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Motor retention question?

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Missileman

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I have a question about motor retention.
Some time ago my daughter started construction of a 3" Bullpup.
In fact it is almost done.
No thought was given to motor retention.
The 38MM motor tube is flush with the end of the boattail.
There is not much room to do anything.
I had thought of adding a short piece of motor tube and using a Slimline retainer but am afraid a butjoint of the extension won't be strong enough.
Any suggestions?
 

cls

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masking tape.

masking tape will hold a 38mm motor just fine. in fact we've started calling it rocket tape around the house.


just don't put tooooo much on, it's hard to get the motor out. ask me how I know this.


oh yeah, carry a good closet pole to poke the motor out of the MMT. (doesn't work with baffle systems.)
 
A

Austin

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If there is any space between the edge of the boattail and the motor closure ring, you can install threaded inserts to allow you to use a bolt/washer combo for retention. You could also shape a flat piece of metal into a hook on one end, then hook the bottom of the case and screw the strip to the side of the BT, making sure your screw bites into the plywood lower Centering Ring.

Carl
 

Ryan S.

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i did this, witha n already built bird, just screwed two long screws into the the CR and through the screws were washers that were ground on one side so all I needed to do was twist the washer and slightly tighten the screw.

I would just use tape, its easiest, and it works well, I have never had a motor come out while using tape but I have when using a MOtor clip (AT).
 

Missileman

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Thank you all.
I will probably resort to "cringe" friction fit.
You see on this rocket there is no aft CR.
The engine tube O.D. is the same as the I.D. of the aft end of the boattail. Hence there is no room to do anything.
 
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