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moonburner 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

Reply to
David
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Try using AN type propellants with a regular Bates grain configuration...

JD

Reply to
JDcluster

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:

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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

Reply to
bob352

25-33% D

Tech Jerry

Reply to
Jerry Irvine

The are many variables to predicting exact performance. Burnsim

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should help.

Reply to
Phil Stein

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

Reply to
bob352

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

Reply to
W. E. Fred Wallace

I do.

They should get over it.

Reply to
Jerry Irvine

Correct.

Reply to
Jerry Irvine

Correct my a$$. BTW, did you just get out, haven't seen you around much on RMR?? (:-)

Reply to
W. E. Fred Wallace

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