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mmittelman

Line Dump cause

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I had a bad last opening of the day on Sunday. I believe it was a line dump but would appreciate input or suggestions, as I received what is probably a minor concussion and lacerations to my neck, so in short it wasn't fun.

My Sabre2 190 has always sniveled, whacked, or both. I have almost 200 jumps on this canopy. On my last jump of the day I had an uneventful skydive. I tracked off and did my usual wave an pull. I instantly felt my risers crossed behind my neck and my head forced forward with a lot of force. The canopy opened very hard, adding to the impact. After that extremely hard opening, my canopy opened instantly, so I don't think it was line twists. I was knocked pretty hard and was seeing stars, it took a lot of effort to land back at the DZ safely, and I was groggy for a day.

A few notes:
- My stows can be a little short, maybe 1.5 inches instead of 2.5
- I always seem to have either too much line remaining or too little when I'm done stowing, and I haven't figured out which is worse

So... any thoughts? I don't want another opening like that one.

Any feedback would be greatly appreciated.

- Mike

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I believe it was a line dump



Line dump is when line stows release pre-maturely, but the canopy remains inside the deployment bag until line stretch. This will have almost no impact on how the canopy opens

Bag strip is when the locking stows release pre-maturely and the canopy comes out of the deployment bag prior to line stretch. This can cause extremely hard opening, injury and/or canopy damage.

I have asked for video of bag strip on a sport rig before and no one has ever come forward with any. I have video of some extremely hard openings that were not caused by bag strip or line dump. I think people blame bag strip or line dump for hard openings when that isn't the cause.

#1 cause of hard openings, I believe, is the slider not being against the slider stops during deployment. During packing, it is easy to allow the slider grommets to slide down the lines, off of the stops, an inch or more. This will cause a hard opening.

Take a look at a reserve free bag, 2 locking line stows only. The rest of the lines are in a pocket. I have deployed a number of mains out of a fee-bag style bag without a change in opening characteristics. Essentially, it is line dump on every deployment.

Derek

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Line dump is when line stows release pre-maturely, but the canopy remains inside the deployment bag until line stretch. Bag strip is when the locking stows release pre-maturely and the canopy comes out of the deployment bag prior to line stretch.



Derek, I (and I think many others) have described "line dump" as having all the stows release, in which case there will probably be "bag strip" too.

To be thorough perhaps we need to describe 3 situations, 1. only the "normal" stows releasing, 2. lines and locking stows releasing, and 3. both of those plus bag strip.

But this may cause even more confusion. You know how people are so eager to latch on to some new explanation or answer and then it gets spread around (correctly and incorrectly).

Your explanation of reserve freebag stows being released suddenly is a good one, and explains that the locking stows are the really important ones.

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Would bag strap explain the risers crossed behind my neck?



No, and I think it is very unlikely you experienced bag strip. Again, I have asked if anyone has video of bag strip on a sport rig and I have yet to every see video of it. It is very rare.

The bag can spin, especially if one line group snagged on the bottom corner of the reserve container. If you still had excess speed from a non-flat (diving) track, one shoulder lower than the other, one leg strap tighter than the other, one leg strap farther down your leg than the other, etc.

While packing, ensure that the slider grommets are against the slider stops. Keep them there with your knees not on the grommets (which damages the fabric and actually moves them away from the stops) but on the slider material above the grommets. Make nice even line stows. Make sure to leave 18+ inches of line, neatly stowed, from the last stow and the links. Be sure your hips are square with the horizon and shoulders even during deployment. Work on flat tracking, where you fall rate is slower than your normal belly fly speeds. Deploy after coming out of the track and slowing your forward speed but before your vertical speed picks back up to normal again. Don't double wrap rubber bands. They simply do not need to be that tight. I had a bag lock on a tandem from double stowed bads and recently had to re-pack someone's reserve after a bag lock from double-wrapping the rubber bads.

Derek

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I was getting very inconsistent openings on a saber 210. Eventually I ended up reading PD's packing instructions and finding that few people (myself included) know that they have a specific way you're supposed to pack them. Basically a camera pack.

So far in the last 4 jumps it seems to have made a big improvement. Some around my DZ have said that the sabre/sabre2's are known for either long snivels or brutally hard slammers. Most did not know there was any different packing procedure. Are you tucking the nose in or rolling 4 cells on each side and letting it hang?

