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It’s been some more tension knots accidents recently, I believe it’s the only accident who don’t involve a pilot error (we know how to deal with line over by now) What can we do to prevent it ?
Since 2004 (and 550 jump) I have sew two folders inside my tail pocket on all my canopy in case it help to have cleaner line streaching, and if it doesn’t help, I don’t think that it make it worst.
But I don't think it’s enough, so I am thinking to do as some others friends and spray silicone on my lines, It should make them last longer and also increase the chance of a potential knot sliding out. I am looking for a non-styky product (not to collect dust), does anybody have a recommended product ?
I think also that there is less tension knots in sky diving than in base (Does anybody have stat about this, knowing that a loosy pack job can also be responsible of a tension knot), If it’s right, why ? The only thing I can think off is that in sky diving because of the benji loop (if you make them tight as recommende by PD), the line don’t come free as they do in base, wich possibly doesn’t produce enought slack to build a knot.
Then what about attaching inside the tail pocket 3 or 4 benji loop (cut in the middle length) in order to old few line loop? Did it been tested ? What would be the inconvenient ?
Thank’s for your thought
Christophe

In my experience, tension knots happen much
more frequently with older, furry, dacron lines.

SKY canopies rarely have dacron these days,
instead spectra line is slippery (less friction).

Staggered upper brake cascade may help. Try the outlaw, with no tension knots so far that I know.

While I have no issue with your modified tail pocket it will not prevent tension knots. Tension knots are traditionally formed at linestretch during the inflation stage of deployment, not in the tail pocket. Tension knots traditionally involve the control line cascade and the C/D cascade. Rapid deployments are known to contribute to the chance of tension knots. Skydiving has less tension knots than BASE due to the softer/longer snivel type openings. However, tension knots are the most common tandem malfunction due to extra control lines, heavier loads and drogue deployed canopies.
So what can we do to prevent tension knots? Pack neatly. I always clear my control lines below and above the slider in an effort to keep them from mingling with the C/D lines. When jumping terminal I actually place the slider mesh between the control lines and C/D lines to ensure separation. I actually think this is where painters tape can improve a slider up opening (even though I don't use it). When jumping terminal take the time to slow down enough for a comfortable opening. Opening at high airspeeds can cause problems.

I disagree. There is a lot the jumper can do to reduce the chance of tension knots.

Do not do this. I doubt it will be as effective as you think. It will also attract dirt and increase the chances of hard openings.

See above. Also it may just seem less likely because skydiving parachutes have more numerous malfunctions than BASE canopies. It may just seem like a BASE canopy gets more tension knots simply because it is one of the few malfunctions they are susceptible to.

This is old school. It was done in the past on early BASE rigs. We don't do it anymore. Don't go back to doing it.

Thank's to your points, there are some good infos, but I don't agreed with all. Sorry if my answer below sound a bit agressive, it would be easier around a beer

- I will keep my folders for sure. I really believe that some case of tension knots start there, and the main point is that neider of us can prove anything about it!
And by the way what is this "traditionally" word doing there, somebody have decided that things are happening this way and we cannot think diferents ? Do you have seen by any chance hundred of videos slow motion, tension knot showing that they NEVER start to build up in the tail pocket
Let's try to be open mind here, we have no prove of anything.

- I heard this argument over and over about silicone catching dust, I watch the canopy of a friend who spray it with silicone every 100 jump (700 so far) and it's doesn't attract dust at all. Did you test silicone somewhere by your self?
Your other point is right, if you have old lines it will speed up the opening, so it's not a good ideas with a canopy with allready a very strong opening. but that's also prove that the silicone is working

- I still believe that even with good packing you can end up in hospital not having done any mistake, and that make it the only case of accident of the type. You think you limitate your risk, "maybee", but are you sure you will never have one ?
Let's try to be open mind about solution.

