Tiedown ropes

Discussion in 'Hangar Talk' started by freerangequark, Feb 21, 2018.

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  1. Feb 21, 2018 #1

    freerangequark

    freerangequark

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    My wife flies her plane frequently to a neighboring airport where the airport owner has recently replaced the tie-down ropes. The ropes are three-quarter inch yellow polypropylene and are completely impossible to easily and reliably tie down an airplane.

    He offered to get better rope at the tiedowns, but wanted advice on what diameter and type of rope works well for airplane tiedown.

    Any good recommendation? I was thinking rope about 3/8" or 1/2" would be plenty strong, but wasn't sure about the material for a good locking knot.

    Thanks,
    Glenn

    27356023_1565886993460753_3832753093582120670_o.jpg
     
    Last edited: Feb 21, 2018
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  2. Feb 21, 2018 #2

    Neil

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    I like to use Bow Line from the Marine Department at Academy Sports. Works good on boats too. I think Lowes has it by the foot.
     
  3. Feb 21, 2018 #3

    PittsDriver68

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    Second that suggestion. 1/2" nylon won't break before the airplane does.

    Best of luck,

    Wes
     
  4. Feb 21, 2018 #4

    freerangequark

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    Thanks! 1/2" Twisted Nylon Rope it shall be. :)
     
  5. Feb 21, 2018 #5

    Larry Lyons

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    Try and talk him in to getting a marine grade, they wont fray as quickly and won't get scratchy with age either.
     
  6. Feb 22, 2018 #6

    4-Shipp

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    You can find bow lines of various lengths and strengths/diameters in the marine section of Walmart or similar stores. These will have a large loop pre-woven into one end. This makes quick work of securing then to the common cleat recessed into many ramps.
     
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  7. Feb 27, 2018 #7

    Lotahp1

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    What we had air Wiley Post was about 1/2 and was made up of really soft, really fine threads. It was outside in Oklahoma Weather...-10f to +105f...for literally 10-15 years. Some were replaced as needed etc but a lot of them were old. Sorry no help on exact type of rope but I just remember it being really soft and threads almost silk like.

    One of the things I almost bought at Oshkosh this year was a set of tie down ropes with a bar. The bar is made of plastic or aluminum and it’s attached at one end of the rope and when you tighten it it puts a load on the other side and holds it. Really quick and positive. You simply just don’t see ropes at a lot of airports anymore. Even if they have tie downs in the ramp. I held off...figure I’ll buy a bag of “The Claw” tie downs and upgrade the ropes with this kind of rope.

    Like these...the rope they use is in description below View attachment IMG_1519702238.742106.jpg
    The SlideDowns 7/16” kernmantle braided rope is super strong, the powder coated slide is made from aircraft grade aluminum and then precision drilled allowing for easy sliding but also a tight hold. Vinyl coated hooks prevent any scratching. The SlideDown is easily adjustable to reach most anchor points, and can be shortened to accommodate just about any length. Set of 3
     
    Last edited: Feb 27, 2018
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  8. Feb 27, 2018 #8

    IanJ

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    I carry Dyneema tie-down ropes in the Champ. I got two 10 or 12 ft lengths at West Marine, cost about $30, but the Dyneema rope is ridiculously strong and high quality. I wish I'd gotten them slightly longer, but they've worked in the situations where I've needed tie-down ropes. I recommend at least double the nominal ground-to-tiedown-ring distance to allow for some slope and knot tying slack, which is a bit more than I got.

    I got something like this, either the 10mm or 8mm size:

    https://www.westmarine.com/buy/new-...or-coded-flecks--P002_071_002_011?recordNum=4

    I use a bowline (pronounced BO-len) knot (http://www.animatedknots.com/bowline/) on the ground end, and a sort of mutant bowline at the wing, keeping the all important twisted loop in the standing end (the ground-connected side of the rope). Having the twisted loop in the standing end of the rope prevents the knot from riding up in a gust, which in combination with a tight tie-down rope prevents rapid accelerations on the plane.

