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Happened on a slider-up tower jump in Russia:

http://www.skydive.rostov.ru/...97c7a8d7371d48175656

The bridle ended up wrapped around the tailpocked. Jumper landed ok.

bsbd!

Yuri.

Do you have any more details on the jump? Any witnesses? Possible causes?

Thanks.

oooh, that is really, really strange.

How can the bridle wrap around the tailpocket? When the PC is loaded, it's pulling on the canopy attachment point. Until the canopy starts to pressurize, the drag on the PC keeps the bridle too tight to haf-hitch around the tail of the canopy.

The only time I could see the bridle having a chance to do this is after linestretch, as the tail is not pressurized yet.

It would have to occur after linestretch because the lines aren't trapped in between the bridle and the tail.

It seems like a lot of things would have to fall into place just right (or wrong, I suppose) for this to happen.

spooky.

Edit: What type of canopy was this? Is the canopy know to have a backsurge on opening?

Still totally lost...

Quite strange indeed.

Reminds me of a similar incident where my PC flipped back on opening and tangled in my brake lines. Or when Donk landed and found a knot in his bridle, apparently caused by his PC bobbling around after pitching.

Now that I think about it, this mal reminds me of Nathan's daisy chained canopy jump in Moab back in 2000. Unfortunately for Nathan, his tailpocket sealed the daisy chain and he rode 1.5 cells into the soft talus at 60 mph+

Nothing is perfect.....glad everything turned out OK for the Russian.

The difference, at least to me, is that I can find an explanation for the other malfunctions.

This one... boggles my mind completely.

Was there any damage or burns to the tail from either the bridle or lines ?

Thanks.

Ah!! I watched a friend of mine have the exact same thing as this - we could not work out (even after watching the video back many times) why or how this occured. He flew down with his bridle and PC wrapped around his control lines on one side - did you have any thoughts about how this happened?

how about a rapidly whirling pilot chute with a slacked bridle during the end of line stretch?

>>Maybe he had a tail inverson and a wildly osciallting PC that wrapped it up. I dunno. Kinda creepy.

well there is that.................

I guess I look more deeply in "explained" reasons for things than I should sometimes!

Chaos on opening can cause some strange shit.................. but we all like to try and explain why......... (dont we?? )

A few years back I had that EXACT malfunction at Kjerag. Hard opening and probably a tail inversion and a bridle that wipped back and forth, and than back again, at opening. I nearly chopped it away (yes, I was using a reserv ). Lucky for me the wind was strong so I managed to land on the main landingarea without a flare.

On the same load Per Flare (on his 2:nd BASE jump ever) had a nice opening but broke his back on the landing. Strange how things turn out...

/Micke

Hi Yuri

That little mal usually happens on collapsable pilot chute systems (I assume the one you showed is a non collapsable BASE p/c).

During the tail end of the pressurisation sequence, the drag of the canopy becomes greater than the drag of the pilot chute (and it interferes with its air flow and ability to remain pressurised - which is what it is meant to be). The descent rate (& air resistance) of the complete system (p/c, canopy, suspended load) becomes less than the p/c. This means that the p/c & bridle start to descend at a faster rate than the remainder of the system. At this stage you have minimal to no forward speed so the p/c does not inflate fully and "drag" behind the canopy.

For a parallel, large pilot chute do not have handles on them due to the fear that the bridle will wrap around the handle and prevent it from inflating.

If the brake settings on the canopy are deeper and the deployment sequence is not perfectly symmetrical (i.e. you are marginally unbalanced in your harness of there is a slight crosswind component during deployment, or the canopy does not commence pressurisation evenly on each side, etc), the canopy will buck around a bit. It may surge forward a bit, then back, perhaps you will have a bit of sideways momentum as well.

While this is happening, the bridle & p/c is tensioned up, then loosened, then it gets pulled a little to the side, then it wants to accelerate again (remember that an uninflated p/c and bridle will fall faster than an inflated canopy).

This sequence of events is most common on tandem canopies and you will often see a bridle and p/c wrapped around the A lines or brake lines.

Sometimes, when the p/c and bridle fall again, they loop. If you can imagine throwing a rope onto the ground from some height, when it hits the ground, some of it will be coiled up, some will spread out, etc.