Do you know why rubber band in tail pocket didn't work in the past ?
Don't forget that a the beggining people were making very few jump, so they had very few tension knots and it was not an issue for them. Now we base jump 100 time more, so it become a problem

Take care

Christophe

Tension knots are a problem, and we're actively seeking a solution. If anyone has good, high quality tension knot photos or video that they can provide we will add it to our database for study.

The best information that we have right now suggests that tension knots are most likely to occur during line stretch, when all of your lines go taut. Since your control lines are the longest, they go taut last and there's a brief moment in time when they are slack relative to the rest of the line kit. This is when we believe that tension knots are most likely to occur.

That said, managing your control lines is the best solution we're currently aware of with regard to tension knots. A tailgate (or similar method), slider-up, slider-down, or slider-off, should help reduce the odds of a tension knot...along with clean packing.

Line dump can create issues, but we cannot definitively say that it is correlated with tension knots. It's definitely correlated with hard openings though, which are a whole different problem and why we introduced the top loading tail pocket.

 

Just because Hank may have claimed to have packed the most 'perfect' packjob of his life does not make it necessarily a good pack job! Maybe all of his others are really shitty and that one was just less shitty!

Well said.

Just wondering how you have determined those factors are the cause of tension knots in skydiving. Shouldn't you also include the type of line being used and the wear on the lines? I believe that plays more of a role than a drogue or heavier wingloading would. I can maybe see the weight being an issue by tensioning the lines more quickly on opening thus not allowing any potential knots to come out during deployment but I can't really see a drogue playing a role. Can you explain how you think a drogue can contribute? Thanks.

I've had one tension knot in my BASE and skydiving career(4000+jumps). It was on a Pegasus220 skydiving with a wingloading at about .7. It had fat dacron lines that were nearing the end of their life and were noticeably fuzzy and worn and I think this was the main contributing factor for the tension knot.

Ditto Here

5700+ Deployments and only 1 Tension Knot
{pauses typing to knock on some wood} on a
very old tandem main with fuzzy dirty lines.

Tension knots are the thing in BASE that scares me the most. I applaud your efforts to try to reduce them.

Echoing what others have already said, dont spray shit on your lines or canopy. Its shocking what happens to nylon over time with things you dont even consider harmful to it.

I have never had a tension knot, but ive seen 5 in person over the years. Line dump is a cause that is usually attributable to sloppy packing, or tail pocket velcro wearing out. Apex has their style tail pocket, but I always wonder how many line dumps are from poorly stowed lines and become entangled and then cause the velcro to open. In this scenario, I can see a wad of lines getting trapped in the tail pocket itself if it is sewn shut like the apex model. Dont know if this a real or imagined fear, but I think being careful when closing the velcro is a better option.

Unequal length upper control lines have been a suspect, especially the extra 5th line on some canopies. This combined with dacron uppers that have wear seems to create an increased risk. I like the idea of using specta/vectran uppers. There is a DZ close to me that tried to get every jump it could out of tandem linesets before replacing them. They had a rash of something like 3 cutaways from tension knots in a week or two.

Ive seen multiple methods of dealing with tension knots tried with varying levels of success. I think pumping brakes to attempt to relieve the tension seems to be the best idea, but ive seen that done without any effect. Ive also seen them come out with just unstowing the brakes alone. Some of them involve a slow turn, some youre spiraling to your death rapidly.

Tension knots are such a rare malfunction, its hard to judge what is helping and what isnt. I think your idea with the tabs in the tail pocket has the potential to help, but I cant really say how much. Skydiving reserves use essentially the same line stowing system we do, and there doesnt seem to be a problem with tension knots.

One of the reason I always pack with clamps is that I can always assure there is tension on my lines continuously. Im not saying it helps for sure, but it makes me feel a little better.

