1 lb rocket question(s) from a new guy

[Guest no6]

Hi all,

 

Last week I test fired my first 1 lb rocket.

 

Kaboom! As was expected...

 

I have the Wolter 1 lb tooling and the NEPT tubes. I used a 60/30/10 formula but my 30 was all meal powder. It's what we had available at the time.

 

My 80 mesh charcoal arrived today. Hooray! So now I would like to try a 60/30/10 mix but replace 20 of the coal with the 80 mesh. How do you mix the 80 mesh coal in with the new 60/10/10 granulated composition? Do you screen it together? Or do you mix it in with the 60/10/10 and then granulate all of it?

 

Thanks for looking.

 

Edit: Core burner rocket.

Edited January 6, 2011 by no6

[dagabu]

I am a little confused with your statement, 60:30:10 would normally stand for 60 parts Potassium Nitrate, 30 parts charcoal and 10 parts sulfur. All three, whether milled together or separately should be finely powdered so that they will make a homogeneous mixture.

 

I sounds like you said that you were using 30% black powder meal plus 60% Potassium Nitrate and 10% Sulfur. If that were the case, you would have 82.5% Potassium Nitrate, 4.5% charcoal and 13% Sulfur. If you were to measure out 100 grams of your mixture, I would first mill 25 grams of your charcoal to dust and then add another 20 grams of the 80 mesh charcoal. This would bring you pretty darn close to the 60:30:10 mixture you were looking for.

 

You can just screen them all together but I suggest that you use very hot water, add it slowly until you can form a ball of the powder in your hand and screen is through a 4 mesh (small hardware cloth) screen, let dry thoroughly and then try again.

 

Hope that helps some.

[Guest no6]

I am a little confused with your statement, 60:30:10 would normally stand for 60 parts Potassium Nitrate, 30 parts charcoal and 10 parts sulfur. All three, whether milled together or separately should be finely powdered so that they will make a homogeneous mixture.

 

I sounds like you said that you were using 30% black powder meal plus 60% Potassium Nitrate and 10% Sulfur. If that were the case, you would have 82.5% Potassium Nitrate, 4.5% charcoal and 13% Sulfur. If you were to measure out 100 grams of your mixture, I would first mill 25 grams of your charcoal to dust and then add another 20 grams of the 80 mesh charcoal. This would bring you pretty darn close to the 60:30:10 mixture you were looking for.

 

You can just screen them all together but I suggest that you use very hot water, add it slowly until you can form a ball of the powder in your hand and screen is through a 4 mesh (small hardware cloth) screen, let dry thoroughly and then try again.

 

Hope that helps some.

 

Oh right. That was confusing. I used 60grams PN, 30 grams willow charcoal, and 10 grams sulfur ground finely in a ball mill in this formula. Only making small batches at the moment, The mixture was then wet and kneaded and pushed through a screen. I pound the motors with a rawhide mallet. I think that motor was just too hot and it blew the pass fire off. The nozzle was intact.

 

I've read that to cool down the mixture you can add 80 mesh charcoal. So would you take a finely ground 60 gram PN, 10 gram charcoal, 10 gram sulfur and mix it together with the 80 mesh and then wet and push it through a screen?

[AdmiralDonSnider]

I would start out with all of the charcoal being hardwood for the first tests. You can then speed the mix up by using different kinds of charcoal e.g. willow. Many report that the charcoal is a very critical factor in these rockets.

 

You can also make them blow up consistently and start modifying from there, replacing hot charcoal with slower burning types, or fine with coarser grades. I don´t think that any of the ingredients has to be ball-milled for the rocket mix, so superfine KNO3 can also drastically alter the burn rate.

 

Hardt has some really useful info about dialing these rockets in.

[dagabu]

Lets start with the easy stuff, use very small increments, less then 1/2 a diameter each time you pound. If you add a lot of powder at once, you get soft spots and even fissures in the fuel grain that lead to an over pressure. Second, your "passfire" is called a bulkhead and it should be 1 ID thick minimally to hold the pressure. You can use clay to make the bulkhead.

