stix Posted June 25, 2016 Share Posted June 25, 2016 http://www.foodnavigator.com/Science/Sugar-doesn-t-melt-it-decomposes-say-researchers This has been around for a while, and I draw attention to those that make r-randy, ie. the "apparent melted" method to be aware. For those that make sugar rockets using pressed powder, this doesn't apply, but still may well be worth reading. I've come up with my own melted/dry pressed hybrid, KNSUSB18: KNO3 62SU 20 (sucrose)SB 18 (sorbitol) In this mix, Sorbitol is the binder. That is, Sorbitol 'melts' at around 100C and sugar at around 180C. Therefore KNO3 and SU powder is "suspended" in the sorbiitol liquid. The results work very well if you can work with a plasticine like substance. Perfect with my method. Back to the question, I'm wondering at what point (temperature) does sugar lose it's mojo?. Decomposition has been witnessed by myself through observation and reality ie. burns like shit if caramelised. With my method the sugar should not be compromised. but I don't know for certain, hense the question. Link to comment Share on other sites More sharing options...
Redrocketman Posted July 15, 2016 Share Posted July 15, 2016 I believe that with your method decomposition would be minimal, due to the fact your only heating to 100deg c ( or not much more I assume ), though some degradation would occur by heating to that temperature. Depending on type of motor I'm making I might dry heat & case bond full grains to make casting easier, or dissolved & boil off for bates grains. Either way, I think the rate at which the mixture is heated is what effects decomposition. The faster the temp it rises to the desired temp, the more pronounced decomposition is. Ie, raise temp slowly. Long & short, it starts losing its omph from the start of heating though at that point the degradation would be negligible. Link to comment Share on other sites More sharing options...
stix Posted July 19, 2016 Author Share Posted July 19, 2016 That composition was developed simply because I was sick of getting burnt fingers ouch!!. Although I've made a few insertable grains, the formula posted above has yet to be tested in an actual motor. The idea was to make a plasticine type fuel, in which I have succeeded. This has all been done before using 'corn/glucose syrup'. I've tried the corn syrup method, but never been satisfied with the result because the 'unknown quantity' is the water in the syrup which affects the burn rate. Link to comment Share on other sites More sharing options...
WSM Posted July 20, 2016 Share Posted July 20, 2016 http://www.foodnavigator.com/Science/Sugar-doesn-t-melt-it-decomposes-say-researchers This has been around for a while, and I draw attention to those that make r-randy, ie. the "apparent melted" method to be aware. For those that make sugar rockets using pressed powder, this doesn't apply, but still may well be worth reading.I've come up with my own melted/dry pressed hybrid, KNSUSB18:KNO3 62SU 20 (sucrose)SB 18 (sorbitol)In this mix, Sorbitol is the binder. That is, Sorbitol 'melts' at around 100C and sugar at around 180C. Therefore KNO3 and SU powder is "suspended" in the sorbiitol liquid. The results work very well if you can work with a plasticine like substance. Perfect with my method.Back to the question, I'm wondering at what point (temperature) does sugar lose it's mojo?. Decomposition has been witnessed by myself through observation and reality ie. burns like shit if caramelised.With my method the sugar should not be compromised. but I don't know for certain, hense the question. Here in the Western US, I've witnessed a fellow make (and fly in an air frame) a grain like you describe, at one of the launches hosted by the rocket club at their site in the Mojave desert. I was impressed by the (un-caramelized) white color of the propellant grain (or bright red color if catalyzed with iron oxide). Have you tried sorbitol and potassium nitrate without sucrose? I'm not sure if that would be viable and wonder if that would work? I'm not the sugar candy sort of rocket guy; the hygroscopic nature of the mix puts me off (even in dry desert heat!). I have once (maybe about thirty years ago) tried a dry pressed KNO3 and sucrose end burner (model rocket sized engine with a small throat) which worked and exhibited an interesting progressive burn. It started slowly but finally got up to flying speed, canted to about 45o, and flew to parts unknown at an increasing pace till out of sight. I'm glad it was so small; it couldn't have gone too far (I didn't repeat the experiment for obvious reasons). WSM Link to comment Share on other sites More sharing options...
stix Posted July 20, 2016 Author Share Posted July 20, 2016 (edited) Thanks WSM. Yeah, I have tried straight KNSB, ie. Potassium Nitrate/Sorbitol. I found the physical strength to be too weak. It wasn't hygroscopic like KNSU. After leaving a few test strands for a few days/weeks the outer surface became crumbly and eventually completely gave way. The addition of powdered confectioners sugar has made the fuel 'stronger' as in brittle strength. The reason doesn't seem to add up, but that's my finding. What I end up with is a nice silky warm pasticine that can easily be formed and doesn't burn your fingers. When cool it can then be re-heated and re-shaped and pressed. I've yet to make an actual motor with the fuel - I have only made the grains to be inserted later. [EDIT] I can assure you that the original formula posted in post #1 was derived from many tests (20+) and hence, not just speculation but actual data. Edited July 20, 2016 by stix Link to comment Share on other sites More sharing options...
WSM Posted July 20, 2016 Share Posted July 20, 2016 (edited) Thanks WSM. Yeah, I have tried straight KNSB, ie. Potassium Nitrate/Sorbitol. I found the physical strength to be too weak.It wasn't hygroscopic like KNSU. After leaving a few test strands for a few days/weeks the outer surface became crumbly and eventually completely gave way. The addition of powdered confectioners sugar has made the fuel 'stronger' as in brittle strength. The reason doesn't seem to add up, but that's my finding.What I end up with is a nice silky warm pasticine that can easily be formed and doesn't burn your fingers. When cool it can then be re-heated and re-shaped and pressed.I've yet to make an actual motor with the fuel - I have only made the grains to be inserted later.[EDIT] I can assure you that the original formula posted in post #1 was derived from many tests (20+) and hence, not just speculation but actual data.Thanks for sharing your hard won formula and experiences. I'm not sure about Oz, but in the States confectioners sugar has about 3% corn starch added. That may or may not play into what you're seeing when you use it. Good luck with your research. It sounds like fun. WSM Edited July 20, 2016 by WSM Link to comment Share on other sites More sharing options...
kramrocket Posted August 14, 2016 Share Posted August 14, 2016 If one has the system and reliable means, powder pressed is best !!! Link to comment Share on other sites More sharing options...
stix Posted August 15, 2016 Author Share Posted August 15, 2016 The main issue with powder pressed is maintaining density with large motors, ie. 50mm (2")+ in diameter. Link to comment Share on other sites More sharing options...
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