In conclusion, tension knots are scary. Replace your uppers if theyre getting worn. If you dont know how to do it, find a local rigger that can show you how, its a good project to be able to do yourself.

but you can do an educated guess,
- the absolute majority of tension knots ive seen were all above the slider. we should see tension knots below, and also some involving the A/B lines if those would already build in the tailpocket. (the one or two videos ive seen that involve knots/entanglement below slider cant be called "tension knot" but rather clusterfuck.... and all of the time have a pretty clear reason. just give cam tracey a shout...)
- we probably would see more of them slider down if they would build in the tailpocket already.

so my educated guess is, its something that happens above the slider during when lines are out and getting loaded.

also to be noted, this odd malfunction where the bridle wraps/knots around the tailpocket could statistically occur more often the heavier and stiffer your tailpocket is, looking at your pictures its very light material, just wanted to say...


well, in base i guess we have the problem that theres little to no written documentation, and only a fraction of the jumpers is more than 10years in the sport, give it 20, or even 30 its getting scarce.
so theres a lot of ideas popping up with stuff that has been already tried out decades ago, and probably ditched for a good reason, but theres probably few people still around that know about it and know what the problem was back then... so some people will reinvent the rectangular wheel and probably find out again why the current mainstream round wheels ended up our current setup.


a good friend and older jumper told me this a few years back. this may seem harsh, but if you think a tension knot is the only thing thats currently not under your control youre mislead. i think theres a LOT of other stuff that can send you to the hospital or kill you even if you didnt do anything wrong.


well, first off, it can cause hangups. this is why we dont have rubberbands on (most) skydiving reserves (the pdf freebags eg. do have something remotely resembling (loose) elastic linestows). the single elastic that all of them have is the safety stow, and thats made in a way so that one side cannot lock the other side to prevent a total.

also to be noted, the idea with the additional flaps in the tailpocket has been out there for a really long time...
maybe one of the older guys here know why this disappeared again...

so now my two cents about tension knots. just thinking out loud here...

a lot of people seem to picture tension knots as "classic" knots, so something gets slack, forms a loop and catches some thing else in there.
so my current guess is (without anything to prove this), that its more like a line catched inside of a twist of other lines.

you know, when you walk up your lines for a propack, sometimes your fingers get stuck, forcing it doesnt help, one has to let go of the tension a bit and wiggle it loose.

the tension knots ive seen and collected videos of, all have the "knot" involving the brake cascade and one or more CD lines. while all lines besides the brake cascade want to spread to the same angle and the same distance, the brake cascade lines spread "sideways" in comparison to the other cascades, and at a different angle.
so my theory is that if there is a CD line getting inbetween the brakelines before canopy starts spreading and the brake cascade is not oriented in the direction its supposed to spread, the brake cascade would turn and probably twist the CD line with it, probably catching it there. as long as everything is under tension it would stay put.
so this is why once i have the slider up and everything tidied up i walk my brakelines from the rig up to the canopy and remove all "interweavings" of CD lines from the cascade and put the on the top of the other lines inside the slider grommet.

but i guess sooner or later we will get some good pictures, since gopros are now able to record at 4k, and theres going to be better cameras every year, so at one point someones going to be unlucky enough to catch a glimpse at a tension knot on his super hi res video...

friction seems to be a massive contributor to tension knots, hence more of them on fuzzy lines. dacron has a really high friction coeffecient, but then again, weve already seen tension knots on light canopies with spectra lines aswell. i wonder if were going to see some more with the vectran lines since they also have a really high friction coefficient.

so i was thinking about using spectra for the brake cascade on my canopies, but then again, weve seen them with spectra aswell...
as long as nobody is doing the proper statistics its hard to find what effect line material really has. (i guess we should ask canopy manufacturers? since they should have a rough idea of how many canopies with each kind of lines on are out there...)

so yeah, please everyone switch your cameras to 4k....
(attached a few pictures of various tension knots...)

take care!
hirschi

From my personal experiences and ongoing education in 15 years of career skydiving and rigging.

Definitely. Dacron is the worst.

Think of all the forces being applied to a drogue in freefall. The majority, if not the entire force, is applied to the DBag immediately upon release.

