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Those Cool Tie-downs

Ironflight

Ironflight

VAF Moderator / Line Boy
Mentor
I just found these pictures on the camera ? had been meaning to post them for a month or so. Our two-place airplanes have standard RV tie-down rings, and they work just fine ? but Tsam just seemed to want something special! These ?rings? come from Cleveland Tools, and we find that it is easy just to leave them in all the time ? I am sure someone can compute the drag and subsequent airspeed loss, but they sure seem to be pretty small.

P1000737.JPG



Because we are space limited on Tsam, we carry some high-tech Spectra line for tie-downs, and while we could get by with S-hooks to put through the tie-downs, we are carabiner people?so we spent some time at REI trying every ?biner they had until we found something that fit.

P1000738.JPG



These all work about as well as regular rings and ropes?.but they somehow fit the ?alien? look of Tsam better!

Paul
 
Great

I've had mine for a couple years now and I love them, mostly..

If I use my own tie down ropes which or 3/8 in they work great. At most GA airports the tie downs are 1/2 inch and with a little weathering and dampness, they have become too big to go through the larger holes, so a carabiner or other type hook must be used.

Another cool thing, is if they are positioned just right, I sound like a P-38 whistling out of the sky at higher speeds.

I also leave mine in all the time and it sure makes it easier to tie down.

Also, I have my regular old rings in the rear baggage compartment for when someone forgets theirs..
 
Yeah - it was the problem of different sized ropes and chains that made us want to find some carabiners that fit - to take the unknown out of the equation.

I hadn't noticed the whistling - we'll have to check that out! :D
 
I leave mine in all the time too. Also carry tie down straps. The rubber coated
Hooks fit fine thru the big hole.
 
Too bad. Those small-radius edges really knock the strength of Spectra or Dyneema line way down. For 1/4" line you're looking at perhaps 25% of the rope strength remaining over those. Small line will have less loss due to the relative size of the radius of the edge compared to the radius of the rope.

Also, if the Spectra line has no outer cover, it's pretty slippery. I've found that knots slip at about 25% of the rope strength in single-braid Dyneema, which is similar to Spectra. It's fascinating to watch the bitter end of the line slither through the knot, while the form and tightness of the knot holds until the end.

Of course those tests were at a slow rate of load (or in this case, strain) application. I don't know how they'll behave in a rapid load, except to break at the sharp edge.

Dave
 
Another reason for a carabiner

When we needed to give Tsam a field "engine lift" during Golden West, the offered engine lift hook didn't fit Tsam's more diminutive hook. I pulled out the climbing carabiner and the problem was solved!

The ropes we use for all our plane tie-downs are static, braided caving/rescue ropes that have abrasion-resistance outer sheaths. Of course, we know not to put them over abrupt corners as David is correct that ropes cut like butter when under sufficient tension (like a person's weight). But, it is very impressive how much better caving ropes resist abrasion compared to climbing ropes. And, the ropes strength is almost entirely in the core, so cutting through the sheath actually isn't all that bad, as many an old-time caver (including me) can attest!
 
In case anyone is wondering why Louise knows so much about ropes, you might want to read this. She has a lot of experience exploring caves as part of her work. The referenced article was written several years ago, and I am aware of more recent expeditions to some pretty deep caves. She definitely knows ropes.
 
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Louise Hose said:
When we needed to give Tsam a field "engine lift" during Golden West, the offered engine lift hook didn't fit Tsam's more diminutive hook. I pulled out the climbing carabiner and the problem was solved!

The ropes we use for all our plane tie-downs are static, braided caving/rescue ropes that have abrasion-resistance outer sheaths. Of course, we know not to put them over abrupt corners as David is correct that ropes cut like butter when under sufficient tension (like a person's weight). But, it is very impressive how much better caving ropes resist abrasion compared to climbing ropes. And, the ropes strength is almost entirely in the core, so cutting through the sheath actually isn't all that bad, as many an old-time caver (including me) can attest!
Click to expand...

Not knowing a thing about ropes, can you give us a brand/part number/vendor? I really like the looks of these tiedowns + carabiner, and may consider getting them, but want to make sure I don't do something stupid that will fail under load...

Thanks!

ETA: On a side note, assuming one used their own ropes, and I'm sure to open a religious war here, what's the best method for tying down to a hard point? I.e., what combination of knots on which point (plane and hard point) do you use?

In my experience, people just seem to tie random knots until they think the rope is "tight" and TLAR, but there must be at least a couple of recommended methods for tying down, no? :)
 
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Flying Scotsman said:
ETA: On a side note, assuming one used their own ropes, and I'm sure to open a religious war here, what's the best method for tying down to a hard point? I.e., what combination of knots on which point (plane and hard point) do you use?

In my experience, people just seem to tie random knots until they think the rope is "tight" and TLAR, but there must be at least a couple of recommended methods for tying down, no? :)
Click to expand...

Bowline and half hitches are all you need to secure just about anything.

Here is an EAA video on tying down.
http://www.eaavideo.org/video.aspx?v=616323497001
 
Flying Scotsman said:
ETA: On a side note, assuming one used their own ropes, and I'm sure to open a religious war here, what's the best method for tying down to a hard point? I.e., what combination of knots on which point (plane and hard point) do you use?

