Old thread but, Quest 4runner has a four engine cluster held in by a washer, nut screwed into threaded rod tailing from aft. Always thought it was genius, never really pondered safety, doh!Although it is slightly more complicated to construct, it is far better from a safety standpoint to attach retainers with screws that thread into the rocket, rather that having them bolt onto a fixed metal stud that projects out of the rocket. Designing a hobby rocket with a spear-like metal projection, even if it is at the aft end, is not the safest of practices.
MK
Very astute observation!The retainers that screw INTO threaded inserts still will have the screw project OUT the rear. I don't see it as a bigger issue than engine hooks that project out the end of the rocket. I'd be much more concerned about metal tipped nose cones at the FRONT of the rocket if it should come down ballistically.
Can be as simple,complex,easy,cheap,heavy, light or expensive as you want it to be. Foil tape is about as cheap as it gets if you want reliability. Although foil tape itself is rather expensive. Think I paid $15 for my last roll?Can you guys show me pictures of your homemade motor retainers? I need ideas.
BTW here's a picture of my homemade engine retention system:
why not? it's cheap and just as effective. Crazy Jim is probably one of the biggest proponents of friction fitting.I hope you don't use masking tape on reloadable HPR motors . . .
Yep! Masking tape for friction fit and aluminum HVAC foil tape for a secure wrap around motor tube and rear closure/thrust ring of motor.I hope you don't use masking tape on reloadable HPR motors . . .
why not? it's cheap and just as effective.
why not? it's cheap and just as effective. Crazy Jim is probably one of the biggest proponents of friction fitting.
https://www.rocketryforum.com/threads/rookie-stupid-question.104748/#post-1191121
I've always used all thread bonded to the motor mount tube. One piece with 3 to 4 inchs of bonded area works on most applications. Sometimes a thin spacer is needed between threads and motor mount tube to allow for aft closure clearance.View attachment 385740 View attachment 385741
One of the best methods since the '70s!!! Lucerne Test Range Approved!
Yep! Masking tape for friction fit and aluminum HVAC foil tape for a secure wrap around motor tube and rear closure/thrust ring of motor.
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