I've personally had at least 15 in 12000+ parachute rides. Couldn't even guess how many I have witnessed or repacked reserves from.

This is incorrect. Your control lines are not even close to the longest line when your brakes are set on opening. They are actually significantly shorter than the D lines. They are also one of the highest loaded lines during deployment while again the D lines are the least loaded.
I believe that this difference in length and loading of two lines in direct contact with each other is the biggest cause of tension knots.

You are welcome to continue trying all of your ideas. But as Hirschi already said, everything you have mentioned has already been tried before.

I wasn't there but I would say hangups/bag locks, off headings, slower deployments etc.

I understand and agree that what you say could easily be the cause of some tension knots. However I have seen your "Classic" version where the burn marks clearly showed lines looping upon itself into a knot . So I think both versions exist.

What are people's thoughts on building cascaded uppers for non outlaw canopys?

Have people tried and failed? Is this just a marketing gimic? Would it be to hard to recreate the proper tail shape?

First thank’s to all to your input, I learn a lot and change my mind on many points. Thank’s for your patience for my Franglish and my way to communicate. I put most of your point on the face book paralpinisme page and it’s been a lot of talk over it, mostly on the silicone aspect.

My conclusion so far are (I considere here just the way to prevent knots and what probably cause them) :

- Much more people are doing researche and are concern about tension knots that I thought and that’s good.

- They are no “absolute solutions” yet simply because there are not enought stats and image on what’s happening – and that there are probably few different scenario.

-Look like every body agreed that friction increase seriously the risk of tensions knots. it’s logical, as what happen probably is that a lot of tension knot build up, but most of them slide out, friction is what old them in place.

- So, spraying silicone on the line would definitely increase knots sliding out.
It would also by the way :
1) Decrease the tearing of the line and so increase their life time.
2) Decrease the risk of line dumb and increase the life time of the tail pocket.
3) Increase the speed of deployement with slider up, as he would go faster down (Not especially good but not a major problem.)

Critisize on using silicone have been serious and from most people :
- Silicone will collect dust and wear the line.
- Don’t spray chemical/ hydrocarbure over your line, it’s going to damage them.

But look like no one have tested it and that this just a general opinion and a cautious guess.
Guys, silicone would probably divise by at list two (just my estimation) the risk of tension knots, I believe that it deserve some serious testing !

Well, news are that I found out that there are more French people than I thought using hardware silicone on their line and they are all happy with it.
Second news is that 2 of them have to change their line and have already offert to give their old one to be tested and compare to other old one.
- Third news, I just learn that some guys use a silicone without solvants !
I will off course post the result here.
Thank’s again every one

Christophe Dubois

Cause: using lines to suspend pay load rather than a tractor beam

Possible contributing factors:
- line wear
- twisted brake lines
- bad packing
- cascade design / interaction with CD cascade

How to resolve:
- pump brakes
- pump riser
- stall canopy (worked for me)
- pull high enough to try above

Have there been any recorded knots on the Outlaw?

Yes, I have only outside GoPro video of it though.

- even on a low pull, stalling into the dirt is infinitely better than landing in a spiral.

 

Well, I find it incredible that I tell you that number of people in France are using it since years and that it's working and that you are not even curious or interrested about it!
We have professional chimiste that explain that Silicone is completely neutral and that it can be found without solvant, but you know better than all!
Talk about nerow mind people!
But nothing new under the sky, stupid people where saying that train will never work that Edison was a fake, ect, ect
Please make a favor and don't bother to reply
Christophe Dubois

I see no mention of the primary stow . I always check my brake lines for twists and wrap the primary stow how ever many times it takes to be good and tight.

You are right, a good primary stow is essential and to be very very tight, it's a recommendation as well from Stan of Atair canopy.
I personnaly use two rubber band as primary !
It help to straighten the line as best as possible before the slider go down -or that the canopy start to open.

