dbattman 0 #1 January 30, 2003 Who can post a little info on Vectran/HMA lines and their history of wearing from the inside out? We have an experienced swooper in ICU due to a suprise steering line snap on landing (see incidents). What I am interested in is how these lines wear and what warning signs should be looked for as they age. If what I understand is correct, there have been several cases of steering lines wearing from the inside-out and snapping when they are under the most stess (i.e. landing phase). If this is the case with Vectran lines, why use them for control inputs over something that might be a little thicker, but more reliable? More info is appreciated from those in the know. EDIT- the steering lines were HMA, not vectran. Quote Share this post Link to post Share on other sites
Rdutch 0 #2 January 30, 2003 I know that PD uses thicker vectran lines on the control set. I asume this is an industry standard. A lower control line set made out of vectran cost only $20 and takes about 5 minutes to install. All the vectran lines I have seen that were worn out, were very noticably worn out, but not bad enough looking as a spectra line set with as much wear. So you can see that vectran hides its wear a lot better than spectra lines. But you could easily see they had a lot of use. No one should take chances with a worn line set, it is too easy to replace. Ray Small and fast what every girl dreams of! Quote Share this post Link to post Share on other sites
cpoxon 0 #3 January 30, 2003 Peter Learmonth's accident I'm pretty sure there was some follow-up from the manufacturer but I can't locate it at the moment. Quote Share this post Link to post Share on other sites
hookitt 1 #4 January 30, 2003 I just sent Peter an Email to see if he could comment about this.My grammar sometimes resembles that of magnetic refrigerator poetry... Ghetto Quote Share this post Link to post Share on other sites
Samurai136 0 #5 January 30, 2003 A photo of what the wear looks like would be cool too. Ken "Buttons aren't toys." - Trillian Ken Quote Share this post Link to post Share on other sites
dbattman 0 #6 January 30, 2003 The rigger is coming back from USPA and will do an inspection over the weekend. I don't know if he has any plans to take or post pictures, but I can put in a request. Quote Share this post Link to post Share on other sites
dbattman 0 #7 January 30, 2003 OK- here's where a little but of my ignorance comes in (I'm still flying a Falcon). Tell me if I've got this wrong. HP canopies are sensitive to changes in trim, so line shrinkage and creep is a problem over time. Therefore, use the inelastic high-tensile lines. As an added benefit, the lines can now be thinner due to their high strength. So, the thin control lines are passing through the riser areas and rubbing on the links or the rings or the slidder grommets. I'll have to take a look at some other canopies, but is there an external, protective sheath around the control lines for protection? Quote Share this post Link to post Share on other sites
PhreeZone 20 #8 January 30, 2003 Control lines tend to be beefier lines then the rest of the canopy uses. My Jedei has Spectra 550 for all the lines and Spectra 825 for the control lines. Some of the Xaos lines are rated for 325 pounds or so and the control lines are rated for upwards of 900. Using thicker/heavier lines for the control is good other wise the wear on the lighter lines would cause a broken line in no time.Yesterday is history And tomorrow is a mystery Parachutemanuals.com Quote Share this post Link to post Share on other sites
Rdutch 0 #9 January 30, 2003 Good idea you should patent it. Not that I have seen yet. But after looking around today a lot of sailing companies are putting a protective coating on Vectran lines, good enough to use them on salt water sailing boat's. Maybe the parachute industry should look into this a little, I also read that some companies use a wax to make the line last longer, and this has to be reaplied. Anyone hear of this, sounds like another option, my last set ov Vectran lines dried out real good and this caused extra wear on the areas that saw extra friction. Anyone have any thought's on this? Ray Small and fast what every girl dreams of! Quote Share this post Link to post Share on other sites
PhreeZone 20 #10 January 30, 2003 Swap out the Vectran for Dacron... simple fix.Yesterday is history And tomorrow is a mystery Parachutemanuals.com Quote Share this post Link to post Share on other sites
Rdutch 0 #11 January 30, 2003 not a realistic option Ray Small and fast what every girl dreams of! Quote Share this post Link to post Share on other sites
PhreeZone 20 #12 January 30, 2003 On the lower steering line it should be an option. From the Cat eye down just replace it with something in the range of 800 pound Dacron. Virtually impossible to miss worn dacron and its keeps its size over a long time too.Yesterday is history And tomorrow is a mystery Parachutemanuals.com Quote Share this post Link to post Share on other sites
