I know I'm not supposed to use a carabiner, but...

[BDB]

...I hate trying to loosen the cruddy quick link that is mounted to the eyebolt on the forward centering ring of my 4" rocket. I can fit my arm down the booster tube, but it takes 10 minutes and a lot of swear words to get the sucker loose every time I want to do some harness maintenance.

I know that crappy aluminum caribiners can result in this (image from this thread):


But has anyone used a locking carabiner like this one from REI:

 

[rharshberger]

...I hate trying to loosen the cruddy quick link that is mounted to the eyebolt on the forward centering ring of my 4" rocket. I can fit my arm down the booster tube, but it takes 10 minutes and a lot of swear words to get the sucker loose every time I want to do some harness maintenance.

I know that crappy aluminum caribiners can result in this (image from this thread):
View attachment 305928

But has anyone used a locking carabiner like this one from REI:
View attachment 305929

While I havent used on of those particular ones, they are rated so you know the specs, and they are locking, I think it would be fine as long as the ratings are not exceeded. Climbing carabiners also have a pin on both ends of the gate to stop the carabiner from opening if it gets stretched out of shape.

 

[MCriscione]

I would suspect that, as that is a load rated piece of gear, you would be fine. Specifically, that one is a 27kN rated (7kN open or across the gate), which equates to ~6,000 lbs (~1500 lbs). I'd imagine that's plenty for nearly any L1/L2 rocket (and probably most L3s). On the other hand, they're going to weigh a fair bit more than the little 1/4" quick links.

Edit: All 'real' climbing carabiners will have a load rating (in kN) stamped/engraved on their spine. If they don't, don't use them for climbing...or your rocket!

 

[dixontj93060]

Delta links are very common for larger builds because they tend to help flatten any wide (1"+) TN loops. Giant Leap has carried them for years (https://giantleaprocketry.com/products/components_recovery.aspx#Quicklinks). Again, application depends on materials and strength test results.

 

[Lowpuller]

The problem with climbing biners, I'm a climber, is that the rating is seriously reduced if loaded improperly. I think it would be very difficult to insure proper loading as it takes constant attention when you use them for climbing.

 

[Len B]

I have purchased a set of "real" carabiners like the ones in the photo and I intend to use them for an L3 capable rocket I am building. I will only abandon them if my L3 (L4 in Canada) advisor tells me I cannot use them or the RSO tells me the same. They seem fine. Maybe an L3CC person can chime in and let us know what they think. I think there are a lot of potentially worse failure points. (bulkheads and the attachments being very common)
Thanks for asking!

 

[Buckeye]

If you only thumb-tighten the quicklink, how is that different than the locking carabiner? I guess the carabiner may have nicer threads and more leverage with your fingers.

Personally, I install a loop of kevlar to the motor mount anchor and complete with a good ol' knot. No added hardware. I don't usually expect a lot of harness maintenance.

 

[dr wogz]

My 2¢...

Why not a length of steel cable with two eyes at each end, permanently attached to the lower CR. Attach the rest of your harness to the upper eye for easier harness maintenance.

See Cosmodrome Rocketry, how they do their kits..
https://www.cosmodromerocketry.com/Instructions/BlackBrantII/instructions_BBII.pdf
Item 'G'..

https://www.sriperformance.com/hood-pin-cable-p/mik-911.htm

 

[Pat_B]

Carabiners are designed to be used in a particular orientation so that the load is mostly along the long axis away from the gate where the carabiner is the weekest. That's why the carabiner you've shown has a pear shape, so that the rope hangs down along the long axis. That's further accomplished by using runners when climbing to keep the rope where it belongs. You don't want cross loading, and that's likely to occur during ejection when the forces on the carabiner are all over the place. With that being said, it's possible that the overall strength of the carabiner might still work for rocketry, but the overall design is for climbing where the climber is properly managing the routing of the ropes/webbing that are attached.

 

[watermelonman]

I would have no problem using that. As a long time climber, my father and I had a simple rule. Once climbing gear gets used for a non climbing activity, like pulling out a stump, it was never to be used for climbing again.

Heck some of the stronger ones like the Petzl I frame ones were plenty strong even with the gate open. Obviously you run the risk of disconnection, but it was comforting to know none of my gear was going to break with any load I could possibly generate. After that it was user error. Maybe duct tape the gate if using a non locking biner for rockets in a pinch!

 

[ThirstyBarbarian]

Why is the quick link so hard to work with? Is it getting gunked up and hard to turn? The ones I have used don't seem to be much trouble to undo.

