Sufur free bp?

[pyrohacker]

If 16 mesh doesn't work well, why are you going larger?

You tell me! What should I do then?

[pyrohacker]

Mumb...

By "tiny shells", I think he means shells even smaller than 2", and that he wants to increase the grain size for shells larger than what he was making before.

 

Maybe not, but it 'read' that way to me.

 

Lloyd

Yeap you're right Lloyd. Less than an inch shells used to work with #16 mesh size grains but larger than that about 1.5", 1.75", 2" shells don't. They fall off the mortar or doesn't fly more than a couple of feet.

[FlaMtnBkr]

Smaller grains should burn faster - to a point. Powder will burn slower because all the empty places between grains goes away and those act like channels for flame to more quickly move thru the mass.

 

But if your powder won't lift a 2" shell but a couple feet, it needs a lot of work and is quite weak and slow. In order of importance, you need to work on milling, good charcoal, and quick drying. If you have questions, just ask.

[Mumbles]

It sounds like perhaps you're having an issue of confinement. Black powder, like most other pyrotechnic compositions, burns faster under pressure. There is a real phenomenon in which the lift kind of transforms from a "poof" to a "bang" and is similar to self-confinement. You have to get over that threshold to get good lift performance usually. To me it sounds like you're 1" shells fit tighter into the mortar than the 2". 10 mesh BP is not going to solve the problem if this is the issue. If anything it'll make it worse. There are a couple of things you can try.

 

Make bigger 2" shells. This is most easily done with cylinders which have hand rolled casings by just increasing the former size. I like 1.75" formers for 2" shells personally. Ball shells or reusing some sort of OTC tube wont make this as accessible.

 

Use more lift. There's no hard and fast rules with the amount you have to use, just guidelines. We tend to hear 10% for smaller shells, but there's nothing stopping you from using 20%.

 

Find a way to confine the lift. This can be as simple as tightly adhering the lift bag to the shell with pasted paper or a tape of some sort. This can help it start building up pressure and get the BP consumed faster.

 

The last thing is to work on the quality of your BP itself. Re-evaluate charcoal sources. Look into being able to better mill or grind or mix components. Look into your granulation process. There are a lot of areas where tweaks can be made.

[pyrohacker]

Smaller grains should burn faster - to a point. Powder will burn slower because all the empty places between grains goes away and those act like channels for flame to more quickly move thru the mass.

 

But if your powder won't lift a 2" shell but a couple feet, it needs a lot of work and is quite weak and slow. In order of importance, you need to work on milling, good charcoal, and quick drying. If you have questions, just ask.

Thank you FlaMtnBkr. I'll consider your advice.

[lloyd]

"They fall off the mortar or doesn't fly more than a couple of feet."

------------

 

Woof! I agree with Mumbles. Your 2" shells don't have the lift properly-contained! If the powder was adequate for 1" shells, then, if anything, the SAME powder would be too powerful for larger shells... not less so.

 

Lloyd

[pyrohacker]

"They fall off the mortar or doesn't fly more than a couple of feet."

------------

 

Woof! I agree with Mumbles. Your 2" shells don't have the lift properly-contained! If the powder was adequate for 1" shells, then, if anything, the SAME powder would be too powerful for larger shells... not less so.

 

Lloyd

Sometimes it fall off the mortar and sometimes it flies a couple of feet. I'm not getting the same results each time made the tests using the same #16 mesh size bp grains.

[MrB]

Try a bit of wadding between the lift and the dummy shell. That should be enough to figure out if you have a confinement issue. But i agree, it sounds like you do.

B!

[pyrohacker]

Try a bit of wadding between the lift and the dummy shell. That should be enough to figure out if you have a confinement issue. But i agree, it sounds like you do.

B!

Don't you think it would be better if I make more room in the lift chamber so the gases may have more space available to perform better and develop more pressure? Let me know.

[Mumbles]

I would disagree. More space means a bigger volume to pressurize. You want the complete opposite of that. Reduce the volume and ideally increase the compression so the BP can pressurize that smaller area faster and more efficiently.

[NeighborJ]

Even using a tightly packed lift bag can provide the momentary pressure spike needed to get the high pressure reaction going. Loose powder and a larger combustion chamber can make the shell fall from the end of the gun.

[lloyd]

SOME headspace above the powder is beneficial -- but not a lot. If there's more than about 25% of the powder's volume in empty headspace, you'll lose performance, rather than gain it.

 

Lloyd

[Powderman]

Hello, I decided to write my first post here, I am having some fun with making samples of sulfurless BP. I decided to go without sulfur for now, it is practical to have no smell when doing at home. And I am curious what is it capable of. At the moment I am making only small samples with mortar and pestle, I have found info that 2:1 should be fastest and 3:1 shoul burn hottest (KNO3-charcoal). I like 2:1 so far, I am using my own willow charcoal and self made dextrin, but it seems it works well also with a bit sugar and dextrin is not needed (66-5-29 KNO3-sugar-charcoal). Soon the weather will be acceptable for some outdoor testing, because of the small quantities I am making I should think about a test which works with a gram or two...

Edited March 22, 2021 by Powderman

[justvisiting]

Here's an article I found while cruising the 'net last night:

 

https://apps.dtic.mil/dtic/tr/fulltext/u2/a150455.pdf

 

The title is 'A comprehensive Review of Black Powder', by Ronald A. Sasse.

[Powderman]

I am back after some studying and testing, it seems that my sulfurless BP works. I can shoot stars from self made cardboard pipe with steel wire ignition at the bottom, it takes about half second to heat and ignite BP with one 18650 lithium-ion cell. My stars are also sulfurless BP based, some with added charcoal and some with Al or Mg...

BP test:

Star test:

[Richtee]

I am back after some studying and testing,

 

OK.. so what was the formulations used? Or are you still at “pinch of this an’ that” and mortar and pestle?

[Crazy Swede]

Pyrohacker, adding as much as 10 % Fe2O3 will definitely slow down your mix!

 

It is a catalyst and a high temperature oxidiser but more than about 1-2 % will only be ballast in this application.

 

Sorry,

Just realised I answered a four year old post!🙄

Edited May 2, 2021 by Crazy Swede

[Powderman]

OK.. so what was the formulations used? Or are you still at “pinch of this an’ that” and mortar and pestle?

I like 66-5-29 (KNO3 - table sugar mixed with 3% Fe2O3 - willow charcoal). KNO3 and sugar are powdered in coffee grinder (separately) and charcoal in blender. To shoot few stars only little is needed, so I make 5g batches (3,3g+0,25g+1,45g) at a time with mortar and pestle. First I grind it a bit dry, then I add 25% isopropyl alcohol (2ml) and continue grinding until the texture is really fine. Then I granulate it on piece of waxed paper with knife (like chopping an onion) and dry it on hotplate... If I want it hotter, I use charcoal from rotten willow, it is very soft and easy to process with mortar and pestle, otherwise I use normal willow charcoal. For stars I give less effort with grinding, it saves time and works well...

I know how it seems, but honestly, I am unable to shoot all the stuff I made because I can not make a lot of noise on my backyard and it is too cold to go somewhere else after dark and play with.