-Michael

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I want to understand a similar concept about linedump/ bagstrip. I would think that if your locking stows are tight enough, it really would not matter much if the other stows are slightly looser because the slack in the lines would be taken out before the locking stows release. So, even if the other stows release prematurely, as long as the locking stows are tight, you should still have a fairly normal opening (assuming everything else is in order).

Comments?

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It is unlikely you had bag strip/line dump. The results of such an event can be destruction of the canopy, harness or risers, and is exceedingly rare.

It is more likely that you had your garden-variety hard opening. This can be caused by not seating the slider against the stops, opening in a track, opening with a shoulder low etc but can sometimes just happen.

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Did you buy the canopy new or used? I'm just wondering because some of the original Sabre 2's have been replaced by PD, mine included.
She is Da Man, and you better not mess with Da Man,
because she will lay some keepdown on you faster than, well, really fast. ~Billvon

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- I always seem to have either too much line remaining or too little when I'm done stowing, and I haven't figured out which is worse



Too little is worse, and is most likely the cause of your line twists (your risers crossing qualifies as line twists).

First off, why are your stows too short? If you are the one making the stows, just make them longer.

Additionlly, the length of your lines, and the size of your bag never changes. Figure out what size line bight, and what number of stows will get you closest to the corrrect amount of line slack when you're done. Simply repeat this procedure each time you pack.

Packing is not, and should nto be a random event. You need to develop a pack job for your rig that results in a neat, and correct pack job.

How wide you make your canopy before you fold it will depend on the width of your bag. How big you make your fold will depend on the depth of your bag.

How you stow your excess steering line will depend on the amount of line, and type of line stow your risers are equiped with.

How big and how many lines stows you make I already mentioned earlier.

How much bridle you leave in between the pin and pc pouch will depend on the size of your rig and placement of your pouch.

How you fold your PC will depend on the size of the pouch and the size of the PC.

All of these factors are individual to your rig, and it's up to you to develop the techniques for making all of these parts work together in the best way possible.

Pay attention to these areas, and note is you need a little more stuff here or a little less stuff there. None of this should be random, or variable from pack job to pack job.

Having a system in place will let you pack neater, and faster with improved reliability.

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Don't double wrap rubber bands. They simply do not need to be that tight.



Hey hook, how tight do you think they need to be? I conducted some experimentation with a fish scale, and found that with some line configurations, the only way I could get the pull force the manufacturer recommended was to use large bands and double wrap.

I understand the whole 'in theory' you could free stow all the line except for the locking stows, and in fact jumped during a time when we did exactly that! But I'm guessing there's a reason the manufacturer recommends 8-12 pounds of force on the stows. And even small bands on a microlined 7 cell canopy won't produce that kind of pull force...

"If all you ever do is all you ever did, then all you'll ever get is all you ever got."

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. Some around my DZ have said that the sabre/sabre2's are known for either long snivels or brutally hard slammers.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>.

There are vast differences between the two canopies and vast differences between how you pack the nose on original Sabres versus Sabre 2.

Back when the original Sabre was introduced, it was fashionable to show a pilot chute at 2,000 feet and hardly anyone jumped with cameras strapped to their heads, ergo original Sabres open quickly. Also remember that original Sabres were introduced before Cypres, making low openings more a "point of debate" than the cost of a new cutter, reserve repack, etc.
Hee!
Hee!
Yes, original Sabres open hard. So many riggers sewed additional pockets, flags, etc. onto Sabre sliders, that eventually the factory made larger sliders standard.
When packing original Sabres, roll the bejesus out of four nose cells on the left side, then roll the bejesus out of four nose cells on the right side. Stuffing these rolls deep into the center cell fell out of fashion more than a decade ago.

On the other hand, Sabre 2 was designed to open soft enough for camera men, so you can leave the nose open, etc.
IOW, Sabre 2 is far more tolerant of sloppy packing,

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Hey hook, how tight do you think they need to be?



I think they need just tight enough to hold the lines and make for an orderly deployment. The concern is wrapping lines around a main flap or around another line stow. You can make small bands tighter by installing them twice. They are lark's-headed onto the d-bag, and then you wrap them again before pulling them tight. Same thing works for large rubber bands. I learned that trick from tube stows.

Derek

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I had a bad last opening of the day on Sunday. I believe it was a line dump but would appreciate input or suggestions, as I received what is probably a minor concussion and lacerations to my neck, so in short it wasn't fun.