dbattman 0 #13 January 30, 2003 Cross-post from Bytch in the 'Incidents' forum. Good info to have. If HMA is so volatile and unpredictable with regards to failure, is it used on lots of canopies out there or just for a select few of the 'Dodge-Vipers'? I could see some applications in high-performance swoop competition to try and get a little bit more out of the canopy, but the average skydiver that I know can't afford to pay for a reline several times per year on their fun-canopy. I guess it would be application-specific? Here's some information on various line types that I received from Simon at Icarus. --- Vectran, Spectra and HMA VECTRAN Advantages: Will maintain its trim qualities over the life of the line-set. Disadvantages: Will wear faster than Spectra and will require replacement at around 500-700 jumps on the suspension lines and 250-400 jumps on the lower control lines. SPECTRA Advantages: High wear resistance. Lines will last 1000 jumps+. Disadvantages: Will loose its trim qualities RADICALLY. As an indication, a Spectra line set with 500 jumps will have control line shrinkage of between 5" & 8", the outboard A lines will have shrunk 3" to 5" and the trim across the span is likely to be out by 2" to 4". The canopies performance will start to become effected in only 100 jumps. As a result, Spectra is not recommended on high performance canopies. The line set will need replacing at least as frequently, or more frequently than Vectran due to shrinkage. Note: This is not an issue on low performance canopies. HMA Advantages: Same trim advantages as Vectran. Has a smaller diameter than Vectran offering less drag. (Note: if the canopy is direct lined like the XAOS, there is NO drag reduction due to the additional suspension lines). Disadvantages: Will wear faster than Vectran and have a life expectancy of 200-400 jumps. WILL BREAK WITHOUT WARNING. ICARUS WILL NOT BUILD PRODUCTION CANOPIES WITH HMA FOR THIS REASON. --- pull & flare, lisa My website is boring I am the Bytch, and the rest of you are not. (apologies to Bruno for stealing the tag line...) Quote Share this post Link to post Share on other sites
PhreeZone 20 #14 January 30, 2003 HMA is currently only in production on the Xaos line of canopies I believe.Yesterday is history And tomorrow is a mystery Parachutemanuals.com Quote Share this post Link to post Share on other sites
r2hubert 0 #15 January 30, 2003 Is there a way to know what kind of lines I have just by looking at it. After reading all this I'm kind a concern what kind of line I have on my canopy. Pictures of different lines will be a great help. Thanks. -- Renaud SMA #9 "Mind is like parachute. It only functions when it's open." Quote Share this post Link to post Share on other sites
Watcher 0 #16 January 30, 2003 And the rest of the ground zero canopies (Nitron, Synergy, Fusion). They did well on my Nitron. Jonathan Quote Share this post Link to post Share on other sites
Watcher 0 #17 January 30, 2003 http://www.aerodynamics.com/Ground_Zero/PAGES/xaos21.htm Half way down the page, there is a picture. Dacron is white very thick, spectra is white thinner weave. Vectran starts wheat colored, then gets more greyish. Then HMA is more of a light brown and stays that color very thin. Most canopies have spectra, Crossbraced tends to have Vectran, HMA on Precision's new Ground zero canopies, older canopies that are really large tended to have Dacron to be slowly phased out by spectra. Jonathan Quote Share this post Link to post Share on other sites
billvon 3,085 #18 January 31, 2003 >not a realistic option I did it; it works fine. Another plus is that dacron doesn't shrink so there's one less thing to worry about trim with. Quote Share this post Link to post Share on other sites
masher 1 #19 January 31, 2003 QuoteCross-post from Bytch in the 'Incidents' forum. Will loose its trim qualities RADICALLY. As an indication, a Spectra line set with 500 jumps will have control line shrinkage of between 5" & 8", the outboard A lines will have shrunk 3" to 5" and the trim across the span is likely to be out by 2" to 4". The canopies performance will start to become effected in only 100 jumps. As a result, Spectra is not recommended on high performance canopies. The line set will need replacing at least as frequently, or more frequently than Vectran due to shrinkage. Note: This is not an issue on low performance canopies. Just wondering... Would it be possible to 'pre-jump' the lines. Stretch them, or shrink them, so they don't do it (as much) on your canopy?-- Arching is overrated - Marlies Quote Share this post Link to post Share on other sites
TitaniumLegs 8 #20 January 31, 2003 Depends on what you mean by lower steering line. If you mean from the brake setting point to the toggle, (PD calls this the brake-to-toggle line), that isn't enough. The Vectran steering line on my EXTreme FX 99 failed at the top of the upper part of upper finger trap that forms the brake setting. PD calls the line from the cascades to the brake setting the lower steering line. From my experience, you need to replace that too. The bottom couple feet of it get almost as much friction as the brake-toggle line. You can replace the steering lines with Spectra, but then you're subject to shrinkage. Most shrinkage happens in the earlier part of a line's service (or so I was told by one of the manufacturers). So do you leave extra to allow for shrinkage? By the way, there are two common ways to construct a break setting loop. Only one of them is really a "cat eye". With a cat eye, the LST and BRK-TOG are one line, and a very short line has both end fingertrapped into the steering line to form the cat eye. The advantage is that if one side of the cat eye fails, you don't lose the whole steering line. The other way to construct it is with two separate lines both fingertrapped such that the loops chain the lines together. The loop on the line you want to lock (the upper of the two in the case of steering lines) is made large enough to accommodate the tab on the steering toggle. The upper trap has the loop so the pressure of the tab is on simple line, rather than the point where the fingertrap enters the line. This type of brake setting seems more prevalent, although I’m not sure why. A third way to make this connection would be to finger trap two lines straight into each other. This isn’t used since it puts