stix Posted August 13, 2016 Posted August 13, 2016 UHHH... do you mean hygroscopic? Sorry, didn't mean to shit in your cornflakes. Damm OM, why didn't I pick up on that!! For the record, my previous comment was made very late in the evening - so no cornflakes in sight, but perhaps my beer had gotten a bit warm after someone pissed in it I've found that 're-melting' my KNSU fuel degrades the performance even to the point that it almost doesn't ignite - when it does, it burns slower. After reading that others experience the complete opposite effect, ie. burns faster, then the reasons for those differences need to be discussed. I'll start with my standard KNSU 65/35 fuel. The KNO3 is ball milled into a fine powder (flour like). Then mixed with pure confectioners sugar (fine powder). Both are then milled together for about a 1/2 hour. The dry ingredients are then melted in an electric frypan @ approx. 185C for the sucrose to melt/decompose. Grains are then cast. The introduction of karo/glucose syrup introduces water. My view is that any retained water will slow the burn rate as it's a natural burn rate inhibitor. What happens when this type of fuel is re-melted? I think that RRM already pointed this out, or similar. The second melt drives off the remaining water and also melts the sucrose more than the first melt and therefore homogenizes the ingredients better than they were - therefore a faster burn rate is observed. Therefore in my view, the fuel was never made 'properly' in the first instance. The introduction of Red Iron Oxide is somewhat controversial. Well if it wasn't before - it's going to be now . Well, perhaps not controversial but its use needs some understanding and discussion. With KNSU+Karo fuel, perhaps RIO smooths out and counteracts the slower burn rate due to the retained water?. In my experience, none of the Sucrose, Glucose/Dextrose, Xylitol, Erythritol, Sorbitol fuels that I've ever made have required the use of RIO in CORE BURNERS. The motors would definately have cato'd if it was used. The only motor I've ever made using RIO was an END BURNER. I used a old burnt out ESTES 'C' motor casing. I stuffed it with melted KNSU+1%RIO and drilled a short 5mm port at the nozzle end. Attached a stick a lit it. I took off so fast that I almost pissed myself laughing I'm not saying that using karo/glucose syrup doesn't work well, because there are many fellow sugar fuel enthusiasts that have documented its success more than I have or likely ever will. However, what I will say with some certainty is that introducing water makes it harder to make a consistent fuel because you never really quite know how much water is actually left. Your methods will need to be much more precise. That's why I dropped the "re-crystalised' method and went to the "dry ingredients" method. This has been my experience. We all have our own methods which is great - repeatability is very important, also castability is right up there. Perhaps it's always going to be a compromise between the two. Anyway, if you've read all this post then you deserve to crack a nice cold beer - I know I will.
kramrocket Posted August 13, 2016 Posted August 13, 2016 "The dry ingredients are then melted in an electric frypan @ approx. 185C for the sucrose to melt/decompose. Grains are then cast." DECOMPOSE !!! I'm having that cold beer...
stix Posted August 13, 2016 Posted August 13, 2016 (edited) Yes indeed Kram, I'd be slamming down a few quick ones. Apparently sucrose does "DECOMPOSE" and not really melt as we know it. I read about this a while ago: http://www.amateurpyro.com/forums/topic/11774-sugar-doesnt-melt-it-decomposes-say-researchers/ Edited August 13, 2016 by stix
Redrocketman Posted August 17, 2016 Author Posted August 17, 2016 I'd love a beer - crap, a bit early.....( 4.05am )! I think on average there is no more than 25% water in light corn syrup. If I'm making my regular 65/33/2 mix, then there should be no more than 0.5% of the total batch weight in water to drive off. Am I right? That amount I would have thought would be driven off after the 1st cooking. Maybe I can keep cooking the initial batch a while longer & gain more?? I may not have said but I do not introduce any water to the mix. Grind kno3, add icing sugar. Dry mix by hand for 10 - 15mins ( ball mill busted... ) Pre heat corn syrup, add dry mix & stir in. RIO has been removed for the simple fact it's not necessary. ( ur rite there Stix ) on the subject of Estes motors, I similarly loaded one with the re-melted stuff, and just drove a framing nail through the nozzle while still soft!! Packed an epoxy delay & BP charge, we'll see how it holds up!! Would be a lot cheaper. The kids cost me a bit in those little things
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