RippedCord 0 #1 September 23, 2003 How many of you have had to cutaway because of line twists? Was it because the canopy was elliptical or "high performance?" I've always (in the 75+ days I've been doing this) thought that line twists were no big deal. The following quote from 'happythoughts' in the How do you get to thousands of jumps with no cutaways? thread really surprised me. QuoteAbout every 80-100 jumps, I get twisted up. I blame it on bad body position. I still jump an old Sabre. When it twists up, it continues to fly straight and level while I can kick out the line twists. If an elliptical twists up, it generally starts spinning like a &^$% and heads for the ground, you have to chop it quick. AMDG Quote Share this post Link to post Share on other sites
quade 4 #2 September 23, 2003 In the 75 or so days you've been doing this, you haven't jumped a high-performance canopy yet -- right? Anyway, to me at least, it's no surprise at all that people that jump higher performance, elliptical canopies have more cutaways due to line twists. That's not to say it's no possible on big ol' 7-cell boat canopies, but a heck of a lot less frequent. I credit my 1647 jumps and no cutaways to a combination of factors, none of the least of which is gear selection based on reliability and consistancy rather than the flavor of the day and swoopability.quade - The World's Most Boring Skydiver Quote Share this post Link to post Share on other sites
Hooknswoop 19 #3 September 23, 2003 Line Twists: Line twists have gone from a common nuisance to a common malfunction on small, highly loaded elliptical canopies. There are techniques for reducing the chances of incurring line twists and correcting them if you do get them. The first step to handling line twists is to prevent them in the first place. The looser the chest strap is the wider the 3 rings will be on deployment, which makes it harder for line twists to develop. Of course, be sure that your harness is secure enough to keep you from sliding out of it. Make sure your leg straps are even. For free flyers, a piece of bungee or elastic between your leg straps will help keep the leg straps from creeping to the back of your knees and keep the risers loaded evenly on deployment. Evenly loading the harness on deployment by keeping your hips and shoulders level with the ground will help keep the canopy opening on heading. A pre-mature brake release can easily cause line twists and limits your ability to steer away from others immediately after deploying. When stowing the lines on the deployment bag, keep the stows neat and even. Refer to your owner's manual or call the manufacturer for the correct size rubber bands. Leave 12 to 18 inches of excess line between the side with the least amount of excess and the corner of the reserve container. This will prevent the lines from hanging up on the reserve container and twisting the deployment bag as it leaves the container. A worn out pilot chute can spin on deployment, which can spin the deployment bag. Replace a pilot chute that has holes in the fabric or tears in the mesh. Re-line a canopy that is out of trim. If one end cell “A” line has shrunk more than the opposite side, the canopy will open turning in the direction of the shorter line. Also, if one steering line has shrunk more than another or has excessive twists in the line, the canopy will want to turn in the direction of the shorter line on opening. Take care when setting the brakes of your canopy and take out any twists in the steering lines, which shorten the line. Pulling the slider down to the 3 rings can prevent self-induced line twists and most importantly, smooth control inputs. Even if you take all possible precautions, line twists still happen. If you find yourself under canopy with line twists and the canopy is flying straight, simply kick out of the twists. Make sure you are kicking in the right direction. You can also twist the risers to bring the twists closer to you and reach above the twists for leverage to get yourself out of the twists. Let's say that you weigh 170 lbs. And that when you open, you have 60% of your weight on one leg stap and 40% on the other. So the harness shifts on opening, so that the links are not even. The canopy begins to spin, creating spinning line twists, i.e. harness steering. As the spin rate increases, so do the "G" forces. Initially you had 102 lbs. (60% of 170 lbs.) in one leg strap and 68 lbs. in the other leg strap, a 34 lb. difference. Now, because of the spinning, you are pulling 2 "G"'s. Now in one leg strap there is 204 lbs. and 136 lbs. in the other, a 68 lb. difference. If the canopy is spinning with line twists, react quickly, look up at your links and make them even by shifting your weight in the harness. Be careful not to overdo it and cause the canopy to spin in the opposite direction. At the same time, make sure your brakes are still set. You can use any reference you want, but I’ve found using the links to make the risers even is easiest. The canopy should stop spinning and fly straight. Now kick out of the line twists. Again, make sure you are kicking in the right direction. A canopy that is spinning in line twists loses altitude rapidly. It is critical to maintain altitude awareness. If you are on your back, it is because as the canopy opens and you sit down into the harness, you are in a de-arched and stable back-to-earth free fall position. The speeds generated by a spinning canopy can be close or even overlap with free fall speeds. The same aerodynamics forces that would put you back-to-earth in free fall will put you back-to-earth under a spinning canopy. Remember under a highly loaded elliptical, you don’t have much time depending on your pull altitude and you do not want the twists to include the excess cutaway cable in the back of your risers. This can make for a difficult or impossible cutaway. Riser inserts have been proven to reduce the pull force during a cutaway from line twists. Derek Quote Share this post Link to post Share on other sites
