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  1. #1
    Join Date
    27th November 2017
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    41

    Aft Closure as Half Of Motor Retention?

    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.

    Thanks

    Paul B.

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  2. #2
    Join Date
    10th July 2007
    Location
    Melbourne, Australia
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    1,468
    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.

    TRA 13430, Level 3

    "Everybody's simulation model is guilty until proven innocent" (Thomas H. Lawrence 1994)

  3. #3
    Join Date
    15th May 2016
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    2,351
    Deleted
    Last edited by DavidMcCann; 19th December 2017 at 02:05 PM.
    David McCann
    Dave's Rockets | My Flights
    URRG |URRF 4| Level 2 | TRA# 14210

  4. #4
    Join Date
    30th January 2016
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    Makes sense to me, haven't heard of any such thing.

  5. #5
    Join Date
    21st January 2009
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    Manitowoc, WI
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    Rocketman used to make what you describe; I've only seen them out in the wild once or twice.

    TonyA referenced them here: http://www.rocketryforum.com/showthr...42#post1695142

    -Eric-
    Eric Cayemberg
    TRA 7783 L3
    TAP

  6. #6
    Join Date
    30th January 2016
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    Quote Originally Posted by ECayemberg View Post
    Rocketman used to make what you describe; I've only seen them out in the wild once or twice.

    TonyA referenced them here: http://www.rocketryforum.com/showthr...42#post1695142

    -Eric-
    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.

  7. #7
    Join Date
    21st January 2009
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    2,280
    Quote Originally Posted by dhbarr View Post
    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.
    Eric Cayemberg
    TRA 7783 L3
    TAP

  8. #8
    Join Date
    30th January 2016
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    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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