Can normal CTI reloads that have ejection charges, be modified for use in PML rockets that use CPR based ejection systems like the 4 inch AMMRAM kit?
I do exactly the same thing, although I omit the grease. The disc covering the bp can sometimes be hard to remove since it's a bit slippery but the point of an exacto blade makes it easy to grab. Save the bp in a film can or other small container for future use.I do it all the time. I just remove the paper disk and dump the powder (sometimes takes some scraping to get it all). Then I squirt a blob a grease in the powder well, fill the rest with dog barf and top it off with a strip of masking tape.
Since there can occasionally be an early burn-through of the ejection grain, I pot the charge well with epoxy. Oh yes, and I put in a penny. It's kind of difficult to blow that out.
And if it's a 54mm motor, be sure to glue in the forward closure. That'll save a rocket at some point too.
Jim
Is the penny really needed? I've only used their smaller motors, but epoxy alone has worked well so far for me. Ya know...cuz pennies are expensive. :wink:Since there can occasionally be an early burn-through of the ejection grain, I pot the charge well with epoxy. Oh yes, and I put in a penny. It's kind of difficult to blow that out.
Is the penny really needed? I've only used their smaller motors, but epoxy alone has worked well so far for me. Ya know...cuz pennies are expensive. :wink:
I suspect that epoxy alone would be fine. But pennies just fit so nice. This has to be the literal definition of cheap insurance.
But seriously, don't forget to glue in the forward closures in CTI 54mm motors. Use a nice red epoxy fillet, per the pic. More likely to save you a rocket than the penny.
Jim
Jim, What's the issue with CTI 54 mm motors? Do you do this for all 54 mm CTI motors or just for the ones that you remove the ejection charge from?
Jim, What's the issue with CTI 54 mm motors? Do you do this for all 54 mm CTI motors or just for the ones that you remove the ejection charge from?
...Use a nice red epoxy fillet, per the pic...
Jim, this is the first time i've heard of this. Are you using a special epoxy ("red"?) that I've not heard of, or are you just highlighting the fillet in your diagram?
It looks like the epoxy is bonding the grain, the liner and the forward closure. Seems like that would burn up pretty fast. is there any data on how much more pressure the closure can hold with this technique?
Jim,
Would you please describe how best to create this internal Pro54 closure fillet? Do you apply a bead of epoxy to the aft edge of the delay, insert into the closure, and then stand it up to allow the epoxy to adhere to the case insulator? Do you lightly abrade the insulator , and/or the delay end for improved epoxy adherence?
Thanks...
Thank you! BTW, do you wait for the epoxy to cure before inserting the propellant grains, or do you insert them (as would be done when normally building the motor) while the epoxy is still curing?
Ok. As I recall, the 3 Pro54s I've used (K2045, K650, & I150) were not glued-in. Perhaps that is not the case for larger Pro54s. Nonetheless, it's nice to get your input and experience on this - Thank you.It seems to me like the lower closure it typically already glued in. I don't know if that is always the case, but it has been on all of the motors I have recently assembled. Therefore, the grains have to be installed at the point where you glue in the forward closure. I'm not sure it matters if the glue is in contact with the grains or not.
Jim
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