Webbing and Rope Guides for Recovery Anchors

Hi all,
I am looking for anyone with real world experience using webbing or rope guides as recovery anchors. This is in terms of 10-20 lb rockets. If so, what kinds, sizes etc. Below are examples...

Webbing guide: https://www.mcmaster.com/#8030t15/=y93d9k

Rope guide: https://www.mcmaster.com/#8860t81/=y93d2q

Why I'm considering the use of rope guides or webbing anchors?

1.) Lower profile than U-bolts, Eye-bolts, or Eye-nuts. In a 3" or 4" airframe, the previously mentioned anchors eat into the recovery space because they stick out 1-2" from the bulkhead and take up unnecessary space.

2.) Easier to install. Webbing guides can be installed via tapped holes on aluminum bulkplates - removing the need for nuts on the backside (U-bolts)

3.) Shorter profile = lower weight

What McMaster doesn't provide is load ratings for the guides. Outside of me starting ANSYS on my computer and doing an FEA, I have no way of finding out the rating. Just by looking at the webbing guide, I can see that it will have a lower load rating than a rope guide due to the smaller radii (higher stress concentration).

Another option for low profile anchors are tie-downs. However from the ones I purchased on McMaster are heavy and overkill (load rating wise) for a 15 or 20 lb rocket.

Any help or insight is much appreciated!!! Thanks!
-Kip

Link to old thread regarding webbing guides: https://www.rocketryforum.com/showthread.php?56345-Interesting-hardware-footman-s-loops

No real answers were presented in that thread...

Kip,,
I have never heard of a complaint that a U bolt or eye bolt took up too much space...
You must be insanely tight on room to have that for a concern..
If your that tight on room I'd go with a thinner / lighter harness that's really long to try to make up some needed room
before I skimped on the attachment point.. ( No disrespect intended Kip,, the attachment point is a possible failure point )...

And 100% for sure you said threaded into aluminum,,, with no steel nut to back up the threaded aluminum bulkhead....
No way I'd trust aluminum to hold a threaded screw for the harnesses attachment point....

Teddy

onebadhawk said:

Kip,,
I have never heard of a complaint that a U bolt or eye bolt took up too much space...
You must be insanely tight on room to have that for a concern..
If your that tight on room I'd go with a thinner / lighter harness that's really long to try to make up some needed room
before I skimped on the attachment point.. ( No disrespect intended Kip,, the attachment point is a possible failure point )...

And 100% for sure you said threaded into aluminum,,, with no steel nut to back up the threaded aluminum bulkhead....
No way I'd trust aluminum to hold a threaded screw for the harnesses attachment point....

Teddy

Click to expand...

Yes space is primo on this build otherwise I would go with the tried and true U-bolts. I have already sized down my chutes, minimized my recovery harness length and size. In regards to threading in aluminum, you can calculate the amount of thread engagement necessary so that the bolt shaft fails before the female threads strip. You would be surprised how little engagement is necessary to achieve this, a good rule of thumb is one bolt major diameter of engagement.

Wow Kip,,
That sure sounds like you've done your homework,,
Good for you man...
I sure wish I could help,,
but I've never heard of using those as harness anchors...
Sure must be a special build to be so tight on room...
All the best of luck with it...

Teddy

Hey Kip,,
Maybe if you ran a die up each leg of a U bolt you could keep it tight and low / short....
It would take up less room that way....

Have you ever heard of a crosby clamp ??
They are used on wire rope to make a loop...
Part of that type of clamp is a super tiny U bolt....
Take a look at those,, they may be of use....

Teddy

Crosby clamp....

https://www.google.com/?gws_rd=ssl#q=crosby+clamp

Teddy

I use the rope guides on a 4" dia. 10 lb rocket with #10 all thread running through the av bay. No problems.

How about these https://www.ptrocketry.blogspot.com/p/rocketry-nut.html

onebadhawk said:

Crosby clamp....

https://www.google.com/?gws_rd=ssl#q=crosby+clamp

Teddy

Click to expand...

I have used these on several builds where space was a premium and they worked well.

Kip_Daugirdas said:

Hi all,
I am looking for anyone with real world experience using webbing or rope guides as recovery anchors. This is in terms of 10-20 lb rockets. If so, what kinds, sizes etc. Below are examples...

Webbing guide:https://www.mcmaster.com/#8030t15/=y93d9k"] You would be using two 1/4" fasteners to attach this to the bulkplate(Very Strong) and it should be perfect for a 1" webbing based recovery harness. Mr. Chernok would be the resident expert on what might happen with a narrower harness as it slid back and forth or got pinched moving side to side.

Rope guide: https://www.mcmaster.com/#8860t81/=y93d2q Largest screws you could get into the mounting holes would be #5 (0.125"). This would reduce the load bearing capacity some what but it would work nicely with a small tubular harness or a quick link.


Any help or insight is much appreciated!!! Thanks!
-Kip

Click to expand...

Neither of these is load rated because the stated use is for guide only. But hey when has that ever stopped us. :wink:

Thanks for help!

At the moment I think I will go with rope anchors on the booster end (just from looking at them they have better load capability). Then use the webbing guides on the nosecone and interstage. All will be secured with 1/4-20 or 10-32 hardware.

I will report back and let you guys know how things go, but I'm not too worried