trag Posted February 23, 2009 Posted February 23, 2009 I am slowly working my way around to pressing some model-rocket-style rocket engines, mainly using the instructions in Sleeter's book on the topic. I noticed the colored smoke kits over on Skylighter and it seems like a rocket engine with a bright orange smoke delay would be very nice. The problem is that the smoke mixes all use potassium chlorate. My understanding is that it is a *bad idea* to mix chlorates with, or put them in contact with sulfur, and the BP for the rocket fuel is sulfur-containing black powder. So I went looking for other colored smoke mixes, but all the ones I found which produce distintive colors also seem to need chlorates or perchlorates. So I have two questions. First, is my understanding correct, that it would be a bad idea to put a smoke delay containing KClO3 on top of black powder. Second, is there a way of getting a pretty colored smoke delay into a black powder rocket. This isn't terribly important, but I think it is kind of interesting...
TheNitrateFellow Posted February 23, 2009 Posted February 23, 2009 (edited) I am not a rocket expert, but I think that you can make your rocket engine with a passfire and then connect your smoke mix by a fuse or something. The smoke mix has not to be in contact with the BP. The rocket you're building has a core or end-burning design? Edit: tried to put an image, it didn't work. Best regards, The Nitrate Fellow Edited February 23, 2009 by TheNitrateFellow
Ralph Posted February 24, 2009 Posted February 24, 2009 you could quite simply press the smoke mix (after you have made your plug and what not) once you have pressed your smoke mix make about a 1cm thickness plug of delay mix (like that used in Roman candles usually KNO3 45 Charcoal 50 and Dextrin 5 ) this mixture dose not contain sulfur and will separate your rocket fuel (I am assuming your using BP) the other alternative is to use sugar fuel I have had great results using uncooked sugar fuel if it is pressed well it works just as well as its cooked counterpart stay safe
Mumbles Posted February 24, 2009 Posted February 24, 2009 There are probably worse things that you can do besides pressing them together. I do like your attention to safety. The main issue from chlorate and sulfur comes from impact I do believe. I don't think the clay bulkhead will work very well. It leaves a very limited surface area the smoke mix can burn from. If you are able to comprehend what Ralph said, his advice is reasonably sound. Press a plug of non-sulfur containing mix above the top of the fuel grain. Be forewarned that most of these smoke mixes burn rather slowly. An intermediate layer may not be such a bad idea. It might be needed to prevent the delay from taking too long. I'd suggest something like sulfur-less BP, but there are many options. If the composition layer above the fuel is too thin, it will blow through from the thrust pressure, and you would lose the smoke trail delay.
jacob Posted February 24, 2009 Posted February 24, 2009 Why not just put some smoke mix in a tube and attach it to the side of the rocket? What colored smoke mix(s) did you find that used Perchlorate as the oxidizer?
trag Posted February 25, 2009 Author Posted February 25, 2009 (edited) Press a plug of non-sulfur containing mix above the top of the fuel grain. Be forewarned that most of these smoke mixes burn rather slowly. An intermediate layer may not be such a bad idea. It might be needed to prevent the delay from taking too long. I'd suggest something like sulfur-less BP, but there are many options. If the composition layer above the fuel is too thin, it will blow through from the thrust pressure, and you would lose the smoke trail delay. Hmmm. It sounds like a bit of experimentation is in order. Thank you for the suggestion and the warning about burning through the thin smoke layer before much smoke has been emitted. If I use the smoke mix, I will definitely separate it with a sulfurless layer. Skylighter's safety page seemed quite dire on the subject and I'm accustomed to having the use of all my fingers and both eyes... So I need a thick enough delay layer to prevent burn through. However, a smoke layer's thickness, chosen for the proper burn time, may be too thin to prevent burn through. Hmmm. Again. Sleeter's book recommends a ported plug (is that a passfire?) at the top of the smoke layer and before the ejection charge. I was going to omit it because commercial engines do not use one and it seems a needless complication. But it might be useful to reinforce a thin delay layer and keep it from breaking until it actually burns through at the center. BTW, Mumbles, thank you for clueing me in to the red gum buy over on Passfire. I went ahead and signed up with Jeff G. (and sent the check) for a bag. I may be jumping in with too much feet, considering that I'm just getting started, but it sure seems like quality ingredients are hard to get at affordable prices and it's worth stocking up. Plus I found another fellow to split off 20 lbs to. Edited February 25, 2009 by trag
trag Posted February 25, 2009 Author Posted February 25, 2009 Why not just put some smoke mix in a tube and attach it to the side of the rocket? Model rocketry is fairly stylized. Smoking side tubes isn't really done, nor is it a asthetically attractive option to me. Plus, a standard model rocket has a tube for a standard sized engine. In order to attache smoke tubes I would have to modify every rocket. What colored smoke mix(s) did you find that used Perchlorate as the oxidizer? I'm not 100% sure that I did, as I was just skimming the recipes for oxidizer, but I thought some of the recipes in Passfire's database used perchlorate.
