Hello Andy and all,
Quite right in every regard, though I was not aware that ICI made Jetex pellets in non-explosive regulated buildings. I continue to give the matter of GN deep consideration. While GN has many excellent qualities (being entirely comprised of gas molecules: CH6N4O3, if we regard the carbon as readily converted to CO and CO2), it's only become available to the public in USA very recently, and even now it's sold to the public by only one purveyor that I know of (Firefox-fx.com). It'll likely be even more restricted as time goes on, and is already on the no-no list in Japan, and much (if not all) of Europe.
I'm the first to agree that we want and need something that can be mixed and made in a bicycle shop. At the same time, GN is a quite safe oxidizer, in my experience and opinion, not being as easily reduced as KNO3, for instance, or any of the perchlorates. Though it's an ingredient in low-flash explosives and military propellants, it's not itself an explosive (comparing GN to nitroguanidine, for instance).
A parallel example that I'm working with is 2,4-dinitrotoluene (2,4-DNT). It's a close sibling of old fashion TNT, and just one step away from that tri-nitro state, it's now also sold in USA and shipped via surface mail (as is GN, wet NC, AP, Zn powder), regarded merely as "flammable solid." I studied the qualities again long and hard before cautiously melting samples, and grinding a few grams in the coffee mill. In this case, 2,4-DNR (dinitroresorcinol) was the ICI choice, and that is indeed regarded as explosive, and isn't to be found on any market. I'm experimenting with 2,4-DNT as a safer, available alternative--nothing more--since 2,4-DNR won't be found anytime soon.
Moving past GN for a moment, what's left is ammonium nitrate (AN, again all gas components: NH4NO3), and again becoming very hard to find and buy. The only readily avail AN in USA these days is prilled (small round pellets, for easy-flowing into mine bore holes, etc) and even that is limited to (IIRC) one-pound per year. Most pyro dealers here don't even offer it any more.
GN isn't easy to formulate into a self-sustaining mixture. It is a fine oxidizer at pressure, but getting it going takes considerable energy input (unlike the perchlorates, or some other nitrates). 2,4-DNT itself isn't going to substitute for the 2,4-DNR, so now I'm sliding again back to AN-oxidized Jetex.
The one way I've found, after many experiments and considerable research, to get GN formulations going at atmospheric pressure and temperature is by adding a serious "helper," either a dichromate, for instance, or NC. I prefer the latter, and I'm continuing experiments with both.
My perspective Andy is to look only at reagents that will likely work, and only those "fairly readily available" to experienced, unlicensed pyrotechnics experimenters. If it's too pricey, or too toxic, or too sensitive, or regulated out of use, I skip that avenue.
FWIW, the Rapier compositions are excellent propellant, in that context. I'm working today to see if it's possible to make a variation on that AP/Zn/DICY/epoxy-bakelite mixture that can be used in regular Jetex motors. Sure-fire ignition thru the tiny nozzle is one hurdle (many mixtures are simply too hard to get lit so they will keep going on their own). Adjusting the size of the AP granules is another, to achieve best burn time *and* good specific impulse (Isp: ounce-seconds of thrust per ounce of propellant).
Notes on recent experiments are posted here:
sites.google.com/site/jetexpropulsionlab/test-results
Let's keep this discussion alive: we all have a LOT to learn on this esoteric art and craft, and brainstorms could lead to breakthroughs.
Edward