Near the end of 1958, D. Sebel & Co (successors to Wilmot, Mansour) filed a British Patent Specification for "Combustion Mixtures," number 943,991. It's archived here:
archivesite.jetex.org/archive/patents/patent-sebel-943,991.html
I've taken to nicknaming this formulation "S-Stoff 991" to completely differentiate it from all previous Jetex guanidine nitrate formulations.
In truth, I don't like to speak of S-Stoff 991 in the same breath as referring to the original propellants from Imperial Chemical Industries (ICI). I have on the laboratory table beside me the reagents for both S-Stoff 911 and ICI-type, and tomorrow I intend to mix a batch or three of the former.
It's going to be a chore I don't look forward to, quite honestly, since the key ingredient in S-Stoff is that colorful salt of potassium and chrome: potassium dichromate [aka bichromate]--clearly nasty, potent, vile, those beautiful California-poppy colored crystals in the candy jar. It's really the first cousin of Vesuvius' Fire, ammonium dichromate. It's a potent oxidizer, and then some, in toxic sorts of ways, alas.
So if I manage 3 or 4 batches tomorrow, off comes the respirator, eye protection, face shield, gloves, and Tychrem hazmat suit, and I'll turn to my personal favorite solid propellant: GN-based, 2,4-dinitro fueled, V2O5 catalyzed, asbestos-fiber enhanced, ICI formulations. Those reagents are quite gentle, even predictable, compared to the nasty brilliant orange crystals of dichromate/bichromate.
Check this out, for reference:
www.wired.com/wired/archive/14.06/lab.html
I'll report later on the results, and intend to begin posting test photos sooner than later, as well.
Yea, chromates will do tricks for the alchemist and sorcerer, and sometimes the pyrotechnist as well, and it's all because of the industrial-strength, heavy-duty loading of oxygen atoms:
K2Cr2O7 [potassium flavor]; (NH4)2Cr2O7 [ammonium flavor]
Compare with, for instance, KNO3 [saltpeter], NH4ClO4 [ammonium perchlorate, as in Rapier], and CH6N4O3 [guanidine nitrate].
I've worked with high-energy chemicals all my long life, and I proceed with these Jetex dichromate experiments slowly and carefully, strictly in the interests of publishing recent and modern accounts of what's possible in a small lab. When all's said and done, I doubt if anyone else will want to tread this path knowingly.
Maybe I'll be wrong! More anon,
Dr Edward Jones
Mojave, California