Video of tension knot from KL event

[Craig]

This is the video of Brazilian Louis Sabia's (he doesn't object to being named) jump at the KL event where he suffered a tension knot:

http://www.poxon.org/Craig/BASE/movies/Tension_knot.MPG (5.21 MB)

He want's it to be known that he was back up and jumping within 5 minutes on his second rig! I think you'll agree, he did an abosultely outstanding job.

If anyone is interested, this MPG was captured from DV using a Sony DCR-PC330. I was impressed by the quality of it compared to what is produced by similar methods on my old PC110. Also, the length of recording is only limited by the size of the memory stick (upto 1GB). Solid state recording is not far away...

[dexter]

THAT..... was scary. Nice job.


Stay safe out there! ---Dex
dexterbase@hotmail.com

[Small]

His smiling face at the end says everything - I'm alive!!!

Gus

[imported_Mac]

JEZUZ! - Not nice!

Good Skills!

WHOA!

[Yuri]

Yo !

This brings up exciting memories... i had a similar mal a couple of years ago (funny enough, visiting Sabia in Rio). The canopy would either stall or spin, just like on this video. The rate of descent wasn't too bad, but it happened over a busy highway and having unsteerable canopy really sucked. I recall more gnarly tension knot videos - it happens every now and then. Now that lineovers are properly addressed with line release toggles this is a problem we may want to look at.

I now use WLO toggles on all of my slider-up jumps. This will obviously clear steering-line-only problems, and possibly ease up a situation where steering line is entangled with other lines. However when more lines are involved firing WLO may not be enough, so the general question is - what else can we do to? The goal would be to have a steerable canopy, even if severely crippled. Anybody up for brainstorming ? ;-)

bsbd!

Yuri.

[dexter]

Can we have some more details of your jump where you had the tension knot? Also, anyone who's had a tension knot could contribute as many details about their jump as possible. Let's identify the causes then we can more intelligently work on a solution.

Stay safe out there! ---Dex
dexterbase@hotmail.com

[Tree]

While talking with Adam at CR about tail pockets and velcro the tension knot issue came up. A major cause of tension knots is tail pocket dump. If your tail pocket velcro is repositioned after a jump (not cleanly closed, just as you left it), your lines are bursting the pocket open and the lines a just dumping out. I was getting this all the time and the wear on my lines told the tail. To fix this, and prevent the most preventable cause of tension knots, keep your velcro in great shape, and better yet, change the position of the velcro on your tail pocket so that the hook is on the top of the closing flap, and the loop is on the piece of webbing that flips up over the closing flap. This is a much more secure closure to the tail pocket. I did this mod on mine and Yuri's canopies in 30 minutes with my Brother home machine. Easier to close, no exposure of lines to the hook side, and a more secure closure. Nice.

Cya,

Tree :P

[Yuri]

Yo !

Fox V-Tec slider-up, about 5 sec delay, nothing unusual about a pack job. That canopy already had a very secure tail pocket that was still closed after the jump, so line dump is not a likely cause here. Lines were free when i looked at them right after landing, but tension knots tend to disappear once tension is released. Didn't find any line burns on the fabric either. Canopy behaved exactly like Sabia's did on this video, alternating between a spin and a stall and refusing to fly.

The Aussie video of a tension knot spinning into the talles of a large cliff shows the same canopy behavior (stall/spin) once again.

I believe that tension knots will happen once in a while, just like lineovers do - you may at best reduce the probability. Thus it would be nice to see what else can be done if releasing a steering line doesn't clear it.

bsbd!

Yuri.

[dexter]

When you have a tension knot, rear riser input on the opposite side will result in a stall. No rear riser input allows the canopy to spin. So... It seems the only thing you can do is use front riser input on the opposite side. Not really a great option huh?

So the tension knot is held together by your weight on the lines, is that a correct assumption? When tugging repeatedly won't work... what to do?

If you could temporarily unweight the lines it might clear. Maybe?
Is there a way you coud do that without radically stalling or turning the canopy?

Stay safe out there! ---Dex
dexterbase@hotmail.com

[GazK]

I had a similar tension knot mal from a slider down jump on a cliff in France in 1998, A and B lines on the left hand side (as far as I could see at the time) were knotted together, and like in the video, the canopy had a tendency to turn/spin. I was able to use the rear right hand riser to hold off the spin, but this left me on the edge of the stall. Not particularly nice with a hunk of rock behind you. I managed to hold the canopy reasonably straight but with a relatively fast descent rate. As I came towards the talus, I let up the right hand riser to get a little forward speed, although in a turn. This gave me enough to manage a sort of flare between trees onto a 45 deg slope.

I cracked a full face helmet up the side, and got some nasty bruises thru my elbow pads, but walked away thanks to the pads I was wearing.
I now jump with a Dainese safety jacket and full face mountain-biking helmet!

I had done my early skydiving progression on freefall rounds, and I reckon this helped me on a canopy that had virtually no forward speed.

Thanks for starting this thread - up to now I hadn't heard of anyone else having the same problem. I had no Idea what might have caused it, but it may be tail pocket dump. The jump was a long 3 sec slider down.

cya,
Gaz

[base570]

Here's a thought...
what if you were to cut the line with the tension knot? I realize that this would be used if it were the only resort but flying with a broken line is easier than trying to handle a spinning/stalling canopy, isn't it? You would be trading a little performance and structural stability for more of a controllable/landable canopy that will fly more straight. Anyone have any thoughts on this?

Jason
BASE570

PS - hope you cut the right one:P

[john123]

nice jump thanks for posting

[john123]

thanks for posting

[hikeat]

Did the guy in the video use a primary stow?

[wormly81]

Very interesting video! I hope this is the correct place for a few questions regarding tension knots for those who have (unwanted) experience in such occurances. Assuming that linedump is not occuring on a normal basis (i.e. the tailpocket mods talked about earlier are done and there isnt evidence of linedump occuring):

In the video it seems to me that the tension knot is affecting the D and control lines mostly on the outside right side of the parachute. It seems the effect this has on the canopy is that of both rear riser pressure and toggle pressure simultaneously stalling and turning the canopy in that direction. Do you agree with my assesement that the control lines were involved in the tension knot? Knowing there is no universal answer, is there a place where tension knots are more likely to occur? It seems that the same flight characteristics are observed in many of these mals which would indicate to me that we are talking about something that normally occurs on rear lines? Are they found above or below the cascades or are the cascades involved? Has anyone strong feelings about the effect that slider up vs slider down affects the situation? Is there a potential that a tailgate would have a positive effect in controlling the rear lines which, in the small data set I have seen (the two accounts here plus video/analysis of Karina's accident), appear to be the cause?

Sorry for the 1000 questions, I did do a search and was hoping more information was out there.