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Granulate and ball mill again for rocket fuel


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#1 fr3dopyrox

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Posted 11 March 2019 - 05:38 PM

Hello I want make black powder for rocket using this method, it is for super bp cored tooling : I ball mill 35 minutes :65/25/10 , granulate wth hot water without dextrin, dry with drying chamber, and ball mill again 20-30 mn , I want press 1 lb cored rocket, Do you think it will give best results than only using meal ? Thanks for reading...

#2 Ferret

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Posted 11 March 2019 - 11:25 PM

That's ... an interesting method. Did you come up with that yourself or read it somewhere?

 

The only benefit I see of granulating after such a short milling time and milling again is that the water addition will help make the powder faster once it is dry due to the wet integration. However you could skip the granulation all together and simply mill the powder longer for the same results. instead of milling for two sets of 30 minutes mill the powder for 24 to 48 hours and use that if you are going for a hotter powder. 

 

Not sure if what you want is hotter powder or weaker powder, since you upped the charcoal by 10% over black powder which would make it slower but are trying to use a technique to then increase the burn speed of the powder somewhat. It is true that getting the burn rate of the powder just right can make or break the rocket, but myself and I know a few other pyros are of the mindset that the tooling should be made for the powder and not vice-versa. Hence, get tooling that is designed make a motor with good, hot, straight BP and use straight BP in your motors. 

 

If you already have the tooling and regular BP proved to be too hot/CATO, then I would just increase the charcoal content as you stated but skip the granulation/re-milling process, mill for a regular amount of time. If you want less dusty motor packing you can granulate to a fine grain size, around 3-4fg, and pack the granules as you would the meal powder without all the dust you get from packing meal. I do that with a hydraulic press though, not sure if you could pack it hard enough via hand-ramming to eliminate voids. Voids = Cato. 


Edited by Ferret, 11 March 2019 - 11:28 PM.


#3 fr3dopyrox

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Posted 12 March 2019 - 02:29 AM

That's ... an interesting method. Did you come up with that yourself or read it somewhere?
 
The only benefit I see of granulating after such a short milling time and milling again is that the water addition will help make the powder faster once it is dry due to the wet integration. However you could skip the granulation all together and simply mill the powder longer for the same results. instead of milling for two sets of 30 minutes mill the powder for 24 to 48 hours and use that if you are going for a hotter powder. 
 
Not sure if what you want is hotter powder or weaker powder, since you upped the charcoal by 10% over black powder which would make it slower but are trying to use a technique to then increase the burn speed of the powder somewhat. It is true that getting the burn rate of the powder just right can make or break the rocket, but myself and I know a few other pyros are of the mindset that the tooling should be made for the powder and not vice-versa. Hence, get tooling that is designed make a motor with good, hot, straight BP and use straight BP in your motors. 
 
If you already have the tooling and regular BP proved to be too hot/CATO, then I would just increase the charcoal content as you stated but skip the granulation/re-milling process, mill for a regular amount of time. If you want less dusty motor packing you can granulate to a fine grain size, around 3-4fg, and pack the granules as you would the meal powder without all the dust you get from packing meal. I do that with a hydraulic press though, not sure if you could pack it hard enough via hand-ramming to eliminate voids. Voids = Cato.


Edited by fr3dopyrox, 12 March 2019 - 02:31 AM.


#4 fr3dopyrox

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Posted 12 March 2019 - 02:43 AM

Hello It is a video on YouTube called :super fast willow black powder , yes you are right it maybe too hot for rocket cored, only for burst maybe ,thanks

Edited by fr3dopyrox, 12 March 2019 - 02:53 AM.


#5 Carbon796

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Posted 13 March 2019 - 12:17 PM

Rule number one, with pyrotechnics information, don't trust anything on youtube as being correct, knowledgeable, safe, or trustworthy. The unknowing, posting vids on youtube, generally out weigh the knowing.

If it was supposed to be super fast willow bp it would be milled far longer than 2-30 min sessions. It also wouldn't be granulated with hot water.

