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#401451
I noticed on a current video that the towee was on the end of a pro-tow rig, looped through what I assume was an aluminium carabiner! :?

Interesting that they are using that metal biner at the end of the towline. Seems to be a snapback hazard that was proven to be dangerous many, many tows ago. I say this because I use to own a DF and run a flight park and the metal rings and biners were never a safe option. Now I see it's still a thing at Wallaby of all places. What has changed?

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#401452
Wallaby's safety record hasn't changed... they have possibly the best record of all popular US flying sites!

Which is not to say safety can't still be improved. But you may be "fixing" a problem they don't have? Actually... not fixing anything, griping about it here! :roflcat:

Give Malcolm a call and ask why he's using biner's, and after understanding his rational you can suggest an alternative if appropriate. For whatever it's worth, I can't remember aerotowing anywhere that DIDN'T have a biner or ring on the end of the towline. What did you use instead?
#401453
We always used a teardrop plastic rope thimble. http://www.wesspur.com/splicing/splicin ... shers.html Scroll down a ways to see it.

Similar to what our wing wires go around before the nicco. Tough, light, durable and WAY safer in case of a snap back. Ask Micheal Roberts about using metal at the end of ANY towline...look him right in the "eye" when you do.

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#401456
Re: Michael Robertson... that wasn't a very funny joke. That was also way way "back in the day"... like the thread title asks, maybe something has changed since then?

Re: plastic teardrop thimble- That sure seems like a damn good idea to me! You do lose the ability to have the pilot hook up their tow bridle before the tug arrives... which allows the pilot to take their time, and the ground crew to inspect, without feeling rushed by the idling tug and possibly line of other pilots behind them. Not that safety should be compromised for expediency, but hey, we're human, and we know how humans operate (or fail to operate) sometimes.

Maybe- and just throwing an idea out, obviously I can't speak for Malcolm or any other tow pilots/parks- there is a feeling that an accidental premature release right after takeoff from a not-quite-connected release poses a greater risk than the biner on the rope, so being able to clip the towline right into the completely connected release is the lesser of two evils? I dunno... just trying to think of why the biner might be preferred... besides the obvious convenience factor...

Kind of a side question, but in what situation might an aerotow rope snap back toward the pilot? The tow lines are spectra I believe, which should be about 0 stretch under the tow loads we experience (load = < weaklink strength). Most (all?) AT releases are spectra now too. So maybe that's what changed... I wouldn't be surprised if "back in the day" people were towing with polypro ropes or something that can stretch and snap back should the tug-side of the rope release. Admittedly a bit of speculation here...
#401457
We used polypropylene with not one single break in 5 years. The Michael R. comment was not a joke. Pre-stretched and replaced when necessary. Any line can break. When it does one should be as safe as possible.

Poly is great for learning to tow with IMHO. The length we kept to around 150 feet. Light and forgiving and safe. Not to mention less expensive. The stretching issue can easily be removed with proper care and replacement. YMMV.

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#401467
AIRTHUG wrote: Fri Dec 08, 2017 10:53 am Re: Michael Robertson... that wasn't a very funny joke. That was also way way "back in the day"... like the thread title asks, maybe something has changed since then?

Re: plastic teardrop thimble- That sure seems like a damn good idea to me! You do lose the ability to have the pilot hook up their tow bridle before the tug arrives... which allows the pilot to take their time, and the ground crew to inspect, without feeling rushed by the idling tug and possibly line of other pilots behind them. Not that safety should be compromised for expediency, but hey, we're human, and we know how humans operate (or fail to operate) sometimes.

Maybe- and just throwing an idea out, obviously I can't speak for Malcolm or any other tow pilots/parks- there is a feeling that an accidental premature release right after takeoff from a not-quite-connected release poses a greater risk than the biner on the rope, so being able to clip the towline right into the completely connected release is the lesser of two evils? I dunno... just trying to think of why the biner might be preferred... besides the obvious convenience factor...

Kind of a side question, but in what situation might an aerotow rope snap back toward the pilot? The tow lines are spectra I believe, which should be about 0 stretch under the tow loads we experience (load = < weaklink strength). Most (all?) AT releases are spectra now too. So maybe that's what changed... I wouldn't be surprised if "back in the day" people were towing with polypro ropes or something that can stretch and snap back should the tug-side of the rope release. Admittedly a bit of speculation here...
10-12 years ago when flying at Whitewater WI I noticed they were using poly, I was use to spectra. On a turbulent day I could feel the stretch and had to ready to compensate to prevent a surging type of condition.

I inquired about the use of poly and it was explained that if they lost a rope in a active farm field it would cut easy when the combine or other equipment found it. Spectra would bind the farm equipment and cost many hours to remove
or worse damage or break the farm equipment
#401469
True Ron. There was more elasticity to the poly.

If it's pre-stretched, we felt it provided us with a safer platform for low-time and no time pilots. Our flight park thermals were a little "punchier" then southern flight parks. The little stretch it gave was a bonus we were told by students. We never had any issues with surge except were one would expect it during a tow with any type towrope. I personally liked how the beginning and ends of any surge or rough air was smoothed out. We had Spectra too and used it if asked.

Out in the flatland's of Kansas the "farm friendly" quality was a bonus as well!

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#401480
Related to line-stretch and elasticity...

There's a really old story about the Wills Wing crew clearing brush and such on launch one day... and they went to pull a sage bush with one of their trucks (for some reason I think I remember it being Mike Meier's truck- which if you know Mike, that makes the outcome of the story even funnier...)

Well they got the bush out! But the stretch of the rope or strap was so significant that the bush snapped back and went smashing right through the back window of the truck!

Hearing that story as a pretty young kid- told with Rob's typical effervescence and enthusiasm- and it really made a lasting impression on me.

That, and the story of how they JACKED UP a Jack in the Box drive through, pulling in to pick up their order... in the test vehicle... with the boom still up. The irony of it, jacking up Jack in the Box. And Rob's storytelling... ugh, miss that guy so much...

Back on topic- like the story of the bush through Wills Wing's back window- personally, I see using any tow line that has any more elasticity in it than is necessary/affordable/practical/whatever... to be a greater area for concern than the metal ring or 'biner at the end of the line. Even that plastic thimble could hurt like a B*** if a tow line with elasticity was under load and it snapped, or the tug released (intentional or not), or the weaklink on their end let go, or whatever... I'm pretty sure even a plain naked on of the rope would hurt like hell and could put in eye out if it snapped back at the pilot. Not to mention the risk of wrapping around things like the basetube.

Again- just MY personal opinion- tow lines that stretch add a risk over spectra etc tow lines... and I am only sharing my opinion since this topic is about metal 'biners being a safety risk in the event of snap back... because addressing snap back seems to be a greater safety gain than pointing out the metal 'biner on the end of the line (usually covered by a plastic funnel or similar). Of course- each is not mutually exclusive of the other. Belt and Suspenders ain't no problem :mrgreen:
#401481
Whether a kickback occurs between the pilot and a carabiner has to do with the stretch (or lack of stretch) in the bridle, not the tow line. If the line breaks near the biner, maybe it would kick back. But if there isn't any elasticity buildup in the bridle-harness system, there wouldn't be much kickback.