the pressure of the toggle tab on the point where the upper line enters the lower line. The A-B and C-D cascades are usually made by running one line straight into the other, but there is nothing putting pressure on the fingertrap. On the subject of wear: The worst wear seems to happen at a discontinuity in the line: - Where the line tapers over the end of a finger trap - Cascades - Knots (always check your steering lines for knots and untie them before packing and jumping the rig! Knots weaken the lines and are a source of abrasion as the get whacked by the slider and keeper ring). One problem with wear on certain line types, especially Vectran, is that as the line starts to fray, the loose fibers get pushed into the gaps in the weave thus hiding them. It hadn’t occurred to me until this thread, but wax would obviously tend to hold fibers down as well. Some people call this "glazing" or "blazing". The point is that it is harder to tell with Vectran. This is what got me in trouble. Not knowing any better, I assumed that the wear characteristics of Vectran couldn’t be worse than Spectra, and that wear would be as obvious. The manufacturers would never introduce a product that was worse than the previous, would they? Seems they believe dimensional integrity is more important than structural integrity. Well, OK, to be fair, it was still a fairly new product and they may not have had all this figured out yet. The result is that my left steering line failed at the tip of the upper finger trap of the brake setting loop. You would expect a line to fail during deployment or unusual circumstances like a collision. We can deal with that if we’re high enough. When you’re coming out of a high-speed dive, just slightly in the corner, on a cross-braced tri-cell loaded 2:1, and your line decides to say goodbye about 2 seconds before impact, by the time you figure out what to do about it, your legs are already broken and you’re about to hit for the second…third…fourth…fifth time. The manufacturers now recommend replacing the steering lines every 300-600 jumps. I think that’s a little optimistic as mine had less than 300 jumps. For perspective, I’m not a rigger. I had to learn this the hard way. I was hoping nobody else would have to. This is the third accident I know of. The second was fatal. (See http://www.skydivingfatalities.com/ Look up non-US, 2001 #23) That’s what comes to mind for now. I may have more to say later. Peter D-19246 and some other stuff PS: Now you know why I’m Titaniumlegs… (>o|-If you don't believe me, ask me. Quote Share this post Link to post Share on other sites
hookitt 1 #21 January 31, 2003 Hey Peter, Thanks for piping in. Love ya man. TimMy grammar sometimes resembles that of magnetic refrigerator poetry... Ghetto Quote Share this post Link to post Share on other sites
dbattman 0 #22 January 31, 2003 From the PA website on the Xaos canopy. Quote Another area of concern in the development of the Xaos and other Ground Zero canopies was to find a material to use in suspension lines that would not only yield a lower coefficient of drag but also a material that could tolerate the friction of the slider for the duration without detrimental effects. Unfortunately, the results of controlled testing for durability of Vectran line were not manifested in Vectran's widespread and common use. On more than one occasion, a Vectran control line would snap at the most inopportune time (on the landing flare) and with high performance canopies, this is absolutely not acceptable. Users of canopies with Vectran line must inspect their canopies before every jump, and monitor the wear of both the suspension lines and the control lines. With the Xaos-21 and other Ground Zero canopies, Precision is utilizing a fiber known as HMA for suspension and control lines. HMA is an acronym for High Modulus Aramid fiber. Our experience during the past two years indicates that HMA line not only packs smaller, it also tolerates the slider's friction quite remarkably, while at the same time retains its linear stability as well as Vectran. Xaos-21 canopies (and other Ground Zero canopies) each contain three different sizes of HMA line including 352, 440, and 946-pound tensile strengths. The braided diameter is smaller than either Spectra or Vectran. Perhaps it is time to begin searching for a new material, at least for control lines. I know several people who would agree- they're out in the waiting room. Quote Share this post Link to post Share on other sites
PhreeZone 20 #23 January 31, 2003 Is that from PD or is that from PA? And can you provide a link to that page?Yesterday is history And tomorrow is a mystery Parachutemanuals.com Quote Share this post Link to post Share on other sites
dbattman 0 #24 January 31, 2003 Here's the clicky link. Go down about 2/3. http://www.aerodynamics.com/Ground_Zero/PAGES/xaos21.htm Quote Share this post Link to post Share on other sites
apoil 0 #25 January 31, 2003 QuoteHMA is currently only in production on the Xaos line of canopies I believe. The entire ground zero line uses HMA. At least the Nitron, HP non crossbraced elliptical does. The Nitro and Blade in germany use HMA. In fact it was the import of the Nitro as the Nitron that brought HMA with it. They are an outstanding line material. I wouldn't jump a canopy without it. I've seen them worn. They wear visibly. Not like spectra, but if you keep track of jumps and are prepared to change them they aren't likely to suddenly snap on you. But that means not throwing your canopy to the packers and walking away for 400 straight jumps. You have to actually look at your gear to see what's going on with it. Quote Share this post Link to post Share on other sites
