Milling of sugar comp?

[gunner1]

So I was wondering out loud to myself if milling potassium nitrate/sugar rocket fuel together is a safe practice. I'm pretty sure that it would help with the burn rate.I know that it's a fuel and oxidizer combo but people mill black powder safely.

[dagabu]

I can say for certain that ball-milling black powder is NOT safe... But the risk may be worth the outcome.

 

Milling potassium nitrate/sugar is much less risky than BP, you will find that doing so will result in a nice sphere of fuel and not dry & fluffy fuel as you may think.

 

Mill the KNO3 by itself and buy powdered sugar, the corn starch will not slow it down enough to notice.

[MadMat]

I forget about all of that and dissolve my sugar/KNO3 mix and boil off the water. It is, in my opinion, the best way to ensure maximum performance each and every time.

[stix]

So I was wondering out loud to myself if milling potassium nitrate/sugar rocket fuel together is a safe practice. I'm pretty sure that it would help with the burn rate.I know that it's a fuel and oxidizer combo but people mill black powder safely.

 

That's the method that my brother uses. He mills for around 24hrs using oven dried KNO3 with pre-heated brass media. Comes out nice and fluffy. The problem with that method (in my view), is then you need to press the hell out of it to compact it properly. He has a nice screw press that does a great job. Takes a lot of time though. Also, the milled fuel was way too fluffy which made it difficult tou pour increments. He did experiments with paraffin wax/oil and a few other things to keep the dust down - I can't remember what the end results were though.

 

I'm with MadMat in regard to dissolving or melting (in my case). Although mine ends up being a plasticine type concoction.

 

My brother and I did some tests, and the resulting "power" or specific impulse of the fuel was much the same using either method, but like I said, you need a darn good press.

 

We still argue about the merits of each method - it's all fun and to each their own.

[MadMat]

I'm with MadMat in regard to dissolving or melting (in my case). Although mine ends up being a plasticine type concoction.

 

Hey, great minds think alike

[dagabu]

I agree with you both but that's not what the OP asked. Even then, iron oxide can be added to catalyze the fuel if using the R-candy methodology.

[MadMat]

Dag, as a matter of fact, I agree with you about the risk probably being less than that of milling BP. But you see, my point was that the dissolving and boiling or dry melting methods will ensure repeatable maximum performance, so why go through the risk at all. I would like to add, just in case gunner1 doesn't know, if he plans on trying either of the cooking methods and is making larger engines, adding a little corn syrup to the mixture will help prevent the grain from cracking. I say this because I once heard someone say they wanted to mill/mix the dry powders and ram the engine to eliminate the possibility of the grain cracking because they were making larger engines and a crack in the grain is a real good way to get a CATO

Edited February 5, 2019 by MadMat

[dagabu]

Agreed. How much are you using? I would think 10% of the sugar would more than enough?

[stix]

I agree with you both but that's not what the OP asked. Even then, iron oxide can be added to catalyze the fuel if using the R-candy methodology.

 

That's a good point. For some reason I thought the OP was asking "would milling improve the power". Sometimes we just see what we want to see.

 

Regarding the safety question with milling KNSU, I haven't seen or heard of accidents during milling using non-sparking media. Then again, I can't read instructions properly, so probably best not to listen to me when it comes to safety questions.

[MadMat]

Personally, I have never used corn syrup, since my engines aren't that big. From what I have read, around 3-5% of the sugar is sufficient. Some of you may find it interesting that the same thing is done in candy making. Corn syrup is added to the candy mixture while cooking to prevent crystallization of the sugar. Imagine how a caramel would be if it had large crystals of sugar in it.

Edited February 6, 2019 by MadMat

[stix]

I did try corn syrup, but my issue was how far to go?

 

I mean, corn syrup contains moisture??. So when added to a mixture, whether using the dissolved or melted method, the moisture from the corn syrup could be retained in the mix.?

 

Therefore my current view is to eliminate ALL possibility of unnecessary H2O. The "melted" method seems to fulfill that. BUT, the "dissolved" method, once the water has been "driven off", well, there is a point when the "dissolved" mix is very potent.

 

It's a matter of degrees.

[dagabu]

Indeed! I guess if you are looking for relative safety, raw chems mixed and pressed is the way to go. If you want all the power you can squeeze out of a fuel, R-candy with a catalyst and corn syrup is the way to go!

[stix]

Debatable, I guess.

[dagabu]

Proven; the most powerful fuels are not always the best. The worlds largest sugar rocket is just a simple KNSB sugar propellant. Straight up R-candy with sorbitol, if it were table sugar, you would need the corn syrup to keep it elastic when casting the grain. The OP didn't mention the type of sugar so I was guessing it was KNSU propellant.

 

Throwing out "Debateable" does not answer the question of whether I am correct or full of schidt? Please, jump in and throw your thought out there.

 

"Sorbitol is not only very hygroscopic, but also retains a large amount of water, it is well known that sorbitol can absorb moisture from the atmosphere when the amount of available water is low." Looking at the simple chart below, one can interpret the results to show it has limited use outside of laboratory conditions due to its rapid absorption of water at only 70% RH!!

 

 

https://mach5lowdown.com/category/rocket-projects/sugar-shot-to-space/

[gunner1]

Man, alot of good info here! Thanks guys!