Curious if your full stall was done with the risers or brakes ?

Id be interested in any stats on lineovers and if people stow their brakes on landing or while packing. Ive always been very paranoid of twists, and never stow on landing, but know many people that do. (I stow on landing in skydiving and have a shit ton of twists I have to take out every once in a while)

I don't think that to stow on landing protect you from twist, especially that most of time you are still in the jump.
I believe that even few twists are a factor on tension knots in base, so I quickly untwist on each packing. When you find your way,he doesn't even take a minute more and you are relax !

The oldest example I have seen of this type of construction was on a military square built in 1971. The idea is not a new one so I am going to assume the reason it is not more common is simply due to ease of production. It also eliminates the ability of replacing the lower steering lines.
Try it out and see what happens. I doubt tail shape will be the issue, it's a big fucking square. More likely you will have issues finding the correct line length for each splice and run into the tension knot problems that were suffered by some 5th control line set ups.

The off heading rate increased because the tail pocket was bouncing from side to side (and pulling the pack job with it) as each stow popped on alternate sides.

You can create a replaceable lower by finger trapping in a separate piece for the bottom 3 or 4 feet of your control line. Then you only replace that bottom piece, so you don't have to try to rebuild the cascaded upper when you replace the lower.

Squirrel's new brake setting style (with the spectra loop instead of a long continuous piece of dacron) also appears to greatly reduce the frequency of required replacement.

Hi Tom
I was guessing something like that!
Christophe

How furry are we talking here? I have attached and linked the picture of worn Dacron lines from PD's website. Should I consider replacing my lines for fear of tension knots with only slight wear (17%)?


Jumping blackjack only slider off.

http://blog.performancedesigns.com/wp-content/uploads/2015/11/dAC1.jpg

Risers

How furry are we talking here?


Very!

Way worse than 'Heavy' wear in your link:
http://blog.performancedesigns.com/...ads/2015/11/dAC1.jpg

I think that maybe people are focusing on the last 5%, and missing the first 95%.

To reduce the chance you have a tension knot, before worrying about most of the stuff being discussed here, be sure you are dialed in on:

1) Pack neatly
2) Untwist control lines
3) Have a good primary stow
4) Check all your lines (not just the control lines) for twists when you hook up your canopy (or just do it right now if you've never done it before)
5) If your lines look worn enough to worry you, get a reline--it's cheap mental insurance for your presence of mind on the exit point

I see a lot of people skipping basics and running around wanting to create experimental new systems, when just focusing on the basics would fix 90% of the issue.

Be carefull, someone could take it for truth... Each jump as its rule and using 2 rubbers band on the primary stow and very tie on a SD or PCA or static will be dramatic! The primary stow is to prevent an asymetrical deployment of the canopy.

About tension Knots as W_Heisenberg said, never used some chemicals on nylon, never!!!

For me, lines stretched during packing with a good folding in the TP are the best way to eliminate tension knots and more carrefully on light canopy with thin lines. After, as for line over don't be too much paranoiac... if you do your packjob correctly.

Take care

You are right, I should have precise on slider up !

But something else bother me, you said :
as W_Heisenberg said, never used some chemicals on nylon, never!!!

Why should we accept a sentence just like this without any, but any (from you or others) justification, tests, research and exerience, when there is a chance to save live with silicone on line!

YOU and your kids are eating chimical every day, do you think your skin is less fragil than nylon ?
There all millions of chimicals, let's not generalyse, as we said (our association) have a chimiste who certifie that silicon is absolutely neutral and will not agress nylon - but did we really need this information, how many women have breast with silicon?

For the one ready to have their own opinion and ready to not follow the " chimical are dangerous" theory, the silicone who are using is one wich is use on wet suit so directly in contact with the body and have no solvant or allergene.
https://www.gearaid.com/products/silicone-spray

Id also consider that silicone on lines will also need to be reapplied frequently if its really to be of any benefit, will trap a lot more dirt/grime on your lines making them wear faster, and probably stain the canopy/container over time. Also, it is only of theoretical benefit on a problem that is extremely rare in the first place. I think there are much better measures to make a habit before this one.

