Nozzle question

geof said:

I am trying a new method for motor retention. In the photo are the parts. Regarding my question, the important parts are the 2 Aerotech 38mm reload aft closures on the left (old and new style), and the silver disc. The disk fits over the aft closure, and the nozzle fits through the hole in the disk.

But that's the question: will the nozzle fit through the hole? The diameter of the disk hole is larger than the diameter of the hole in either aft closure. Therefore, the only way that the nozzle wouldn't fit would be if the nozzle flared outward after it passes through the aft closure, downward (away from the motor). I have never seen a motor like that: the nozzle has always come straight out from the aft closure like a cylinder.

The silver metal disk is really a pain in the *** to grind, so I would like to stop. But if any nozzles flare outward, I would need to grind the hole bigger. Has anyone ever seen a 38mm motor nozzle that flares outward? In fact, now that I think about it, this would seem impossible because you would never be able to get the nozzle through the aft closure from either direction. But maybe there's something surprising that I don't know about. Can anyone confirm that my sense of things is true for all 38mm motors?

Thanks,

Geof
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ClayD said:

if the nozzle was wider than the port in the closure how could you install the nozzle?

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The only problem, is that if the nozzle is shorter and the exhaust gets sucked against the disk, it could melt your retention.

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Make the hole in your retention plate 1.45" diameter to play it safe, in case you ever end up using a CTI motor with its recessed nozzle.

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geof said:

[YOUTUBE][/YOUTUBE]

That's what I (eventually) realized, too. Thanks.



I'm safe there, thanks.



Thanks. I'll check that to be sure.

I think this question is fully resolved. Thanks for your help, folks.

[I may try to adapt my retainer so that it would allow a 29mm motor in the rocket, but I think this won't be possible because my motor adapter causes the motor casing to sit further aftward, which means the threads on my device would need to extend beyond the real motor tube, causing a melting concern when a 38mm motor is used. I'm just happy to move beyond my standard T-nuts + clips method, however!]

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ClayD said:

its a neat design! you should post some installed pictures when complete.

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