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I recently pounded in with a tension knot. The tension knot occurred above the slider between the brake lines and the outter C-D cascade on the right hand side. I could not clear it before slamming into the rocks. I was using direct and indirect control and no sort of red line reefing (slidergater, tailgate, tape, modified direct etc). I cleared the red lines only to the slider (duh!). The canopy is a Fox 260 ish with about 50 jumps. The lines are in great condition. The opening was unsually hard and one side of the tailpocket was busted opened. I had pulled out of a full track. It was not humid and my lines were dry.

A couple of days after my incident another tension knot occured to one of my jumping aquaintances (seen on video). The tension knot occured between the brakes lines and C-D cascade towards the outside of the canopy (i dont remember which side). It was an unusually humid day. The same day another jumper spiraled in with what he believed to be a line over though no witnesses saw any canopy deformation. This is also believed to have been a TK. Humidity was likely a big factor as I noticed my lines being quite sticky when packing that day.

So: long story short. I am simply trying to collect data regarding packing and tension knot occurence. I doubt that I will be able to collect enough information to draw any conclusions from, but hey, at least its a start. Also, I am aware that a grand majority of jumpers do not use any form of red line reefing and that thus more incidents with tension knots will have occured in that group. So If you know someone or are someone that has spiraled in with tension knots, would you please be so kind and list any little tid bit of information regarding the incident that you can remember.

Since every single video of tension knots SU I have seen occur happened between the brake lines being entangled with the outsidish C-D cascade of the same side this seems to suggest a common causal mechanism? I think SU tension knots occur after the tail has begun opening (i.e. after the tail reefing device has done its job) and thus any sort of tailgate etc... is not gonna really help to minimize the occurence of tension knots.

If you have video of a tension knot please post the link. If you do not want the video or your story to be public please send it to me personally. I appreciate everyones input.

p.s I do not believe my tension knot to have occured because of line dump.


Here are some videos I have found so far:
http://vimeo.com/22397324?ab
http://www.youtube.com/watch?v=-7aJHFT3PQ8 (not very clear whats going on)

Threads about incidents:
http://www.basejumper.com/...sion%20knot;#1340139

Did you all learn to pack from the same person? Seems like an odd cluster of tension knots? Sure your not catching lines in the velcro?

I am pretty sure we learned packing from different people. I learned packing as a rigger and from Tom Aiello as well as through watching others. I am pretty certain I didn't catch any lines in the velcro. Even so that would seem unlikely to contribute to tension knots above the slider (maybe line dump?).

Was your primary stow band broken or worn unusually after that jump?

Do you still currently have 20 BASE jumps?
I only ask because knowing the denominator
affects how one would perceive the incident(s).

The only tension knot I have had was on a
tandem SKY jump, never BASE (knocking on
wood), it was old gummy lines and the knot
was up high around the tail near the steering
lines and/or the upper D line on the right side.

I could not clear it, I could get the wing to fly
sorta straight but near a stall if I pulled the
other toggle way down.

Glad you survived the landing!!

I spun in with another one. New OSP with 20 jumps. Brake line, C-D entanglement. I was using a a modified direct control method that acts as a slider gate. The direct control rubber band is stretched around all the red lines and pinched of in two places by the slider. The red lines were cleared before the direct control/slider gate bite and before the indirect control bite. The direct control/slider gate did seem a little loose though. I usually use a small cut in half rubber band for my slider gate/direct control. I was using a large cut in half rubber band on the OSP. Tail pocket velcro is still closed. Pilot chute size was appropriate for the jump. Track was good, deployment uneventful. The canopy started turning almost immediately after inflation. I made sure to check that no lines were caught in the velcro while packing.

Either my slider gate/direct control, released prematurely or this substantiates the idea that this type of tension knot forms after the tail has begun opening and the slider starts descending.

