Quote:
Originally Posted by ghrocketman
I never tried reloading 13mm cases with Sugar-propellant. The walls seem too thin to me.
I have reloaded Estes/Centuri 18mm and 24mm cases as well as FSI 21mm and 27mm cases. Have never tried to reload the fairly 'new' Estes 29mm cases, but see no reason why it would not work.
When I have used them, I pour the propellant around a nozzle-diameter core rod about 2/3 the depth of the total propellant that allows a bit of end-burn at the top of the grain, which allows staging to an upper motor.
I have never reloaded them more than once as it burns away a bit of the casing. The nozzles would be in good enough shape to allow more firings though.
I have also used Epoxy mixed with KNO3 or KCLO4 for a cold-pourable propellant. That is a bit more energetic than sugar-propellant but a lot more costly.
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Thank you for that information--it's good to know. As I was reading it, it occurred to me that it might be possible to "preserve" the cases--and maybe the nozzles, too--by first coating the inside surfaces of spent motor cases with some kind of flame-resistant liquid or resin. Something like waterglass (see:
www.google.com/#q=waterglass&* ), an aqueous solution of sodium silicate, would penetrate the charred inner walls (and maybe the inner nozzle surfaces) of a spent motor case and protect them (it's often used for that purpose on rolled jet pipes [made of paper, card stock, or very thin sheet balsa] in Jetex, Jet-X, and Rapier powered F/F [Free-Flight] model jets). It and/or some other agent(s) could be re-applied inside the motor cases as necessary. Also:
Given tbzep's positive results with re-loading 13 mm mini motor cases, such "preservation-preparation" before every so many re-loads might enable even these thin-walled little motors to last indefinitely. If so, it would certainly make the batch production of sugar motors of the type in Teleflite Corporation's "The Incredible Five Cent Sugar Rocket" booklet (they're roughly 13 mm mini motor-size, see:
https://murdercube.com/files/Electr...PPR_Zine_91.pdf and
http://www.google.com/#q=the+incred...ar+rocket+pdf&* ) simpler, easier, quicker, and cheaper (after a number of motor case reuses), because the steps involved in making their gummed-paper motor cases and their putty nozzles (which are cylindrical-bore and less efficient, being formed using nails) could be omitted.