In my experience, people just seem to tie random knots until they think the rope is "tight" and TLAR, but there must be at least a couple of recommended methods for tying down, no? :)
Click to expand...

"Random Knots..." - see, this is what happens when parents emphasize Soccer over Scouting....no one knows how to tie good knots anymore! :)

A bowline gives a good solid connection to a hardpoint on the ground, and I am a fan of the taught line hitch (which is a variation on the classic half hitch) coming down the standing part of the rope after looping through the aircraft attachment point.

Paul
 
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Knots

Flying Scotsman said:
In my experience, people just seem to tie random knots until they think the rope is "tight" and TLAR, but there must be at least a couple of recommended methods for tying down, no? :)
Click to expand...

As my father-in-law says...."Don't know a knot? Tie a lot." He was a very active cave diver so he knows plenty of knots. I've enjoyed learning some of them from him.

Actually, as an airport manager, I've seen plenty of different knots to tie down planes. While some wouldn't hold very long in a Kansas thunderstorm, some are just amazing. I've spent more time than I care to admit, out on the ramp, trying to reverse engineer a few of them.
 
carabiners?

I bought these, and spent an hour at REI, and could not find a 'biner that fit, except for a small aluminum one.

I am worried that the little aluminum carabiners, which are made for clipping gear to your harness, not for clipping yourself to a rope, are not strong enough for tie-downs.

So, for now, these pretty tie-downs are sitting in my tool box.

Also, the holes in the tiedown "ring" remove so much metal that the tiedown itself is not as strong as I think it should be. The web site says they yield at 1500 lbs. That's probably good enough.

If I could find some small stainless steel carabiners that fit, I guess I would try them again.
 
Here's a photo of one that I made a few years ago (they're painted now):



Good for a half-knot or so over the round rings if you plug the hole when flying!

Greg
 
yes, although kind of fussy

Mark Albery said:
There is an alternative to the caribiner. From my local Lowes':
071514009827lg.jpg
Click to expand...

Yes, that is a very good solution, I use shackles like that on the halyards on my sailboat. But it is a bit fussy to have to put those on first, then tie the rope through it. 'Biners are so quick - just wish they made one small enough that was strong enough.

They do make shackles with a spring-loaded 1/4-turn latching pin, but they also are not strong enough.
 
Just remember...

If you are leaving the tie-down rings in the plane, depending on what they are made of they may react with the aluminum bracket they are screwed into.

I have seen one RV-10 that has left the ?stock? tie-down rings in place and the corrosion is evident and the plane isn?t that old.

That is the one reason I always remove my rings.
 
Ironflight said:
"Random Knots..." - see, this is what happens when parents emphasize Soccer over Scouting....no one knows how to tie good knots anymore! :)

Paul
Click to expand...

There's an app for that (Grog Knots). I never can remember knots. Also
The biner was a great idea. Spent some time in REI myself recently.
 
Ironflight said:
"Random Knots..." - see, this is what happens when parents emphasize Soccer over Scouting....no one knows how to tie good knots anymore! :)

A bowline gives a good solid connection to a hardpoint on the ground, and I am a fan of the taught line hitch (which is a variation on the classic half hitch) coming down the standing part of the rope after looping through the aircraft attachment point.

Paul
Click to expand...

LOL! My problem is that scouting was so many years ago, I don't *remember* all those skills! Bowline, half-hitch, clove hitch, sheepshank, square...yeah, I got those.

But hey, thanks for reminding me how *long* ago I learned about knots in Webelos, Paul... ha ha!
 
OK, OK, this thread inspired me to replace the painful-to-handle orange nylon rope I mindlessly threw into my bag in case there were no tie down chains. Having used it on a number of occaisions I have come to hate it. So, when I was at Home depot I, again mindlessly, spotted some braided synthetic rope that FELT a lot better and threw it in the cart, looking forward to replacing the despised orange stuff.

I got to the hangar and prepared to cut and cauterize it to size. I found it's only good to 214lbs! O.K. it is now relegated to knot tying practice and learning.

Could we get a recommendation on specs and source for the caving ropes Louise? REI? I can guarantee you that it will NOT be used for either caving or climbing:eek:
 
Amsteel, while strong, is not suitable for tie-down ropes. It doesn't hold knots well. They slip open under load. The stuff is simply too slippery. Also, it's sensitive to sharp corners and small radiuses, both of which cause a decrease in strength - thing stress concentration.

That said, 1/4" of the stuff would probably suffice. It'll lose all but about 25% of its strength in a knot - and that might still be enough.

There are a number of "double-braid" ropes that have an Amsteel core and a polyester cover which are probably better choices than bare Amsteel. Of these, I prefer Endura Braid to Warpspeed. The Endura Braid has better feel. 1/4" diameter is more than ample.

Try Regatta Braid, it's a decent rope that holds knots well, feels good to the hand, and is durable. West Marine sells it. This is what I settled on years ago for my plane, and the ropes have performed well and lasted. For this rope, 5/16" is the right diameter.

Dave
 
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