 

The reason why you want to start with a stout bulkhead is that you WANT to find the place where you get CATOs nad then back off from their. The rule in BP rockets is, "If they are too hot, add charcoal, if they are too cold add Potassium Nitrate."

[Juiceh]

I have the Wolter 1lb core burner kit. My Kno3 is granular form, that I mill down to a fine powder beforehand. First, I ball mill 6:1:1 for a while, 6+ hours(I use a tweaked out Harbor freight 6lb tumbler spinning my drums aprox. 85 rpm). Then I open up the mill and add 2 parts 80 mesh charcoal, close up the mill and let it run for 15-20 minutes. Not enough time for the 80 mesh particles to be reduced much, but just enough time for the mix to be homogeneous. Then remove the mix from the mill and damp with 25/75(99%IPA / H20) and rice it.

 

I do 300 gram batches per barrel with 200 .50 cal lead balls for grinding media in each barrel. Both drums at once.

 

I have done a 6:3:1 with all pine charcoal from rolling thunder that I milled in the mill alone until it was a fine powder and then added the Kno3 and Sulfur and milled for 6+ hours. Riced it after milling and that worked with the Wolter kit as well.

 

I currently have 4 working BP formulas for my Wolter kit, above are 2. My other 2 are accelerated versions with an additive mixed in just before the ricing process.

 

My BP chems are from ebay, the 80 mesh is from skylighter. I tried a 6:3:1 of all the ebay bp chems. It Cato'd.

Edited January 6, 2011 by Juiceh

[AdmiralDonSnider]

First, I ball mill 6:1:1 for a while, 6+ hours(I use a tweaked out Harbor freight 6lb tumbler spinning my drums aprox. 85 rpm).

 

Rocket mix is intended to be hand-integrated by screening. Ball milling the comp will result in vastly different burning characteristics.

[dagabu]

Rocket mix is intended to be hand-integrated by screening. Ball milling the comp will result in vastly different burning characteristics.

 

I disagree, there are many accepted methods of producing BP rocket fuel. Raw chems screened through a kitchen strainer will not create enough thrust for the rocket to fly, ball milled comp (all ingredients milled together) will result in a CATO almost every time.

 

Pre-milled chems screened together will provide for a consistent mix every time. Is that what you meant?

[Mumbles]

I think that is what he meant. It of course depends how your chems come "raw". My charcoal and sulfur are both sufficiently fine to use as-is from the bag. The nitrate is generally the more granular chem, unless purchased from a dedicated pyro supplier vs. agricultural.

 

I would suggest screening the pre-milled chems together, or just milling for a short period of time. That way the chems will be well integrated without being pounded into one another. All the chems are mixed together, and then wetted and granulated together. With willow charcoal, 20 granular 10 willow may be a pretty good mix. I often hear 60 nitrate, 15 hardwood airfloat charcoal, 15 80 mesh charcoal, and 10 sulfur being quoted for a good mix. With the hotter charcoal, it's probably a good idea to back it off a little bit more as you have suggested.

[Guest no6]

Lets start with the easy stuff, use very small increments, less then 1/2 a diameter each time you pound. If you add a lot of powder at once, you get soft spots and even fissures in the fuel grain that lead to an over pressure. Second, your "passfire" is called a bulkhead and it should be 1 ID thick minimally to hold the pressure. You can use clay to make the bulkhead.

 

The reason why you want to start with a stout bulkhead is that you WANT to find the place where you get CATOs nad then back off from their. The rule in BP rockets is, "If they are too hot, add charcoal, if they are too cold add Potassium Nitrate."

 

Yep, my bulkhead was not thick enough. It was probably less than 1/2 ". I'll fix that.

