BP isnt as powerful as I thought.

[DeepOvertone]

I'm sure I'm posting the same thing as every newbie, but its just a little depressing... I just made myself a 3lb rocket motor(end burning) out of my usual bp dust. I rammed it dry and let her rip. This was the first test aimed at the sky, the rest have been static to make sure the nozzles wouldnt blow out or anything else. Well needless to say, It didnt impress... It made a lazy arc over the highway... I was biting my nails hoping it wasnt going to hit any cars or anything. It cleared by a long shot but still. Anyway, this batch was made with skylighter airfloat, discount chem kno3, and discount chem sulfur ball milled for a few hours. I'm hoping that its the quality of the kno3 and sulfur thats keeping me down. How about the charcoal? Is willow the only thing hot enough for end burners? Back to the drawing board I guess..

[BLAST420]

Im not one too tell you from experiance....but it seems as long as you have descent chemicals(milled) then mill it CORRECTLY using 3 lbs mill make sure to mill with 2lbs media as said in ball millin forum check it id say you just might want to make a few more batches........CHeck here...........there is alot of info on this topic!!

 

http://www.apcforum.net/forums/index.php?s...hl=black+powder

[jacob]

How long is a few hours? you may just need to mill it longer.

 

The optimum amounts for a pyro ballmill are, 1/2 the jar full of media and a bit over 1/4 the jar full of material.

 

There's also an optimum jar rotation speed, witch for powders is 65% of the critical speed (critical speed is the speed at witch centrifugal force sticks the media to the sides of the jar) to find the critical speed you divide 265.45 by the square root of your jar ID minus your media OD.

 

For example, say you have a 6'' jar and 1'' media, 6-1=5

The square root of 5 is 2.2 (about) so then 265.45 divided by 2.2 is 120 (about) so 120 is the critical speed, then 65% of 120 is 78 so 78 is the optimum speed.

 

Hope this helps, and let me know if I need to clear anything up.

[hst45]

Endburners really need hot fuel to perform well. As jacob said, try longer mill time and you should note a significant improvement. Also, a smaller nozzle can improve impulse.

[DeepOvertone]

I'm not positive, but I dont think it has anything to do with my milling. I have a nicely setup ball mill. Most of my batches mill for at least 3 hours possibly more than that. I tend to think its the ingrediants more than the milling. I've heard of people having weak kno3 before. I'm going to make a fresh batch using the skylighter kno3 and sulfur that I just got to see if it speeds things up any.

[DeepOvertone]

Note that my rocket tooling is using a 1/4" choke for a 1" ID tube. The tube was about 4" long with a very light stick for guidance.

[TheSidewinder]

Deep,

 

First, the commercial hardwood airfloat leaves much to be desired when it comes to making BP for lift or end-burners.

 

When using Willow or Yellow Pine charcoal, then finely ricing after milling, I've produced some rather impressive BP. (And I started with pretty coarse KNO3.)

 

Second, if your mill is actually a Rock Tumbler, my experience has been that it takes a hell of a lot longer run-time than 3 hours.

 

Personally, I use what's considered the best brand of Rock Tumbler on the market..... But it's still a Rock Tumbler. It's a Lortone QT-66. Dual 6-pound jars.

 

(Note: the "6 pound" designation was originally the weight of the rocks and polishing media that it could hold. You'll NEVER get 6 pounds of BP out of it.)

 

I mill for a FULL twenty-four hours, using 3/4" Brass rodstock for media. Each jar is ~1/3 full of media, and holds about a half-kilo of mixed chems. If I use both jars, I mix a one-kilo batch of chems (750g KNO3, 150g C, 100g S, plus 50g Dextrin), screen it a few times to get it well-mixed, then split it between the jars and mill for the 24 hours I mentioned.

[Swede]

I think the mill time really is the key. Let a small batch mill for 24 hours+ and then compare that meal with your old meal, with simple burn tests. You'll know when the BP is too hot. I got CATO after CATO, loud ones, with core burners at least. I finally did end up mixing in 20% additional airfloat for my rockets just prior to ramming, and that solved everything. Plus, it makes a nice tail! Good luck!

[jacob]

3 or 4 hours is about the shortest amount of time you can go with an optimized mill, that's not to say your setup won't work, but you'll probably just need to mill it longer, on your next batch try a much longer time (12-24 hours) and see what happens.

I'll be surprised if it doesn't help.

[WarezWally]

I mill for a FULL twenty-four hours, using 3/4" Brass rodstock for media. Each jar is ~1/3 full of media, and holds about a half-kilo of mixed chems. If I use both jars, I mix a one-kilo batch of chems (750g KNO3, 150g C, 100g S, plus 50g Dextrin), screen it a few times to get it well-mixed, then split it between the jars and mill for the 24 hours I mentioned.

