boule Posted August 31, 2013 Posted August 31, 2013 OK, quick question wonderin whether my chemistry is completely off. We use sodium and potassium salicylate for whistle mix. Both of them are, if you don't come accross a cheap bulk buy, quite expensive.The salicylate derivative that is available commercially in bulk is usually ASS (Aspirin) for vet use. It is not a metal salt but still posesses the typical benzoic ring which is responsible for the rather energetic burn and has the acetyl group added.Now, I was wondering whether the extra group has a lot of influence on burn characteristics since it is dragging the electron bonds a little bit around or if I can use ASS as a rocket fuel with perc. Thx for the reply!
nater Posted September 1, 2013 Posted September 1, 2013 The abbreviation for aspirin is ASA as in acetylsalicylic acid. The sodium salicylate that we use for rockets has been used as a pain reliever in the past, it is too harsh on the stomach. Currently aspirin is modifed a different way and making it is a common high school chemistry project. I would also think that the starch used to bind tablets would create problems for rocket fuel. If you want to make cheap whistle, look into benzoates. As a food preservative, you might find a cheap source. I just got 50 lbs of potassium benzoate for $26 from one of our fine vendors. ( he's out now)
boule Posted September 1, 2013 Author Posted September 1, 2013 (edited) Nater, I am not talking about getting Aspirin tablets but rather the bulk substance with a 99% purity, so no worries about having starch or any other binder interfering... and it is still bad enough on your stomach that you need to administer a PPI with it if someone takes it for more than a few days. Knowing about Benzoates (and yeah, missed out on PGI and that vendor) does not really answer my question. If my aim is just to get something cheap, I can also use sorbate just as well as benzoate but both do not have the same characteristics as salicylate whistles. So the question remains:Due to the chemical similarity, ASS might be suitable as a whistle fuel... does it work or not? Edited September 1, 2013 by boule
FlaMtnBkr Posted September 1, 2013 Posted September 1, 2013 There have been some pretty sensitive chemicals used in whistle fuel over the last 50 years that are no longer used because they are dangerous. Sometimes a similarity between chemicals is just that. I'm sure if something as inert as aspirin worked it would be in wide use. There is lots of experimentation in amateur pyro so I'm sure it has been tried many times in the past and it just doesn't work. I have also never read about sorbate working as a whistle fuel? Sodium saly can be had for about ten bucks per pound in an air milled state. Is not that expensive unless you are planning on cranking out a lot of 6 lb motors. Benzoates are even quite a bit cheaper and that isn't even in bulk quantities. I would stick with the tried and true fuels and splurge for the air milled which should only be a couple bucks more per pound. But it will be much easier to get a good loud and powerful whistle fuel than trying to mill it fine enough yourself. In my experience, getting the whistle fuel small enough in possible size is the key to good whistle.
Mumbles Posted September 1, 2013 Posted September 1, 2013 It never hurts to try out ASA for whistles. It's cheap enough to warrant some experimentation if you can't easily get some of the more conventional fuels. The biggest difference is of course aspirin is free acid, while the salts are more typically used. You might want to also try making sodium or potassium asprinate as a possibility. Sorbates sort of work. They've been recently rediscovered and worked with on the UKPS forum. They've been relatively accurately described as flatulent whistles. They don't make as much noise as benzoates or salicylates, and the tone is more reminiscent of passing bodily gas. It's hard to tell how well it'll work. Out of curiousity, what property of salicyliates are you after that benzoates lack?
Arthur Posted September 2, 2013 Posted September 2, 2013 Pyro progresses by experimentation! However be careful anything like whistle is sensitive and powerful. Work out a safe system of work and sort out the protection -shields and clothes. and work small for a start. Commercial asprin tablets here are 98% asprin and this can be dissolved and recrystalised from alcohol.. BUT in pharmacy form ASA is terribly expensive.
boule Posted September 2, 2013 Author Posted September 2, 2013 Sorbates sort of work. They've been recently rediscovered and worked with on the UKPS forum. They've been relatively accurately described as flatulent whistles. They don't make as much noise as benzoates or salicylates, and the tone is more reminiscent of passing bodily gas.Ah yes, the infamous farting rockets. If you do very small increments of BP vs sorbate whistle, it gets the typical "pressed" effect and really sounds like the rocket is making its way to the sky by fecal propulsion. It's hard to tell how well it'll work. Out of curiousity, what property of salicyliates are you after that benzoates lack?Let's just say close to 10lb expired for free coming my way at the end of the year that initially started me thinking about chemical similarities and the possible use as a fuel. But even then, if you look at vet supplies, you can get the ASS for a lower price than benzoate (at least in 25lb lots). Additionally, the sound of salicylate/iron is somewhat more pleasing than benzoate/copper and it is supposed to give a higher thrust.Let's just say I'll give it a try and will attempt to get a video, OK?
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