Basejumper.com - archive

If anybody still doubts
http://www.youtube.com/watch?v=-xMrYA3eWHA

Orbiting PC and you want to delay it to toggs vs risers?
It is right there in the video. same direction as the orbiting PC. Why not just hook your PC up symm?Respect for the link. But do really thinkthat if the jumper doesnt heed advice about symm PC attachtment that they would go for advisement on toggs vs risers? Nice try though.
Take care,
space

I've seen guys here with hundreds of jumps who were teaching their friends, and neither the student nor the mentor even knew what symmetry of attachment was--let alone that it was desirable.

so what do you mean? that it is unimportant? I think not. It should be a sticky in the brain that asymmetrical stuff doesnt behave symetrically. Am i such an asshole that I dont accept that peps that cant figure this out should do the for their own good? It is right there on video time and time again. Why does no one get a clue.. backing away from keyboard now...
Take care,
space

I turn the loop on end of the bridle completely
inside out before I snug the larks-head knot to
make sure the PC is attached as symmtrecial as
is possible . . .

This will not fix an asymmetrically built PC but
it will prevent a good PC from being attached
asymmetrically. Do you guys agree??

I mean that you may be giving the jumper in the video too much credit.

It's entirely possible that no one has ever shown or taught him anything about PC symmetry. And it's also very possible that the people who taught him to jump did not themselves know anything about symmetry either.

I agree with you that it is fundamental knowledge and should be taught before the first jump, but it seems that more and more people are throwing themselves into BASE with less and less knowledge.


Tom, I think that your method is pretty good, but any method will work so long as you verify the symmetry of attachment after connecting the PC to the bridle.

I soooo did not notice that, what an embarrassment We did a lot of PC switching that day, so just got plain careless. Thanks a lot for pointing that out!


We know all about the symmetry issue. A lot of jumps non-stop that day, and we switched PC around on almost every jump, so just like wrote earlier, looks like i stopped paying attention to details

I don't have a lot of experience(240 jumps, 65 objects), but this is not the first time i've noticed that I started to trust my gear way to much and stopped doing all the gear check i did before. That's just dangerous
And I'm glad i realized this now and not in a hospital bed...

Thanks. I am having a major crisis with peeps not listening to me. It means i dont exist hahaha. Not at you specifically.It is flavoring my posts i understand.
take care,
space

I don't agree. But then again I rarely agree with anything you say
I do the same as you described but mainly to keep the larks head looking all pretty and shit. You still need to make sure you have attached your bridle symmetrically though. Doesn't matter how neat your larks head is if your PC is hanging off to the side.

When I play this video on slow-mo it seems to me that the canopy deploys, establishes a heading, and remains more-or-less on that heading. The POV camera seems to indicate that the jumper spun below the canopy to induce the line twists.

I see the orbiting PC, but I don't see how the orbiting PC caused/contributed to the jumper's rotation.

What am I missing?

~ Chris

Most BASE line twists develop from off heading openings. The jumpers body is facing one way and the canopy is facing another, and the jumpers body "slingshots" back around under the canopy as the canopy surges, spinning the jumper up into twists. An orbiting PC can often be the cause of the off heading opening, which in turn is the cause of the line twists. This is more common on slider up openings (because the shallow brakes cause more surge) but happens slider down as well, especially when using shallower brake settings.

I haven't actually watched this video. Is the opening on heading to the jumpers body?

Tom, what you're describing here seems to be exactly what's happening. The canopy does not originally open on-heading. But the heading it establishes is more-or-less maintained.

Thanks!

~ Chris

Seeing something similar.
The canopy opens with ~120-180 off heading, pretty much facing the tower. Grabbing the toggles, the left is unstowed just a smidge before the right. To me (IMO) this causes the canopy change heading, flying away the tower. BUT this caused linetwists.

- As for Orbiting PC:
It lookslke the PC is over the jumper, as the pin pulls/canopy extraction the PC goes over the jumpers heads, then starts a clockwise orbit. Goes Over the shoulder, and then down past his ass. This can cause many problems

Interesting, I saw a 180 opening (pc oscillation) then toggle input to correct opening(during inflatation) then after correction the jumper body absorbs the energy from the correction .

Asymmetrical opening. riser loading.Shall I do a stick man in MSpaint? Not at you directly, but for all.
take care,
space.

No MSPaint masterpiece necessary. But thank you!

While I'm a big proponent of system symmetry, I think we need to highlight something else that exacerbates these situations as well - tiny postures after the pilot chute toss and/or reaching for the risers immediately after pilot chute toss.

Once I toss my pilot chute, I try to get as big and wide as I can, to minimize any tendency to rotate and spin up in the situation Tom described. I make my arms and legs wide. But we see a lot of video showing people tossing the pilot chute and immediately reaching toward the pack try for the risers. And this scares me in several ways:
1. It creates a smaller/narrower posture, which can rotate more easily.
2. If the hands only catch one riser while they're in transit, an asymmetric riser loading is going to occur (increasing chances of off-heading).
3. Hands blindly reaching for risers can dislodge a toggle.

~ Chris

PS Space, I remain interested in your notes/anecdotes about the low bridge over the reflective lagoon in my neck of the woods...

Maybe for you dont need the MS paint. Check out exactly what you posted. A shoulder low dep would equal
If it is so sensitive. the pc is off to side. Would you db or pca this way? No. Crosswinds exactly prove this IMHO. I can promise all that if one jumps with you a pc assym off headings, linetwist would be the norm.
Do the math. one shoulder low vs off to the side. It is tangential. that includes the drag from the pc also..
which bridges :)
take care,
space