I pumped the brakes to no avail. I did not open my WLO as I was unsure as to whether this would resolve the issue (I know people have managed to clear tension knots this way as well). I hit the ground after about 3 rotations. Whenever I managed to stabilize the turn, the canopy would level out for a second, stall and surge back into the direction of the knot after bleeding of the airspeed garnered in the turn. I planed out too high on the last rotation and ended up stall surging into the ground. I PLFed and walked away mostly unharmed. I impacted a field past the power lines off of high ultimate.

Lessons for me: If you know you can survive the impact with only minor injuries, don't try to solve the problem rather try to keep your wing overhead as best as you can. Feet and knees together and always try to get your legs in front of you. If you have to land the tension knot maybe try to time the rotation so that you can flare out of it. Stabilize the turn as quickly as you can an realize that the canopy is going to start surging again.

Glad you are okay.

Can you post a pic of your modified technique?

Not sure I fully follow your description.

Other than the knot, how do you like your OSP?

I had one slider up on a 2005 285 troll mdv. I've seen a few slider down also on Trolls.

Glad you're okay buddy. I'd also be curious to see some pictures if possible to clarify your description.

How well-established is your hypothesis that a tailgate/tape doesn't change the probability of a tension knot? Is this widely accepted as true?

I have no idea, but I don't use a TG/Tape when jumping slider up. I'd be open to changing that if I can understand how it would help prevent a tension knot.

When you hooked up the lines to the risers, did you check for twists? I don't mean the brake lines. I mean the actual A-D lines as they attach to the hard links.

I'll post a pic when I get around to packing. Seems like a chipped a piece of my L4.

The OSP is a fine canopy. I would like something with an even lower aspect ratio though

Joe - its just a half baked idea of mine

The canopy came on a card from the mfctr. The lines may have a twist or two in them. I didn't check. I doubt that a few twists would have much of an effect. A line has to be pretty twisted up to wind up on itself. I don't buy the twisted brake line argument as the cause for tension knots either.

edit so that timmy is pleased: The line groups are not twisted timmy. I am not that fucking stupid or trusting =)

Give me some time and i will speak about aspect ratio and my ideas about the pros and cons of hi vs low AR. But this is new age flicking. My oldschool opinion is that one needs a high AR for deploying next to an object. i havent found any info to say otherwise. i will search though. This has nothing to do with creating tension knots imho. only for the rpm range is wider for hi AR.
back in amoment after i think. glad you pulled it off.
take care,
space
edited too add a link. here is the link. http://www.basejumper.com/...;;page=unread#unread

You're a professional rigger and admitted to not checking if the line group was twisted hahaha..... I'm sure its fine.

Glad you're alright buddy.


Edit: you said lines, as in, individual lines. Not line groups. The first part of my post is no longer valid.

i cant say precisely if you packed wrong of course. but from your post, it seems you packed your canopy and not the lines slider risers and rig.
some amount of line dump happens on all deployments. but i dont think this was a prob. separate the lines from one group to another. I thought this was common knowledge but i am a bit autistic. if i took a photo of my lines during the ground phase, you would see ab cd e e dc ba in continuity with the risers and the canopy. Milking the lines lines suck when stowing. My so called logic means in line stowage, that one should think about the bight of the lines. inner radius vs outer radius. yoy brake lines should be separated of course and on the outside of the bight and the ab on the inner. line tension between the inner and outer turns are a lot differerent than what is intuitive because of the friction interaction with the closing stow. put the lines to the chord that you want to open first in the inner radius the ones you want to open last in the outer. Slider is 2nd priority.
i hope this helps put things into perspectives. anyone can challenge me on this. i may be wrong but i can still learn and teach.
tc,
space

edit to add something i take for granted. pc calibration. i always make sure on each pack job that my calibratable pc is calibrated. pc are wierd animals geometrically they open from the side on the half from the radius. If you have an orbiter it will of course change line tensions making the risk of tension knots quite high. a pc should have less than 4 rpm in my opinion.
If your instructor did not teach you to calibrate the pc sym. the instructor sux and all you learned from should be questioned.

What size was the canopy?

Putting together a spreadsheet:

https://docs.google.com/..._EzGcQSfM/edit#gid=0

american 280.