    If you can grab your tie-down knot and shove it up the rope toward the wing, it's not a good knot. It will ride up in a gust or heavy wind, allowing the plane to flap around, which can damage things worse than if it were securely tied. Most tiedown knots I see are a kind of granny knot over the straight standing end, which moves easily. They look good, but only serve to keep the plane from actually flying away if it's really blowing.
     
  9. Feb 28, 2018 #9

    Larry Lyons

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    If we are going to get in to it, I use the bow-line at the ground and a modified half hitch at the wing. The first time through for the half hitch I pull the middle of the bitter end through, cinch it up tight against the tie down loop and take that, now loop of rope and make another half hitch. this know works well, its quick, you can get things tight, and the second half hitch will never get to tight and the first one that takes all the guff now has a long piece of rope that you just pull on and it will pull out the half hitch, no matter how tight it may have been drawn up. I know; clear as mud!
     
  10. Feb 28, 2018 #10

    IanJ

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    Makes sense. Much better than the doubled half-hitch a foot down the standing end that I normally see. :rolleyes:
     
  11. Feb 28, 2018 #11

    smizo

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    we replaced all the tiedown ropes at the airport with ratchet straps 2 years ago. work great. just gotta spray them with lube once a month. that's the job of the airport kid.........

    Glen, thats a nice looking 150 you got for your wife.
     
  12. Feb 28, 2018 #12

    planebuilder

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    Nylon isn't great for tiedown ropes, it won't stand up to UV rays, polypropylene is worse, it's the stuff that gives you slivers as it ages in sunlight. Polyester lasts much better out in the sun, that's what good marine rope is. If you want good ropes, get Yacht Braid, not Twisted rope. Twisted rope will spin and twist as you pull it through a ring, if you use rope a lot it becomes a nuisance. Yacht Braid has the strong rope strands inside, and an outer braid protecting it from abrasion and UV. Don't buy inexpensive rope from big box stores that looks like Yacht Braid. When ever I buy rope, I take a small knife to the store and open the end, peeling it back an inch to see what's inside, there is a lot of cheap stuff out there, that looks great, but is filled inside the outer cover with what looks like folded up toilet paper! 1/2" would be minimum diameter, I usually buy 5/8, remember, it will be outside for a long time, you don't want that 1/2" rope to be holding your plane, when it has lost 50% of it's strength, but still looks ok. I have inspected ropes on other planes and complained to the airport, I lost an airplane once because someone else had weak old ropes on their plane, and it broke loose in a storm and landed on top of mine. When you look at the value of your airplane, good rope is cheap insurance.
    Oh yeah, since I'm rambling, don't trust ratchet straps for too long, the webbing is so much thinner than a rope that the UV rays can get into it easier and degrade it quicker.
     
    Last edited: Feb 28, 2018
  13. Mar 1, 2018 #13

    Dana

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    Problem with ratchet straps, or any tiedown rope with a hook on the end, is that if it slackens even a little bit for any reason, is that any bouncing of the plane in a wind can make the hook fall out of the tiedown ring on the plane (or the ground anchor). I've seen too many planes with the hook tiedowns hanging loose from the wings or laying on the ground to ever use them myself. Carabiners would be OK, but you never see them on tiedowns.

    The ratchets make it possible to overtighten the tiedowns and overstress the plane. Maybe not an issue for the owner, but when the well meaning passerby finds it loose and goes to tighten it...

    Aircraft Spruce sells 3/8 and 1/2" twisted nylon tiedown ropes. Last time I needed ropes, their price was better than anything I could find locally.

    I still use the "midshipman's hitch" friction knot my first flight instructor taught me 40 years ago, and even in hurricanes I haven't lost a plane yet...
     
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  14. Mar 1, 2018 #14

    Lotahp1

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