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Model Forum / General / Rockets / January 2006moonburner port size
Is there a recommended size for the port (core) in a moonburner? What ration of port diameter to propellant diameter would give the most neutral burn? (I am using the term moonburner to indicate a single offset port grain with the edge of the port touching the edge of the propellant. Not a c-slot). Also, a more general and related question - if I wanted to design a long-burn 54mm EX motor for a saucer with a 6 - 8 second burn time, in the 1000 NS range, what grain geometry would you recommend? The main requirement is that the case not melt through! I have been trying to think of ideas for an end burner with a very fast propellant, but I just don't think it will work. I'd need so much insulation at the aft end (reducing the diameter of the exposed aft end, even with a slot or small core for a spike) that the initial thrust wouldn't be high enough to lift the saucer+motor. I think I'm going to have to go with a moonburner or D-slot. Thanks. -- David Try using AN type propellants with a regular Bates grain configuration... JD > Is there a recommended size for the port (core) in a moonburner? What > ration of port diameter to propellant diameter would give the most neutral [quoted text clipped - 16 lines] > > -- David Hi, David- To reiterate what JD says-propellant TYPE will have a direct bearing on which grain geometry you use. As for your first question, I'm really not that familiar with anthing but a typical Bates grain(helps keep the math a little easier, ya know), but a good place to ask might be here: http://www.newtons3rdrocketry.com/forums/ These guys seem to genuinely welcome EX inquiries, and I've personally had questions answered just by browsing old posts. And, like JD said regarding the saucer, AN would probably be the best route, just make sure your casing liner is up to the job! Good luck, and keep us posted! Bob 352 > Is there a recommended size for the port (core) in a moonburner? What > ration of port diameter to propellant diameter would give the most neutral > burn? (I am using the term moonburner to indicate a single offset port > grain with the edge of the port touching the edge of the propellant. Not a > c-slot). 25-33% D Tech Jerry > Also, a more general and related question - if I wanted to design a > long-burn 54mm EX motor for a saucer with a 6 - 8 second burn time, in the [quoted text clipped - 9 lines] > > -- David  SignatureJerry Irvine, Box 1242, Claremont, California 91711 USA Opinion, the whole thing. <mail to:01rocket@gte.net> Please bring GROWTH back to consumer rocketry. Produce then publish. http://www.usrockets.com >Is there a recommended size for the port (core) in a moonburner? What >ration of port diameter to propellant diameter would give the most neutral [quoted text clipped - 15 lines] > >-- David The are many variables to predicting exact performance. Burnsim (www.burnsim.com) should help. Open apology to Jerry- I didn't intentionally mean to slight your expertise- I just know how some people regard EX/Amateur subject matter in this particular forum. (...if you know what I mean) Bob 352 > Open apology to Jerry- I didn't intentionally mean to slight your > expertise- I just know how some people regard EX/Amateur subject matter > in this particular forum. (...if you know what I mean) > Bob 352 Bob 352 I read nothing you posted in this thread as a "slight of expertise", requiring an apology to anyone, including Jerry; unless you consider Jerry's short posting, without any explanation, so complete as to be the last word and end all response. (:-) BTW, Your added comments on to JD's response added significantly to answering David's question. Also, no slight intended to Jerry, just stating the obvious fact, when reading the content of the visible postings for this thread. Fred > Jerry's short posting, without any explanation, so complete as to be the > last word and end all response. Correct. SignatureJerry Irvine, Box 1242, Claremont, California 91711 USA Opinion, the whole thing. <mail to:01rocket@gte.net> Please bring GROWTH back to consumer rocketry. Produce then publish. http://www.usrockets.com > > I read nothing you posted in this thread as a "slight of expertise", > > requiring an apology to anyone, including Jerry; unless you consider [quoted text clipped - 5 lines] > -- > Jerry Correct my a$$. BTW, did you just get out, haven't seen you around much on RMR?? (:-) > Open apology to Jerry- I didn't intentionally mean to slight your > expertise- I just know how some people regard EX/Amateur subject matter > in this particular forum. (...if you know what I mean) > Bob 352 I do. They should get over it. SignatureJerry Irvine, Box 1242, Claremont, California 91711 USA Opinion, the whole thing. <mail to:01rocket@gte.net> Please bring GROWTH back to consumer rocketry. Produce then publish. http://www.usrockets.com |
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