Thank's for your reply.
We found out that about 10 people at list are using silicone on their line in base in France.
All of them say that the silicone they use is not sticky and doesn't catch dust at all and don't make the canopy dirty at all.
They find out that they have to reaply every 100 jump
It make the line really slippery as they opening is immediately harder (slider going down faster)

dacron is a polyester... (just trolling :-)


first off, if its ok for humans is not a valid argument. theres plenty of stuff you even eat, put on your skin, etc, or stuff that comes out of you, that you shouldnt put on your lines.
talk to the canopy manufacturer what is ok to use on their product, and if they refuse (because they dont want to have the liability), try to locate the manufacturer of the line.

second, im pretty sure that pure silicone isnt doing anything bad to dacron, and im entirely sure it doesnt do anything bad to spectra. (cypres loops anyone?).
the problem is to get your hands on pure silicone, with all the available commercial divers, car cleaning products, etc. you cant be sure what additional stuff is in there, aswell as what contaminants they are getting in there when producing the stuff. (dont forget about the propellent if it comes as a spray can)
so you could go there and buy a bottle of pure approved silicone lube from cypres, the problem here is going to be how to apply it properly, which leads to...

third, it is going to attract and accumulate more dirt than without the silicone. there shouldnt be a discussion about that. its obvious if you got sand stuck on it its bad, but im thinking more about the small-cant-really-see dirt. just look at your yellow cables on your skydive rig, or pull some rag through your housings. that stuff will build up on/moving into your lines.

last, i dont know if that dirt can/will damage your rig, depends mostly on what it actually is. and that can vary a lot i guess, depening on where you jump, store, move your rig around. so you could end up that one guy has perfect record with that method, and that other guy has random broken lines after a low number of jumps.

so if you want to have a lower friction coeffecient for your lines, and were talking slider up here, switch to spectra lines instead.

Silicone is for fake tits and good sex toys. Leave it in the bedroom not on your base rig

I always ensure that my lines have been properly lubed with KY jelly. Plus, if you ever find yourself in a gangbang, you can use the lube at your discretion.

You are correct. I misunderstood Todd during our discussion and hadn't considered brake settings. In retrospect, it's obvious now that I think about line length during packing.

That said, tension knots occur between the same two stated line groups, I just mixed up which lines were longer.

Thank you for correcting me! Much appreciated, and I'm glad we could correct the record. =)

We still want photos and video though! Any footage provided will be studied as we consider the causes and possible solutions.

I always place my slider between the control lines and D lines and then stow it into the indirect control on terminal jumps. We know these two line groups are the most likely to cause a tension knot, we also know that it usually happens above or at the slider, and we also know it happens at the time the lines are being loaded. So in my mind placing the slider between the two line groups helps to keep them separate until the lines are loaded. Remember it is your control lines that push your slider down, so it will remain in place between the two groups until there is enough load to make it move by which time the threat of tension knots should have passed. I feel it also acts as a pseudo tail gate as well.
P.S. I used to do this on all slider up jumps but feel it may have been causing heading issues on subterminal jumps.

Could you post a photo of your pack job with the slider up, showing where you place the lines relative to the slider? Please?

Thanks.

I was originally shown this method as a version of the good old slider gate. Since then I have also come to the conclusion that it keeps the offending tension knot lines separate, at least above the slider any way.

From my time in the tandem world, worn lines are the biggest cause of tension knots. I'd say starting at the 400 jump point is when they start to become an issue.

Line sets are what 300$? I'd be replacing line sets every 300 jumps if I was in the big wall base world, or sooner. At a 1$ a jump it's pretty cheap insurance.

i pack exactly like this, but i do not use a stow on the slider, i just wrap the lines with the excess slider on each side. kinda like a burrito.