Swede Posted February 25, 2009 Posted February 25, 2009 I think Ralph's idea is best. At your bench, next to your normal fuel mix, have a small cup with the sulfurless compound (do a search for sulfurless BP; there are many recipes.) Arrange the cups in such a way that to get to the chlorate smoke mix, you MUST encounter the sulfur-free BP, reminding you to use it. A very thin layer is all that's needed. As for the smoke mix, with some careful experimentation, you might be able to accelerate the burn speed a bit with a higher % oxidizer, catalysts, or both.
psyco_1322 Posted February 25, 2009 Posted February 25, 2009 Just make a batch of chrysanthemum of mystery and use that as your intermiadte delay. The famous Steve LaDuke uses it quite often and should fit your requirments well. Cut up short sections of your rocket tubing and press in defferent amounts of smoke comp, and time them until you get an amount that fits your time frame.
Miech Posted February 25, 2009 Posted February 25, 2009 Using the smoke mix as loose powder would solve the problem of the low burn rate at least partially. It will still burn slow, but at least ten times faster then when pressed. You'll need to attach it to the rocket in another way than just putting it on top of the fuel grain.
Seymour Posted February 26, 2009 Posted February 26, 2009 While Sulfur in contact with Chlorates is very sensitive, it is the acid that much of sulfur contains which can react with the Chlorate to for Chlorine dioxide, which is where the path to self ignition starts. If the acid is there it could travel through the KNO3/C barrier via osmosis. The chances of this occurring could be reduced by the addition of a base. Perhaps sodium bicarbonate for availabilitys sake, to one or all compositions, if the Sulfur is not known to be acid free. This will be more important in high humidity when osmosis is more likely to occur. Alternatively, Vaseline or another oily/waxy substance could be added to the BP and or prime. This will not be very important if you are not going to be storing them.
Mumbles Posted February 26, 2009 Posted February 26, 2009 That's not a bad suggestion. My instinct tells me that the charcoal would have enough natural carbonates and salts to neutralize what little could possibly start to diffuse, but it would also help to slow the delay if needed.
trag Posted February 26, 2009 Author Posted February 26, 2009 (edited) I think Ralph's idea is best. At your bench, next to your normal fuel mix, have a small cup with the sulfurless compound (do a search for sulfurless BP; there are many recipes.) Arrange the cups in such a way that to get to the chlorate smoke mix, you MUST encounter the sulfur-free BP, reminding you to use it. A very thin layer is all that's needed. As for the smoke mix, with some careful experimentation, you might be able to accelerate the burn speed a bit with a higher % oxidizer, catalysts, or both. Thank you for all the great suggestions everyone. If I replied to each individually, I'd post about six different messages, so I'm sticking all my thoughts in this one reply. Swede's addendum to Ralph's idea sounds like a plan. Adding in the suggestions/warnings in lower posts, perhaps what I will do is use a sulfurless BP cut with 3 - 7% baking soda. This will further slow its burn rate, but that's not a problem for a delay mix anyway. I would like to be a bit more analytical about this as it is very possible that I will store built motors for long periods. Once I've worked out the kinks and gained some experience, I'll most likely build batches of motors using about 1 lb of BP per batch/build (3 - 30 grams propellant/motor). Then those motors will be around until I have a chance to fly them, and weather conditions and life can make that interval quite long some times. Plus I'll want about 30 - 50 motors on hand at any given time to use on good flying days. So regarding analytical. There will be some amount of sulfur (x% by mass) in the BP of the propellant. Is there a way to estimate what percent of that might be involved as acids? Then I could add an amount of baking soda (to my barrier sulferless BP) calculated to neutralize the maximum amount of acid that might be present. Can I test the pH of my sulfur to help with the estimate? IIRC, sulfur is not water soluble, but I guess any acid content would be... So I could stir a measured amount of sulfur with distilled water and then measure the pH to see if any acid dissolved. I'm planning to buy my sulfur here: Sulfur The MSDS they have there claims 100% sulfur. I'm not sure if that's indicative of low/no acid content or not. I guess that amount of acid possibly present could also be modified by some percentage subject to migration as well. Anyone considered this kind of problem before? How does one approach it? Edited February 26, 2009 by trag
psyco_1322 Posted February 26, 2009 Posted February 26, 2009 Does the smoke mix itself not contain a certain percent of carbonate/bicarbonate to reduce burn times anyway? It could very well be put into the delay bp mix to slow it down a bit also. I still don't see the small amount of acid seeping through a good 1/2" - 3/4" of press bp, especially if it was waxed as if it were fuel. Considering this is all relating to sulfur-less bp. Hey, another option, just leave sulfur out of the hole damn rocket and use a sulfur-less fuel.
