IMR4064 Burn Rate Data

[InigoMontoya]

Hello, folks:

I'm looking for burn rate data on IMR4064. I'm not talking about "this powder burns faster than that powder." I'm talking about the actual numbers. I'm talking about a table of "X inches per second at Y psi" for a variety of pressures. Heck, as long as I'm asking, even better would be the equation of the format Rate = A*P^B (or whatever is appropriate in this case).

Perhaps my google-fu is weak, but I've found nothing so far.

[Dr. Strangelove]

However, I'm not the six fingered man...

You haven't found it not because of weak google-fu, grasshopper, but because it doesn't exist.

Pressure vs. burn rate depends on a variety of factors, ignition source, size of the container, lot# of powder, etc. We get good estimates based on test in pressure barrels but they are just that, estimates, not solid info to be counted on in every situation.

The best source would be the powder company itself, call them, they all have 800 numbers and are glad to answer questions. I doubt they have this type of info, and doubt even more they would be willing to divulge it even if they did. They are a great source for questions about their product.

[InigoMontoya]

Sure, in an assembled system powder burn rates will depend on several factors and even if it didn't there's experimental error and such to deal with.

But the bulk material in a non-powder form should have a well defined burn rate (with error bars, sure, but what experimental data DOESN'T have error bars?). Now, it may be that the companies don't release that information, that's a distinct possibility.

As for the companies, I've so far found them to be completely worthless. Granted, I've not tried recently (this quest is years in the making), but in the past all I've managed to get was blank stares from their engineers. I suspect that the engineers I spoke to were production engineers; not the sort of person I'd expect to have such knowledge. But ask for a formulation specialist and they act like they've never heard of such a person. ***?

For what it's worth, I work in the energetics industry. I just don't normally deal with powders. I DO however, deal with people like formulation specialists and the like. I KNOW they exist (hell, I married one of them). With what I see in my day job, I find it VERY difficult to believe that the companies wouldn't have this information ("strand data" would be one of the keywords)... Of course, that doesn't mean they'll release it, but I can respect that answer from them. I can't respect the clueless silence I get from them.

[Sport45]

Sounds like you've already gone to the source. How on earth did you expect us to know more than them??? We even take the "powder burn rate" charts with a healthy grain of salt since no two are ever alike.

[darkgael]

Gotta agree with Sport about this, Inigo. You've done the "gone to the source" thing and had no success. The data that you seek is specialized and, I suspect, requires extremely sophisticated equipment to acquire.
Why would you expect to find that data here if you could not get it from IMR?
Just curious.
As I understand the little bit that I know, propellants are rated according to the results of a "closed bomb' test. There should be data from that. It would be specific to that particular test, though. Is that what you seek?
Pete

[Sport45]

Also, "burn rate", the way we use it, doesn't necessarily relate to the linear speed of the flame front through the propellant. What we are probably comparing in our charts is the rate of pressure rise in the closed bomb that darkgael mentions. That pressure rise would be a function of speed, temperature, the amount of gas generated per unit volume and other factors I'm not aware of. The actual speed of combustion means little to us. Well, it means little to me.

[SL1]

There is some information in QuickLOAD that you MIGHT use to back-calculate something that you could use. I don't seem to be able to copy it, much less figure out how to post it here. (It is a window with a combination of graphics and text.) So, maybe you could start with the website for the program distributor here: http://www.neconos.com/ .

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.

SL1

[GeauxTide]

I confess the blank stare came upon me for a couple of minutes. You are talking about the formulation and chemical addition to powder in the manufacturing process to effect the burn process, I believe, hope, think. Manufacturing processes tend to be proprietary and confidential; i.e. Coca Cola formula.

[InigoMontoya]

"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.

[SL1]

InigoMontoya,

You sound like you may have some information that many of us on this forum would be interested in. So, I hope you stick around and contribute when you see a chance to educate us.

Many of us are primarily interested in figuring out how to use components that we have (or can get) by interpreting data from other combinations of components, because there typiclly isn't pressure-tested data on the exact combination that we intend to use. Some of us are trying to figure out how to load "wildcat" cartridges for which there is not pressure-tested data.

That has gotten us into using things like Homer Powley's empirical correlations for pressure and velocity with Dupont powders in the .30-'06, which have been used to produce several commercially available "load programs" for other cartridges and, more recently, Hartmut Broemel's simulation program "QuickLOAD."

There are a lot of discussions on this forum that exchange information and speculation in that quest to get safe loads for component combinations that do not have published data. I think that I can speak for many members here when I say that somebody using a laboratory pressure-test apparatus would offer a useful perspective to these discussions.

