Twotails Posted August 16, 2009 Posted August 16, 2009 I ran across a formula, and made a few substitutions to the formula, but i just want to bring it by people who have maby tried this formula. Origanal formula Gold starType: pumpedLancaster Potassium Perchlorate 13.5%Potassium Chlorate 13.5%Potassoium Nitrate 15%Lampblack 49%Dextrin 6%Shellac 120 mesh 3%moisten with 33% alcohol There was only one problem with the above formula for me. I lacked both Dextrin and Shellac. so i improvised Altered formula Gold starType: hand rolled Lancaster (100g test batch)Potassium Perchlorate 13.5%(13.5g)Potassium Chlorate 13.5%(13.5g)Potassoium Nitrate 15%(15g)Lampblack 49%(49g)Nitrocellouise 9%(9g)moisten with acetone I desolved the NC in as little acetone as i could ( maby 1/2-3/4c) and used just enought to make it moist enought that it shined when pressed, but still a dry comp. I rolled the stars by hand, into even sized balls. (got a few dozen made with 100g batch) I tested some of the leftover dried comp, and wow, im not to sure about gold (looked red to me) but it was beautiful, tiny sparks the floated and seemed to hav a mind of there own. anyone see a problem with the above? anyone know what (or if) i'd have to prime these with?
TheEskimo Posted August 16, 2009 Posted August 16, 2009 I have not used this formula personally, but I do have one thing to add. Try to stay away from comps using chlorate, since you are just starting out. Virtually any star comp can now be accomplished using KNO3 or KCLO4. I think that there are people here that have been making pyrotechnics here for years, and haven't touched chlorate. Goodness knows that I haven't. Correct me if I'm wrong.And for dextrin, it's super easy and cheap. Buy a box of cornstarch. Spread on a cookie sheet. Turn the oven up to 400 degrees Farenheit. Cook until golden-brown, stirring the cornstarch every 20 minutes.
Twotails Posted August 16, 2009 Author Posted August 16, 2009 As i've said before, im not new to pyrotechnics, I like useing chlorates and perchlorate based stars, i do normaly stick to blackpowder based comps ( for i make black powder anyway ) I knew about the cornstarch methode, along with useing liquid starch. I had NC all preped for making fuse, so used it for this insted. I also like chlorates becouse they are a hard substance to work with ( incompatability issues) I reaserch a chemical for weeks before getting it, and look over each MSDS Before working. I dont take safty lightly, even when i work with my morter and pestles, I have several, each for a diffrent oxidiser, and one for sulfer mixtures. I've only been doing pyrotechnics for a few years, but i've been reading about them for longer. im just getting into arieal pyrotechnics now. also i've noticed that my potassium chorate smells like milk sugar, any reason why?, im not sure if it smells like milk sugar, it just smells...milk-ish. maby its the plastic it was in, i got it from hobby chemical supply (usa store)
Arthur Posted August 16, 2009 Posted August 16, 2009 You have just found that not all substitutions work! Call it research, write it up! Shellac is retail from painters supply stores and pyro hobby places, dextrin is a food ingredient and a retail from ebay and pyro suppliers, also you can cook your own dextrin from cornstarch. I know Ron Lancaster, he is a good chemist, he does not use chlorates in HIS OWN formulae to restrict the incompatibility problems, His books also include several collected formulae from other makers, all of which were good or special when collected but many have been superseded now.
Twotails Posted August 16, 2009 Author Posted August 16, 2009 The origanal formula called for potassium chlorate, I got it from the PFP Pyrotechnics Database http://members.shaw.ca/gryphon223/PFP/ . They have some good formulas. from what i saw last night, the stars are very reactive. It looks like it will have a nice long hangtime. I have a question, my morter is about 1/2in too wide for this shell. is there any way to make it fit better (i have no other shells) so i get some height? also what should i use as a break charge?
scarbelly Posted August 16, 2009 Posted August 16, 2009 What size shell are you making? as you can imagine, a 1/2" difference in shell size is huge on a 1" shell, but for larger shells it may not make as much of a difference. Have you already pasted the shell? Pasting should increase the shell size a bit.
Twotails Posted August 16, 2009 Author Posted August 16, 2009 its going to be a canister type shell, about 2 1/2-3 inches across, and i have to cut the length, i found a nice thickwalled (toilet) paper tube (its like five or six times thicker then normal TP tubes). i havent built it yet, so....any clue on a break charge?
Arthur Posted August 16, 2009 Posted August 16, 2009 Half inch is an OK clearance on shells over 6" diameter, Add a piece of thick string under a layer of brown paper if the shell is much smaller than that. Otherwise fins a smaller mortar. OR you could try making a mortar liner form thick card (expect it to be destroyed but it should give you one good shot. If your shells and mortars are a bad fit bet different hemis of card discs, or get better sized mortars. You cannot shoot a good shell from the wrong mortar.
Twotails Posted August 17, 2009 Author Posted August 17, 2009 Ok, wit ha few laer of kraft paper it fits, now how do i calulate break for a canister shell? and is it still 1/10 the weight of my shell for lift?
TheSidewinder Posted August 17, 2009 Posted August 17, 2009 Twotails: The answer is: it depends. For a shell weighing between 1/2 and 1 pound, my experience has been that you need more than 1/10 the weight, but it's not a linear extrapolation in that range. I used 22-24 grams of commercial (4Fg) lift for a cannister shell that weighed just a bit more than a half-pound. You'll have to experiment a bit.
flying fish Posted August 17, 2009 Posted August 17, 2009 (edited) It never hurts to launch a dummy shell to find your lift calibration. Edited August 17, 2009 by flying fish
Twotails Posted August 18, 2009 Author Posted August 18, 2009 Ok so i made my shell, it weighs 90g, i made a second shell Exacly like the first exept i filled it with popcorn/and a small bag of sand. i also tried out my burst charge(7g BP), for lift i used just over 10gBP. the first time it launched wonderfuly, got to maby 200ft(maby less), then poped, exept the popcorn/sand dident come out, it landed, and the shell was (mostly) intact. i then made a third one, filled it like before exept i put a 14 gram charge of BP into it, weighed out my lift, and launched. it went about the same height, and when it exploded, it worked! im sure stars wll work better, but, at least i know it works.i had to take apart my first shell, and add more break charge.
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