[Guest no6]

I have the Wolter 1lb core burner kit. My Kno3 is granular form, that I mill down to a fine powder beforehand. First, I ball mill 6:1:1 for a while, 6+ hours(I use a tweaked out Harbor freight 6lb tumbler spinning my drums aprox. 85 rpm). Then I open up the mill and add 2 parts 80 mesh charcoal, close up the mill and let it run for 15-20 minutes. Not enough time for the 80 mesh particles to be reduced much, but just enough time for the mix to be homogeneous. Then remove the mix from the mill and damp with 25/75(99%IPA / H20) and rice it.

 

I do 300 gram batches per barrel with 200 .50 cal lead balls for grinding media in each barrel. Both drums at once.

 

I have done a 6:3:1 with all pine charcoal from rolling thunder that I milled in the mill alone until it was a fine powder and then added the Kno3 and Sulfur and milled for 6+ hours. Riced it after milling and that worked with the Wolter kit as well.

 

I currently have 4 working BP formulas for my Wolter kit, above are 2. My other 2 are accelerated versions with an additive mixed in just before the ricing process.

 

My BP chems are from ebay, the 80 mesh is from skylighter. I tried a 6:3:1 of all the ebay bp chems. It Cato'd.

 

I will definitely try your first formula next. That is the way I was leaning just didn't know how to add the 80 mesh. Thank you sir.

[Guest no6]

Rocket mix is intended to be hand-integrated by screening. Ball milling the comp will result in vastly different burning characteristics.

 

I will try this as well. Cheers!

[Guest no6]

I think that is what he meant. It of course depends how your chems come "raw". My charcoal and sulfur are both sufficiently fine to use as-is from the bag. The nitrate is generally the more granular chem, unless purchased from a dedicated pyro supplier vs. agricultural.

 

I would suggest screening the pre-milled chems together, or just milling for a short period of time. That way the chems will be well integrated without being pounded into one another. All the chems are mixed together, and then wetted and granulated together. With willow charcoal, 20 granular 10 willow may be a pretty good mix. I often hear 60 nitrate, 15 hardwood airfloat charcoal, 15 80 mesh charcoal, and 10 sulfur being quoted for a good mix. With the hotter charcoal, it's probably a good idea to back it off a little bit more as you have suggested.

 

My chemicals are fine enough to screen by hand.

 

You all have given me some excellent suggestions. Thank you very much. I hope to test fire my second rocket this weekend. I'll keep you posted.

[Guest no6]

I think that is what he meant. It of course depends how your chems come "raw". My charcoal and sulfur are both sufficiently fine to use as-is from the bag. The nitrate is generally the more granular chem, unless purchased from a dedicated pyro supplier vs. agricultural.

 

I would suggest screening the pre-milled chems together, or just milling for a short period of time. That way the chems will be well integrated without being pounded into one another. All the chems are mixed together, and then wetted and granulated together. With willow charcoal, 20 granular 10 willow may be a pretty good mix. I often hear 60 nitrate, 15 hardwood airfloat charcoal, 15 80 mesh charcoal, and 10 sulfur being quoted for a good mix. With the hotter charcoal, it's probably a good idea to back it off a little bit more as you have suggested.

 

Thank you for your very insightful post. And thank you for coming down to my level of technical jargon with the wetted and granulated part. What's the newest and coolest term for this? Ricing?

[AdmiralDonSnider]

... ball milled comp (all ingredients milled together) will result in a CATO almost every time.

 

Pre-milled chems screened together will provide for a consistent mix every time. Is that what you meant?

 

Yep. I argued against three-component milling of rocket mix in a BP fashion. Screening requires presieved/premilled raw materials of course. In my case saltpeter is the only chem I´d have to grind.

 

For me one important reason why I stick to core burners using traditional rocket fuel is that I don´t have to ball-mill anything to produce a good fuel. Thus I´d first try tuning the mix with a hotter charcoal before considering to put anything into the mill to gain thrust. Why not use BP endburners if you´re going to mill anyway?

[Eric70]

Yep. I argued against three-component milling of rocket mix in a BP fashion. Screening requires presieved/premilled raw materials of course. In my case saltpeter is the only chem I´d have to grind.