Most traditional, cored / nozzeled, bp type rockets, are made from scratch mixed comps. Sometimes lightly granulated to cut down on dust while handling. A milled comp will usually result in a cato, especially with a hot charcoal.

Edited by Carbon796, 13 March 2019 - 12:22 PM.


#6 Maserface

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Posted 13 March 2019 - 02:46 PM

I think Steve LaDuke once was advocating the process of milling, wetting/granulating/drying, and milling again.  I can only speculate why (but I wont).

 

If you are making rockets, you don't HAVE TO ball mill anything. If you have 'fine' potassium nitrate, charcoal, and sulfur, you can make rockets!

 

60:30:10 is a good place to start, try a rocket and if its a little anemic add 5 parts potassium nitrate, and if its too fast add 5 parts charcoal. Keep good notes of your changes and you will end up with the perfect formula :)



#7 Arthur

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Posted 13 March 2019 - 03:36 PM

BP is usually milled to increase the burn speed, more mill time more burn speed. However, for cored rockets a lower than ultimate speed is usually necessary. Keep some constants and keep good notes, change the mix -one line at a time, and change the mill time til you get the speed that you want without splitting the tubes. Weigh accurately, use dry ingredients.



#8 pyrokid

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Posted 13 March 2019 - 04:22 PM

Does anyone have any starting point for core geometry for a nozzled 75/15/10 motor? Is this a worthwhile idea for a pusher motor?

#9 Maserface

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Posted 13 March 2019 - 05:17 PM

Define pusher(?)

 

Typical nozzled skyrocket dimensions (based on tube inner diameter) are as follows:

 

Nozzle opening: 1/2 x diameter

Top of core: 1/4 x diameter

Core/taper length: 7 x diameter

Total spindle length: (including nozzle section) 8 x diameter

Tube Length: 10 x diameter


Edited by Maserface, 13 March 2019 - 05:19 PM.


#10 pyrokid

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Posted 13 March 2019 - 05:24 PM

The conventional wisdom is that 75/15/10 is too hot for the standard cored nozzled rocket dimensions. I'm wondering if performance could be increased in a worthwhile way by changing these dimensions to allow the use of 75/15/10 fuel. The goal is lifting [relatively] big shells!

#11 Maserface

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Posted 13 March 2019 - 08:19 PM

Have you tried 75:15:10 in a standard nozzled skyrocket? The reason I ask is because I have, and Ive had them work (it takes a little extra effort)! But for sure, straight commercial black powder is more than likely going to explode in a standard rocket (been there done that too).


I would start by shortening the tapered length, like 5 or 6 diameters on the tapered length. Commercially a hybrid/universal spindle is going to get you there. Will it lift more? Probably not ;)

For heavy lifting rockets, I would make the fastest black powder I could, and make nozzle-less rockets instead. A friend of mine makes some ridiculous black powder/whistle hybrid rockets, They ROAR, and still have an attractive tail!

#12 dagabu

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Posted 13 March 2019 - 09:41 PM

I love this thread, the standard, "Ask 10 rocketeers how to make a rocket and you will get 11 answers." thing just happened.

 

Listen, there is no standard, the standard is what Landcaster, Stoddard Conklin or Simzu wrote or what someone made for the military or for sale. 

 

Also, the idea that one should make the spindle work with the powder or that you should make the powder work with the spindle is also nonsense, we don't live in the dark ages people! We have scales that measure to the 10th of the grain, you can exactly replicate your powder to work with any spindle you like and you can turn a spindle to match any powder you want to make, the choice is yours.

 

Bottom line: Think about what you want to achieve, stay the course with a single powder or tooling set, find a stable combination and write the damn thing down! Just recording your efforts is often times much more important than all the dusty work we do to dial in a comp or tooling. 

 

As far as making BP, do like Mase says, start simple, then pick a time to ballmill if that is your thing and trim the chems to match what you have for tooling. Or do like I do and just use airfloat charcoal, sulfur, hot water to dissolve your KNO3 and mix it together into a ball, run through a screen, dry and press a rocket. Too hot? Add more charcoal to the next batch. 

 

Good discussion though, just dont get so bogged down with what "right" is and what "standard" is, there is no such things among artists. 


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