 

[BDB]

I figured there would be some climbers here that could give some insight.

Why is the quick link so hard to work with? Is it getting gunked up and hard to turn? The ones I have used don't seem to be much trouble to undo.

It is getting gunked up, but the bigger problem is that the 54 mm motor mount tube extends past the forward CR. It's easy to get my arm down the 4" booster tube but difficult to get my fingers into the space between the airframe and the MMT. On my current 4" build, I made sure that the MMT tube doesn't protrude much past the filet to to forward CR for this very reason.

 

[ThirstyBarbarian]

I figured there would be some climbers here that could give some insight.



It is getting gunked up, but the bigger problem is that the 54 mm motor mount tube extends past the forward CR. It's easy to get my arm down the 4" booster tube but difficult to get my fingers into the space between the airframe and the MMT. On my current 4" build, I made sure that the MMT tube doesn't protrude much past the filet to to forward CR for this very reason.

The tight space can definitely make it difficult. Usually a 4" airframe is pretty easy to get your arm into to work with, but if the 54" mount extends very far, that would make it really tight for the fingers. I'd probably go with the steel leader idea to get your harness attachment point out into the open part of the airframe. Or borrow a small child with little hands, or possibly a monkey.

 

[tomsteve]

a little bit of Vaseline on the threads of quicklinks keeps mine easy to use.

 

[Pat_B]

Here's a good article directly from a 'biner mfg- https://blackdiamondequipment.com/e...d=qc-lab-off-axis-tri-axial-carabiner-loading

 

[rharshberger]

Carabiners are designed to be used in a particular orientation so that the load is mostly along the long axis away from the gate where the carabiner is the weekest. That's why the carabiner you've shown has a pear shape, so that the rope hangs down along the long axis. That's further accomplished by using runners when climbing to keep the rope where it belongs. You don't want cross loading, and that's likely to occur during ejection when the forces on the carabiner are all over the place. With that being said, it's possible that the overall strength of the carabiner might still work for rocketry, but the overall design is for climbing where the climber is properly managing the routing of the ropes/webbing that are attached.

Given the shape of the pictured carabiner minor axis loading is going to difficult as under tension the carabiner should self-orient along the major axis. Something will have to force the harnesses to pull along the minor axis.

 

[Pat_B]

Most caribiners are indeed designed to 'encourage' the load to be along the major axis, yet accidents still happen. A big problem is the interference of the rope or webbing with the safety lock, even for a fraction of a second when a dynamic load is first applied. For rocketry, the webbing will likely have loops in it that get connected to the caribiner. Those loops will likely be sliding around the carabiner prior to being under a load. It's when that load first jolts the carbiner, prior to the webbing falling into its proper position, where the failure can occur.

It's worse with webbing because of its width which also happens to get a buckle in it when pulled into the curve of the caribiner. It's those weird situations that form the basis of climbing accidents from equipment failure.

I'd suspect that under most situations that a caribiner would indeed work out OK for rocketry. But quick links are a better choice by design.

 

[K'Tesh]

Here's an idea... I'll call the '"U Loop" Shock Cord Attachment Method'.


Tie/sew a loop on one end of your shock cord, pull it through the eye bolt/U bolt. then attach a quick link to it. Then create another loop that will be (when attached by the quick link on the other end) almost even with the front of the recovery bay. Attach them by the quick link. To prevent possible entanglement of the parachute, a sleeve could be slid down the length of the loop.

To inspect, just pull the loop of shock cord down through the motor tube, or around to see how things look, it it's good, pull it back into the normal position.

When replacement is required, you can tie the new shock cord to the loop at one end, and pull it through the eye bolt/U bolt, make your loops and you're back in business.

Sure, it might use nearly twice as much kevlar, but the ease of use will likely be well worth that.

This could be adapted for other harnesses, where the shock cord is a single length of material, but I think as two parts would be more cost effective in the long run.

 

[Igotnothing]

One other consideration for climbing-style carabiners - I do not believe they are designed for attachment to hard steel components. They are designed for climbing/flying harness materials and straps. Forcing a load path into them with a steel eye bolt/u-bolt may cause deformation or failure.

 

[OverTheTop]

See Cosmodrome Rocketry, how they do their kits..

I love how Cosmodrome do this with their kits too. Works really well.