 

For me one important reason why I stick to core burners using traditional rocket fuel is that I don´t have to ball-mill anything to produce a good fuel. Thus I´d first try tuning the mix with a hotter charcoal before considering to put anything into the mill to gain thrust. Why not use BP endburners if you´re going to mill anyway?

 

 

Amen brother.

 

Hand-screened is more than sufficient for core-burning BP rockets. That is what I like about these rockets.

 

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

For those relatively new to rockets (n06) everyone has a different way of doing things, here is another take on it...

 

My 1# BP cored rocket formula is:

 

15 oz KNO3 (powdered)

6 oz Charcoal (softwood charcoal ground in old meat grinder and powderized in coffee grinder)

3 oz Sulfur (rubbermakers)

 

Weigh out each, put materials in a big ziploc storage bag, gently turn the bag upside, rightside, side to side for 5 minutes. Use two old bowls to screen it back and forth 3 times and put it back into the bag. Please go outside to do the flipping, turning and screening. Do this in the spring. If you live where it is very cold right now, the air is dry and there is plenty of static electricity to help you end up in the hospital or 6-feet under. Be careful and remember safety first.

Edited January 9, 2011 by Eric70

[TYRONEEZEKIEL]

I dont know about yall, but I use straight 75:15:10 or 74:14:12 meal when I do my rockets using balsa charcoal. I leave about 3/4" of milled kitty litter as my bulkhead. I dont have catos ever. My motors are 3.5"-3.75" long overall, and I use just under a 3' square dowel for stability. I hot glue and tape the stick on. I get usually at least 300' of flight with a few stars on top.

 

My previous cato experience came from not grinding the kitty litter fine enough, and it wouldnt really bite into the tube and make a solid block. another failure of mine, is i used to use flat nozzle as I would just ram a bulkhead, propellant, then another bulkhead and hand drill a hole. since there was no funnel for the gases, it blew the nozzle. Try building a motor, clamping it to something, or stick it nozzle side up down into some bricks, so the rocket wont get away from you. then see where you have your failure.

[Guest no6]

Well I have taken the advice of Admiral and dagabu and others and switched to all hardwood charcoal. And two different batches of black powder have been made and riced.

 

The first batch was screened by hand. It's 60/20/10/10. The 20 is 80 mesh. This will be rocket #2. You know I sure hope this one works because I really like the idea of not having to mill anything.

 

The second batch was Juiceh's formula from his post. Ball milled the 60/10/10 for 3.5 hours (shorter than Juiceh's I know) then added the 20 of 80 mesh for 15 minutes. this will be rocket #3. I hope this works as well because I have enough mixture for 3 more rockets.

 

I just finished pounding each of them and added my mixture in small amounts as dagabu suggested. I'll put the sticks on them tonight but they won't be fired for a day or two. My pyro buddy wants to watch.

 

Oh, and I've made a spreadsheet. How cool is that?

 

Cheers! I'll be back to post the results.

[Guest no6]

One more question: My bulkheads currently do not have pass fire holes. Are they necessary?

[Juiceh]

Rocket mix is intended to be hand-integrated by screening. Ball milling the comp will result in vastly different burning characteristics.

Interesting, I've heard this before. I'll give it a try next time. The reason I ball mill is because I started off in rockets with a United Nuclear 1lb core burner kit. Their recommended fuel is ball milled BP slowed down with motor oil. I totally screwed up my first batch of fuel for them and added too much motor oil which turned the rockets into inverted gerbs on a stick... I then omitted the motor oil from the process because it was messy and I didn't want to deal with it so I cooled the mix down to 6:3:1 with 2 parts of the charcoal being 80 mesh added for the last 15 minutes of milling and had good results. I used the same method when I upgraded to the Wolter kit and haven't had a problem. Wolters formula for 1lb is 6:3(1 airfloat, 2 80 mesh):1, I figured I was making it how it was supposed to be. I still use the United Nuclear "Rocket Scoops" for each increment.

