psyco_1322 Posted August 18, 2008 Posted August 18, 2008 I found this formula in the PFP. Wondering if anyone has ever tryed it or if its even possible to work as a flash comp. I tryed a gram at the convention using silcon powder, its had a bit of a time trying to light. I didnt try it confined but will when I get home. Thoughts about it? Photo FlashPotassium Perchlorate - 67Silicon - 33
Swede Posted August 19, 2008 Posted August 19, 2008 Interesting. It may be a less sensitive variation on an old theme. Ultimately cost is going to drive the issue, I think. Let us know how it goes.
psyco_1322 Posted August 20, 2008 Author Posted August 20, 2008 Well the Si I got was at $8/lb and Perc was $4/lb so it would be cheaper than Al pound for pound. What exactly do you mean by "It may be a less sensitive variation on an old theme"? Is there something from the past I missed?
Swede Posted August 20, 2008 Posted August 20, 2008 No, the "old theme" is just a stupid way to say any variation from 70:30 perc/Al which seems to be the gold standard for safe® FP. In other words, variations, adding sulfur, using permanganate, tend to be more dangerous and more sensitive, not less. What I'm having trouble saying is perhaps a Si-based composition may perform very well, AND be safer to handle.
FrankRizzo Posted August 20, 2008 Posted August 20, 2008 (edited) Silicon dioxide's heat of formation is just over half of aluminum oxide's. Expect the power/noise output to be much less gram-per-gram. I think the silicon would be better used in primes. Edited August 20, 2008 by FrankRizzo
psyco_1322 Posted August 21, 2008 Author Posted August 21, 2008 So if its half the heat, should it not light up easier? Guess if it requires less energy to light up than the resulting energy being produced would be slighty lower also. Resulting in a less powerful explosion. If I did my chem math right I think the "correct" ratio for the reaction would be closer to:KClO4 - 71Si - 29 Putting the formula I found way out of ratio with what it would be happy burning at.
Mumbles Posted August 22, 2008 Posted August 22, 2008 Nope, heat of formation has nothing to do with ignitability. Just the reaction will form 1/2 less energy.
tentacles Posted August 22, 2008 Posted August 22, 2008 That's not really such a far jump out of stoichiometric. Look at the best BP formulas compared to stoich. - the "PGI Lift" (also known as that swiss guy's formula) is fairly far off, but does the job well. Frank and I made some MgAl/Perc, er, report shells, and found they worked fairly similarly from 50/50 to 70/30. 60/40 was fastest and 50/50 considerably brighter.
psyco_1322 Posted August 22, 2008 Author Posted August 22, 2008 Thanks for clearing that up Mumbles. Yah I played with some magnalium flash ratios one day doing open air burn tests. I got about the same results as you guys. I think it wasnt until 80:20 did I see a slow down in burn rate. I did notice that the 50:50 was a bit brighter but seemed a tad slower. Its too bad my 100g report header on that rocket hit the ground and broke off at teh convention. It was made with that 600 mesh magnalium, I really wanted to see that....and nothing else after it. lol I did find it the next morning so its not lost for good.
qwezxc12 Posted August 22, 2008 Posted August 22, 2008 (edited) Thanks for clearing that up Mumbles. Yah I played with some magnalium flash ratios one day doing open air burn tests. I got about the same results as you guys. I think it wasnt until 80:20 did I see a slow down in burn rate. I did notice that the 50:50 was a bit brighter but seemed a tad slower. Its too bad my 100g report header on that rocket hit the ground and broke off at teh convention. It was made with that 600 mesh magnalium, I really wanted to see that....and nothing else after it. lol I did find it the next morning so its not lost for good. I made a few 2in and a 3in 50:50 -600 mesh Mg/Al salutes to mix in with the pile of Ti ones back on the 5th of July. A 3in one with ~70g of 50:50 blinded everyone...I couldn't see shit for the huge spot in my vision for quite a few minutes...not really fun when you're trying to shoot (and enjoy) a little show. I'm no longer bothering with big Mg/Al salutes...I will be making either a 4in or 6in shell of shells filled with 1in Mg/Al shells, though. Something more like this, but with Mg/Al, instead of Ti... 4in Ti shell of shells Edited August 22, 2008 by qwezxc12
FREAKYDUTCHMEN Posted August 22, 2008 Posted August 22, 2008 Very nice shell, can you tell us what mesh size your Ti was? I think about 10# or so.
psyco_1322 Posted August 22, 2008 Author Posted August 22, 2008 10 pounds or 10 mesh? Either way sounds good. The Ti mess doesnt really matter that much as long as its kinda coarse and not like 100 mesh or something. Well I did put some 1000 mesh into a salute and got a few sparks but they were really short lived, probably coming from the clumps of it. Got a few questions about the shell of shells. 1. What size where the inserts? How many? 2. Im guessing about 1 second on timing, is that what you used? 3. Inserts homerolled or were they those little plastic inserts you can buy? Thats it, thanks.
qwezxc12 Posted August 23, 2008 Posted August 23, 2008 (edited) I made that shell back in March '07, so this is partially from memory. FREAKYDUTCHMEN,The Ti was 18-30 mesh sifted through a -24mesh kitchen strainer, so figure 24-30ish mesh Ti. psyco_1322,The inserts were 1in ball shells fused with visco cut for a little less than ~2 seconds (generous 1/2in) and primed by dredging in MgAl spiked meal. There were 26 in the 4in shell. Close counting in the video shows 24 salutes, so two were blind. That's why I cross-match now. The shell was broken somewhat gently with meal coated rice crispies and a dash of straight 7:3 whistle. Glad you liked the shell. Edited August 23, 2008 by qwezxc12
psyco_1322 Posted August 24, 2008 Author Posted August 24, 2008 Im going to give a shell of salutes a try sometime. Might end up using bottle caps for the salutes and stack them inside a 4" cannister shell. That crossmatching of visco still gets me, lol. The silicone flash does not flash. I tried it again and all I get is a slow burning, hard to light comp. It turned my salute into a lame fountain. It doesnt even burn brightly as a photo flash should.
flying fish Posted September 7, 2008 Posted September 7, 2008 ^^^I tried this as well a couple weeks ago, and had the same result. I couldn't get it to light with a fuse, so I placed one of my pumped glitter stars on top of it, and lit the very top of that. When the star burnt down to the Si "flash" it ignited producing a reaction which was much slower and dimmer than the star itself! Pretty lame, all in all. My silicon was "-200 mesh" from the ebay supplier "fine powders". It might be interesting to mix in small amounts of flake aluminum, sulfur or other things to increase the ignite-ability. Probably not useful though as anything more than a curiosity.
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