The rules proposal is in the general section, since that is where the line construction and materials are specified for all events. At Bob Underwood's suggestion it also includes wording for all the events that allow stranded lines to refer to the general rules for materials and construction. I don't think any of the events except speed actually referred to the general rules, so technically they've never applied to stunt, combat, racing, carrier, scale, or special events. Now they will.
As some background from what I've been able to determine, these high performance fishing lines are all made from what is called gel-spun ultrahigh molecular weight polyethylene. Honeywell is the manufacturer in the US. Dyneema is the major manufacturer in Europe. I believe they are the only two suppliers because it is a patented, licensed technology. In response to Paul S's commentary, Spectra(tm) and Dyneema(tm) are the trade names for the fiber, like Nylon, Rayon, etc. As far as I can tell these two companies are the only manufacturers of the fiber. Quite a number of companies take the fiber and turn it into lines of various kinds- Power Pro, Spiderwire, Tuf Line, Stren, Momoi, etc.
In various informal tests the Spectra lines are much less likely to get damaged in ordinary handling and stand up much better to use. They are available, as fishing line, in many different diameters, colors, and strength ratings. All of the brands I've tested(Power Pro, Spiderwire, Tuf Line) can be made into useable lines simply by tying a loop with an overhand knot. The strength is very uniformly half, or slightly less, of the rated strength. The lines break either at the knot, or a couple inches away. According to the kite flyers, there are various techniques, such as putting a sleeve of other material over the line, and possibly using certain types of knots, that will get a higher breaking strength. I have not been able to do this. Sleeving the line with Dacron fishing line, as the kite flyers do, before tying a knot in it made no difference. I did find two knot variations, detailed in pictures with the rules proposal, that helped. Tying the end in a double overhand knot added about 10% to the breaking strength and is very easy to do. For attaching lines to line clips a half-blood knot gives similar strength. The Palomar knots I tied did no better.
Just for comparison purposes, .018 stainless steel lines break at almost exactly 50 lb. pull. They always break at the termination, whether it is wrapped, or crimped, or they break at a previously kinked spot in the middle of the lines. 100 lb. Spectra fishing line(Power Pro brand), has a diameter of about .0181 in.(it's a bit hard to measure exactly since the line is soft). With simple overhand knot terminations it breaks at 45-47 lb. Using the double overhand knot or a half-blood knot increase the breaking strength to about 50 lb. Pictures of the knots were sent in with the rules proposal.
The Spectra line weighs around 5 gr. for a 52.25 ft. set, 018 steel weighs 31 gr. This is probably its biggest advantage. Even though the lines may be a bit draggier, the lower weight makes the plane much more responsive and controllable. It's easy to see 018 or even 015 lines flopping around in maneuvers. If the plane slows a bit the weight of the line begins to make it wobble around a lot. Less line weight means less tip weight and less flopping around.
In a couple simple abrasion tests, hanging a 15 lb weight from line and rubbing across it with another line stretched to 10 lb. or so on a bow, the 100 lb Spectra held up to 200 1 ft. strokes. 018 Stainless steel held up to 50 strokes under similar test conditions. We've done quite a bit of combat flying using 30 lb. Spectra, which is the same strength as .012 steel lines. The steel lines broke/kinked/tangled at about 10 times the rate of the Spectra lines. In about 30 matches none of the Spectra lines were damaged, but 3 sets of steel lines were either broken, kinked, or otherwise damaged in line tangles. However, when I ran the abrasion test above, using steel wire on the bow against the Spectra line, the Spectra only held up for 10 or so strokes, which is at odds with the flying tests. The rules proposal recommends that until more experience is gained, all fliers in multi-flyer events(combat, racing) must use lines of the same material. The CD could handle this by an announcement in the contest promotional materials, or on a match by match basis.
The gel-spun ulltra high molecular weight lines offer many advantages over steel wires, both solid and stranded. The GSUMP material is does not kink. It is almost totally immune to fatigue(the lines will not break from vibration at a point where they have been bent or knicked). The high visibility colors make it much easier to see the lines laying on the ground. They are highly resistant to wear when rubbed against each other(approximately four times more wear resistant). They stretch less and are easier to make up when they do wear and need replacement. The lines are made of many, many fibers so when wear and fiber breakage are seen they can be replaced in a timely manner.
I haven't been able to do any meaningful shock load testing. We did observe though that some of the fishing lines, labeled "fusion" or similar terms, bond the fibers together into a solid line. This material is much more shock sensitive. The rules proposal specifies braided(stranded) line to avoid this.
We did do some less formal testing flying combat with Half-A's. 30 lb test Spectra lines outlasted .012 stainless at least 10-1. Gil wiped out 3 sets of steel lines flying against Spectra lines in about 30 matches. The steel lines all failed due to damage from line tangles, and none of the Spectra lines failed, which seems to be a bit at odds with the abrasion testing.
Cost wise, Spectra costs the same as stainless steel in the sizes we use. You can get 1500 yds. of Power Pro 100 lb. test for $170. , just under 4 cents a foot. Since I've yet to have a set of Spectra lines fail or wear out, long term costs should be low. Sig, Brodak, Aeroproducts, all can easily stock some fishing line of their own preferred brand if they want to service the market.
Stretchiness doesn't seem to be an issue in use. I've used them on stunt and combat planes and not noticed any. Braided metal lines get stretched and spring back every time you use them since the lines coil and uncoil(twist in the manufacturing process) and get all sorts of interesting curlicues in combat. You may have noticed that some lots of stainless cable try to get curlies after every flight, while other batches don't. It indicates the mfg'er got the twist in the individual wires wrong.
Topic: Q & A for alternative flying lines (Read 2311 times)