 

The second batch was Juiceh's formula from his post. Ball milled the 60/10/10 for 3.5 hours (shorter than Juiceh's I know) then added the 20 of 80 mesh for 15 minutes. this will be rocket #3. I hope this works as well because I have enough mixture for 3 more rockets.

3.5 is probably fine. To be honest, I sometimes let the mill run way longer than 6 hours, doesn't seem to make much difference after that though. My POS harbor freight mill runs near optimal rotational speed for the drum size tho, so if your using an untweaked mill your grinding won't be as efficient as mine would be in the same time frame. But everyone seems to say it doesn't need to be anyway. http://smiliesftw.com/x/dunno.gif If I do a small burn test of the 6:1:1 mix after milling it should poof and be gone pretty quick like good quality BP. I was actually surprised how fast it was and was worried the 80 mesh wouldn't be enough to cool it down.

 

I did a test shoot of my 4 different formulas a couple weeks ago. I filmed them, here's the video from my phone.

 

 

My 3rd formula is very hot! Ever notice how some whistle rockets make a quick zig-zag at the initial take off? Watch #3 closely. I did not make these rockets with any special delay fuel above the core. Delay fuel is the same as core fuel. I need to use a slower burning fuel above the core for my 3rd formula so that it gets enough time to reach apogee before igniting the header. I believe my 3rd fuel is just shy of the CATO cusp for BP coreburner fuels. These fuels have been very reliable so far. No CATOs in quite some time! http://smiliesftw.com/x/eekx3.gif

 

Any & All critisizm\advice welcome! I make no claims to be an expert in this stuff. I just know that what I've done has worked for me.

Edited January 10, 2011 by Juiceh

[dagabu]

One more question: My bulkheads currently do not have pass fire holes. Are they necessary?

 

Not if you dont want to pass fire...

 

If you put a shell or report on top you will need a passfire hole.

[Guest no6]

Thank you sir! Sticks going on now.

 

And my grog and paraffin wax are in the house so I'll be making a batch of nozzle mix and a batch of bulkhead mix next weekend. I'd like to see for myself both sides of that debate. I just used bentonite clay for these two rockets.

[Juiceh]

Put the passfire hole off to the side of the bulkhead near the casing wall. If you put the passfire hole in the center where the flame front of the propellant reaches first it will passfire before all of the motors fuel is spent.

 

I used plain powdered bentonite clay for the nozzles and bulkheads of the rockets in the video I linked in my last post. So, you should be ok. A mix of Grog, clay, and some wax will perform a little better. I've used a little bit of United Nuclear's "nozzle mix" which is a combination of clay and grog. There was less erosion, but that stuff is expensive. So I picked up some grog & kyanite to experiment and make some of my own once I pickup some paraffin.

Edited January 10, 2011 by Juiceh

[Guest no6]

Thanks Juiceh. Will do.

 

UPDATE:

 

Well rocket #2 was fired. Great success! Remember this was the one that was screened and not milled. I'm very happy this worked. Screening the mix only takes a few minutes. Definitely the way to go.

 

This is a powerful rocket and it flew beautifully. I used quick fuse with visco as a leader and held it in by taping the fuse to the stick. Worked a treat!

 

Unfortunately I forgot rocket #3 on the coffee table so will have to update on that one later.

 

Thanks everyone for your help! I've learned a bunch.

[dagabu]

Thanks Juiceh. Will do.

 

UPDATE:

 

Well rocket #2 was fired. Great success! Remember this was the one that was screened and not milled. I'm very happy this worked. Screening the mix only takes a few minutes. Definitely the way to go.

 

This is a powerful rocket and it flew beautifully. I used quick fuse with visco as a leader and held it in by taping the fuse to the stick. Worked a treat!

 

Unfortunately I forgot rocket #3 on the coffee table so will have to update on that one later.

 

Thanks everyone for your help! I've learned a bunch.

 

no6, remember rule #3, if there is no video, it never happened.

 

Plus, you may want to have something to show the kids some day about how you made your first rocket.