taiwanluthiers Posted July 10, 2012 Posted July 10, 2012 I tried to put some random stars and stuff at the end of the rocket, drilled a hole at the clay plug but when the rocket hit apogee, nothing. I was just wondering what if I just omitted a clay plug next time so the propellant will ignite whatever comes after? Video:
nater Posted July 10, 2012 Posted July 10, 2012 (edited) Did you stick anything in the hole to pass fire? Loose fuel, a piece of black match, paper firecracker fuse? When I have used a bulkhead, I drilled a hole through it, stuck 2 pieces of paper fuse in the hole, then covered the top of the bulkhead with some loose BP. After that, whatever kind of heading you want. Of course, you don't need a clay bulkhead on a BP motor either. As long as you have enough comp pressed above the spindle, it should hold pressure fine. I have been pressing 2 increments of fuel above the spindle and no clay bulkhead with good results. Edited July 10, 2012 by nater
taiwanluthiers Posted July 10, 2012 Author Posted July 10, 2012 I didn't, but next time I have stuck a piece of paper firecracker fuse in the hole. I don't know if blackmatch works because ones I made had problems with hang fire.
pyrokid Posted July 10, 2012 Posted July 10, 2012 In my limited experiences with rockets, I have found that a double bulkhead eliminates blowthroughs completely. In my one pound rockets, I add maybe a half inch of clay, and then I add durham's water putty until it is flush with the top of the tube. This makes drilling a passfire much less of a headache. Dagabu (A member here), advocates simply pressing extra delay. I have never tried that, but the one blowthrough that I have had, I simply rammed clay on top of my delay. It looked like some kind of warped mine when it blew up. As for ignition issues, I'd put something in the passfire to ensure that fire makes it to the payload.
Blackthumb Posted July 10, 2012 Posted July 10, 2012 I USE A PIECE OF PAPER FUSE...THIN GREY...INTO THE PASSFIRE HOLE..(DRILLED TO THE SIDE OF THE TUBE)...THEN SOME COMP AND THEN THE "HEADER". Nater has it correct...no blow outs...
dagabu Posted July 10, 2012 Posted July 10, 2012 In my limited experiences with rockets, I have found that a double bulkhead eliminates blowthroughs completely. In my one pound rockets, I add maybe a half inch of clay, and then I add durham's water putty until it is flush with the top of the tube. This makes drilling a passfire much less of a headache. Dagabu (A member here), advocates simply pressing extra delay. I have never tried that, but the one blowthrough that I have had, I simply rammed clay on top of my delay. It looked like some kind of warped mine when it blew up. As for ignition issues, I'd put something in the passfire to ensure that fire makes it to the payload. True, I use a fast burning comp (BP) with some Ti added for a tail for my work horse rockets and W 39-J for longer duration and prettier tails. I have found that 1.5 times the ID for a delay bulkhead will hold almost any fuel grain and with really hot whistle, 2 ID are just not enough whistle for a good long burn so I fill the tube all the way up. I no longer use any clay in my bulkheads, the timing was always off and hang fires were common. I USE A PIECE OF PAPER FUSE...THIN GREY...INTO THE PASSFIRE HOLE..(DRILLED TO THE SIDE OF THE TUBE)...THEN SOME COMP AND THEN THE "HEADER". Nater has it correct...no blow outs... I use this: http://www.skylighter.com/images/web_pictures/gn1205.jpg It is fast paper fuse, made with pot perc and has three strands. It is wicked fast and very hot.
taiwanluthiers Posted July 10, 2012 Author Posted July 10, 2012 That's the only fuse I can buy in Taiwan... have about 20 feet of it and not much I can do with them because they burned too fast. I use them like quickmatch because it burns as fast as quickmatch.
dagabu Posted July 10, 2012 Posted July 10, 2012 That's the only fuse I can buy in Taiwan... have about 20 feet of it and not much I can do with them because they burned too fast. I use them like quickmatch because it burns as fast as quickmatch. I actually have used it a lot in crossettes to fuse the shot as well and it works better then most BM, just strip off the paper and use one strand in the shot hole all the way down and fill the cavity with whistle. -dag
dan999ification Posted July 11, 2012 Posted July 11, 2012 i use no bulkhead, the headers have a 1/4 inch passfire tube with 3-5 strands of bm where a time fuse would be on a mortar shot shell, the bm touches the fuel grain and goes into the shell centre, once it takes fire [and it will] there is no stopping it providing you havn't crushed or restricted the passfire in anyway. dan.
Col Posted July 24, 2012 Posted July 24, 2012 I dont use a bukhead either, 2 strands of homemade bm using exactly the same method as Dan. 100% reliable thus far.
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