The tail pocket is a natural catch point. Its got material that extends above the canopy material.

Now, when the canopy gets to the end of the pressurisation cycle, many of you have already mentioned a possible scenario of tail inversion. The canopy may concertina and surge forward, the tail pocket flicks up and to the front of the canopy. Then it starts to surge back again and the bridle goes slack and forms a loop. Jus at that time the tail pocket (with its catch points) passes near the loop and catches it. The p/c fills with air (pressurises) and locks the loop in.

Hey presto, the tail is locked into a bridle hitch knot.

Anyway, that is what I have seen in the past. What do people think?

How do you prevent it?

- ensure your canopy is set up properly (brake settings, minimal surge on opening, no snappy openings as they will exaggerate the affect of surge and variable pressure during the pressurisation sequence, etc).
- symmetrical deployments.
- ensure your p/c attachment point, bridle, p/c are geometrically symmetrical and that if they are worn or stretched, that they are even (symmetrical).
- etc.

I don't think a rotating pilot chute will cause the problem in itself. It may however, exacerbate the movement of the bridle when it starts its accelerated descent. Note that I am talking about "RELATIVE" acceleration. Not absolute.

p.s I have had a bridle do a full loop around the centre cell of my canopy on a skydive which resulted in a bow tie. The opening was not absurdly funky but it did buck around a bit. It was a collapsable p/c. I remember the canopy surged forward and then back. As it came back I could feel a little relative lift being generated. What happened? As it surged forward the p/c was already collapsed (it wanted to fall faster). The forward surge whipped the bridle and p/c forward. As it started to surge back the p/c kept going forward with the bridle attachment point acting as a pivot. Think of a horseman cracking his whip here! It surged back enough for the the bridle to be stretched but it still had momentum. Because the p/c had momentum but it had a fixed pivot point the only thing it could do was alter its motion from straight ahead to a turning moment. It rotated through the centre A lines as the canopy ended its back surge and started surging forward again. The bridle was now under the bottom skin. The canopy reached an equilibrium or "stabilised" and with a bit of input from me started flying forwards. It is only when the canopy has forward drive that the p/c starts trailing behind again.

Obviously, most (I hope all ) BASE p/c are not collapsable and they will create more drag in full flight and are more likley to lock a knot in.

my $0.02

Thanks Tom, very informative.

*BUMP*

There have been a couple more cases of this "weird mal" recently (maybe we should actually give it a name now?)

Maestro from Mucho BASE had the same mal last month and I heard Mike 915 recently also.

"Tail pocket entanglement" ?

what kind of jump was the Russian jumper doing ? what is the possibility that any of the jumpers experiencing the same Mal. were doing anything similar ?
Similar in object, exit,delay or type of discipline like Tracking or WS ? Similar in type of equipment used ?.
.

I will ask Maestro and Mike to post their accounts, maybe Micke can also? Yuri can you provide any details?

ps. first observation, if you intend to jump slider up and your name begins with M, pack careful..

How does this affect the flight characteristics of the canopy? I would have thought the effect would be minimal, since you're really just choking off a very small part of the canopy's tail.

Michael

 

In the case I witnessed the canopy flight characteristics were severely affected. The tail of the canopy was very distorted, flying almost like a round, little drive, quite fast sink rate and oscillating. Maestro just managed to out fly the talus and PLF on to open ground. If he had pulled any earlier things would have been ugly...

Bit off topic - but talking of weird mal's

Chopped a sigma tandem last week - line dump

Ended up with the main hitting the reserve after it had cleared and then the main risers wraping around the rear right line group and slider.

Worked out ok after some committed problem solving :)

Them skyhook's are quick !!

Pete Mac

Crazy... But I see how that can happen.

Video - main and freebag seperated fine, just got hit by the wreakage!

Luckly in did not turn into a downplane, could reach the main lines and pulled it in before the main inflated fully.

Does break your faith in "do the drills, you'll probably be OK!"

Anyway that's tandems lots of physics.

Pete Mac

Line dump happens all the time, it's not a big deal unless the bag is stripped off the canopy in the process. Actual bag strip happens very seldom. Did the bag get stripped off the canopy? Hard opening? Tension knots? ... Just curious.

based one this picture the only reason i can see this happen is bridle was janked around tail when closeing pin container

It would be very difficult to do that. The distance from the attachment point of the canopy and the closing pin is too short. It looks like the wrap is above the pin anyway.

