Those Cool Tie-downs

[Ironflight]

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.




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.




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

Paul

[RV8iator]

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..

[Ironflight]

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!

[Chino Tom]

I leave mine in all the time too. Also carry tie down straps. The rubber coated
Hooks fit fine thru the big hole.

[David Paule]

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

[Ironflight]

Originally Posted by David Paule

Too bad. Those small-radius edges really knock the strength of Spectra or Dyneema line way down.

Dave

That's another reason why we use the carabiners David.

[Louise Hose]

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!

[rv7boy]

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.

[Flying Scotsman]

Originally Posted by Louise Hose

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!

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?

[bruceh]

Originally Posted by Flying Scotsman

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?

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