Silverturk Posted October 8, 2006 Posted October 8, 2006 Hi, This weekend I tested some different rocket motors. They burned fine, but some of them had a mysterious problem, they burned through the casing! The motor didn't blow up (CATO), but it burned through on the side of the rocket casing, near the nozzle. In one case, it burned through the upper end cap. Why is this happening? Could it be tiny cracks in the case, coming from when i rammed the nozzle and the fuel? Or is the casing bulging out because of the pressure? Oh, I am rolling my own tubes out of craft paper and wood glue.
Mumbles Posted October 8, 2006 Posted October 8, 2006 Well, how thick are your walls? This is more than likely your problem. Another thing you may want to try is using a heavier paper, such as manilla folders. It will make your walls a lot harder too. Also, what size of rockets are you making, and what composition. Another thing to attempt is making making the nozzle angled on the inside. I am assuming you are not using commercial tooling for these. It will guide the gases out the nozzle instead of to the wall-nozzle meeting.
itwasntme Posted October 8, 2006 Posted October 8, 2006 Press them, i bet it wont happen anymore. That would make it worse, unless he is using a PVC support thing. Ozzy, I really think you're mentally retarded, are you autistic? What are the wall sizes measure them with a very good ruler and tell us. Try a PVC support. It's a just a PVC pipe the same ID as the Id of your tubes with a cut down the side using hose clamps to hole it together.
Mephistos Minion Posted October 9, 2006 Posted October 9, 2006 If you are using home made tooling, whack your hollow rammer into a drill chuck or a lathe and take a file to it, round it down so that it will direct the gasses. You can do this to your spindle to, so that your nozzel looks like the picture, what this does, is gives the nozzel alot of area of bite on the tube, but the thinner hole means less resistance on the gasses. Sorry about the shithouse diagram, took me 2 minutes. http://img.photobucket.com/albums/v466/mephistosminion/Shithousediagram.jpg
rocket Posted October 9, 2006 Posted October 9, 2006 I’ve have had this problem as well, the problem was that my tubes had air pockets in them and that they where to thin. Try making you tubes thicker that’s if you make them yourself. I heard that is you try to dry you tube to fast you end up with the air pockets in your tubes.
Silverturk Posted October 9, 2006 Author Posted October 9, 2006 Thank you for all the replies! The walls are about 4 - 5 mm thick. It's a 1/2" ID black powder rocket. And, as a lot of you thought, I don't use any kind of rocket tooling (even though I got a friend that will make it for me very soon), so I am drilling out the nozzle hole and core. I will try to see if my problem is what rocket is describing, since i have been drying my tubes in the oven for 6 - 8h in 80-90C. Don't know if thats too fast, but after that, they are completely dry. I just measured the weight of 1 m^2 of my paper, and it weight about 135 grams. Don't know if that's a lot or less, but anyway, my tubes becomes really hard. I can easily stand on them without they are deforming. If I drop one of tme on the floor, you can hear the nice, bright sound, because its (almost) completely solid. At least I havn't discovered any air pockets when I split them.
Mephistos Minion Posted October 10, 2006 Posted October 10, 2006 Your paper is about 85lb in the silly american system. No wonder it makes nice solid tubes
Silverturk Posted October 10, 2006 Author Posted October 10, 2006 So my paper is thicker. Does that mean that i can make better tubes? Edit: Today I tried some new rocket casings. I made one lika my precios ones, and one "new" where I left abut 10 cm in the inner parts of the casing un-glued. I thought this would prevent the casing from getting little tiny cracks when ramming, or that the very tiny air gaps would resist the heat of the flame... or something. I don't know which theory that is most accurate, but anyway, the casing didn't get any burn-throughs now. I tried a motor with a case rolled exactly like the previous I made at the same time. It didn't get a burn through, but in some parts of the casing, it had little tiny spots where the hot gasses almost burned through.
allrocketspsl Posted October 17, 2011 Posted October 17, 2011 I roll my own tubes and have gotten three burns from the same tube,one second burn on my one pounder and the walls have hardly any burn marks!Cored of course
Mumbles Posted October 17, 2011 Posted October 17, 2011 Did you really have to bring up a post from 5 years ago to add essentially nothing to it?
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