Quick link weight rating question

[noffie79]

I think I've seen on here that you want a quick link with a rating of ~50x the weight of the rocket, is that correct?

 

[ChrisAttebery]

I've seen 100x thrown around. That's typically what I use.

 

[noffie79]

Ok. Well, I used a 220lb quick link in a 36oz rocket. Hindsight being what it is, I was hoping that would be enough. My harness has sewn ends and I had to use a quick link to eye bolt on the MM. The ~600lb link I have was a bit too big. Even going with the 100x rule, I should be in good shape. Agreed?

 

[burkefj]

I think you will be fine. It all depends on what you think your max recovery force will be, and what the other components of the recovery system are. I use a 220 pound link in my 5-6 pound foam structured large rockets, but they use altimeter ejection and recovery forces are small, if I ever did get a 40G recovery force on them, something else would have failed before the link...If your sewn end loops are large enough you can always loop your harness through the eye bold and feed it it through it's own loop and get rid of the quick link altogether.

Frank

 

[Winston]

Ok. Well, I used a 220lb quick link in a 36oz rocket. Hindsight being what it is, I was hoping that would be enough. My harness has sewn ends and I had to use a quick link to eye bolt on the MM. The ~600lb link I have was a bit too big. Even going with the 100x rule, I should be in good shape. Agreed?

What is the rating of the attachment point of your shock cord?

 

[noffie79]

What is the rating of the attachment point of your shock cord?

That I do not know...

 

[Winston]

That I do not know...

As a guess, do you think it would handle 220 pounds?

 

[noffie79]

As a guess, do you think it would handle 220 pounds?

Oh yeah. It's tubular nylon with about 3 inches of stitching

 

[Winston]

Oh yeah. It's tubular nylon with about 3 inches of stitching

I was referring to its attachment point. How is that anchored to the rocket? If you could somehow suspend 220 pounds from it, do you think the attachment point would hold?

 

[noffie79]

It's attached to an eye bolt mounted to the motor mount. Per Madcow instructions. Motor mount is epoxied in place.

 

[Tonimus]

What he's getting at, is there is no point in a 1/2 ton quick link if the anchor point can't handle it. Secondly, when a parachute is deploys, maximum shock isn't going to be the whole weight of the rocket, but just the component being shocked. In most of my rockets, the nose piece is the heavier, and that is what I size my quick link for. I personally use a 25-50x factor for most of my rockets, as a shock load of that much would rip the mount out anyway.

 

[noffie79]

What he's getting at, is there is no point in a 1/2 ton quick link if the anchor point can't handle it. Secondly, when a parachute is deploys, maximum shock isn't going to be the whole weight of the rocket, but just the component being shocked. In most of my rockets, the nose piece is the heavier, and that is what I size my quick link for. I personally use a 25-50x factor for most of my rockets, as a shock load of that much would rip the mount out anyway.

I never looked at it that way, that the maximum shock is just the component being shocked. I've always looked at it as the weight of the whole rocket. Since that's the case, my 220lb quick link will be more than enough. Thank you guys for the help.