Try doing that with your rig on purpose and I bet it's not an easy task.

i can hypothisise on how this happened, its just like tension knots in the lines. the trailing edge of the canopy is flailing around a lot being that it has no lines to it, you can see on slider down openings the tail is just dort of floppy, so it flipped up and wraped around the bridal. of course, the pic looks like the bridal wrapped around he canopy. it could have switched when tension was distributed differently. (try it with twisted lines, same thing happens)
Also, as a canopy opens from high speed, it drags a LOT of air with it very fast, and creats an extreme downward flow of air. i think it would be very easy for the PC and bridal to be effected enough in this turbulence to become wrapped in the lines of the canopy or even the tailpocket. keep in mind that as the canopy opens, in the second it takes for the jumper to go from 80 to 20 MPH, the air that the canopy has initialy dragged with it for the first quarter of a second is going close to 80MPH, and as the canopy is slowing down, where does this air go? it does decelerate quickly, but its going in the same direction as the canopy, therefor, PC/bridal tangles.

Just my idea.

If the center C-D lines had an additional cascade attached to the trailing edge of the center cell (where it's free of steering lines), do you think it will subdue the tail inversion and its ill effects (lineovers and weird bridle wraps)? Just thinking.

i believe it would. ir is a good. idea. of course, it would make these cascades become slack while the control lines are being pulled. right?

yeah, they will be tensioned very little in full flight and slack when steering lines are pulled. They can also cascade higher than slider grommets, to avoid thick knot at the cascade. The question is, will they really work? If they cascade too high, they won't prevent unpressurized tail go up. However, they still will reduce the extent to which the tail can go up, by the principle that the triangle's side is shorter than the sum of the two other sides.

its not worth it.

*BUMP*

Just heard about another case in CH Jumper injured but nothing too serious.

i think the point calvin19 was mentioning totally makes sense. the air is moving with the canopy and with the pc. at the moment the canopy opens the canopy obviously is getting slowed down. but the air has momentum and goes on... that causes the pc (which then is getting pulled by the air) to 'fall' on the canopy. (it happens quite sometimes on skydives that the pc is lying on top of the canopy after opening )
i think here the problem is the also the tailpocket itself. if the bridle falls onto the canopy while the tailpocket is just waving up (during opening) it might cause a loop around the tailpocket that can not come off because the canopy is getting 'bigger' torwards its end (caused by the tailpocket). that maybe acts like a hook and keeps the bridle from moving off the canopy when it's getting pressurized.

just some ideas which kinda make sense to me

take air
jojo

hmmm,...i repaired for a friend two times between 5 jumps the centercell around the tailpocket...it was burned and rippend pretty badly....
was wondering how this happend and thought he made some fuckups during packing, but there was nothing obviously wrong.....

now it starts to make sense....

scary....

murphy strikes again....

maybe we should reconsider how tailpockets are build....
take thinner material like ZP and avoid thick velco to give it a better chance to let it slip though the "loop" from the bridle...
or buil it "inside" the canopy...
just a thought...

I think line dump would be worse than these weird mals.

why line dump....?
it s still a tailpocket....only build differend...
function is the same....

Hello James,

Here's mine again:

What do you mean by that?

Remember line dump means nothing if the slider stays up until line stretch.

With a bagged parachute, if the locking stows stay closed, what happens to the rest of the lines has no effect. If the bag is stripped off the parachute, then it's possible to allow the canopy to expand slightly prior to line stretch.

If the slider stays up by use of a primary stow and/or a secondary stow (primary being much more important) dumped lines will make no difference

I assumed you meant make the hole larger and less restricting that the bottom of the tailpocket has to let line in and out.

what about slidergate?

or maybe slider tailgate with addition of CD 3+4 (classic S/D config) in it ? not directly restricting the center cell, but i guess it could induce some tension in it while the canopy begins to expand, avoiding tail fluttering or inversion in the central zone

was anyone using some tail restriction method while experiencing this mal?

Happened to me today, ws jump.

Stalled canopy and cleared it.