Attaching a coupler...

I've become a real fan of the zipperless bulkhead assembly for recovery, and it brings up a real question as I build this Sentinel. I'm hoping to attach the coupler/bulkhead assembly to the aft body tube so that somewhere down the road I can remove the entire thing to modify this rocket for dual deployment.

I really get the heebie-jeebies at the thought of doing it with rivets or something of the sort because with the zipperless design, the bulkhead goes to the front of the coupler and has to hold up to ejection gases passing through the vent holes in the bulkhead. I would think that this could cause problems with the holes enlarging even in a reinforced tube. Any thoughts?

I have done something similar with small screws. I used 4 of them and reinforced the holes with thin CA.

Mike at Binder Design recommended blind T-nuts, which I kinda like. Is there such a thing as a blind T-nut that could be epoxied into the inside of a coupler where the threaded part only goes up about 1/4"? If so, where can I find such a creature? All the places I've found blind T-nuts seem more interested in putting the spikes there than offering short clearance.

Try McMaster Carr at: https://www.mcmaster.com/

They have just about every possible part on the surface of the earth in stock. Their listings of T-nuts include the overall length of the nut so you should be able to select the one you need.

OBTW if you epoxy the nut to the bulkhead or centering ring you can mash down the tits on the nut so they won't go through the plywood. They are only there to prevent the blind nut from turning in the hole when you apply torque to the screw/bolt etc.

Ken

Kermie,

I take a grinding bit on my Dremel and grind those spikes off. put the t-nuts in, fill the threads with grease and epoxy around them. works like a champ!