If you have to mill for 24 hours to get decent BP then either your charcoal or mill is of poor quality.

 

Using poplar charcoal I can churn out some very decent product in about 2 and a half hours in a optimized hexi shaped mill with lead & brass media. Any longer and the performance increase in minimal.

[DeepOvertone]

Thats what I've heard regarding mill times. But I've got nothing to lose but a little electricity so I'm gonna make a new batch using the same chemicals and mill for 12 hours. I'll also use the new chems I got and make another batch milling for 3 hours and compare all of the batches and see what happens.

[TheSidewinder]

If you have to mill for 24 hours to get decent BP then either your charcoal or mill is of poor quality.

 

Using poplar charcoal I can churn out some very decent product in about 2 and a half hours in a optimized hexi shaped mill with lead & brass media. Any longer and the performance increase in minimal.

As I said in the piece of my reply you didn't quote, my "Ball Mill" is actually a rock tumbler, and a damned good rock tumbler at that.... if I wanted to polish rocks. And it's a round tub, just like the Harbor Freight varieties, unlike your (properly-shaped) Hex tub. But it's still just a rock tumbler. Add to that the fact that I'm using Brass only, rather than Lead or a mix of same, and you arrive at the longer milling time.

 

Now, I don't have to mill for 24 hours to get "decent" BP. I can do that in 8-12 hours.

 

But to get BP that is "excellent" I mill for 24 hours. It might only require 18 hours, I don't know. It's just easier to start the batch in the morning at say... 10am, and stop it the next morning at 10am, which eliminates one variable in the equation. And it saves me from having to do any "mental math", something that gets harder as you get older. (As you'll discover some day. )

 

My somewhat imprecise burn tests, using a manually operated stopwatch and a 6-foot length of 1/2-inch wide Aluminum U-channel shelf bracing filled to level for its length, indicate that the 24-hour batch, finely riced as I said, is as fast as commercial FFg , or just a BIT faster, and just a bit slower than FFFg.

 

I *THINK* that Mumbles and CplMac have seen one or two of the 3" cannister shells I've shot, in which I used it exclusively for lift and break. And I'm absolutely certain that one experienced WPAG member (who's not here) did, and commented on its "nice lift, nice break". The stars? I'm still working on those.

 

What KNO3 do you start with? Mine's rather coarse. It's not the prilled stuff, but it's not the powder-fine KNO3 I've occasionally seen either. It's roughly table-salt size, but larger rather than smaller.

[WarezWally]

My KNO3 is just prills roughly ground in a coffee grinder, fairly inconsistent but good enough.

 

The poplar charcoal is excellent, I think it makes most of the difference. What charcoal are you using? Willow takes a bit longer to get the same results and I don't even bother with hardwood anymore.

 

I have seen the ball mill you use and they are quite good for the money.

 

 

Personally I think charcoal is the most important 'ingredient', you can use crappy KNO3 and sulphur with excellent charcoal in the crapest of ball mills and get great results in a few hours yet I can use the best sulphur and KNO3 with mediorce charcoal and mill for 12+ hours and end up with fuel thats only good for core burner rockets.

[Swede]

It is kind of entertaining to see who has the fastest BP, and discuss charcoal and such, but I don't think putting a "time limit" on milling is doing members a service, if you know what I mean. Not everyone has a proper mill, correctly charged with good media. I think the impression they get is that 2 or 4 hours is the correct mill time, and if they don't get hot/fast BP at that point, then they start to doubt their ingredients, rather than simply milling longer.

 

The cheap 3lb rock tumblers make great BP... it just takes longer.

[WarezWally]

Like I said before, go with what works for you and fuck everyone else

 

The BP I make Is good enough, I just dont like hearing a ball mill running for 24 hours so I try to figure out how to get respectabkle results in as little of time as possible.

[FrankRizzo]

Wally: I used to use the same Lortone rock tumbler to make BP with paulownia charcoal (one of the absolute best charcoals). While a 3 hr run produced acceptable results, an 8hr run made powder that was at least 50% better. The power increased a *bit* more continuing on to 12hrs, but my runs were usually between 8-9hrs.

 

As an experiment, use a 3" mortar and a baseball and time the round-trip flight of the ball when using equal weights of 2.5hr powder and 8hr powder. If you see no startling difference, keep doing it the quick way. I think you'll be pleasantly surprised at what a few more hrs can do for you.

 

Once you see that 8hr powder is much better, upgrade your motor and pulleys to upgrade it into a real ball mill and get the same results in 3hrs.

