Aft Closure as Half Of Motor Retention?

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Well-Known Member
Nov 27, 2017
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Eugene, OR
Has anybody considered an aft closure that's threaded (outside thread) on the normally knurled portion as a possible interlocking portion to use with a threaded (inside thread) motor retainer? What I'm envisioning is a motor that could essentially be screwed into the rocket. Your input appreciated.


Paul B.

I see no issues with attaching it that way, except it becomes modified hardware and can't be considered for a non-research launch (I don't think). Forces on the larger diameter from thrust are in remarkably similar locations to normal. Need to make sure the thread can withstand the maximum thrust without yielding.
I've seen the flanged 38/54 closures, but if I'm understanding OP correctly this would be a standard aft with threading in place of knurled thrust ring.

Ah, gotcha. I'd possibly be concerned with the aft closure unscrewing from the case when unscrewing from the airframe, leaving the case in the motor tube.

I think I'll just stick to Aeropacks, clips, and even a few wraps of masking tape over the motor tube-to aft closure gap.
I jumped to threaded fore & aft both, possibly with grub screws.

For instance, a threaded tapped plugged forward together with a tailcone aft would be a pretty slick zero-bulkhead recovery tether.

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