pyrogeorge Posted January 23, 2009 Posted January 23, 2009 i tried this formula but the comet tail isn't white as i expected..what goes wrong??the Al was from machine-factory,and i screen it to 20mesh...can somebody help me?thanks
Gunzway Posted January 24, 2009 Posted January 24, 2009 i tried this formula but the comet tail isn't white as i expected..what goes wrong??the Al was from machine-factory,and i screen it to 20mesh...can somebody help me?thanksWhat color was the tail?
pyrogeorge Posted January 24, 2009 Author Posted January 24, 2009 Almost no tail..it was like BP comet without Al.
Swede Posted January 24, 2009 Posted January 24, 2009 20 mesh Al sourced from machine tool swarf may be too coarse... I suspect the Al did not ignite. Just a guess. The aluminums used in a machine shop are heavily alloyed, whereas Pyro Al tends to be pure. Maybe that's it. Can you give it a try with the same Al, but finer? Is there a way to increase the temp of the burn of the comet? Maybe a bit more oxidizer, or the addition of a small amount of fine Pyro Aluminum to bring the temps up so as to ignite the coarser stuff? Just some thoughts.
qwezxc12 Posted January 24, 2009 Posted January 24, 2009 I bet Swede is right...I never had any luck with just using coarse AL turnings and BP. I always added additional metals to heat up the burn and get the AL tail to ignite. Here's an old video of a 2" BP greenmix + metal comet bound with resorcinol resin.Formula:70....BP greenmix15....100-200mesh MgAl15....Al flitters (FireFox's old 'chips and shards' sparkler grade - basically 12-30 mesh Al machining swarf, machine oil and all) 2in comet video
pyrogeorge Posted January 24, 2009 Author Posted January 24, 2009 (edited) I saw this video.it used 20mesh al but it gives white tail.. http://www.youtube.com/watch?v=LNWHr-jIBo4...re=channel_page Edited January 24, 2009 by pyrogeorge
Seymour Posted January 24, 2009 Posted January 24, 2009 I suspect Zmuro used something along the lines of coarse flake (flitter) Aluminium. Perhaps Zmuro will see this topic and be able to provide real details. Flitter Al is more reactive than machining swarf, which would explain it. Hotter BP (generally also faster burning) will light Aluminium more effectively than cooler BP. Perhaps (if you have not already) you could ball mill it for longer, or use a hotter charcoal? This in addition to Swede's and Qwezxc12's advice to add more reactive metals to get the burning temp right up, should ensure ignition of even the most stubborn of Al.
Mumbles Posted January 27, 2009 Posted January 27, 2009 Nope. If it can't light 10%, it definitely can't light 20%. As already suggested, try adding some extra fuels, such as fine metals. Adding some Perchlorate would also do the trick most likely.
pyrogeorge Posted February 3, 2009 Author Posted February 3, 2009 maybe the problem was in BP because of not good milling.The charcoal was wet and the powder was stuck around the jar,but i believe that was milled.. I test an amount of BP and i saw white spots in the ground,this mean not good milling,right??
andyboy Posted February 3, 2009 Posted February 3, 2009 maybe the problem was in BP because of not good milling.The charcoal was wet and the powder was stuck around the jar,but i believe that was milled.. I test an amount of BP and i saw white spots in the ground,this mean not good milling,right?? To much KNO3.
pyrogeorge Posted February 3, 2009 Author Posted February 3, 2009 i think that was from not good milling
Seymour Posted February 3, 2009 Posted February 3, 2009 If it's well milled, excess oxidiser should still just go up as smoke, unless there was an extreme excess. I think Pyrogeorge has it spot on. I assume you live in the Northern hemisphere, which could support my theory that dampness is causing the Black powder to clump to the sides, and inside that clumped powder there will be un-milled prills/crystals of Potassium nitrate. I'd say these are melting when the Black powder burns, and creating the white spots you describe. To much KNO3. Even if you make a highly over fueled mix, such as the 6/3/1 rocket fuel, but use unmilled Potassium nitrate, you will get the white spots on the ground.
pyrogeorge Posted February 3, 2009 Author Posted February 3, 2009 i will re-mill the other quantity of BP from same batch and i will test it again..
Mumbles Posted February 4, 2009 Posted February 4, 2009 I use a thinner flake in the following formula. Not quite a streamer, but not quite a firefly. Somewhere in between. It makes nice comets. 50 KNO315 Sulfur10 Charcoal (airfloat)10 Charcoal (80 mesh)10 Aluminum fltters, coarse5 Dextrin
pyrogeorge Posted February 8, 2009 Author Posted February 8, 2009 The main problem was in the BP as i said..i remilled my composition and now is better and faster than the previous milling.It was't from too much kno3 but for the wet charcoal and it causes bad milling..
andyboy Posted February 8, 2009 Posted February 8, 2009 The main problem was in the BP as i said..i remilled my composition and now is better and faster than the previous milling.It was't from too much kno3 but for the wet charcoal and it causes bad milling.. Wet charcoal weighs more then dry charcoal so I still suspect that your ratio is of.
pyrogeorge Posted February 8, 2009 Author Posted February 8, 2009 (edited) thanks for your reply andyboy.. Yes,but i didn't find white dots as the first time..i will be more careful next time with my charcoal Edited February 8, 2009 by pyrogeorge
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