I personally would have no trouble using a carabiner in a HPR rocket if I had to, assuming I could put up with the extra mass. I would never use it for climbing again afterwards though :wink:

You may be able to use some anti-sieze compound (or Vaseline as someone suggested) on the threads to help with undoing the quicklinks.

 

[CORZERO]

The failed carabiner in your post was a novelty, impulse rack keychain item. Whoever used that (with the idea that it would actually work) was an idiot. The second pic of the Black Diamond carabiner is a proper carabiner. If you can get a carabiner like that to fail then which carabiner you use is the least of your problems.

 

[CORZERO]

Carabiners are designed to be used in a particular orientation so that the load is mostly along the long axis away from the gate where the carabiner is the weekest. That's why the carabiner you've shown has a pear shape, so that the rope hangs down along the long axis. That's further accomplished by using runners when climbing to keep the rope where it belongs. You don't want cross loading, and that's likely to occur during ejection when the forces on the carabiner are all over the place. With that being said, it's possible that the overall strength of the carabiner might still work for rocketry, but the overall design is for climbing where the climber is properly managing the routing of the ropes/webbing that are attached.

Not sure how many falls you've taken while lead climbing but I rarely fell when my rope was hanging "down the long axis" of my carabiner. Lead routes are never perfectly vertical, so I'm not really sure what you mean. Also, "might" work for rocketry? Tell you what, if you can get that BD carabiner to fail under normal/nominal (and probably even most anomalous conditions) I will personally replace your entire kit including materials and time for labor. Good luck.

 

[Pat_B]

You get all of that from a single word- "might"- that I used? You need to lay off the coffee.

I prefer to get my advice directly from the manufacturer who obviously designed their carabiners to be used with the load applied to the major axis despite your advice. And I can't imagine how your get your carabiners to hang from their minor axis when climbing. Every Quickdraw that I've ever owned has been sewn to keep it attached to ends of the 'biner so that the rope can slide through and be encouraged to get caught on the major axis. The whole intent is to keep the load on the strong part of the 'biner. Nothing I've said is contrary to what the manufacturers' recommend.

The vast majority of equipment failures in climbing happen under conditions that the user didn't expect. So less than nominal conditions do crop up without expectation and that's why I said "might".

 

[mkadams001]

One other consideration for climbing-style carabiners - I do not believe they are designed for attachment to hard steel components. They are designed for climbing/flying harness materials and straps. Forcing a load path into them with a steel eye bolt/u-bolt may cause deformation or failure.

Not really, you are always clipping to bolts and hardware that is made of steel.

 

[mkadams001]

I think the locking biner would be ok. I would be more concerned about the cost of the biner. That would make me want to find a way to use the QL. If you can get your arm and a biner in there then there is a way to get a tool in there to work the nut.

 

[Lowpuller]

You could always directly attach the harness to the eyebolt via a larks head knot. It will have the possibility of loosening up but it tighten on deployment.

 

[OverTheTop]

How about looping the harness through the eyebolt and either tie a bowline knot or use a QL where you can get to it? It costs a bit of length on the harness and a little payload volume. I have done the bowline technique before on my 54mm bird, but I always cable tie the loose end of the bowlines to ensure they do not come undone.

 

[dr wogz]

How about looping the harness through the eyebolt and either tie a bowline knot or use a QL where you can get to it? It costs a bit of length on the harness and a little payload volume. I have done the bowline technique before on my 54mm bird, but I always cable tie the loose end of the bowlines to ensure they do not come undone.

I've also slipped a piece of shrink tube over the knot to help them stay together..

 

[cosmodrome]

The other aspect of my harness is that the quick link protrudes half way from the body tube. This has the affect that the quick link hits the end of the tube rather than the thin wire of the harness. In theory this is supposed to help prevent zippers, but I don't have any proof of the effectiveness of this.

 

[spowers42]

Just ran across this and wanted to add a few pieces of info for reference.
CE/UIAA rated lockers are at least 7 kN crossloaded strength which is ~1500lb breaking strengh. For comparison a 1/4" quicklink has a ~900lb SWL. Climbing gear is rated to actual breaking strength without a safety margin, whereas industrial gear does have safety margin. https://blackdiamondequipment.com/en_US/qc-lab-choosing-the-right-tool-for-the-job--carabiners.html explains the difference between SWL and MBS.
Screwgates are probably not the best idea, the thread design is such that it is easy to open one handed. So if you use a climbing biner you might want to consider an autolocking design instead. Or two opposing standard biners are considered the same as a single locker. In that case wire gate is better than solid, since there is less gate chatter than can catch them in an open state.