SL1

[Scorch]

If you are looking for information on how to make a lab gun fire, perhaps you should look in the lab manuals or notebooks of the person who developed it. That failing, and depending on how large of a gun it is, I would ask someone at one of the military weapons and munitions depots about this. Of course, in the current culture of paranoia and suspicion, this may get you a visit from the gentlemen in dark, poorly fitting suits. But if anyone knows about making guns go boom, it would be the military.

[NWPilgrim]

I don't know what a lab gun is, but there are two approaches. Calculate the most likely best load through formulas. Or, experiment with several powders running them through very precise steps and measurements.

If you have spent years just trying to get base data for the calculations it may be time to get out of the book and into the lab. In one week you could do enough experiments to pretty well nail the best loading for that particular gun. Especially if you are already narrowed down to a single powder.

Based on that experimental data perhaps then you could calculate the bun rate and be the first person outside of IMR to glean that nugget of info.

[a7mmnut]

...and likewise, since conversion from the copper units of pressure method to the modern transducer and thermocouple methods all of those would need to be retested or converted and reprinted. Not very likely to happen soon.

-7-

[InigoMontoya]

If you are looking for information on how to make a lab gun fire, perhaps you should look in the lab manuals or notebooks of the person who developed it. That failing, and depending on how large of a gun it is, I would ask someone at one of the military weapons and munitions depots about this. Of course, in the current culture of paranoia and suspicion, this may get you a visit from the gentlemen in dark, poorly fitting suits. But if anyone knows about making guns go boom, it would be the military.

LOL... I *AM* the military. Or rather, civil service, but the point stands. The downsizing of the 90s absolutely gutted a lot of our corporate knowledge database. We were one deep in expertise on this particular gun (and of course it's a one-of-a-kind) and as previously mentioned that one-deep went off the deep end. Result? I'm an energetics guy who normally deals in "other" areas who's been asked to dabble in guns.

[GeauxTide]

A little too condescending for me. Good luck in whatever you're looking for. Maybe Jason Bourne could help.........

[Tex S]

I am curious as to what type of gun you are talking about.

What is it?

[InigoMontoya]

It's a 2-stage light gas gun. And shockingly, it does eat normal rifle powder (or so sayeth the guy who designed it (also the guy who's lost his touch)).

Which is also a large part of why I'm hesitant to just start throwing shots through it. Not exactly a cheap proposition. If you get one shot a day, you're doing well.

[brickeyee]

If you wade deep into QuickLoad you can find the model used for powder burning and the constants for each type of powder.

It is NOT as simple as how long a piece of powder burns.

[Tex S]

I guess I still don't understand what we are talking about...

I don't know what a two stage gas gun is.

[InigoMontoya]

Basic concept of a 2 Stage Light Gas Gun...

[InigoMontoya]

It is NOT as simple as how long a piece of powder burns.

I'm well aware.

But before I endeavor to play quarterback for the Dallas Cowboys, it behooves me to at least practice throwing a football around. Walk before you run and all that.

[darkgael]

Inigo: What size bore/projectile are you working with? How would a particular propellant be contained for ignition? As I understand from my background reading about LGGs, they normally use some cartridge - a shotshell or other; are you looking to do something different?
Is there a particular pressure profile that works better than others?
I apologize as these questions are not exactly on topic.
Pete

[Jim Watson]

It sticks in my head that Arnold (AEDC, Tullahoma, TN) has a light gas gun program. If it has survived budget cuts.

[InigoMontoya]

Inigo: What size bore/projectile are you working with? How would a particular propellant be contained for ignition? As I understand from my background reading about LGGs, they normally use some cartridge - a shotshell or other; are you looking to do something different?
Is there a particular pressure profile that works better than others?

Off the top of my head, it's about a 4" bore, 4 lbs piston. Propellant ISN'T contained for ignition, it's a bag charge (although it is wrapped around a sting that itself does have a contained ignition charge).

As for LGGs using a cartridge, in my experience, that's only for very small examples. Larger guns tend to be bag charges. That's not absolute, mind you, but it's a rule of thumb. In my experience it's about a 50/50 crap shoot on "any given gun."

It sticks in my head that Arnold (AEDC, Tullahoma, TN) has a light gas gun program. If it has survived budget cuts.

Yeah, so does Redstone and Socorro. Problem is lack of funding to formally approach them (and even then the odds of their guns being of a similar design as our's are small).

[darkgael]

Thanks for answering my questions.
About small LGGs and power - again, only what I've read. "One particular light gas gun used by NASA uses a modified 40 mm cannon for power."
How fast does the piston have to be moving in order to be effective? I understand it is probably a range of velocities. Have you or anyone else looked into black powder as it's characteristics are quite different?
Pete