the
neighborhood dogs going off.
1/2" core burners will do just fine with the regular mix of BP. If you go any larger they will begin to pulse and sometimes kato. It can be dialed
in to prevent this by the addition of .5-5% Sodium Bicarbonate.
[Edited on 26-10-2012 by hyfalcon]
[Edited on 26-10-2012 by hyfalcon]caterpillar - 26-10-2012 at 13:19
Possible explosion is not the only problem. I noticed that standard mixture (75:15:10) definitely provides smaller thrust than another one with higher
amount of charcoal. Addition of kalium picrate is useful too- propellant with it burns faster. elementcollector1 - 1-11-2012 at 19:47
