"Sounds like you've already gone to the source. How on earth did you expect us to know more than them???"
In some of my other endeavors I've found that coming to places like this is often the easiest way to find the back door. That is to say.... I'm *certain* that there is somebody out there at the powder company who has the data I want. The problem is that I don't know who he is and I've been unable to navigate the corporate maze to find him. In the past I've come to places like this with questions like mine and seen replies along the lines of, "Wow. Small world. I happen to work for that company and yes, I have that data. I can't just release it to you here, but if you contact...." Blah blah blah.
In other words, I was (and am) hoping that the "right" person(s) just happen to read this thread. I've seen it happen before.
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"As I understand the little bit that I know, propellants are rated according to the results of a "closed bomb' test."
The kind of data I'm looking for would actually come from a very similar test. The difference is that instead of using a sample of powder you'd use a single extruded strand of your bulk material and light it on one end.
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"What does it have to do with loading and shooting?"
Somewhere on this Earth is a rather large laboratory gun. That gun was operated for probably 30 years by a man who really knew how to make that gun dance. Then his wife died and he had a nervous breakdown. He's not half the man he was before and he no longer seems to know how to make that gun dance. In response, the powers that be have asked me to take a peak and see if I can't get it dancing again. I'm a "first principles" kinda guy. The first principle of propellant performance? Linear burn rate. Give me that and I should be able to tell you in advance what your bomb tests (and similar) will do. Exactly? No, but I don't believe I need *exact* to see what I need to see in the data.... But I do need a way to model the performance of the powder and as ya'll have been kind enough to point out, it varies drastically depending on test set up which means I want to start with the simplest, most basic configuration available... A strand test (which is how you get linear burn rates).
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"BUT, do you realize that propellant powders are not homogeneous pieces of nitrocellulous? They have deterent coatings that slow their burning for some distance into their volumes from their surfaces. At least some powders have deterrents that penetrate the grain to some distance, instead of being restricted to the surface, only. So, I am not sure that the data you are looking for exists as a linear flame-front advance rate that is applicable everywhere inside a grain. And, of course, that flame-front advance rate is highly dependent on pressure and somewhat dependent on the temprature ahead of the front. And, "bomb" data has the geometric effects on progressivity/regressivity mixed in with the chemical effects, so you would need to include the geometry of the grains in the back-calculation as well as any actual use of the data for whatever purpose you have in mind."
Yeah, I realize. It definitely complicates things but I think I'll be able to get close enough. Start with the basic linear data. Run a few bomb tests (yes, I can do that). Look for data correlation and then tweak the model to account for burn rate modifiers.
