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Tying knots in aircraft cable.

Discussion in 'Question of the Day' started by Footer, Aug 12, 2010.

  1. Footer

    Footer Senior Team Senior Team Premium Member

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    [​IMG]

    What kind of knot is this? How does it compare to other forms of cable termination in terms of loading/termination efficiency? Should it ever be used? Why or why not?

    As usual, professionals please wait one week before posting.

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    Jack Morones likes this.
  2. Arez

    Arez The Royal Renaissance Man Premium Member

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    What kind of knot is this?
    Circus knot/circus hitch/(one of the big three's name) knot

    How does it compare to other forms of cable termination in terms of loading/termination efficiency?
    As you can see from the picture it is a, relatively, fast method of using wire rope, as there is no additional tools/parts needed to terminate it. However, it will not have the same strength of a more "normal" method of termination.

    Should it ever be used? Why or why not?
    This depends on who you ask.

    Yes, in temporary situations only. But also only by those that have been trained how to tie it properly, and know exactly what it's limitations are. Even then, as sparingly as possible.

    No, unless you are a proffesional rigger or are under the supervision/teaching of one (or have been taught by one and know it's limitations).

    I say: this is a dangerous knot, especially when people forget how to tie it correctly (I've seen people forget to tie the clove hitch first). People see that picture and the others associated with it, or have learned it from another source and try learning to tie it. Then they try it for real and can't remember how to do it. That said, I have never chosen to use it.

    A few other concerns I'm not going into:
    How long should the tail be?
    Which direction should you go, and does it matter?
    Can you use the rope afterwards (clip end or trash completely)?
    How much should you clip?
    Where can you I find someone to teach me this knot (good luck)?
    How much weight can it hold?

    Sent from my iPhone using Tapatalk
  3. techfreek

    techfreek Member

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    I have tied this knot a few times. It was taught to us as the "circus knot" from what I remember it is used when circus's are setting up their tents, they use this knot. They had us use this knot for rigging a few signs, but we do not use it a lot. I will say this is a fast knot to tie.... if you have strong enough hands (not easy bending aircraft cable around itself in that small of a space)
  4. What Rigger?

    What Rigger? Active Member

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    I know the answer!!! But I'll wait a week.... :-+
  5. mjw56

    mjw56 Member

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    Ill second the circus hitch. Since its based on a clove hitch ill say it has a 25% strength reduction for the clove(pg 7-29)and another strength reduction for the bend around the pipe(pg 7-23). I wouldn't use it for overhead lifting, or anywhere life safety comes into play.
    sources: Entertainment Rigging by Harry Donovan
  6. MisterTim

    MisterTim Active Member

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    That looks like what would be a Haywire Twist in fishing. I know it's relatively strong and safe for overhead use, because every single drop ceiling I've worked inside is held up with this type of knot.
  7. venuetech

    venuetech Active Member

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    Well I can see which flying company you have worked with.
  8. MNicolai

    MNicolai Well-Known Member Premium Member

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    Overhead use meaning that there are so many "lift lines" that nearly half of them could fail and your ceiling will still be in place. It's by sheer over-engineering that this is "safe for overhead use." It works for what it's used for, but you wouldn't use that for hanging flats from the battens in your theatre.
  9. Scarrgo

    Scarrgo Member

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    Have used this to tie off the truss for flying gigs. Used to prevent left right movement.

    Sean...
  10. mstaylor

    mstaylor Well-Known Member Departed Member

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    I have seen it in use but will wait the prescibed time to enlighten.
  11. ship

    ship Senior Team Emeritus Premium Member

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    Good clove hitch point that I would normally do anyway in such an application in not thinking of noting as a necessary part of the knot's application. (The two knots as presented permissable for wire rope), but I believe I count seven wraps and not the ten I was trained in using. Is this a proper Circus knot? This me not saying efficiency ratings for it, extra length etc. Really really useful if you drop your last wire rope clip on the other hand, and have no more spares. Temporary wiring but cool to do when around newbees these days...

    On the details, many of us know it... sorry it's specific technique is against CB rules for teching on-line. That's one of them things you gotta learn on-site and in personal.
    Last edited: Aug 13, 2010
  12. LXQuito

    LXQuito New Member

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    I've seen it in use and used it myself in a few specific applications, but like the other pros, I'll wait until the prescribed time to elaborate.
  13. MNicolai

    MNicolai Well-Known Member Premium Member

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    Focusing in more on the topic at hand, it's worth noting that the previous comments about this being used in drop ceilings is usually a task done with bailing wire and not aircraft cable. For that matter, it's the same way my acoustical clouds above my audience are suspended. I wouldn't recommend it as some of the lines aren't pulling much (any?) of the weight and after the contractor put them in at the wrong angles and the wrong heights, there were so many in place that it would've been very costly to fix.

    It does look near the PVC that this knot somewhat resembles that of a clove hitch, known well for it's ability to be adjusted after it's been tied. With the added twists and such, I couldn't comment as to whether or not this knot is also cable of that functionality without actually tying it myself.
  14. mstaylor

    mstaylor Well-Known Member Departed Member

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    I saw this used in circus rigging. We did the tech for the Moscow Circus some years back and the show riggers used no shackles at all. Everything was terminated using this knot. I wouldn't use it to hang people from but they sure did.
  15. michael728

    michael728 Member

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    if you don't know a knot, tie a lot. this knot looks like a wannabe clove hitch.
  16. mstaylor

    mstaylor Well-Known Member Departed Member

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    It is a clove on the pipe but I'm not sure what they tied to retain it.
  17. Chris15

    Chris15 CBMod CB Mods Premium Member

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    It's been a week now, so I can buy in...
    The conventional wisdom is that if you aren't Foy, you shouldn't be tying knots in wire rope.
    Discuss if you wish...
  18. BryanKacz

    BryanKacz New Member

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    I've heard it called a Foy Knot, but then again people who work for Flying by Foy have told us to call it a Carney Knot.
  19. mstaylor

    mstaylor Well-Known Member Departed Member

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    Where I saw the Russians do it, they hung all their own acts with my crew supervising. My crew also hung all the US equipment.
  20. ship

    ship Senior Team Emeritus Premium Member

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    Where I tied the knot, I was taught ten wrapps up and down, and this only were your lost the last wire rope clips in parts and needed to get more but also secure the line. I have never used such a thing in production but was told it was as efficient as a wire rope clip - 60% or 80% wasn't told to me on efficiency.


    Yes, it will hold and probably be fine in direct instruction for teaching but it's also something that is last resort for most purposes. Circus knot can be done, but just cause it can be done does not mean anyone shoud start using it.

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