Ralph Posted August 23, 2009 Posted August 23, 2009 maybe might try a 3" comet (2.5") it could work. well mabey a fast burning comp like just nice fast bp would leave you with the red trail but you would defintely need some kind of fast very low dross comp
Mumbles Posted August 24, 2009 Posted August 24, 2009 The tail of micro stars is accomplished by having the microstars burn much slower than the bulk comet composition. Using the same color composition for both will just be a laborious way to make a comet with very little to no tail. The only way to get any semblance of a tail would be if the difference in wetting the two fractions (matrix and microstar), or the density contributed some sort of burn rate variance. Otherwise when it dries, it will all be the same. With that being said, it's not impossible. What you'll want to do is put a slow burning prime on the micro stars. Thats pretty much how the colored "glitters" are done that have recently emerged from china. I've heard a high concentration of very dense materials (barium, lead, and bismuth compounds for example), can help to slow the micro stars accent and appear to give a longer tail.
qwezxc12 Posted August 25, 2009 Author Posted August 25, 2009 The tail of micro stars is accomplished by having the microstars burn much slower than the bulk comet composition. snip... I've had success using Ammonium Perchlorate color stars (3/16ish) embedded in a BP based Al streamer type comet. The streamer burns fast and vigorously, ejecting the slower burning color stars in the tail. A 3" comet of AP Red in C6 +25% 30um spherical Al is nice. I bound the comet matrix with Resorcinol resin to avoid any interaction between the KNO3 and AP.
KruseMissile Posted October 24, 2009 Posted October 24, 2009 I hope this would be the right thread. Whats the best way to attach comets onto can shells(3-4" to be exact)? Top or bottom? Thanks
Mumbles Posted October 24, 2009 Posted October 24, 2009 Well, no one really attaches comets to can shells. Properly constructed can shells don't really have a flat or even surface to attach a comet to. Just like ball shells, I'd think it'd be best to attach to the top so it doesn't get cocked off by the lift. One of the more unique methods I've seen was to press a donut shaped comet, and put it around the timefuse.
Bonny Posted October 24, 2009 Posted October 24, 2009 I hope this would be the right thread. Whats the best way to attach comets onto can shells(3-4" to be exact)? Top or bottom? Thanks You can simply glue the comet on TOP with hot melt glue, and maybe a wrap of pasted paper to be sure it stays on. For 3" cans (and maybe 4"...never tried) you can bottom fuse, leaving lots of empty space on top for the comet. The donut idea sounds pretty cool, but might be a PITA to press such a comet.
Twotails Posted October 24, 2009 Posted October 24, 2009 why not in place of a donut, place several smaller comets on the bottom? It might work. Althogh there would be the chance of them being broken off at launch. would it be safe to say, one could have black match, or quickmatch leading off from said bottom comets, and some sort of preforated disk to aid in the launching of the shell? It would be easyer if you could somehow press a shell into a comet, therefor having the rising effect of a comet, and it finishing like a shell, possably undoable, but, Hmm sounds slightly possable. two ways i think it could be done. 1) pressing a hollow into the comet, and filling with stars like a large crosset(not likely to work) 2) a comet press equipped with two molds, the first having a raised middle, (it would only be half of the sphere) same OD as the ball shell(or can shell) your useing, the second built the same way exept with a small nipple the would make a hollow for the time fuse. you could easly fit said shell into the hollow, "glue" the comets hemispheres shut with BP/NC slurry, and run a few stransd of QM to the top, resulting in full ignition. Those are just what was floating in my mind, doubt they would work, and it would just be easyer to put pressed comets onto the top of the shell. or so it seems.....
Mumbles Posted October 25, 2009 Posted October 25, 2009 You seem to have some desire to make every simple operation exceedingly complicated.
Ventsi Posted October 25, 2009 Posted October 25, 2009 (edited) I though I'd ask, I just made some 3/4" cavity star/ mini-comet tooling and I've been having some problems. Its made out of wood , the cavity goes from 3/8" and tapers to 5/16", its 3/8" long. I tried pressing some moistened fine bentonite with it and once the stars are formed it is very hard to get the star off the male part with out breaking the star in two. I decideed I should give a more *slippery* coating and sprayed it with some Heavy duty spray-paint. Is there anything else I can do to prevent the formed stars drom breaking upon release? Edited October 25, 2009 by Ventsi
Twotails Posted October 25, 2009 Posted October 25, 2009 You seem to have some desire to make every simple operation exceedingly complicated. yes, seems that way, it how i think. And maby if you coated the male part with somthing like, Frendly plastic?(turns plyable in boiling water) or maby some kind of hard drying resin?
scarbelly Posted October 25, 2009 Posted October 25, 2009 Spray it with pam before each use? Using something like acrylic or latex paint over it would probably work.