Miami 0 #4 September 23, 2003 QuoteAnyway, to me at least, it's no surprise at all that people that jump higher performance, elliptical canopies have more cutaways due to line twists. The two cutaways I have had over 3200 jumps have both been on tandems. Surprisingly most crossbraced canopies fly straight with line twists, or at least the 93 fx I had did. I haven't had twist on my Xaos yet, but I have been told by other Xaos owners that they tend to fly straight in twists also. (of course now that I said that I'll probably spin up and chop this weekend!)Miami Quote Share this post Link to post Share on other sites
AggieDave 6 #5 September 23, 2003 Check the "how Aggie almost died" thread in this forum...you'll have to search, since its a few months old, but that'll give you an interesting story about line twists with a fairly loaded elliptical canopy (1.7:1).--"When I die, may I be surrounded by scattered chrome and burning gasoline." Quote Share this post Link to post Share on other sites
RippedCord 0 #6 September 23, 2003 Clicky: What not to do (how the Aggie almost died) AMDG Quote Share this post Link to post Share on other sites
PhreeZone 20 #7 September 23, 2003 Guy at my DZ got a new FX 116 - Choped on the first jump due to spinning line twists. Corn field ate the canopy Yesterday is history And tomorrow is a mystery Parachutemanuals.com Quote Share this post Link to post Share on other sites
happythoughts 0 #8 September 23, 2003 QuoteI've always (in the 75+ days I've been doing this) thought that line twists were no big deal. Your original statement was that you thought that line twists were no big deal. They generally aren't. However, the post by Hooknswoop makes a lot of good points, I quoted it below. If you are spinning, or on your back, then they are. You can be out of control and your canopy is doing exactly what the steering line input says to do, dive to the ground. Then they are a big deal and you'd better get rid of it. Until you have some experience, fly something docile. You didn't go from a bicycle to some crotch-rocket motorcycle at 8 years old, same with canopies. Take some time, take canopy flight classes, scare the pee out of yourself once or twice. Be safe so I get to meet ya. Hooknswoop: QuoteA canopy that is spinning in line twists loses altitude rapidly. It is critical to maintain altitude awareness... The speeds generated by a spinning canopy can be close or even overlap with free fall speeds... Remember under a highly loaded elliptical, you don’t have much time depending on your pull altitude and you do not want the twists to include the excess cutaway cable in the back of your risers. This can make for a difficult or impossible cutaway. Quote Share this post Link to post Share on other sites
sducoach 0 #9 September 23, 2003 Three cut a ways. One Spectre 150, one Apache 180, one PC. Zero on elip's. All were packing errors, one mine, two "others". However, I have experienced many more line twist on the elip's. Body position is much more critical however again, Altitude awareness if primary, secondary on elip's, when the nose breaks down, it's time to go no matter what the altitude. The canopy is the pivot point of the "spin" while the jumper is the "energy" required to continue the spin. As the canopy breaks down it begins to accelerate very rapidly and the "energy" increased due to "g" loading and effective mass of the jumper. Both of which can overcome your ability to cut a way, move, or remain "awake" for the crash. Most elip's can recover as long as there is adequate altitude and the nose does not break downhill. Blues, J.E.James 4:8 Quote Share this post Link to post Share on other sites
Garycal 0 #10 October 5, 2003 Iuse aDiablo 190 & have had several line twists but never had to dump it. Body position at pull time is a little more imporant i have found myself looking over my right shoulder this causes my left shoulder to dip a little thats when i get the twists but i never have had it go into a spin.It could be dumb luck or the light load i put on the canopy 0.947 Quote Share this post Link to post Share on other sites
Aviatrr 0 #11 October 5, 2003 Quote or the light load i put on the canopy 0.947 That is a HUGE factor in how the canopy will react to line twists, IMNSHO! Mike Quote Share this post Link to post Share on other sites
ryoder 1,590 #12 October 6, 2003 QuoteIuse aDiablo 190 & have had several line twists but never had to dump it. Body position at pull time is a little more imporant i have found myself looking over my right shoulder this causes my left shoulder to dip a little thats when i get the twists but i never have had it go into a spin.It could be dumb luck or the light load i put on the canopy 0.947 I load my Diablo 190 at 1.2. I had 60 jumps on it w/o a spin-up, and was wondering what all the fuss of ellipticals and line-twist was about. Then on jump 61 I looked up to see line-twist. "No big deal", I thought, I've had that before. I started to kick out. Three seconds later I was on my back, pulling G's, and looking past my feet at the horizon going by in a blur. That was when the Diablo and I parted company. I now have about 200 jumps on it, and it has tried to spin up on two more occasions, but I was just BARELY able to kick out fast enough to catch it before got out of control. I also have about 100 jumps on a Samurai which I load at 1.4, which has never spun up, (knock on wood)."There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones. Quote Share this post Link to post Share on other sites
Garycal 0 #13 October 7, 2003 I will remember what you wrote and find out this next weekend if my looking over my right has any thing to do with the line twists Iam usally stable when i toss so i see on Sunday Quote Share this post Link to post Share on other sites
