3/8" lifting eye?

I have a pretty extensive amount of hardware pieces like these forged eye nuts and eye bolts I keep around.

And, they’re good quality! I should ask this elsewhre, but how do you keep forward closures from unscrewing after main deploy with closed, forged eyebots? Duct tape? I know, that most reloads of highest power (M and above) put tension on the threads–at least, in my limited experience, and that’s what I’m counting on. Though my next flight will use a Cesaroni reload (M1400) in an AT motor casing (75/6400). Uneasy about that, ’cause I’ve never tried it. Any suggestions, or words of caution?

Thanks, Doug. I’m using U-bolts on my next rocket, for no other reason than I trust them to work. 😉 You need any MBA’s with an English degree who’s always loved, studied, and lived science down there in NM? 😉

Doug, I would have to disagree. Ive never seen this be an issue. UNLESS the flyer didn’t prep it right, But thats not a failure of the method but a failure in doing it right. ALMOST every flight ive flown in 38/54/75/98mm sized motors has used nothing but eyebolt in the forward closure of the motor case to tie the harness to on the booster end. I wont tie my harness to anything but. I use a good nut underneath the eyebolt to lock it in place it NEVER goes anywhere. Thats better then 100 flights and never a problem. To each his own. But I cant see an issue if its done right. I know guys with lots of experience Like JW and James and Tony A and I could list more that do it the same way. Some of them have pushed well past the 30K mark. Yet never an issue. I cant say ive seen any data to support it as a problem. Again unless its users error.. But i see that happen on all sorts of stuff. Be it electronics, motor building, ect….

I like the eye nut concept because it puts the load straight into the threaded rod, which is the only thing typically holding the ends of the av bay together. Otherwise, the offset of the u-bolt from the threaded rod(s) means that the bulkhead has to resist the torque from the harness pulling one way and the threaded rod pulling the other. Without that torque, then the bulkhead can be made much lighter because it’s only there to seal off the av bay and take in-plane loads to keep the rod centered. You could even do it with something like a fiberglass/balsa sandwich.

Conway mentioned the key to eliminating the unscrewing problem: the locking nut. If you have a 1/4″ nut backed up against the eyenut with a wrench, consider how much torque would be required to back those away from each other. Way more torque that would be possible to impart with harness attached to the eyenut even in the worst-case windup of the shock cord.

Now, if someone can just find a #6 (as in, less than 1/4″) eyenut for me, for my itty-bitty av-bay, I’ll be all set. What I have been doing instead is using a #6 wingnut, then a washer, then another wingnut to serve the eyenut function. The washer closes off the opening without crushing the loop of shock cord that goes in there.

More questions, diving into this as the noob: Has anyone ever seen a front closure unthread from the casing due to recovery harness attachment? It’s pretty straightforward to put a jamnut between the eyebolt and closure, but what about the closure itself?

And then, on the bay, if you have multiple rods with eyenuts, how do you do the multiple attachment with your harness? Or do you just attach to one?

My next build will be zipperless with room for an “all motor” booster section, so I’m still debating the attachment. With the long motor, it’s obvious to use the eyebolt in closure. But with the short motors, you’re back to a regular zipper-prone configuration. Ideas?

Ken