There are issues with using these GSUMP lines. One is that there are problems with tying the ends. Not done properly, the ends can slip or break. Yes, the Combat community is evidently making these things work. But what is the longevity of a set of lines used in Combat compared to how lines are used in CLPA where a set of lines is often used over countless flights (years)? Will those line terminations prove to be adequate after prolonged use?
We ought to think that out a bit - we don't explicitly specify the use of the "AMA Recommended" stainless line terminations. It says:
"Line construction shall be as per the methods described in Figures 1 through 4. The Contest Director may allow alternate line terminations if he can satisfy himself that they are at least as strong as those shown. " In the case of UHMWPE fibers, it seems far more likely that alternate knots will be developed or known that are stronger and less prone to slipping than for new terminations are going to be found for stainless. I think the same sort of wording should be applied. Knots that are not acceptable will quickly get weeded out by the competitors.
I also think we are getting bogged down in the minutiae of the wording a bit. The failed proposal appears to attempt to specify particular materials that are not, near as a can tell, in any way defined by acknowledged engineering standards organizations, but by proprietary processes, and are in no way traceable as to provenance or authenticity. In any case, we don't do that for either music wire, whatever is sold as "music wire" that we get at a hobby shop, or for stainless steel stranded lines. I have had .018 stranded that failed at 65 lbs consistently (more than the "standard" 55 lbs) and I have had .018 stranded fail at 35 lbs. What was the difference? I have no idea, they looked and felt "funky" to me so I test them, and sure enough, they were weaker than normal. No one really examines the terminations at a contest, and what do you want to bet that if I go out to the field on Sunday and find almost every stranded line termination with a single wrap around the eyelet instead of the "specified" two?
In fact, we have gone out of our way to permit materials that do not meet the original definition of "single strand wire" from the general section to permit something that is accepted to be weaker or even much weaker in absolute modulus, because we figure it OK based on lengthy experience, it's strong enough - and much less prone to corrosion than the "specified material".
We count on catching this by both experience (modelers weeding out bad workmanship and bad practices - the hard way) and the pull test.
I see no reason why this shouldn't be applied to nonmetallic lines, too. We have the pull test as the last safety check, and for all intents and purposes, allow almost anything that looks like wire and it about the right size, and despite specifying a lot of stuff, make no real attempt to verify the materials standards. If we attempt to somehow become sticklers on the engineering properties and workmanship with respect to non-metallic lines, we will never get there. The failed proposal illustrates the difficulty - near impossibility, in fact - of going that route. Unless we want to test the materials ourselves, pay for a standards organization to test every single reel, and then sell it, or something like that, we will never get there, it's going to prove hopeless. And it's unnecessary, in my opinion.
The solution is quite simple and has no effect on safety at contests, or safety code - simply allow ANYTHING in terms of lines, no material, sizes, metal or not, and just count on the pull test to weed it out. That has no effect on safety (since all that is required is a pull test for safety code). We already allow that at the Team Trials, which are in compliance with the safety code (now) since we pull test to 10G just like always. It might have an effect on performance, but if someone is dumb enough to fly a 70-ounce piped airplane on .012 stranded, they deserve what happens (impossible precision) as long as it stays together through the pull test. That way, we don't pretend that we are holding some engineering standards that we in fact are not holding even now.
What prevents such an approach? If I was to propose that tomorrow, would it be rejected out of hand? Last time I suggest this, it was stated by some people that "the AMA wouldn't permit it" meaning perhaps that some super-committee that I don't know about has a veto.
Brett
Topic: Spectra Connectors (Read 10078 times)