My Sabre2 190 has always sniveled, whacked, or both. I have almost 200 jumps on this canopy. On my last jump of the day I had an uneventful skydive. I tracked off and did my usual wave an pull. I instantly felt my risers crossed behind my neck and my head forced forward with a lot of force. The canopy opened very hard, adding to the impact. After that extremely hard opening, my canopy opened instantly, so I don't think it was line twists. I was knocked pretty hard and was seeing stars, it took a lot of effort to land back at the DZ safely, and I was groggy for a day.

A few notes:
- My stows can be a little short, maybe 1.5 inches instead of 2.5
- I always seem to have either too much line remaining or too little when I'm done stowing, and I haven't figured out which is worse

So... any thoughts? I don't want another opening like that one.

Any feedback would be greatly appreciated.

- Mike



I think your description explained itself. Ive seen plenty of video where a line twist caused a hard opening. If the line twist is near the top of the canopy it can prevent your slider from catching air, think about the grommets being held together by the twist. the canopy starts inflating and because the slider is held closed by the small lin twist it bangs open. If you have a lot of twists they will hold the slider up a little, but with a 90 or 180 twist it offers verry little resistance to the slider and the opening ends up very hard.


Ray
Small and fast what every girl dreams of!

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I guess all of this thread has been about canopies and lines, but I'm seeing the lacerations to your neck and how you said it looks like you hung yourself.

That reminds me of a bad jump I had once. It was the chest strap that my neck ended up in, which crushed my throat a bit (my larynx was damaged, and I couldn't talk for a week). I had a laceration from ear to ear around my neck.

I packed myself a hard pack job which caused the hard opening. I think that I probably managed to get one steering line around one of the line stows, because that line broke on opening.

But the bigger problem was my container. It was too small for me. And it was older, and not so well maintained, so the leg straps didn't stay tight on the hard open. They slid almost all the way out - if it wasn't for the doubling at the end of the straps, they may have come off completely. That caused me to sink fast in the container, and my neck went right into the chest strap.

A few months later, a jumper in Europe died from almost the same thing.

The solution was my rigger sewed some extra material into the leg straps to keep the friction high enough that the legs straps no longer loosened on openings. The better solution was a new rig that fit me properly ;)

Make sure your container fits, and also that your leg straps don't loosen on opening. Make sure the friction adapters on your leg straps are in good condition. Now's a good time to start making friends with a rigger and learning as much as you can about your gear.

Trapped on the surface of a sphere. XKCD

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The difference you mention between line dump and bag strip is technically valid and accurate, but since bag strip involves line dump on the locking stows it's probably reasonable to use either term in most discussions of main pack jobs. It could depend on whether you wish to emphasize the cause or effect.

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I have asked for video of bag strip on a sport rig before and no one has ever come forward with any.



About a year and a half ago I saw a video that clearly showed this. The owner of the video offered to make a copy after he landed from his next jump. Unfortunately the tape did not get cued up properly before that jump and the video was erased. I was devastated.

There might be numerous other videos out there showing bag strip, but unfortunately it can be hard to recognize. In the video mentioned above the bag strip occurred just before the bag left the top of the frame. If the videographer had been a few feet closer it might simply have looked like a hard opening with no clearly discernible cause.

Even during a normal deployment, the time elapsed from pilot chute release to the d-bag opening might only be 0.5 seconds (15 frames of NTSC video). By it's very nature, bag strip could reduce this time even more. If you don't analyze the video frame-by-frame the bag strip might easily be missed. The video I saw had already been reviewed a number of times by several very experienced jumpers who had not recognized the bag strip.

It doesn't surprise me that no one has fulfilled your request, although it's unfortunate. I would love to see another example on video, too! But for the reasons I just mentioned, a lack of such video doesn't necessarily tell us much about how often bag strip occurs.

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from Billvon: It is unlikely you had bag strip/line dump. The results of such an event can be destruction of the canopy, harness or risers, and is exceedingly rare.



Bag strip can cause that type of catastrophic damage, but the severity of the effects might be influenced by exactly how far the bag is from the end of the lines when the canopy dumps out: if the canopy is closer to the jumper when the bag strip occurs it will have more time to inflate before reaching the end of the lines, with potentially more devastating effects. In the video I saw the bag strip occurred relatively close to the end of the lines, and the opening was extremely hard but did not cause injury or equipment damage. As with anything else, there are variables involved and varying degrees of effects.