Mumbles Posted October 25, 2009 Posted October 25, 2009 It's sticking because your tooling is wooden and probably not smooth enough. You could try to dip it in a minwax sealer type thing, and sand it down. Repeat multiple times until smooth. This will make the surface flat, smooth, and even, as well as protecting it from absorbing water and swelling. There is a reason metal is preferred, and it's not just durability. From there a lubricant will be more effective. Waterglass (sodium silicate) might even work if you have any around. There are spray lubricants that might be of use. I've used silicone and teflon sprays on the underside of my lawnmower and it really helps to keep the grass from sticking. A while ago, people got turned on to a product called "sailkote", which is a marine grade lubricant. It's pricey, but it holds up well, and is pretty slick. They were using it on rocket spindles, IIRC. Jim sells it currently in individual cans. http://www.hobbyhorse.com/pyro_tubes.shtml Lubricants such as graphite powder, cooking spray, WD-40, etc all work well on crossette pumps, so they should work equally well for your application.
Ventsi Posted October 25, 2009 Posted October 25, 2009 It's sticking because your tooling is wooden and probably not smooth enough. You could try to dip it in a minwax sealer type thing, and sand it down. Repeat multiple times until smooth. This will make the surface flat, smooth, and even, as well as protecting it from absorbing water and swelling. There is a reason metal is preferred, and it's not just durability. From there a lubricant will be more effective. Waterglass (sodium silicate) might even work if you have any around. There are spray lubricants that might be of use. I've used silicone and teflon sprays on the underside of my lawnmower and it really helps to keep the grass from sticking. A while ago, people got turned on to a product called "sailkote", which is a marine grade lubricant. It's pricey, but it holds up well, and is pretty slick. They were using it on rocket spindles, IIRC. Jim sells it currently in individual cans. http://www.hobbyhorse.com/pyro_tubes.shtml Lubricants such as graphite powder, cooking spray, WD-40, etc all work well on crossette pumps, so they should work equally well for your application. The wood was sanded until perfectly smooth to the touch, then coated with wax{stupid idea}, then graphite which helped significantly, but not enough. I coated the tooling with a good quality spraypaint which ensured a nice smooth, hard and slick surface, as well as waterproofed it. I suppose a PTFE spray/coating would be best, though I'll give cooking spray a shot, thanks guys.
firetech Posted October 25, 2009 Posted October 25, 2009 I've never had good success with wooden tools. Even if they do work initially, they don't last under pressure. I only use them for tests on tooling before I make the final product out of metal.
Mumbles Posted October 25, 2009 Posted October 25, 2009 Smooth to the touch is not smooth enough for tools. The wax could be causing the problems. It flows like a liquid under pressure and is kind of sticky.
Twotails Posted October 25, 2009 Posted October 25, 2009 thats what i was thinking, If it dont work, try making a new one, or taking off the wax, and maby just using a Polyurithaine coating.
Ventsi Posted October 25, 2009 Posted October 25, 2009 I took off the wax, then coated it with the paint , its now perfectly smooth [think glass] and works well, especially using a little cooking spray. Thanks guys, Í suppose I'll make the next set out of aluminum.
optimus Posted October 26, 2009 Posted October 26, 2009 Well, no one really attaches comets to can shells. Properly constructed can shells don't really have a flat or even surface to attach a comet to. Just like ball shells, I'd think it'd be best to attach to the top so it doesn't get cocked off by the lift. One of the more unique methods I've seen was to press a donut shaped comet, and put it around the timefuse. I think this was covered in an AFN - no idea which issue but it was about 'aerolites' IIRC... I've attached a photo of the donut comet tooling if anyone's interested.
sparksnsky Posted February 10, 2010 Posted February 10, 2010 Here are some 2'' comets I soot recentlySilver comets are a composition from zmuro: Potassium nitrate..40Sulphur..15Aluminium fine (bright)..35Aluminium coarse (-70 mesh)..10Dextrin..+5 The comets are holoed on ignition end. 15gr lift were used for each.
pyrogeorge Posted February 11, 2010 Posted February 11, 2010 (edited) Bright comets!very nice Edited February 11, 2010 by pyrogeorge
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