[Mumbles]

I've seen a decent number of your shells Sidewinder. I seem to remember you talking about one having the home made stuff instead of commercial 2Fg. The only shell I distinctly remember of yours is the time delay blue stars.

[TheSidewinder]

My KNO3 is just prills roughly ground in a coffee grinder, fairly inconsistent but good enough.

 

The poplar charcoal is excellent, I think it makes most of the difference. What charcoal are you using? Willow takes a bit longer to get the same results and I don't even bother with hardwood anymore.

 

I have seen the ball mill you use and they are quite good for the money.

 

 

Personally I think charcoal is the most important 'ingredient', you can use crappy KNO3 and sulphur with excellent charcoal in the crapest of ball mills and get great results in a few hours yet I can use the best sulphur and KNO3 with mediorce charcoal and mill for 12+ hours and end up with fuel thats only good for core burner rockets.

Having a proper mill makes the difference, that's for sure. Prills ground down a bit in a coffee mill, eh? Sounds perfectly good.

 

And the Lortone tumblers do make acceptable mills for the long term. After all, they're designed to run for days at a time if actually polishing rocks, though the jar weight is lower if you use it for that. I figure one-day runs with a heavier jar (or two) won't shorten its life appreciably.

 

I've used Willow and Yellow Pine. Both seem to make excellent and hot BP. The Willow is a bit hotter, I think. And actually, I didn't do the U-channel test with the Pine. I just lit some, and was careful not to singe my eyebrows. Good thing, too, it "poofed" very nicely.

 

I use airfloat if I'm making a batch for priming stars (why waste perfectly good Willow or Pine), and then mill for only 6 hours. Still feels nice and talcy when done, but definitely burns slower. Does the trick as a prime, though.

 

Poplar and Paulowniam eh? Hmm... I'll keep my eyes open for those and grab 5 pounds of each when (and if) I get the chance. I had heard Paulownia was a very good charcoal. Don't remember hearing about Poplar, but that's no surprise. Once I have what I need I tend not to experiment much more. But god knows we have enough Poplar around these parts.

 

You do have a valid point, Swede. But once I got the results I wanted, I simply kept that as a constant to eliminate one variable. Consistency seems to be the key to good results. And in my case, 8 hours just didn't make the "hot stuff" I wanted.

 

But the newbies ought to get the idea after reading all this info from everyone who's done it and gotten good results: If your powder is crap then increase the milling time, substantially if necessary. If that doesn't improve the results, then something else is wrong.

[TheSidewinder]

I've seen a decent number of your shells Sidewinder. I seem to remember you talking about one having the home made stuff instead of commercial 2Fg. The only shell I distinctly remember of yours is the time delay blue stars.

LMAO... those were classic, weren't they?

[Photon_Junkie]

DeepOvertone,

I don't want to muddy the waters, but I have been using the Skylighter airfloat as well. I have found it better than the pine, cedar, and birch homemade charcoals that I have made.

 

There are a million variables in my statement above. My point is...I would exhaust most of the other suggestions before throwing away your commercial airfloat.

Just my opinion, hope it helps.

[DeepOvertone]

Oh believe me, I'm not throwing anything away. Its great for spark trails and such. I'm going to try milling my stuff for quite a while longer. I think that from everything I've been reading since my post, that with my mill I'll need to mill for atleast 12 hours. So I'm going to try that. Havent had the time in a few days to mess with the stuff.

[Mumbles]

If you have a rock tumbler type of mill, you'll be looking at something more like 24 hours.

[crazyboy25]

If you have a rock tumbler type of mill, you'll be looking at something more like 24 hours.

Indeed I have the united nuclear "ball mill" aka shitty rock tumbler. It took 32 hours to make good BP.

[DeepOvertone]

So it seems the answer is a better mill then. If only I was a millionare.. I do have the regular oll 3lb mill from harborfreight. I was milling for 3-6 hours max and wondering why its not the best. So any suggestions on a "proper" mill that I can purchase? I dont feel like making my own. I'm allready making enough stuff.

[Bonny]

So it seems the answer is a better mill then. If only I was a millionare.. I do have the regular oll 3lb mill from harborfreight. I was milling for 3-6 hours max and wondering why its not the best. So any suggestions on a "proper" mill that I can purchase? I dont feel like making my own. I'm allready making enough stuff.

I don't have any suggestions on a "proper" mill...I'd say just use the one you've got. Even if you have to mill longer, who cares?. Use the time for other stuff...

I start my mill and go and do whatever, or run in the evening when I'm sitting around with the family. My mill is homemade and probably far from optimium. I let it go 12 or more hours for BP and don't mind.