People sometimes describe a quick inflation, where the canopy comes out of the bag normally then goes "whack!" But I've often heard people describe an "instant opening," where the canopy seems to open hard and fast immediately after releasing the pilot chute. Doesn't bag strip seem the most likely explanation for these cases where there's a dramatically reduced time between P/C release and snatch force?

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from mmittelman: Would bag strap explain the risers crossed behind my neck?



That could possibly be a result of bag strip. If the canopy leaves the bag prematurely it probably won't remain neatly on heading while it reaches the end of the lines and inflates.

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from Hooknswoop: Don't double wrap rubber bands. They simply do not need to be that tight.



I recognize there are differing opinions about this, but it should be noted that the manufacturer of the canopy in question recommends double-wrapping if necessary to ensure that the stows are tight enough, particularly the locking stows. I've made thousands of jumps with all stows double-wrapped on a wide variety of canopies, including test jumps for that particular manufacturer where the openings were videotaped and analyzed. Many other jumpers and professional packers double-wrap all stows and consider it an important step in minimizing the risk of hard openings. There are also a significant number of people who have eliminated problems with hard openings by double-wrapping their stows.

The most effective way to help someone eliminate opening problems is to actually look over their gear with them and then see how it is being packed. Without being able to do this, the first and best piece of advice we can give is to make sure all manufacturer's recommendations are being followed.

Mmittelman, you said up front that you usually make your stows short, only 1.5". PD believes that short stows promote line dump and specifically state this in their packing instructions. Your first course of action should simply be to make your line stows between 2.5" and 3" as they recommend, and see if that helps.

For more info see http://performancedesigns.com/docs/hrdopn.pdf.

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"Don't double wrap rubber bands. They simply do not need to be that tight. I had a bag lock on a tandem from double stowed bands and recently had to re-pack someone's reserve after a bag lock from double-wrapping the rubber bads."



I don't want to hijack or anything, but after the first 4 linestows I often do a double wrap on the linestows because I think that if I don't, the lines may become undone or too lose. Is this a bad thing?
"In a mad world, only the mad are sane"

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I had a bag lock on a tandem from double stowed bads and recently had to re-pack someone's reserve after a bag lock from double-wrapping the rubber bads.



Just to be clear, the information in my last post about double-wrapping was in reference to using standard rubber line stow bands on sport rigs. Also, I personally use large rubber bands most of the time. I don't double-wrap stows on tandems and I believe that UPT specifically recommends against it. I have seen one bag lock on a sport rig that appeared to be caused by double-wrapping, but the jumper was not using standard rubber bands.

Can you provide more information about the bag lock you mentioned on the sport rig? Standard rubber bands? Large or small? Size and condition of pilot chute? Was the bag actually found with a "stuck" line stow? Any video of the opening? I've heard one or two other people say they've seen this happen, and use that as an argument against double-wrapping, but I'm not convinced there weren't other factors involved in those cases.

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the first and best piece of advice we can give is to make sure all manufacturer's recommendations are being followed.



The last time I followed the manufacturer's instructions without questioning the, it almost killed. PA recommended packing my FX-70 w/o setting the brakes. It folded in half, forwards, and spun so fast I could not lift my arms to the handles and almost blacked out.

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Can you provide more information about the bag lock you mentioned on the sport rig? Standard rubber bands?



For the sport rig and the tandem, standard rubber bands.

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Large or small?



Large.

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Size and condition of pilot chute?



Nothing wrong, but not new tandem drogue, and a very new PC on the sport rig, less than 50 jumps.

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Was the bag actually found with a "stuck" line stow?



Yes, both the sport rig and the tandem. In both cases, the double wrapped bands held with more force than the drogue or PC could overcome.

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Any video of the opening?



No.

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I've heard one or two other people say they've seen this happen, and use that as an argument against double-wrapping, but I'm not convinced there weren't other factors involved in those cases.



I looked at both cases very hard and could not find any other cause for the bag locks.

The tighter the stows, the more the bag rocks back and forth, possibly causing it to spin and if they are tight enough, a bag lock.

Derek

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I don't want to hijack or anything, but after the first 4 linestows I often do a double wrap on the linestows because I think that if I don't, the lines may become undone or too lose. Is this a bad thing?



Try smaller rubber bands.

I have deployed numerous canopies with only 2 locking stows (the rest of the lines in a pouch free-bag style) and no ill effects on the opening.

Derek

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