trag Posted February 26, 2009 Author Posted February 26, 2009 Alternatively, Vaseline or another oily/waxy substance could be added to the BP and or prime. I will be using red gum in the propellant. Probably somewhere between 3% and 8%. Will that have any effect on the acids?
Seymour Posted February 26, 2009 Posted February 26, 2009 (edited) It could perhaps create an osmosis resistant barrier. Will it be added as a powder or will a solvent be added to it too? Using the smoke mix as loose powder would solve the problem of the low burn rate at least partially. It will still burn slow, but at least ten times faster then when pressed. You'll need to attach it to the rocket in another way than just putting it on top of the fuel grain. Alternatively the smoke mix can be granulated. Making different size grains will control the duration of the burnSo regarding analytical. There will be some amount of sulfur (x% by mass) in the BP of the propellant. Is there a way to estimate what percent of that might be involved as acids? Then I could add an amount of baking soda (to my barrier sulferless BP) calculated to neutralize the maximum amount of acid that might be present. The acid formed will be in low quantities. A percent bicarbonate or other base should be fine. As Mumbles said, the charcoal may contain sufficient bases as a major component of the ash content to neutralise the acid. Edited February 26, 2009 by Seymour
trag Posted February 26, 2009 Author Posted February 26, 2009 It could perhaps create an osmosis resistant barrier. Will it be added as a powder or will a solvent be added to it too? I'll add the red gum to the mix as a powder. Then I'll add denatured alcohol to the whole mix as a solvent prior to pressing. I could use acetone instead of alcohol, but the alcohol will evaporate more slowly and presumably give me a longer working time. I don't really mind waiting a couple extra days for the rockets to dry.
firetech Posted March 3, 2009 Posted March 3, 2009 in rockets where i want to use as less space as possible for delay, i will use 2:1 kno3/ sucrose mixture. it creates a very dense white smoke tail and burns extremely slowly. You could do tests with this and put this above the bp to lead to the chlorate mixture.hope this helps
TYRONEEZEKIEL Posted March 30, 2009 Posted March 30, 2009 Just use sulphurless bp ad the fuel. It tends to burn faster anyway. I would imagine that it would have slightly less thrust because of less gas, but that will solve all your problems
firetech Posted April 1, 2009 Posted April 1, 2009 I can't think of the comp at the moment but chrysanthemum of mystery contains no sulfur and could leave a sparky tail.
Mumbles Posted April 1, 2009 Posted April 1, 2009 You might want to give more thought to your posts before making them. Given how slow CoM burns, I highly doubt the rocket would be going anywhere, and would likely be incredibly drossy.
firetech Posted April 1, 2009 Posted April 1, 2009 Mumbles, I should have been more specific..I meant to say that he could use chysanthemum of mystery as a delay comp between the bp and chlorate comps..
Mumbles Posted April 1, 2009 Posted April 1, 2009 Ah, I got it now. Steve LaDuke uses that composition with a few parts titanium (3% I want to say), and it is gorgeous.
xxxjanusxxx Posted April 1, 2009 Posted April 1, 2009 (edited) I think it's very hard to make a smoke delay, that can be seen from that height. It burns very slow, so you can't get enough mixture in the casing for it to be seen. I was thinking of making an insert (sort of fountain with hotglue plug) with loose mixture in it, make sure the venturi is primed well. Place this insert on top of your propellant and press your endplug in the casing. The delay is a bit difficult to make, but perhaps it's possible to lead a fuse on the outside of the casing to the payload. It's just a thought and hopefully useful to you. Edited April 1, 2009 by xxxjanusxxx
firetech Posted April 1, 2009 Posted April 1, 2009 There are some smoke compositions that use only caramelized KNO3/sugar with sodium bicarbonate and an organic powdered dye...youtube has a few examples of this. Here's the most popular:http://www.youtube.com/watch?v=uhTePRt-DKY I've had no experience with this..but its worth a try, and as you can see it produces a lot of smoke.
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